Usc2013 General Anesthesia- Principles

Front 1

What are the goals of General Anesthesia?

Back 1

Amnesia
Analgesia
Muscle Relaxatoin
Control of SNS responses.

Front 2

What are the different anesthesia techniques that can be used?

Back 2

General Anesthesia - most commonly understood.
Regional Anesthesia: (blocks at the plexus)
Peripheral Nerve Block - (more distal than regional) safer now with use of ultrasound guidance. Post op pain control for up to 14 hours.
MAC (Monitored Anesthesia Care) - often done on rm air or with NC

Front 3

When talking with the patient preoperatively, what needs to be explained?

Back 3

Patient needs to be informed of the risks vs benefits of general anesthesia and other options.
Describe the procedure and the role of anesthesia.
Describe the possible complications.

Front 4

What is the difference between MAC and sedation/analgesia

Back 4

Monitored Anesthesia Care implies the potential for a deeper level of sedation than that provided by sedation analgesia. It is always administered by an anesthesia provider.
Standards for MAC pre-,peri- and post-op care are the same as general anesthesia.

Front 5

What makes MAC an attractive form of anesthesia?

Back 5

MAC should by less physiologically disturbing and allow for a more rapid recovery than General Anesthesia.

Front 6

What are the determinants of the anesthesia choice

Back 6

Type of surgery/procedure
Patient expectations and provider's ability to meet those expectations. Can we provide total amnesia?
The ability to meet patient expectations and goals of anesthesia safely. Will the patient's physical condition/comorbidities allow us to provide complete amnesia? Can they reasonable expect to "not feel anything"
The ability of the surgeon to perform the procedure under a particular type of anesthesia.
The comfort of the patient - are they still moving?
The side effects a patient can expect from a particular type of anesthesia (for instance, young female GYN pts often experienc post op N/V)
The level of intraoperative and postoperative monitoring required.

Front 7

What is involved for informed consent?

Back 7

Patient has been informed of the anesthesia technique and alternatives, the risks/benefits of the anesthesia procedure(s). The patient agrees to the anesthesia procedure. No coercion has occurred.
Documentation of the IC

Front 8

What should be on the informed consent documentation?

Back 8

ASA Classification Status
The anesthesia techniques discussed.
The explanation of risks/benefits.
Patient agreement to the technique AND to the risks/benefits.

Front 9

What mnemonic can help remember what to set up in the OR?

Back 9

MS MAID

M = Machine: Machine checkout. Correct vaporizer. AMBUBAG available?

S = Suction, do you have working suction? Is the cannister empty?

M = Monitors, do you have all the monitors needed for that type of case? ECG leads, BP cuff, SpO2, etc ready?

A = Airway; do you have blades, handles, oral airways, tongue blades, boojee, LMA or ETT, nasal cannula other airway adjuncts?

I = IV : Do you have an adequte IV in the patient? Will you need more than one IV? IVF; Primarily LR (NS, LR)

D = Drugs :All drugs prepared and ready: induction, antibiotics, etc.

Front 10

What are the types of Induction?

Back 10

Inhalant

Intravenous

Front 11

What is the most commonly used type of induction?

Back 11

Intravenous

Front 12

What type of patient could benefit from Inhalant Induction?

Back 12

Peds patients : use inhalation induction if they do not already have an IV. You can place the IV after they are asleep.

Hard to handle/uncooperative adults

Patient's with a difficult airway

Pt's needing LMA insertion.

Front 13

When does induction end?

Back 13

When the airway device is in and patient has loss of consciousness.

Front 14

What is the sequence of a normal IV induction

Back 14

1) Preoxygenate: either 3 minutes of 100% oxygen at normal tidal volumes OR 8 big Vital Capacity breaths. Pt. can "smoke" the tube if they are claustrophobic.

2) Give the amnesic (mainly propofol or etomidate)

3) Administer the paralytic (if only using LMA, skip this step)

4) Place the airway

Front 15

Why preoxygenate?

Back 15

Increases arterial hemoglobin O2 saturation and buys the patient some extra time before desaturation occurs while intubating. Denitrogenates the airway, which allows more O2 to be absorbed.

Front 16

How can you tell if the patient's facemask is on tightly enough?

Back 16

Fog in mask (same for ett)
EtCO2 detected by machine.

Front 17

What are the induction agents and their induction doses (MG/KG)? See Barash Table 18-2.

Back 17

Thiopental 3-6
Methohexital 1-3
Propofol 1.5-2.5
Midazolam 0.2-0.4
Diazepam 0.3-0.6
Lorazepam 0.03-0.06
Etomidate 0.2-0.3
Ketamin 1-2

Front 18

What types of patients would you use Rapid Sequence Induction on?

Back 18

With RSI: pt is put to sleep as fast as possible and intubated as fast as possible. Done for pts you are worried about aspirating.

Trauma
Pt's with a full stomach.
Pt' with Slow Emptying (Diabetic, IBS, GERD)

(Not used much with peds).

Front 19

What is the sequence of RSI?

Back 19

1) Preoxygentate before any drugs:
--->3 minutes of 100% oxygen at normal tidal volumes OR 8 big Vital Capacity breaths

2) Give patient opioids 1-3 min before intubation (reduces the effects of direct laryngoscopy)

The next steps need to be performed rapidly:

3) Give defasiculating dose of non-depolarizing NMB (10% of normal dose)

4) Give Induction agent/ Amnestic (propofol, etomidate, thopenthal)
----> DO NOT VENTILATE after pushing paralytic for STRICT RSI’s.
---->(For modified RSI’s you can ventilate but must stay under 20 cm of H2O pressure.)

5) Apply cricoid pressure – compresses the esophagus to prevent aspiration.
----->Press DOWN on cricoid cartiledge (just under thyroid cartiledge – the largest prominence of the trachea).

6) Succinylcholine: push right behind the amnestic (so you don’t lose esophageal sphincter tone and risk reflux)

7) Position head: Sniffing position to align the Oral, Pharyngeal, and Laryngeal Axes

8) Direct laryngoscopy

9) Place ETT

10) Confirm placement: bilateral chest rise/ breath sounds, mist in tube, postive ETCO2

11) Remove cricoid pressure...after placement has been confirmed.

12) NGT if needed.

Front 20

Why is Sevoflurane good for people with reactive airway disease?

Back 20

Sevo is not irritating to airways.

Sevo does not decrease spontaneous respirations.
Sevo does not cause a lot of secretions.
Has a sweet smell.

Front 21

Does N2O help with Sevo induction?

Back 21

Not really,

N2O can provide a second gas effect. but not significant during induction with sevo.

Benzodiazepines are better to use with sevo upon induction.

Front 22

What helps with sevofluorane induction?

Back 22

Benzos - can give in preop (usually versed).

Front 23

How can opiods complicate inhalant induction?

Back 23

Opiods can diminish respiratory drive which means less gas inhaled.


Opiod may complicate inhalation induction w/ sevo: opiods can knock out spontaneous respirations...which is the whole point of giving sevo.

Front 24

What is the sequence of inhalant induction?

Back 24

1) Prime the circuit with gas/inhalant.
--->(you want the 1st thing they breathe to be the N2O and sevo mix (so they will fall asleep FAST.)) 70% NO, 30% O2.

2) Apply facemask – DO NOT let go of face mask.
--->Slow inhalation induction or fast inhalation induction depending on how much the kid is freaking out.
--->If your pt is sitting up, you need to have your hand behind their head. When they fall asleep, their head will fall straight back otherwise.

3) Place IV if needed – AFTER they fall asleep. Someone else does this. Because you are holding the face mask. (DO NOT let go to face mask!)

4) Once IV is in: Turn off N2O. Put patient on 100% oxygen and let the pt breathe. Breathing 100% O2 here counts as preoxygenation.

5) Give Induction agent –(Propofol, Etomidate)
6) Muscle relaxant – (SCh, NMB’s)
7) Direct laryngoscopy
8) ETT placment
9) Confirmation of ETT placement

Front 25

When does Maintenance of the patient begin?

Back 25

After induction and placement of the ETT/LMA and patient is ready for surgical procedure.

Front 26

Goals of maintenance?

Back 26

Same as goals of general anesthesia:

AMNESIA
---> (The problem here: Awareness occurs in 20% of patients. Pts with low BP cannot receive much anesthetic gas.)
ANALGESIA
MUSCLE RELAXATION: Provides optimal field for surgeon.
CONTROL OF SNS RESPONSES:
---> This will be increased with sx and intubation.
--->Pain meds can blunt SNS response.

Front 27

What are the types of maintenance commonly used?

Back 27

-Combination/balanced
-Nitrous/Opioid
-TIVA

Front 28

What is TIVA?

Back 28

Total Intravenous Anesthesia

Front 29

What is TIVA comprised of?

Back 29

Continuous infusion or Boluses (The benefit of continuous infusion over boluses is that if you time it right, you can have rapid emergence).

Amnesiacs: Propofol

Opiods

Muscle relaxants

Possible rapid emergence

Front 30

What is a benefit of of TIVA?

Back 30

Possible rapid emergence.

Front 31

What patient can benefit from TIVA?

Back 31

Patients who are at risk of Malignant Hyperthermia (do not give sux)

Front 32

Combination/Balanced maintenance

Back 32

Use of inhalants and IV drugs to maintain patient during surgery/procedure.

Front 33

How do you select which agents/drugs to use?

Back 33

Selection is based on patient's condition and need.

Front 34

Combination Agents

Back 34

Opioids: control SNS response during DL and for analgesia. DO NOT prevent pt. movement. Difficult to titrate and maintain at therapeutic level. Can be given continuous or as boluses.

NMB: provides skeletal muscle relaxation; decreases amount of volative anesthetic needed, does not decrease pt awareness.

Volatile Agents: Sevo/Des/Iso most commonly used. These are high potency and easy to deliver/titrate. They attenuate SNS responses. Cause dose dependent cardiac depression. Most commonly used volatile agent - nitrous oxide.`

Front 35

How is N2O given?

Back 35

In combination with a volative inhalant, an opioid or both.

Front 36

What is N2Os effect dependent on??

Back 36

Partial pressure in the brain.

(Reflects dalton's law of partial pressures. )

Front 37

What is a benefit of using a NMB agent with a volatile inhalantt?

Back 37

Need less volatile inhalant.

Front 38

What is a risk (small) with isofluorane?

Back 38

hepatic dysfunction postoperatively.

Front 39

What are the stages of anesthesia?

Back 39

Stage I: Amnesia
-Begins with induction of anesthesia
-Continues to loss of consciousness
-No change in pain threshold

Stage II: Delirium
-Noxious stimuli can cause uninhibited excitation and potentially injurious response.
-Patient's pupils are DILATED & DIVERGENT.
-Respirations are irreg or patient may hold their breath. (a good way to determine stage II).
-Injuries can occur here because they are delirious.
-Pts more prone to laryngospasm here. May vomit. May have HTN and tachycardia (increased O2 consumption.)
-More problematic on emergence than on induction. (Induction is quick.)

Stage III: Surgical Anesthesia (The Sweet Spot or The Happy Place)
- The target depth you want the patient to be at.
-Patient's pupils are CONSTRICTED & CENTRAL GAZE.
-Painful stimulus response has decreased (Increased pain threshold).
-Extubate either here or in stage I

Stage IV (Overdosage)
-Pt too deep
-Respirations shallow or absent
-pupils DILATED & NONREACTIVE
-May be hypotensive.

Never extubate in Stage II during emergence. Only stage III or stage I.

Front 40

What are the goals of Emergence?

Back 40

An awake and responsive patient.

Full muscle strength with the ability to breathe spontaneously.

Minimize airway obstruction/risk of aspiration.

Controlled hemodynamics (When pt wakes up, their hemodynamics go crazy, inc HR, BP, etc)

Front 41

What happens during emergence?

Back 41

Surgical stimulation diminshes
Depth of anesthesia is reduced
NMB reversed
Patient is spontaneously breathing
Analgesia provided prn.

Want to keep the pt warm here. (Warmer temps allows faster metabolism and elimination of the anesthetics. Faster emergence.) Medicare mandates that body temp at sx be at least 36.5 deg C for them to pay.

Front 42

Why put patient in supine position when emerging?

Back 42

Easiest position to reintubate if patient crumps.

Front 43

What are some issues that can occur during emergence

Back 43

Agitation - may just be irritable. Patient may be hypoxic/hypercarbic. May be in pain.

Delayed awakening - too much narcotic on. too much gas on.

Diffusion hypoxia - run patient on 100% o2 when you take them off N20 to avoid this.

Front 44

What is the last part of the surgery process?

Back 44

Accompaniment of the patient to PACU and followup anesthesia visit.

Front 45

Should patients be placed on supplemental oxygen?

Back 45

Yes - always - when taking them to PACU/unit.

Front 46

When should the postoperative anesthesia visit occur?

Back 46

within 24-48 hours postop.

Front 47

Problems with volatile anesthetics

Back 47

Isoflurane: causes post-op hepatic dysfunction
Desflurane: CO production
Inadequate analgesia post op due to too much volatile agent given during sx (so they couldn’t give pain meds.)

Front 48

Isoflurane can cause post op ________ dysfunction.

Back 48

hepatic

Front 49

What is N2O/ Opiod Anesthesia comprised of?

Back 49

65-70% inspired Nitrous Oxide in O2

Titrate opiods based on HR and BP.

Muscle relaxants with paralytics as needed

Control ventilation

Front 50

What can cause agitation on emergence?

Back 50

Hypoxia/ Hypercarbia can cause
General agitation
Obstructed airway
Full Bladder

Front 51

Things to remember when transporting your patient to the PACU

Back 51

Accompany patient to PACU/ICU

Monitor vitals if needed – tailor your monitoring based on the pt’s condition.

Supplemental oxygen – mandatory in case your pt gets hypoxic on transport

Monitor airway

Lateral position (on side) may prevent aspiration if they vomit.

Emergency medications/airway supplies available if needed

Report

Front 52

What postion do you place your patient in for recovery from anesthesia?

Back 52

Lateral Position. (to prevent aspiration i case they vomit. )

Front 53

The CMS deal with medicaid and medicare dispursements for sx.....what must you document for them to cover the sx?

Back 53

Post-op temp was 36 deg C or warmer.

Pt was wearing a gown warmer during and after sx.

(Being warm help the pt metabolize the anesthetic and recover faster.)

Front 54

For every degree change in pt temperature, the paO2 will change by _____ mmHg in same direction.

Back 54

6 mmHg