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243 Cards in this Set
- Front
- Back
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The birth of obstetrical anesthesia is attributed to _____ who describes the use of ______ in 1847 for a cesarean delivery of a stillborn fetus in a woman with a deformed pelvis.
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Simpson, diethyl ether
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In 1850, Queen victoria delivered prince leopold with th aid of ______. The lay public noted this and demanded they be treated equally to those of royalty. Thus the use of ______ became commonplace in vaginal delivery.
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chloroform
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In 1874, Zweifel demonstrated that ____ Was present in appreciable amounts in the neonatal ___ and ____, causing neonatal depression, and it was quickly replaced by other methods.
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chloroform,
blood and CSF |
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In 1902 a german obstetrician started using "twilight sleep" consisting of _____ and ____ to cause analgesia and amnesia. It was used until the 1950's but fell out of favor due to maternal and neonatal effects.
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morphine and scopolomine
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_____ analgesia became popular in the 1970s, and a clearer understanding of pain and pain pathways of labor was investigated.
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epidural
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In 1850, Snow used _______ on Queen Victoria during labor.
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chloroform
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The name of the physician to create "twilight sleep" in 1902?
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VonSteinbuchel
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puerperium
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childbirth and 6 wks postpartum
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Most changes to physiology in the puerperium occur during
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the first trimester
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When do most changes to anatomy of the puerperium occur?
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2nd and 3rd trimesters
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Most changes to he puerperium are ____ and the provider must have a good understanding of these changes and how they affect anesthesia mgmt.
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beneficial
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Pregnancy will _____ HR, SV, and CO.
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increase
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What metabolic change is noted during pregnancy?
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hypermetabolic state
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What are the factors influencing the respiratory system and endotracheal intubation during pregnancy?
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- avg weight gain 25-30 lbs
- breast enlargement - incr vascularity of resp tract mucosa - stuffy nose - edema of orpharynx, nasopharynx, and vocal cords - progesterone - most influential hormonal change |
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Airway edema is most prevalent in...
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preeclampsia
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The #1 cause of death during induction of a pregnant woman is
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can't intubate/can't ventilate
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When FRC exceeds VC, you start...
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collapsing alveoli -- atelectasis!
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What effect does pregnancy have on TLC?
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decr 5%
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What effect does pregnancy have on VC and closing capacity?
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no change
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What effect does pregnancy have on inspiratory capacity?
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incr 5%
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What effect does pregnancy have on expiratory reserve volume, residual volume, and functional residual capacity?
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all decr 20%
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Compensatory changes in chest expansion occur due to _____ causing skeletal and smooth muscle relaxation.
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progesterone
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What is the DO2 gradient and how is it affected by pregnancy?
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- dissolved oxygen concentration, differences between alveolar and dissolved O2
- incr A-a DO2 gradient |
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Progesterone causes a ______ in RR.
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increase
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Airway resistance _______ due to progesterone.
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decreases -- causes bronchiole dilation
but -- due to incr pressure from gravid uterus there can be incr airway resistance |
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During pregnancy, O2 consumption _____.
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increases
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Progesterone acts as a direct _______ to the respiratory center to increase minute ventilation while causing a ___ within the parturient chest wall cage.
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stimulant, muscle relaxation
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The decr in FRC, incr in O2 consumption, and incr in a-A gradient all lower maternal ______, making them more prone to ______. It is important to incr Fi02 because during induction there is a more precipitous drop in ____ after only a short period of apnea.
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oxygen reserve, hypoxia, PaO2
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To compensate for the respiratory changes of pregnancy, the oxyhemoglobin dissociation curve is shifted to the _____.
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left -- hyperventilation noted, reflected on ABG changes
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Minute ventilation is increased by _____ at term due to a ___% incr in TV and ___% incr in RR. This helps to decrease the _____ component.
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50% at term, 40% TV, 15% RR, dead space
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Hyperventilation during pregnancy leads to a modest ____.
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Respiratory alkalosis
decr PaCO2, pH 7.44 |
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Airway resistance changes during pregnancy, resulting in a decrease in ______ compliance, but not ____ compliance.
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chest wall decr
lung compliance stays the same |
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Airway compliance changes result in a barrel-chested appearance comparable to that of a ____ patient.
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COPD
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Oxygen consumption is incr by ____%.
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20%
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The oxyhemoglobin dissociation curve shifts to the _____, causing an incr in the amount of DO2.
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right (Rise in 2,3 DPG, H+, temp)
P50 values incr from 26 to 28 mmHg |
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What effect does pregnancy have on MAC?
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decr MAC by 1/2 to 1/3 as early as 8th wk due to progesterone
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Why do pregnant patients have an incr sensitivity of the neural network, with both peripheral and neuraxial blockades? When is this noted in gestation?
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due to incr levels of circulating progeterone
after 24th wk |
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LA dose is increased by as much as ____ during pregnancy.
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1/3
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Nerve blocks are more largely used during pregnancy because...
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limits anesthesia exposure to the fetus
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What are the changes in blood volume seen during pregnancy?
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- incr 35% -- there is 50% incr in plasma volume and 15% incr in red cell mass --> leads to dilutional anemia of pregnancy and a drop in HCT
- blood loss well-tolerated during delivery (250-500 cc vaginal and 500-1000cc c-section) -5% incr in HCT postpartum due to diuresis - usually transfuse after 1500 mL EBL |
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Why is it difficult to estimate blood loss during delivery?
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- mixture w amniotic fluid
- try to look in cannister before irrigation |
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How is cardiac output affected by pregnancy?
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- incr 30-40% in first trimester, 40-45% during labor, 50-60% in immediate postpartum period
- prone to aortocaval compression |
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Why is the greatest incr in CO during the immediate postpartum period?
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autotransfusion when RNs are massaging the uterus
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Left shift of the oxyhemoglobin dissociation curve is seen more often in _____.
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preeclamptic patients
drop in 2,3 DPG -- baby is in distress |
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Hypoxia and hypercarbia can develop more rapidly in pregnant patients because...
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PaO2 falls 80 mmHg/min faster than in non-pregnant patient!
incr O2 consumption, decr FRC, decr RV, decr CO when supine |
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The most important step prior to inducing a pregnant patient for intubation is...
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preoxygenation with 100% NRB x 5 min (or 4 maximal breaths) to denitrogenate them
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What effect does pregnancy have on IAs?
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faster induction, MAC decr by 25-40%
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What are the effects of maternal hyperventilation?
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- constriction of umbilical and uterine blood vessels --> fetal distress -- epidural will help this
- decr affinity for maternal Hgb for O2 - only a problem w prolonged hyperventilation |
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______ can reverse many of the negative effects of pregnancy on the respiratory system.
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regional analgesia
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While a healthy woman can maintain adequate oxygenation with apnea for a period of ____ minutes, a pregnant woman can only tolerate apnea for a period of ____ minutes.
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7 min healthy
2-3 min prego |
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____ can exacerbate rapid development of maternal hypoxia, and can have a profound impact on the fetus by development of _______.
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hypercarbia, acidemia in fetus
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Pregnant women hyperventilate more after the first trimester and experience periods of dyspnea during the latter months of pregnancy with a resultant ______.
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hypocarbia
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The hypocarbia seen in late pregnancy shifts the oxyhemoglobin dissociation curve to the ____, leading to decr 2,3 DPG, thus...
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left,
unloading O2 to the tisues as a compensatory mechanism |
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Capillary engorgement of the resp tract during pregnancy may result in mother being prone to..
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respiratory infections and laryngitis w nasal congestion and voice change
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Capillary engorgement of respiratory tract is exacerbated by...
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stress, preeclampsia/eclampsia
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A common problem during induction for intubation is...
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upper airway obstruction
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Due to the respiratory edema, O2 should always be administered via...
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humidifed face mask rather than NC!
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If the mom becomes hypotensive, are you treating systole or diastole?
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systole -- important for perfusing fetus, keep sbp > 100
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Blood volume increases by ___%. Plasma volume incr by ___%. Stroke volume incr by ___%. Heart rate incr by ____%. Femerol/uterine venous pressure incr by ____%.
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Blood vol - 35%
Plasma vol - 45% SV- 20% HR - 40% Fem/uterine Venous pres- 30% |
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Total peripheral resistance decr by ___%. MAP decr by ____. SBP decr by _____. DBP decr by _____. There is no change in ____.
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Total peripheral resistance- 15%
MAP -15 SBP -0-15 DBP -10-20 CVP - no change! |
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The 5% drop in HCT postpartum is due to _____.
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diuresis
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Blood transfusion is considered after ____ EBL.
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1500 mL
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The greatest incr in C.O. occurs at...
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40 wks gestation - delivery
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Describe aortocaval syndrome
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- hypotension from gravid uterus weight after 20 wks gestation
- can decr CO by 30% - tell woman not to lie on back |
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What is the management plan for aortocaval syndrome?
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- pre-induction hydration
- Left uterine displacement (or RUD) - ephedrine (better for uteroplacental perfusion) - phenylephrine (better when significant hypotension) |
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Venal Caval Compression
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- distension of epidural venous plexus
- decr LA dose 1/3 after 14 wks |
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LUD
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place hip roll under right hip- 10-15% of pts may not respond if IVC is more anatomically displaced - used RUD
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What are the coag changes during pregnancy?
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- enhanced platelet turnover, clotting and fibrinolysis
- accellerated but compensated intravascular coagulation - incr risk for thromboembolic event (encourage early ambultaion post op, use TEDs) |
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What factor concentrations are incr during pregnancy?
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factors 1, 7, 8, 9, 10, and 12
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What factor concentrations are unchanged during pregnancy?
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factors 2 and 5
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What factor concentrations are decr during pregnancy?
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factor 11
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What 2 coag labs are likely to be shortened 20%?
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PT and PTT
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What CV changes occur secondary to elevation of the diaphragm?
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- apical pulse 4th ICS (usually 5)
- chamber dilation and hypertrophy - flattening T wave in lead 3 - Q waves in lead 3 and AVF from incr flow and hypertrophy/dilation - systolic ejection murmur from regurg flow across tricuspid, grade 1 or 2, common SPLIT S2 |
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______ causes an incr in accidental epidural vein punctures.
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venodilation
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Oxytocin with free H20 leads to
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volume overload
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An incr in Hgb > 14 indicates...
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low volume status, HTN, or diuresis
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The largest incr in CO occurs during _____ postpartum.
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within first hour
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An SBP < 90-95 mmHg suggests...
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a decr in uterine blood flow
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There is a 75% incidence of hypotension when a ____ level is achieved during regional anesthesia. This level is necessary for c-section.
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T4
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Describe GI changes during pregnancy:
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1. stomach displaced up and 45 deg to right
2. displaced intra-abdominal segment of esophagus into thorax, which decr lower esoph sphincter tone --> incr pyrosis (heartburn) 3. delayed gastric emptying from progesterone, incr incidence of full stomach to 100% |
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Obesity during pregnancy is associated with a 2-20 fold incr in mortality, with associated complications such as...
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PIH, IDDM, HTN
need a-line may need insulin gtt w D5W |
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______ causes a decr in GI motility and esophageal sphincter tone.
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progesterone!!!
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Parturients beyond the 18th wk of gestation are more prone to...
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vomiting and regurgitation -- treat as full stomach after 12th wk
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What are the renal changes associated with pregnancy?
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- RBF and GFR incr 60% by term (parallels incr CO and blood vol.)
- incr aldosterone - decr plasma osmolarity (Resetting ADH levels) - normal electrolyte balance (incr reabsorption of solute and water in proportion to incr GFR) |
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What hepatic changes are associated with pregnancy?
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- incr ASP, ALT, and LDH
- incr in Bromosulphalein - decr plasma cholinesterase (longer duration for succ and esters) |
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What are the liver changes seen in HELLP syndrome?
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- high ALT, ASP and LDH
- low bromosulphalein |
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HELLP syndrome can be...
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fatal!
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What neuromuscular changes are seen in pregnancy?
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1. incr endorphins
2. MAC decr 40% 3. sedative effects of progesterone 4. down-reg of SNS 5. hypersensitivity response to catecholamines |
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Whose nerve fibers can be blocked faster? Pregos or non-pregos?
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pregos blocked twice as fast!
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What is the major determinant of O2 and nutrient transport to the fetus?
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uteroplacental blood flow
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There is a direct correlation between uterine ______ and fetal umbilical ______.
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uterine blood flow, fetal umbilical PaO2
venous PaO2 more indicative of what's going on w baby |
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Uteroplacental perfusion originates from
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the uterine and ovarian arteries
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Placental blood flow determines...
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O2
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Describe the rise and fall in uterine blood flow
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incr significantly wks 22-36 (most rapid growth spurt) -- stagnant to 40 wks, then starts shrinking at 40 wks
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Uterine blood flow incr from 50 mL/min pre-pregnancy to ____ mL/min at term. If the uterus ruptures, a woman can bleed to death in ____ minutes!
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700 at term
bleed out in 3-5 min |
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The human placenta is described as
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villous hemochorial -- villi are projections of fetal tissue surrounded by chorion that are exposed to circulating maternal blood
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The maternal blood is carried initially by the uterine and ovarian arteries and the divides into ...
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the spiral arteries in the basal plate of the placenta
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Blood is spurted, under arterial pressure, from the spiral arteries into the
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intervillous space
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What happens when blood passes through the villi?
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exchange of substances between maternal and fetal circulation
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Blood is carried into the placenta by
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2 umbilical arteries that successfully divide into smaller vessels within fetal villi
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How is uterine blood flow calculated?
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UBF = (uterine arterial - uterine venous pressure) /
(uterine vascular resistance) |
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Uterine blood flow will decrease whenever...
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perfusion pressure decreases or uterine vascular resistance increases
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Is the uterine vascular bed autoregulated?
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nope! -- must maintain a constant MAP to maintain perfusion!
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Your first action if you suspect decreased uterine blood flow is...
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position pt onto their side
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Decreased perfusion pressure may be caused by...
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decr uterine arterial pressure or incr uterine venous pressure
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What causes a decr in uterine arterial pressure?
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supine position (aortocaval compression)
hemorrhage/hypovolemia drug-induced hypotension (sympathectomy) |
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What causes an increase in uterine venous pressure?
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venal caval compression
uterine ctx drug induced hypertonus (pitocin, oxytocin, LAs) skeletal muscle hypertonus (eclampsia) |
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What can cause an increase in uterine vascular resistance?
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1. endogenous vasoconstictors (catecholamines w stress, vasopressin w hypovolemia)
2. exogenous vasoconstrictors (epinephrine, vasopressor - more phenylephrine than ephedrine), LAs in high concentrations |
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What are the 5 mechanisms for exchange across the placenta membrane?
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- diffusion
- active transport - bulk flow - pinocytosis - breaks |
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What are the drug factors influencing the rate of diffusion across the placenta?
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- lipid solubility
- degree of ionization (LA toxicity) - molecular weight - concentration gradient - protein binding - metabolism of mother - preeclamptics are super hypermetabolic |
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Drugs cross the placenta and enter via the ____
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umbilical vein
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The umbilical vein goes through the _____ (40-60%) or bypasses via the _______.
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liver, ductus venosus
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What can protect against high drug concentrations?
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hepatic drug uptake
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Hepatic enzyme activity in the fetus is _____ than adults
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less
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Once across the placenta, fetal ____ and ____ affect drug deposition.
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pH and protein binding
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Fetal acidosis can lead to ____ of drugs, such as local anesthetics --> accumulation and toxicity!!
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ion trapping
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How does lipid solubility affect drug transfer?
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lipophilic molecules readily diffuse
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How does the degree of ionization affect drug transfer?
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only non-ionized fraction can diffuse
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How does maternal blood pH affect drug transfer?
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acts by affecting ionization of drug - depends on pKa of drug
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How does protein binding affect drug transfer?
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unbound drug diffuses, acidosis reduces the bound fraction
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How does molecular weight affect drug transfer?
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MW < 600 Da readily diffuse
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How does feto-maternal concentration affect drug transfer?
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F/M ratio dictates how much of drug can cross placental barrier
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Between 2 and 10 wks gestation, decribe the critical periods of susceptability
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CNS --> heart --> extremities --> eyes --> palate --> external genetalia
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All _____ cross the placenta in significant amounts.
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opioids
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What are the considerations of meperidine during pregnancy?
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50% protein bound
maximum maternal-fetal uptake occurs 2-3 hrs after IM injection longer half-life of meperidine and its METABOLITE in fetus than mother thereby placing fetus at incr risk for toxic effects less resp depr than morphine effective in doses 25-100 mg IV takes effect in 5-10 min, IM in 45 min can cause transient beat-beat variability problems neonatal effects most likely if delivery occurs 1-4 hrs after admin |
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What are the considerations for using fentanyl during pregnancy?
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highly lipid soluble and readily crosses placenta but it is highly protein bound (85%)
can give in doses as high as 1 mcg/kg without neonatal depr IV 25-50 mcg, 100 mcg IM onset 2-3 min IV, 10 min IM duration 30-60 min potent resp depressant used as continuous infusion or PCA cumulative effects w large doses over time |
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What are the considerations for using morphine during pregnancy?
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poorly lipid soluble, weakle protein bound, readily crosses placenta
linked to neonatal resp depr and somnolence similar dosing as meperidine w similar FHR variability problems 2-5 mg IV, 10 mg IM onset 5 min IV, 20-40 min IM duration 3-4 hr infrequently used |
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What are the considerations for using IAs during pregnancy?
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high lipid solubility and low molecular weight facilitate rapid transfer; Diffusion hypoxia may occur in neonates exposed to N20 immediately prior to delivery (F/M 0.83)
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Which IA has the highest F/M ratio?
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halothane (0.87)
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What are the considerations for using sodium thiopental during pregnancy?
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- F/M 0.4-1.1
- highly lipid soluble and 75% protein bound - readily crosses placenta |
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What are the considerations for using propofol during pregnancy?
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- F/M 0.65-0.85
- exact pharmacokinetics unknown |
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What are the considerations for using muscle relaxants in pregnancy?
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- highly ionized and poorly lipid soluble
- do not cross placenta |
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What are the considerations for using anticholinergics in pregnancy?
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- placental transfer correlates directly w their ability to cross BBB
- atropine readily crosses - glycopyrrolate is poorly transferred |
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What are the considerations for using benzodiazepines during pregnancy?
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- diazepam readily crosses, is highly ionized, and very lipophilic, F/M 1.0 within minutes following injection and reaches 2.0 within 1 hr
- midazolam: F/M 0.76, but has short half-life |
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Contractions are detected by the pressure-sensitive ______, amplified, and then recorded
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tocodynamoter
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Fetal heart rate is monitored using the _____ transducer, which both emits and receives the reflected _______signal that is then counted and recorded.
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doppler ultrasound, ultrasound
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What constitutes normal, brady and tachy fetal heart rate?
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normal 100-160
tachy > 160 brady <100 |
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Is baseline variability desirable?
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yes- want beat to beat variability
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Early decelerations are often from
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head compression
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Late decelerations occur ________, are ominous, and suggest...
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occur outside of the contraction,
that the baby is not getting enough O2 |
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During pitocin infusion, there is prolonged ______.
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deceleration
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What is the waveform associated with head compression
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uniform with early deceleration
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What is the waveform associated with uteroplacental insufficiency?
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uniform with late deceleration
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What is the waveform associated with umbilical cord compression?
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variable with variable onset
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What are the causes and treatments for bradycardia with late deceleration?
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cause: hypotension, uterine hyperstimulation
treatment: IVFs, ephedrine, change position, decr oxytocin |
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What are the causes an treatments for variable decelerations?
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cause: umbilical cord compression, head compression
treatment: change position, continue pushing if variability is good |
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What are the causes and treatments for late decelerations?
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cause: decr uterine blood flow
treatment: change position, give mother O2 |
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What are the causes and treatments for decrease in variability?
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cause: prolonged asphyxia
treatment: change position, give mom O2 |
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What are the 3 phases of labor?
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latent (up to 8 hrs and 2-4 cm)
active (up to 5 hrs and 4-8 cm) transition (1 hr and 8-10 com) |
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The phase of maximum slope during labor occurs during
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the active phase
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First stage of labor
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- from beginning of regular painful contractions of uterus to full cervical dilation
- 1-10 cm dilation - longest stage (2-20 hrs) - mostly visceral pain, can be treated w opioids (T10-L1 innervation) |
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Second stage of labor
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from full cervical dilation to delivery, most painful (somatic, S2-S4), add LA to get pain under conrol
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Third stage of labor
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from delivery of neonate to delivery of the placenta
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Obstetricians do not like to extend the second stage of labor beyond...
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60 min
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Who has faster labor? Nulliparas or multiparas?
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multiparas -- faster total duration, faster stage progression, faster latent phase, faster dilation rate, faster rate of descent
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What is the milzac and wall pain scale?
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"on a scale from 0-10, how do you rate your pain?"
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This stage of labor consists of uterine contractions and cervical dilation, innervated from T10-L1, and is characterized by visceral pain
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first stage
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This stage of labor involves stretching and compression of pelvic and perineal structures, innervated from S2-S4, and is characterized by somatic pain
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second stage
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This is the stage of labor during which the placenta is expelled
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third stage
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During rapid dilation of the cervix during second stage labor, the pain extends..
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down to the toes
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What are the risk factors for increased pain during childbirth?
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1. occiput posterier presentation- hard back part of head pushing down on nerves causing severe back pain
2. young maternal age 3. history of severe dysmenorrhea 4. incr maternal wt 5. incr fetal wt 6. presence of infant's father (depends on whether he's providing support to parturient) |
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Describe the basic OB patient prep for anesthesia?
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- obtain H/P
- assess NPO status (all full stomachs) - ascertain what analgesics have already been given - Large bore IVs - aspiration prophylaxis - place fetal and maternal monitors |
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What are the non-pharmacological techniques for analgesia during labor?
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hypnosis, TENS (transcutaneous electrical nerve stim), acupuncture, lamaze
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List the parenteral agents that can be used during labor
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1. opioids- morphine, meperidine, fentanyl, sufentanil
2. dissociate agents- ketamine, scopolomine 3. agonist-antagonist agents- nubain, stadol 4. NSAIDs 5. sedatives/anxiolytics-barbiturates, diazepam, midazolam |
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What are the 4 types of pharmacological analgesia for labor?
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parenteral, epidural, spinal, CSE
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What are the considerations for using sufentanil during labor?
|
typically not administered secondary to potency
admin can cause transient fetal bradycardia- avoid! if possible 5-10 mcg IV, 10-20 mcg IM onset 2-10 min duration 3-4 hr potent resp depressant, infusion not used |
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What are the considerations of using nalbuphine HCl during labor?
|
10-20 mg IV/IM
onset 2 min IV, 15 min IM/SC duration 3-4 hrs agonist-antagonist maternal sedation (Good sleeper agent) no disinhibition |
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What amide LAs are commonly used for labor?
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bupivacaine, ropivacaine, lidocaine
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What ester LAs are commonly used for labor?
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chloroprocaine 2-3%, tetracaine, mepivacaine
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What are the requirements of a LA to be used during labor?
|
1. effective and controllable analgesia
2. maternal safety 3. no weaknening of maternal powers 4. no alteration of maternal passages 5. no depr of the passenger (Fetus) |
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Bupivacaine for labor
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- most commonly used concentrations </= 0.5%
- concentrations exceeding 0.5% implicated in toxicity - infusion concentrations 0.0625%-0.125% with or without an opioid - most common formulation 0.125% with 1-2 mcg/cc fentanyl |
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Ropivacaine for labor
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- most commonly used in concentrations of 0.125%- 0.5%
- infusion concentration 0.1-0.25% |
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Sequence of LAST symptoms
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circumoral numbness, lightheaded, tinnitus, visual disturbance, slurred speech, muscle twitching, irrational conversation, unconsciousness, grand mal convulsion, coma, apnea/arrest
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Fentanyl as a neuraxial opioid
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- 50-100 mcg bolus via epidural
- 10-25 mcg intrathecal - over 100 mcg does not help w analgesia but incr side effect profile |
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Morphine sulfate as a neuraxial opioid
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duramorph, astromorph
1.5-3.5 mg bolus via epidural 0.1-0.25 mg intrathecal over 3 mg not helping but incr side effect profile |
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Sufentanil as a neuraxial opioid
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- commonly given 20-30 mcg bolus via epidural
- 5-10 mcg intrathecal - associated w transient fetal bradycardia!! |
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Meperidine as a neuraxial opioid
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commonly given as 50-100 mg bolus epidural
10-20 mg intrathecal also works as a LA but causes almost 100% pts to vomit |
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Mu receptor
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- miosis, analgesia, bradycardia, resp depr
- endogenous: met-enkephalin - exogenous: morphine, fentanyl, sufentanil, meperidine |
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Kappa receptor
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- sedation, no resp depr
- endogenous: dynorphin - exogenous: ethylcyclocine, bremazocine |
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Sigma receptor
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- excitatory symptoms, tachycardia, hypertonia, tachypnea
- exogenous: phencyclidine, meperidine |
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Delta receptor
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- analgesia
- endogenous: leu-enkephalin - exogenous: dezocine |
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Epsilon receptor
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endogenous: beta-endorphin
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What are the absolute contraindications for regional?
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- pt refusal
- hypersensitivity - lack of resuscitative equipment - inability to communicate w patient - incr ICP - ignorance of procedure - hypotension/severe hypovolemia - coagulopathy - localized infection at site of injection |
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What are the relative contraindications for regional?
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- primary herpes
- obstructive cardiac lesions - R or L intracardiac shunts - active CNS disease - PIH - myasthenia gravis |
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Which is more difficult to place an epidural/spinal: during pregnancy or nonpregnant person?
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more difficult during pregnancy - some exaggeration of lordotic lumbar curve
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Pharmacokinetics for chloroprocaine
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conc: 2-3%
dose: 45 mg/segment onset: 5-15 min duration: 30-90 min |
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Pharmacokinetics for lidocaine
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conc: 1-2%
dose: 25 mg/segment onset: 5-15 min duration: 60-120 min |
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Pharmacokinetics for bupivacaine
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conc: 0.0625-0.5
dose: 7 mg/segment onset: 10-20 min duration: 120-140 min |
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Pharmacokinetics for ropivacaine
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conc: 0.125-0.75
dose: 9 mg/segment onset: 10-15 min duration: 120-160 min |
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What are the types of epidural needles used in OB?
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touhy vs sprotte
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What are the 2 types of epidural catheters?
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wire vs stiff
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What are the 2 port options for epidurals?
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single vs multiport
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Potential complications/considerations to be discussed with mother prior to placement of epidural
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possible dural puncture, PDPH, neurological damage, infection, may affect labor pattern
more efficacious in early stages of labor, pain incr during second stage, but better than no epidural -- need to feel pressure so they can push if adequate analgesia not achieved, may need to replace catheter |
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What is the preferred positioning for epidural placement if the patient is obese or edematous?
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sitting
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If a patient is on a pitocin gtt and an epidural needs to be placed...
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put the gtt on hold so pt more comfortable to cooperate
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What are the four actions after consent is obtained for epidural placement?
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1. positioning
2. premedication (anxiolytic, opioid) 3. monitoring (FHR, maternal SP02 and monitoring) 4. pitocin augmentation or hold |
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List what is monitored during epidural in obstetrics
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1. VS of mother
2. FHR 3. contractions 4. level of block 5. level of maternal consciousness/awareness (RN!) 6.oxygenation 7. urine output 8. have resuscitation equipment! |
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Epidural needles are inserted below the level of _____, and the needle is placed approx 3 cm into the ______ ligament. You should use the ______ technique.
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L2, interspinous, loss of resistance
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The addition of fentanyl ____ mcg/mL or sufentanil _____ mcg/mL is useful when lower concentrations of local anesthetic is used.
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fent 1-2 mcg/mL
sufent 0.25-0.5 mcg/mL |
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Continuous lumbar epidural infusing requires...
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1. reliable infusion pump
2. continuous pt observation and monitoring (hourly rounds to assess VS and anesthetic level) 3. repeated adjustment to meet parturient's needs |
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What is the suggested epidural regimen for bupivacaine intermittent injection?
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5-10 mL of 0.125%- 0.25% q90 min or
5-10 mL of 0.125% with 50 mcg fentanyl |
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What is the suggested epidural regimen for bupivacaine continuous infusion?
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0.0625%-0.25% at 8-15 mL/hr
or 0.0625-0.125% with 1-2 mcg/mL fentanyl at 8-15 mL/hr |
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What is the suggested epidural regimen for ropivacaine intermittent injection?
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10-20 mL of 0.2% q90 min
or 5-10 mL of 0.125% with 50 mcg fentanyl |
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What is the suggested epidural regimen for ropivacaine continuous infusion?
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0.2% at 10-20 mL/hr
or 0.125-0.2% with 1-2 mcg/mL fentanyl at 8-15 mL/hr |
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What is the suggested epidural regimen for lidocaine intermittent injection?
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5-10 mL of 0.75-1.5% q 60-90 min
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What is the suggested epidural regimen for lidocaine continuous infusion?
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0.5-1% at 8-15 mL/hr
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What are the advantages of CLE?
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- more constant level of analgesia
- more even level of block - more stable VS - greater safety (less: risk of catheter migration, problems if catheters do migrate, motor block that that seen w repeated boluses; greater convenience) - can use to obtain surgical block if c-section needed |
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The most common method of providing epidural analgesia in labor is...
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combo of opioid and LA
bupivacaine most commonly used LA, used w fentanyl or sufentanil |
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Test doses should only be done through the _________ and never through the _____ unless a single shot epidural is being used.
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always use catheter, never use needle unless single shot
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Research has shown that use of higher concentrations of LA (instead of lower doses in combo w opioids) result in...
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- fetal malpresentation
- need for instrumentation - incr in c-section needed |
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The typical dose for bupivacaine is ____ mg, but can be cut back to ____ mg if opioids are added.
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usual 12 mg, w/ opioids 11.25 mg
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T4 dermatome
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- nipple line
- effect on cardiac accelerators - essential for c-section |
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Potential Complications of epidural analgesia
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- accidental dural puncture
- subdural injection - massive epidural analgesia - VS instability - accidental intravascular injection |
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Potential problems with epidural analgesia
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- assymetrical sensory block
- diminishing analgesia (#1 cause is bc epidural fell out or is in wrong place!) - dense motor block - patchy block - migration of catheter - LA toxicity - hypotension - maternal or fetal compromise |
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How is an assymetrical sensory block treated?
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catheter migration- may have gone to one side and need to be pulled back
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How is diminishing analgesia treated?
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catheter may be subdural, usually due to dislodgement
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How is a patchy block treated?
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catheter may be subdural, usually due to partial dislodgement
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How is a dense motor block treated?
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- block may be subarachnoid - catheter may have migrated into a spinal anesthetic
- may need to change concentration of drug |
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What effects does an epidural block have on labor?
|
- slower progression
- cessation of labor - hypotension - fetal hypoxia/asphyxia - somnolence - hypoxemia - N/V |
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What are the properties of intrathecal opioids?
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- analgesia without motor or sympathetic blockade (except meperidine - has LA properties)
- rapid onset < 2 min after fentanyl or sufentanil injection - effective analgesia post-c-section - cost effective |
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What are the common side effect associated with intrathecal opioids?
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- pruritis (#1, esp w morphine and fentanyl)
- N/V - urinary retention - resp depression |
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Since intrathecal opioids are not efficacious for 2nd stage of labor or episiotomy repair, you must use...
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- pudendal block
- biphasic modality: morphine is h20 soluble, placed into a water space it will stay in this area, works within 45 min on spinal roots and nocioceptors in spinal cord, over time morphine tends to spread out (12-16 hrs) to lower part of brain, where resp center is, can last 24 hrs! |
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This technique is viewed as the most significant advancement in OB anesthesia in the last decade.
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CSE technique
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_____ are very effective in controlling 1st stage labor pain, and less effective for 2nd stage labor pain.
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intrathecal opioids
can give fentanyl 10-25 mcg or sufentanil 5-7.5 mcg, with or without morphine 0.1-0.25 mg and/or bupivaaine 2.5 mg |
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CSE is usually performed through ______ Technique.
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needle-through-needle
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2.5-3 mg of bupivacaine combined with 12.5-25 mcg of fentanyl provides ____ hours of analgesia (Depending on the stage, but is not effective in _____.
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2-3 hrs, second stage
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12.5-25 mcg fentanyl with 0.1-0.25 mg of morphine provides ____ hours of analgesia (Depending on the stage) and is not effective in the _____ stage.
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2-3 hrs, second stage
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Before epidural loading dose is given, you must perform _____.
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the test dose (mixed w 1:200,000 epi and watch VS)
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______ is better for first stage labor pain and _____ is more effective for second stage labor pain.
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opioids, LAs
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What is the traditional method of using CSE in combination with an epidural infusion?
|
- bolus before infusion: 0.125-0.25% bupivacaine w or w/o 50-100 mcg fentanyl
or 0.2% ropivacaine w or w/o 50-100 mcg fentanyl - CLE infusion: 0.1-0.125% bupivacaine w or w/o 1-2 mcg/mL fentanyl at 8-15 mL/hr or 0.125-0.2% ropivacaine with or without 1-2 mcg/mL of fentanyl at 8-15 mL/hr |
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Research indicates that when CSE technique is used, the bolus preceding the infusion results in...
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decreased overall analgesic requirements and greater hemodynamic stability
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Patient controlled epidural analgesia (PCEA)
|
- gaining popularity
- often admin immediately following placement of intrathecal opioids w small basal rates and set max hourly dose |
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|
What are the advantages of PCEA?
|
- less variability in peak plasma concentration of drug
- faster onset of analgesia - titratable - greater pain control and satisfaction scores noted compared to traditional infusion rates |
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What is the max hourly dose of bupivacaine 0.125% for PCEA?
|
16 mL
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What is the max hourly dose of bupivacaine 0.125% + fentanyl 2 mcg/mL for PCEA?
|
24 mL
|
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What is the max hourly dose of bupivacaine 0.25% for PCEA?
|
24 mL
|
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|
What is the max hourly dose for bupivacaine 0.1% + fentanyl 2 mcg/mL for PCEA?
|
30 mL
|
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|
What is the max hourly dose for ropivacaine 0.125% for PCEA?
|
30 mL
|
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|
What is the max hourly dose for ropivacaine 0.125% + fentanyl 2 mcg/mL for PCEA?
|
24 mL
|
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Which results in greater pt satisfaction? PCEA or continuous infusion?
|
PCEA
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Caudal block
|
difficult to place on an adult
|
|
|
paracervical block
|
done by obstetrician, inside vagina, ONLY blocks T10-L1, only good for first stage of labor
|
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Pudendal block
|
done by obstetrician, S1-S5 block, effective during second stage of labor
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