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153 Cards in this Set
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- Back
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How many classes of anesthetic risk (determined by the american society of anesthesiologist) are there and what are they? |
6: I-minimal risk II-slight risk III-moderate risk IV-high risk V-Extreme risk/moribund E-Emergency |
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Describe the anesthetic risk associated with a category I patient on the ASA scale |
minimal risk normal, healthy patient ex: OVH, castration |
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Describe the anesthetic risk associated with a category II patient on the ASA scale |
-slight risk -mild systemic distrubances -ex: ruptured cruciate ligament, neonate or geriatric patient |
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Describe the anesthetic risk associated with a category III patient on the ASA scale |
-moderate risk -moderate systemic distrubances or disease with mild clinical signs -ex: anemia, fever, heart murmur, moderate dehydration |
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Describe the anesthetic risk associated with a category IV on the ASA scale |
-high risk -severe systemic disturbances that are life threatening -ex: shock, severe deydration, fever, gastric torsion with arrhthmias |
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Describe the anesthetic risk associated with a category V patient on the ASA scale of anesthetic risk |
-extreme risk/moribund -submitted for surgery in desperation but little chance of survival, patient not expected to live 24 hrs -advanced multiple organ failure, shock, severe trauma |
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Describe the anesthetic risk associated with a category E on the ASA scale of anesthetic risk |
-Emergency -any of the other categories of anesthetic risk presented for immediate surgery |
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what are the main categories of preanesthetic drugs |
-anticholinergics -tranquilizers and sedatives -opioids -neuroleptanalgesics |
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how do anticholinergics exert their effects on the body |
anticholinergics are parasympatholytic drugs that exert their effects by blocking the actions of the parasympathetic neurotransmitter acetylcholine at the muscarinic receptors |
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name some commonly used anticholinergics |
-atropine glycopyrrolate |
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when may anticholinergics be contraindicated |
-in patients with preexisting tachycardia and existing cardiac diseases (may induce tachycardia) -possibly geriatric patients or patients with other conditions (ex: pulmonary edema) who could not handle potential tachycardia -patients with conditions such as ileus or constipation (would further reduce peristalsis) -may cause colic in horses or bloat in ruminants |
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which species would atropine be ineffective in |
-rabbits -because rabbits often have high levels of atropinesterase which breaks down the atropine molecule |
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what are the effects of the anticholinergics |
-reduces salivation but has the tendency to cause thickened mucus secretions (especially in cats and ruminants) -reduces vagal tone -reduces GI activity -may cause ileus in horses -causes mydriasis and bronchial dilation -reduces tear secretions |
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anticholinergics are used for the treatment of? |
sinus bradycardia, heart block, sinoatrial arrest |
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which has a slower onset of action, atropine or glycopyrrolate? and what does that mean? |
-atropine has a higher lipid solubility than glycopyrrolate and therefore is more potent and faster acting -glycopyrrolate has a slower onset of action and less potential for prducing tachycardia or cardiac arrhythmias than atropine and will last longer than atropine |
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what is the reversal agent for atropine |
-physostigmine -signs of atropine toxicity include drowsiness, excitement, potential seizure |
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which anticholinergic would be contraindicated in pregnant animals |
-atropine will cross the placental barrier (And will cross the blood-brain barrier) -glycopyrrolate will NOT cross the blood-brain barrier and will not cross the placental barrier |
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what is a tranquilizer |
a tranquilizer is a drug that calms an anxious patient by reducing anxiety but will not necessarily reduce awareness |
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what is a sedative |
a sedative is a drug that reduces excitement or irritability by causing sleepiness and decreased mental activity |
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what are some examples of tranquilizers and sedatives |
-phenothiazines -benzodiazepines -butyrophenones -alpha-2 agonists |
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what are some examples of phenothiazines |
-acepromazine -chlorpromazine -promazine |
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what is the mechanism of action for phenothiazines and what are they used for |
-the mechanism of action involves the blockade of D2 dopamine receptors in the brain thereby producing sedation and tranquilization -used as atranquilizer to decrease anxiety and awareness to external stimuli |
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what are the effects of phenothiazines |
-antiemetic -antiarrhythmic -antihistamine -exvessively high dosage can cause peripheral vasodilation which can lead to hypotension and/or hypothermia -provides no analgesia but does have a reversal -skeletal msucle relaxation -inhibits platelet aggregation -may produce hematological effects such as decreasing patient's hematocrit -may cause excitement |
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contraindications of phenothiazines |
-seizing/epileptic patients, seizure history, head trauma (lowers seizure threshold) -may cause penile prolapse in stallions, avoid in breeding stallions -may cause splenomegaly, avoid in splenectomies, -avoid in allergy testing because of antihistamine effects -shock, hypovolemia, dehydration, hypothermia, conditions with existing peripheral vasodilation compromise -caution in Boxers with a European bloodline |
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Example benzodiazepines |
diazepam, midazolam, zolazepam, lorazepam |
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benzodiazepines are used for |
-as a tranquilizer agent in pediatric, geriatric, or debilitated aniamsl -not a good tranquilizer agents when used alone in young, healthy animals and may cause excitement |
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mechanism of action of benazodiazepines |
binding to a sepcific site on the y-aminobutryic acid (GABA) receptor in the brain |
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indications and side effects of benzodiazipines |
-provides muscle relaxation (commonly used in conjunction with ketamine) -anticonvulsant (used to treat seizures) -inhalant-sparing properties (reduce inhalant anesthetic requirements) -minimal cardiovascular and respiratory effects (therefore indicated in geriatric, pediatric and other moderate-to-high risk patients) |
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what is the reversal agent for the benzodiazepines |
flumazenil |
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contraindications of benzodiazepines |
-metabolized by liver so avoid in patients with compromised livers (ex: liver disease and porto-systemic shunts) -normal, excitable, healthy animals may not be sedated or tranquilized, may cause excitement in these animals -ataxia and exictement evident in larger animal species and therefore a preanesthetic medication (ex xylazine) is recommended |
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special considerations for diazepam |
-don't give diazepam IM (poor uptake in muscle due to proplyene glycol preservative) -do not store in plastic syringes or IV bags for longer than 24 hrs -protect f3rom light -incompatible with atropine, acepromaxine, barbiturates and opioids (do not mix in the same syringe) |
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what schedule drugs are diazepam and midazolam |
class IV w |
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name some examples of butyrophenones |
azaperone and droperidol |
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which species are butryrophenones most commonly used in |
swine and exotic animal fields |
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examples of alpha-2 agonists |
xylazine, medetomidine, dexmedetomidine, detomidine, romifidine |
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what is the mechanism of action of alpha-2 agonists |
stimulate the alpha-2 adrenoceptors causing a decrease centrally and peripherally of norepinephrine release which produces CNS depression and decreased cateocholamine release |
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alpha-2 agonists have a biphasic effect on blood pressure, what does this mean |
initially there is vasoconstriction and a period of hypertension but eventually the blood pressure will normalize |
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what ar e the indications of alpha 2 agonsits |
-produces calming effects -provides profound sedation -moderate analgesia -muscle relaxation -reduction in the dose of induction an inhalant agents when used as preanesthetic drugs |
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cardiovascular side effects of alpha-2 agonists |
-bradycardia, decreased cardiac output, dysrhythmias (first-, second-, and third-degree heart block) -cause a biphasic effect on blood pressure -profound peripheral vasoconstriction (pale mucous membranes) -avoid in patients with cardiovascular dz or systemic compromise -longer period of hypotension is noted after the initial hypertension due to the decrease in release of norepinephrine |
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non-cardiovascular side effects of alpha-2 agonists |
-dose-dependent respiratory depression -hypothermia -depression in swallowing reflex (caution in patients with laryngeal paralysis) -decreased salivation, gastric secretions and GI motility and may trigger emesis (especially xylazine in small animals) -slight muscle tremors -excitement -diuresis |
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what are the reversal agents for xylazine |
-yohimbine -tolazoline |
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which alpha-2 agonists are commonly used in small animals |
-medetomidine and dexmedetomidine |
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which alpha-2 agonists are commonly used in large animals |
-xylazine -detomidine -romifidine |
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what are the reversal agents for detomidine |
-yohimbine -tolazoline |
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what is the reversal agent for medetomidine |
atipamezole |
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what is the reversal agent for dexmedetomidine |
atipamezole |
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which species are especially sensitive to xylazine and what is done to compensate |
-cattle, sheep, and goats -they are usually given 1/10th the horse dose |
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cattle, sheep, and goats are especially sensitive to which alpha-2 agonists |
xylazine |
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contraindications of alpha-2 agonists |
-cardiovascular disease -respiratory disease -hepatic or renal disease -diabetes -shock conditions -gastric dilation and torsion (dehydration) |
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what can happen in horses or dogs sedated with alpha-2 agonists |
-they may appear very sedate but can still respond to external stimuli by kicking and biting |
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what are some examples of opioids |
-morphine -oxymorphone -hydromorphone -fentanyl -meperidine -methadone -buprenorphine -butorphanol -nalbuphine |
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what is balanced anesthesia |
administering low doses of multiple drugs from different drug classes to achieve hypnosis, amnesia, analgesia, and muscle relaxation |
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what are the 4 phases of balanced anesthesia |
-premedicaiton -induction -maintenance -recovery |
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what is neuroleptanalgesia |
-the combination of an opioid and a sedative/tranquilizer -generally used during the premedicaiton phase of balanced anesthesia -work synergistically to enhance sedation, relieve anxiety, and provide analgesia |
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what are the opioid receptors |
mu, delta, kappa |
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how are opioids classified |
-pure (mu) agonists -mixed agonists-antagonists -pure antagonists |
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examples of pure (mu) agonists |
-morphine -meperidine -hydromorphone -fentanyl |
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what are some examples of opioid mixed agonists-antagonists |
-butorphanol -buprenorphine -pentazocine |
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what are some examples of pure antagonist opioids |
naloxone |
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what is a pure (mu) agonist opioid |
opioids which stimulate all opioid receptors
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what are mixed agonist-antagonist opioids |
opioids which block one type of receptor and stimulate another type of receptor |
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what are pure antagonist opioids |
-opioids which will reverse the effect of pure and mixed agonists with very little clinical effect on their own -reversal occurs because the antagonist has a higher affinity than the opioid at the specific receptor site -it is possible to titrate the antagonist to remove the side effects while maintaing analgesic properties of the opioid |
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what are the clinical effects of opioids |
-analgesia -sedation -dysphoria -euphoria -exitement -bradycardia -panting in dogs -hypothermia -hyperthermia in cats (with hydromorphone) -nausea, vomiting, defecation (esp. with morphine and hydromorphone) -constipation from prolonged GI stasis -mild muscle relaxation -cough suppression -addiction -salivation -miosis (dogs and pigs) and mydriasis (cats and horses) -increased responsiveness to noise -excitement if given rapidly IV |
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contraindications of opioids |
-previous history of exitement -morphine in cases of GI obstruction or diaphragmatic hernia (increased risk of vomiting) |
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contraindications of transdermal fentanyl |
-hypersensitivity to fentanyl or adhesives -suspected or existing intracranial pressure -central hypoventilation -renal or hepatic dysfunction -fever |
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indications of neuroleptanalgesics |
-need for heavier sedation for shorter procedures -cardiac or shock cases |
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contraindications of neuroleptanalgesics |
-patient will become hyperactive to auditory stimulus (need a quiet environment) -respiratory depression (opioid dose dependent) -some patients may pant (temperature regulating center of the brain interprets that the normal body temperature is being elevated because of opioid effect) -opioid may cause defecation, flatulance, vomiting -bradycardia (dose related effected of the opioid) -morphine and meperidine injected IV may cause histamine release -miosis in dogs and mydriasis in cats -excessive salivation -ataxia -excitement |
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How many stages of anesthesia are there |
4 |
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how many planes of anesthesia are there |
4 |
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which stage of anesthesia is divided into how many planes of anesthesia |
stage 3 is subdivded into 4 planes |
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describe stage 1 of anesthesia |
-immediately after administration of injectables -patient is disoriented but not anesthetized -sensations become dull -BP may be elevated -resp rate is generally increased and may be irregular -vomiting, retching, and coughing may occur -pupils are normal in size and begin to dilate when entering stage 2 |
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ideally which stage of anesthesia is bypassed |
ideally a smooth induction goes from stage 1 to stage 3 and quickly bypasses stage 2 |
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describe stage 2 of anesthesia |
-excitement phase -stage of delirium or excitement, loss of consciousness -all reflexes are still present, may be exaggerated -eyes closed, jaw set -animal may struggle and is not anesthetized -excitement and involuntary muscular movement, may appear to struggle -pupils dilated, light reflex still present -resp irregular (panting or holding breath is common) -vomiting may occur |
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describe stage 3 of anesthesia |
-stage of surgical anesthesia -resp is full and regular -pupils begin to constrict -subdivded into 4 planes |
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describe plane 1 of anesthesia |
-light anesthesia -endotracheal intubation can be achieved -eyeball begins to roll, pupil is light resposive, and medial palpebral reflex still present -muscle tone still present -pain reaction still present -resp is half thoracic and half abdominal -BP and HR are normal |
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describe plane 2 of anesthesia |
-medium anesthesia -considered "surgical anesthesia" or the optimal plane for surgical stimulus to occur -resp becomes deep and regular -fixed eyeball, often rotated ventrally; sluggish pupillary response -increase in heart and resp rate is mild in response to surgical pain -peripheral relfexes are absent |
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describe plane 3 of anesthesia |
-deep anesthesia -moderate to severe cardiovascular and pulmonary depression -all reflexes are absent -increased abdominal resp, delayed thoracic inspiratory effort (intercostal paralysis) -resp rate decreases, breaths are no longer deep and regular -eyeballs fixed and usually centrally rotated -pupils begin to dilate -pulse fast and faint -blood pressure decreased, fails to response to surgical pain stimulation |
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describe plane 4 of anesthesia |
-dangerously deep anesthesia -cardiac and respiratory arrest may occur if immediate intervention does not happen -progressive respiratory paralysis -tidal volume decreased -palpebral and corneal reflexes absent -pupils dilated and not light responsive -heart rate decreased, blood pressure significantly low -apnea or jerky inspiration -pale mucous membranes and prolonged CRTs |
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describe stage 4 of anesthesia |
-moribund stage -cardiovascular and respiratory collapse leading to death -resuscitation is needed to save the patient -stage of medullary parlysis -apnea -cardiac arrest |
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indications for injectable anesthetics |
-administration of anesthesia drugs followed by inhalant agents -as anesthetic agents for short, minor procedures (ex suturing, radiographs) -administered by repeated bolus or by infusion such as total intravenous anesthesia (TIVA) -supplement to inhalant agents -can provide long-term sedation (ex: patients in ICU) |
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advantages to injectable anesthetic drugs |
-rapid onset and recovery -simple, require little equipment, -drugs do not irritate airways, minimal adverse effects on cardiovascular and respiratory systems (dose dependent) -provide analgesia and good msucle relxation |
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disadvantages of injectable anesthetic drugs |
-difficulty in catheterization (ex: patient with fibroses in peripheral veins) -IV drugs and therefore may be difficult to maintain if there is no IV catheter in place -some drugs are irritants if given perivascularly -drugs cannot be removed ocne they are injected -cumulative effect of the drugs -risk of airway complications if the patient is not intubated -may cause induction apnea -may cause hypotension -may cause excitement on induction or recovdery |
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examples of barbiturates |
-thiopental -methohexital -pentobarbital -phenobarbital |
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what might be problematic about using methohexital or thiopental as an anesthetic |
neither are currently available in the US |
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which types of animals should thiopental be avoided in |
sight hounds - low body fat will result in prolonged recovery |
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what you consider when dosing thiopental for an obese |
when dosing thiopental for an overweight or obese patient you need to dose based on ideal body weight and not actual body weight because this may lead to an overdose |
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what are some examples dissociatives and what are the dissociatives also known as |
-the dissociatives are also known as cyclohexamines -examples are: ketamine, tiletamine |
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what are some examples of injectable anesthetic agents |
-barbiturates (pentobarbital, thiopental, methohexital) -nonbarbiturate anesthetic drugs (propofol, alfaxalone, etomidate, fentanyl, guaifenesin, chloral hydrate) -dissociative/cyclohexamines (ketamine, phencyclidine, tiletamine) |
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what are some benefits to using thiopental |
-provides a rapid, smooth, excitement free induction provided that a sufficient amount is administered as a bolus prior to titrating the rest to effect |
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what may occur if an inadequate dose of thiopental is given |
-excitement or hypertonus can be seen if an inadequate dose is given to an unsedated or poorly sedated animal |
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what are some effects and contraindications of thiopental |
-may see an increase in heart rate, has a tendency to cause bigeminy at induction -potent respiratory depressant -can cause splenic engorgement, not recommended for splenectomies -causes tissue sloughing and cecrosis if given perivascular |
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what are some special considerations for dosing thiopental |
-it is not recommended to give repeated doses or use as a CRI to maintain anesthesia, it is cumulative within the body and will prolong recovery -highly protein bound so patients with hypoprtoeinemia may exhibit a prolonged duration of effect -lack of body fat can greatly prolong recovery (not recommnded for use in sight hounds) -obese patients may receive an overdose if the dose is based on actual body weight and not ideal body weight |
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what is propofol |
-propfol is a phenol compound -it is a short acting "hypnotic" and alkylphnol derivative -an injectable anesthetic |
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what is the mechanism of action of propfol |
cuases CNS depression by binding to specific GABA receptors in the brain |
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what is the shelf-life of propofol |
-regular propofol should be discarded within 6-8 hrs of opening (some use for up to 24 hrs) -refrigeration does not decrease or prevent bacterial growth -propofol-28 has a 28 day shelf life |
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contraindications of propofol |
-respiratory depression (dose-related): transient apnea has been reported after rapid IV inject, apnea is dependent on how quickly the drug is given and has caused respiratory arrest in some cases -avoid in animals that are hypotensive (ex: blood loss, dehydration) -may see transient excitement and muscle tremors -crosses placental barrier |
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can propofol be given as a CRI or in repeated doses |
-the effects of regular propofol are non-cumulative so it can be given in repeated doses or as a CRI in dogs -it should not be given for more than 3 consecutive days or used as a CRI in cats -propofol-28 should not be used as a CRI in dogs or cats due tot he preservative |
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what is the first choice injectable anesthetic for sight hounds |
propofol |
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what are the uses and side effects of propofol |
-inductions and recovery are smooth and excitement free -more easily and rapidly biotransformed by the liver than barbiturates -minimal cardiovascular effects but may cause tachycardia, bradycardia, transiet arterial and venous dilation, and depression cardiac contractililty -good anticonvulscent -nonirritating with incidental perivascular injection -muscle relaxation -analgesia is poor |
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what is etomidate |
very safe, ultra-short acting, rapidly distributing, noncumulative nonbarbiturate induction agent -imidazole derivative |
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which injectable anesthetic agent would be a good choice for an animal with cardiac disease because of the minimal effect is has on cardiac output, respiratory rate and blood pressure |
etomidate |
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what are some indications and side effects of etomidate |
-causes rapid induction and recovery -has little to no effect on cardiovascular system (no change in heart rate, blood pressure, or myocardial contractility) -causes mild to moderate respiratory depression) -no analgesic properties -rapidly metabolized in the liver -can cause vomiting, diarrhea, nausea, excitement, and apnea on induction and recovery |
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contraindications of etomidate |
-suppresses adrenocortical function for up to 3 hours after administration in dogs (use with caution in patients with endocrine dz especially hypoadrenocorticism) -does cross placental barrier but the effects are minimal because of rapid clearance -can cause hemolysis, phlebitis, or pain after IV injection especially in smaller veins -very expensive compared to other injectable drugs |
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how can etomidate be given |
-can cause myclonus and excitement if used alone at induction so commonly combined with a benzodiazepine to smooth out induction -can be given as repeated bolus or continuous infusion |
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what are some common reflexes used to judge anesthetic depth |
-eye position -eye reflexes (palpebral, corneal, nystagmus) -pupil constriction/dilation -lacrimation -swallowing reflex -laryngeal reflex -pedal reflex -ear flick -whisker reflex |
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with most reflexes: loss of reflexes indicate what in regards to anesthetic depth? a return of a reflex indicates what in regards to anesthetic depth |
-loss of the reflex indicates an increase in anesthetic depth -a return of a reflex indicates arousal from anesthesia |
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how can we monitor the central nervous system while an animal is anesthetized |
-look at a variety of reflexes to help judge anesthetic depth -muscle tone (jaw tone or anal tone) can also be used to judge anesthetic depth |
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Systolic pressure (SAP) is |
produced by the contraction of the ventricles and propels blood through the aorta and major arteries in healthy awake animals the SAP is 100-160 mmHg |
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Diastolic pressure (DAP) is |
the pressure that remains in the vessels when the heart is in its resting phase between contractions -in awake, healthy animals the DAP is 60-100 mmHg |
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Mean pressure (MAP) |
-establishes an adequate perfusion pressure for the vital organs -it is calculated by MAP = DAP + 1/3 (SAP - DAP( -it is NOT an avg. between SAP and DAP -in awake, healthy animals the MAP is 80-120 mmHg |
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under anesthesia, hypotension is a MAP of... |
below 60 mmHg in small animals below 70 mmHg in large animals |
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normal systolic BP for an anesthetized dog |
80-120 mmHg |
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normal systolic BP for an anesthetized cat |
80-150 mmHg |
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normal systolic BP for an anesthetized horse |
100-120 mmHg |
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normal systolic BP for an anesthetized cow |
120-150 mmHg |
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normal diastolic BP for an anesthetized dog |
40-80 mmHg |
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normal diastolic BP for an anesthetized cat |
40-80 mmHg |
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normal diastolic BP for an anesthetized horse |
50-80 mmHg |
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normal diastolic BP for an anesthetized cow |
75-100 mmHg |
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normal mean BP for an anesthetized dog |
60-100 mmHg |
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normal mean BP for an anesthetized cat |
60-100 mmHg |
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normal mean BP for an anesthetized horse |
70-100 mmHg |
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normal BP for an anesthetized cow |
90-120 mmHg |
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what are the techniques used for measuring blood pressure |
-oscillometric -doppler -direct |
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describe the oscillometric technique for measuring BP |
a non-invasive measure of peripheral blood pressure by mechanically inflating a cuff placed around the extremities or tail -gives values for SAP, DAP, MAP |
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describe the doppler method for measuring BP |
-a probe is placed over a peripheral artery and taped in place when an audible sound of the pulsating artery can be heard -an appropriately sized bp cuff is placed proximal to the probe and is attached to a pressure gauge (sphygmomanometer) -the cuff is inflated until the pulse sound stops and then released slowly until the pulse can be heard again |
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which type of arterial blood pressure can be measured using the doppler method |
-only measures the systolic pressure accurately |
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when might the doppler method give an inaccurate blood pressure reading |
has been shown to under estimate the SAP in cats by 10-15 mmHg |
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which type of arterial blood pressure can be measured using the oscillometric method |
-systolic, diastolic, mean |
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when might the oscillometric method give an inaccurate blood pressure reading |
-if you cuff is the wrong size -if the cuff is too wide you will get a false low BP -if the cuff is too narrow you will get a false high BP |
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where are the most common places for placing a doppler probe |
just proximal to the metacarpal or metatarsal pad and the ventral aspect of the tail |
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which method of blood pressure monitoring is the most accurate |
direct |
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describe the direct method of blood pressure monitoring |
a catheter is placed in a peripheral artery and then attachedto an electronic pressure transducer by extension tubing -SAP, DAP, MAP, and a waveform are displayed on a monitor screen |
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which arteries are most commonly catheterized when using the direct method of blood pressure monitoring |
-the dorsal pedal and metacarpal in dogs and cats -the facial, transverse facial, lateral nasal, and metatarsal in horses and ruminants -the auricular artery is also used in cattle and small ruminants |
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what are the drawbacks to using the direct method of blood pressure monitoring |
-invasive technique that requires skill to place catheter in artery -risks associated with procedure including thrombosis and occlusion of blood flow to extremity if catheter is tape too tightly -potential for the patient to bleed out if the extension tubing becomes disconnected from the arterial catheter without notice |
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how do you determine respiratory rate on an anesthetized patient |
-observing the chest excursion is the simplest way -if the patient is covered by surgical drapes observing the movement of the reservoir bag or listening through the esophageal stethoscope are options also |
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normal respirations for an awake dog |
10-20 bpm |
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normal respirations for an awake cat |
15-25 bpm |
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normal respirations for an awake horse |
8-16 bpm |
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normal respirations for an awake cow |
10-16 bpm |
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normal respirations for an anesthetized dog |
8-14 bpm |
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normal respirations for an anesthetized cat |
10-14 bpm |
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normal respirations for an anesthetized horse |
6-10 bpm |
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normal respirations for an anesthetized cow |
6-10 bpm |
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name some types of non-rebreathing systems |
-bain coaxial -jackson rees |
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examples of rebreathing circuits |
circle system
universal F |
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how can rebreathing systems be classified and what does that refer to |
-can be classified as closed or semiclosed -refers to the fresh gas flow rates compared to the metabolic demands of the patient -ex: fresh gas flow rates for a closed system are 6-10 ml/kg/min and flow rates for a semi-closed system are 22-44 ml/kg/min -does not have anything to do with the state of the pop-off valuve |
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rebreathing circuits |
-part or all of exhaled gases, after the extraction of carbon dioxide, flow back to the patient -conserve inhalent, oxygen, heat, and moisture but impart more resistance to ventilation -commonly used on patients over 7 kg |
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what are some of the basic components of all rebreathing circuits |
-y-piece -breathing hoses -one-way valves -fresh gas inlet -pop-off valve -reservoir bag -manometer -air intake valve -absorbent canister |
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what differentiates the circle rebreathing system from the Universal F rebreathing system |
the set up of the breathing hoses |
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what are the fresh gas flow rates for a closed rebreathing system |
6-10 ml/kg/min |
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what are the fresh gas flow rates for a semi-closed rebreathing system |
22-44 ml/kg/min |
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non-rebreathing circuit |
-does not use chemical absorbent for CO2 removal but depends on high fresh gas flow rates to flush the exhaled CO2 from the circuit -commonly used on patients less than 7 kg -resistance to ventilation is minimal but the high fresh gas flow rates contribute to hypothermia and drying of the respiratory tract -also not very economical to operate |
