AIO Anesthesia Toronto Notes 2023

• accidental extubation

• insufficient cuff inflation or cuff laceration: results in leaking and aspiration

• laryngospasm (see Extubation, A20, for definition)

• bronchospasm

• accidental extubation

Difficult Airway

• difficulties with bag-mask ventilation,supraglottic airway, laryngoscopy, passage ofETT through the

cords, infraglottic airway, or surgical airway

• algorithms exist for difficult airways (Can I Anesth 2013;60:1119- 1138),see .\ppcndkcs. A30

• preoperative assessment (history of previous difficult airway,airway examination) and preoxygenation are important preventative measures

• if difficult airway expected, consider:

• awake intubation

intubating with bronchoscope, fiberoptic laryngoscope, video laryngoscope, etc.

• if intubation unsuccessful after induction:

1 . CALL FOR HELP

2. ventilate with 100% O’ via bag and mask

3. consider returning to spontaneous ventilation and/or waking patient

• if bag and mask ventilation inadequate:

1 . CALL FOR HELP

2. attempt ventilation with oral airway

3. consider/attempt LMA

4. emergency invasive airway access(e.g.surgical or percutaneous airway, jet ventilation, and

retrograde intubation)

If you encounter difficulty with tracheal

intubation, oxygenation is more

important than intubation

Oxygen Therapy

• in general, the goal of O’therapy is to maintain arterial 02 saturation (SaO’

) >90%

• small decrease in saturation below SaO’of 90% corresponds to a large drop in PaO’

• in intubated patients, O’is delivered via the ETT

• in patients not intubated,there are many O:delivery systems available; the choice depends on O’

requirements (F

'

iO’

) and the degree to which precise control ofdelivery is needed

• cyanosis can be detected at Sa02 <85%,frank cyanosis at Sa02 - 67%

100 -1

90 Tp H -

12,3-BPG

iTemp 80 -

70 -

--

60 - 12,3-BPG

fTemp 50 -

3«- Low Flow Systems oo

• provide O’

at flows between 0-10 L/min

• acceptable iftidal volume 300-700 mL, respiratory'rate (RR) <25 breaths/min, consistent ventilation

pattern

• dilution of 02 with room air results in a decrease in Fi02

• an increase in minute ventilation (tidal volume x RR) results in a decrease in ROi

• e.g. nasal cannula (prongs)

well tolerated if flow rates <5-6 L/min;drying of nasal mucosa at higher flows

nasopharynx acts as an anatomic reservoir that collects O2

delivered O 2 concentration (FiOa) can be estimated by adding 4% for every additional litre of O’

delivered

provides FiO’

of 24-44% at 02 flow rates of 1-6 L/min

33 - 3

20 .

10 -

-

j

0

) 1(f 20504,

05lS 60

,

70 d096 lOb ' '

PaO?

Figure8. Hb02saturation curve

Reservoir Systems Composition of Air

• use a volume reservoir to accumulate 02 during exhalation, thus increasing the amount of ()2 available 78.1% nitrogen

for the next breath 20.9% oxygen

0.9% argon

0.04% carbon dioxide • simple face mask

• covers patient’

s nose and mouth and provides an additional reservoir beyond nasopharynx

• fed by small bore O2 tubing at a rate of at least 6 L/min to ensure that exhaled CO:is flushed

through the exhalation ports and not rebreathed

• provides F

'

iO’of 55% at O2 flow rates of 10 L/min

• non-rebreather mask

a reservoir bag and a series of one-way valves prevent expired gases from re-entering the bag

during the exhalation phase, the bag accumulates with 02

provides FiO’of 80% at O2 flow rates of 10-15 L/min

n

High Flow Systems

• generate flows of up to 50-60 L/min

• meet/exceed patient’

s inspiratory flow requirement

• deliver consistent and predictable concentration ofO2

• Venturi mask

delivers specific F

'

iOi by varying the size of air entrapment

» O’ concentration determined by mask'

s port and NOT the wall flow rate

enables control of gas humidity

• Fi02 rangesfrom 24-50%

+

AL GRAWANY

All Anesthesia TorontoNotes 2023

Ventilation

• ventilation is maintained with PPV in patients given muscle relaxants

• assisted or controlled ventilation can also be used to assist spontaneous respirations in patients not

given muscle relaxants as an artificial means of supporting ventilation and oxygenation

Mechanical Ventilation

• indications for mechanical ventilation

Tracheostomy

Tracheostomy should be considered in

patients who require ventilator support

(or extended periods ol time. Shown

to improve patient comfort and give

patients a better ability to participate in

rehabilitation activities

apnea

• hypoventilation/acute respiratory acidosis

intraoperative positioninglimitingrespiratory excursion (e.g. prone,Trendelenburg)

required hyperventilation (to lower 1CP)

• deliver PEEP

• increased intrathoracic pressure (e.g. laparoscopic procedure)

• complications of mechanical ventilation

airway complications

a tracheal stenosis,laryngeal edema

• alveolar complications

a ventilator-induced lung injury (barotrauma, volutrauma, atelcctatrauma), ventilatorassociated pneumonia (nosocomial pneumonia), inflammation, auto-PEEP, patient-ventilator

asynchrony

cardiovascular complications

» reduced venous return (secondary to increased intrathoracic pressure),reduced cardiac

output,hypotension

• neuromuscular complications

a muscle atrophy

a increased ICP

• metabolic complications

a decreased CO’due to hyperventilation

a alkalemia with overcorrection ofchronic hypercarbia

Changes in peak pressures in ACV

and tidal volumes in PCV may reflect

changes in lung compliance and/or

airway resistance- patient may be

getting better or worse

Positive End Expiratory Pressure

(PEEP)

• Positive pressure applied at the

end of ventilation that helps to

keep alveoli open,decreasing V/O

mismatch

. Used with all invasive modes of

Ventilator Strategies ventilation

• mode and settings are determined based on patient factors (e.g.idealbody weight, compliance,

resistance) and underlyingreason for mechanical ventilation

• hypoxemic respiratory'failure:ventilator provides supplemental 02,recruits atelectatic lung segments,

helps improve V/Q mismatch,and decreases intrapulmonary shunt

• hypercapnic respiratory failure:ventilator augments alveolar ventilation;may decrease the work of

breathing, allowingrespiratory muscles to rest

Monitoring Ventilatory Therapy

Pulse oximetry.ETCO2 concentration

Regular arterial blood gases

Assess tolerance regularly

Modes of Ventilation

• assist-control ventilation (ACV) or volume control (VC)

everybreath is delivered with a pre-set tidal volume and rate or minute ventilation

extra controlled breaths may be triggeredby patient effort;ifno effort is detected within a

specified amount oftime the ventilator will initiate the breath

• pressure control ventilation (PCV)

a minimum frequency is set and patient may trigger additionalbreaths above the ventilator

allbreaths delivered at a pre-set constant inspiratory pressure

in traditional PCV, tidal volume is not guaranteed, thus changes in compliance and resistance

affect tidal volume

• synchronous intermittent mandatory ventilation (SIMV)

ventilator provides controlled breaths (either at a set volume or pressure depending on whether in

VC or PCV,respectively)

patient can breathe spontaneously (these breaths may be pressure supported) between controlled

breaths

• pressure support ventilation (PSV)

• patient initiates all breaths and the ventilator supports each breath with a pre-set inspiratory

pressure

• useful for weaning off ventilator

• high-frequency oscillatory ventilation (HEOV)

» high breathing rate (up to 900 breaths/min in an adult), very low tidal volumes

used commonly in neonatal and paediatric respiratory failure

• occasionally used in adults when conventional mechanical ventilation Is falling

• non-invasive positive pressure ventilation (NPPV)

• achieved without intubation by using a nasal or face mask

• Bi-level positive airway pressure (BiPAP): increased pressure (like PSV ) on inspiration and lower

constant pressure on expiration (i.e. PEEP)

• CPAP:delivers constant pressure on both inspiration and expiration

Patients who develop a pneumothorax

while on mechanical ventilation require

a chest tube

Causes of Intraoperative Hypoxemia

Inadequate Oxygen Supply

eg. breathing system disconnection,

obstructed or matpositioned ETT, leaks in

the anesthetic machine,loss of oxygen

supply

Hypoventilation

Ventilation-Perfusion Inequalities

e.g. atelectasis,pneumonia, pulmonary

edema,pneumothorax

Reduction in Oxygen Carrying Capacity

e.g. anemia, carbon monoxide

poisoning, methemoglobinemia.

hemoglobinopathy

leftward Shift of the HemoglobinOxygen Saturation Curve

e.g. hypothermia, decreased 2,3-BPG,

alkalosis,hypocarbia. carbon monoxide

poisoning

Right-to-left Cardiac Shunt

LJ

+

A12 Anesthesia Toronto Notes 2023

Table 3. Causes of Abnormal End Tidal CO2 Levels

Hypocapnea (Decreased CO2) Hypercapnea (Increased CO2)

Reservoir

Hyperventilation

Hypothermia (decreased metabolic rate)

Decreased pulmonary blood flow (decreased cardiac output)

Technical issues

Incorrect placemenl ol sampling catheter

Inadequate sampling volume

Hypoventilation

Malignant hyperthermia, other hypermetabolic states

Improved pulmonary blood flow after resuscitation or hypotension

Technical issues

Water in capnogtaphy device

Anesthetic breathing circuit error

Inadequate fresh gasflow

Rebreathing

Exhausted soda lime

Faulty circuit absorber valves

Low bicarbonate

Fresh

gas inlet

VCarbon J dioxide

! absorber

Uni

- direcbonal '

valves

limb Inspiratory>'

Q*j X^

Expiratory

lb V/0 mismatch

Pulmonary thromboembolism

Incipient pulmonary edema

Air embolism Y piece

n

Intraoperative Management <55 -

2

/

lj

Temperature Figure 9. The anesthesia circuit

Causes of Hypothermia (<36.0°C)

• intraoperative temperature losses are common (e.g.90% of intraoperative heat loss istranscutaneous),

due to:

OK environment (e.g. cold room, IV fluids, instruments)

• open wound

• prevent with forced air warming blankets/warm-water blankets, heated humidification of inspired

gases, warmed IV fluid, and increased OK temperature

Causes of Hyperthermia (>37.5-38.3°C)

• drugs(e.g. atropine)

• blood transfusion reaction

• infection/sepsis

• medical disorder (e.g. thyrotoxicosis)

• hypermetabolic states(e.g.malignant hyperthermia, neuroleptic malignantsyndrome,

pheochromocytoma)

• over

-zealous warming efforts

Impact of Hypothermia (<36°C)

• Increased risk of wound infections

due to impaired immune function

- Increases the period of

hospitalization by delaying healing

• Reduces platelet function and Impairs

activation of coagulation cascade,

increasing blood loss and transfusion

requirements

• Triples the incidence of VT and

morbid cardiac events

. Decreases the metabolism of

anesthetic agents,prolonging

postoperative recovery

Sec landmark Anesthesiology Trillstable for nort

nlornuboa on results from study of Wound Infection

a nd Temperature,which detailsthe impactof

mxmotbennia on wound healing and length of stay

asseen in 200 patieimaged 18-80 yr who underwent

electhee colorectalsurgery.

Heart Rate

Cardiac Arrest

• pulseless arrest occurs due to 4 cardiac rhythms divided into shockable and non-shockable rhythms

shockable:ventricular fibrillation (VF) and ventricular tachycardia (pVT)

non-shockable:asystole and pulseless electrical activity (PEA)

• for VF/pVT, key to survival is good early CPK and defibrillation

• for asystole/ PEA, key to survival is good early CPK and exclusion of all reversible causes

• reversible causes of PEA arrest (5 Hs and 5 Ts)

5 Hs: hypothermia, hypovolemia, hypoxia, hydrogen ions (acidosis), hypo/hyperkalemia

• 5 Ts: tamponade (cardiac), thrombosis(pulmonary), thrombosis (coronary), tension

pneumothorax, toxins (overdose/poisoning)

when a patientsustains a cardiac arrest during anesthesia, it is important to remember that there

are other causes on top of the Hs and Ts to consider (e.g.local anesthetic systemic toxicity (LAST),

excessive anesthetic dosing, etc.)

• for management of cardiac arrest,see Appendices, A30

Intraoperative Tachycardia

• tachycardia - HK >100 bpni;divided into sinus tachycardia ( HK = 100-150 bpm) or supraventricular

tachycardia (SVT)

• SVT: can be further divided into narrow complex or wide complex tachycardia

narrow complex:atrial fibrillation/flutter, accessory pathway mediated tachycardia, paroxysmal

atrial tachycardia

• wide complex:VT,SVT with aberrant conduction

• causes ofsinus tachycardia

shock/hypovolemia/blood loss

anxiety/pain/light anesthesia

full bladder

anemia

+

A13 Anesthesia Toronto Notes 2023

febrile illness/sepsis

drugs (e.g.atropine, cocaine, dopamine, epinephrine, ephedrine, isoflurane, isoproterenol,

pancuronium) and withdrawal

hyper- metabolic states:malignant hyperthermia, neuroleptic malignant syndrome,

pheochromocytoma, thyrotoxicosis,serotonin syndrome

•for management of tachycardia,see Appendices, A30

Intraoperative Bradycardia

•bradycardia - HR <50 bpm; most concerning are 2nd degree (Mobitz type 11) and 3rd degree heart

block, which can both degenerate into asystole

•causes of sinus bradycardia

• increased parasympathetic tone vs. decreased sympathetic tone

• must rule out hypoxemia

• arrhythmias (see Cardiology and Cardiac Surtterv. C19)

• baroreceptor reflex due to increased ICE or increased BP

• vagal reflex (oculocardiac reflex, carotid sinus reflex, airway manipulation)

• drugs (e.g. opioids,edrophonium, neostigmine, halothane, digoxin, p-blockers)

high spinal/epidural anesthesia

• hypothermia and hypothyroidism

•for management of bradycardia,see Appendices, A30

Intraoperative

m

Shock Box

SHOCKED

Sepsis or Spinal shock

Hypovolemic/Hemorrhagic

Obstructive

Cardiogenic

anaphylactiK

Endocrine'other (e.g. Addison'

s disease,

hyperthyroidism, transfusion reaction)

Drugs

BP

a- CO x SVR. where CO - SV x HR

SV is a function of preload, afterload,

and contractility

Blood Pressure

Causes of Intraoperative Hypotension/Shock

• shock:inability of cardiovascular system to maintain adequate end-organ perfusion and delivery of

02 to tissues

a)septic shock

see Infectious Diseases,1D20

b)spinal/neurogenic shock

decreased sympathetic tone

hypotension without tachycardia or peripheral vasoconstriction (warm skin)

c) hypovolemic/hemorrhagic shock

most common form of shock, due to decrease in intravascular volume

d) obstructive shock

obstruction of blood into or out of the heart

increased J VP, distended neck veins, increased SVR,insufficient CO

e.g. tension pneumothorax, cardiac tamponade, pulmonary embolism (and other emboli-i.e.

fat, air)

e) cardiogenic shock

inability of the heart to pump an adequate volume of blood

increased|VP, distended neck veins, increased SVR, decreased CO

e.g. myocardial dysfunction, dysrhythmias, ischemia/infarct, cardiomyopathy, acute valvular

dysfunction

f) anaphylactic( K)shock

see Emergency Medicine. PR29

g) endocrine/other

transfusion reaction, Addisonian crisis, thyrotoxicosis, hypothyroid, aortocaval syndrome

see Hematology and Endocrinology

h) drugs

vasodilators, high spinal anesthetic interfering with sympathetic outflow

Causes of Intraoperative Hypertension

• inadequate anesthesia causing pain and anxiety

• pre-existing H I N, coarctation,or preeclampsia

• hypoxemia/hypercarbia

• hypervolemia

• increased intracranial pressure

• full bladder

• drugs (e.g.ephedrine, epinephrine,cocaine, phenylephrine, ketamine) and withdrawal

• allergic/anaphylactic reaction

• hypermetabolic states:malignant hyperthermia,neuroleptic malignantsyndrome,serotonin

syndrome,thyroid storm,pheochromocytoma (see Endocrinology,E29, E40)

n

LJ

Fluid Balance and Resuscitation

• total requirement = maintenance + deficit + ongoing loss

• in surgical settings, thisformula must take into account multiple factors including preoperative

fasting/decreased fluid intake, increased losses during or before surgery, and fluids given with blood

products and medications

• increasingly, Enhanced Recover)'After Surgery protocols recommend consumption of clear fluids up

to 2 h prior to surgery

+

A14 Anesthesia TorontoNotes 2023

•both inadequate fluid resuscitation AND excessive fluid administration increase morbidity

postoperativelv

Maintenance Fluid

•average healthy adult requires approximately 2500 mL water/d

200 mL/dGl losses

800 mL/d insensible losses (respiration, perspiration)

1500 mL/d urine (beware of renal failure)

• maintenance should not exceed 3 mL/kg/h

•increased requirements with fever,sweating, Cil losses (vomiting, diarrhea, NG suction),adrenal

insufficiency, hyperventilation, and polyuric renal disease

•decreased requirements with anuria/oliguria, SIADH, highly humidified atmospheres, and CHT

•maintenance electrolytes

Na ’

: 3 mEq/ kg/d

K'

: I mEq/kg/d

•4-2-1 rule: 4 mL/h first 10 kg, 2 mL/h next 10 kg, I mL/h for every kg after to calculate maintenance

fluid requirement

alternatively, may add 40 to adults who weigh £20kg to calculate maintenance fluid requirement

in mL/h

•e.g. a 50 kg patient'

s maintenance requirements

fluid = (4 mL/h x 10 kg) t (2 mL/h x 10 kg) + (1 mL/h x 30 kg) *40 mL/h + 20 mL/h + 30 mL/h =

90 mL/h * 2160 mL/d

Na '= 150 mhq/d (therefore 150 mEq/2.16 L/d « 69 mEq/L)

K* = 50 rnEq/d (therefore 50 mEq/2.16 L/d *23 mEq/L)

•above patient'

s requirements roughly met with 2/3 dextrose 5% in water (D5W), 1/3 normalsaline

(NS) 0.9%

• 2/3 + 1/3at 100 mL/h with 20 mEq KC1 per litre

Fluid Deficit

• patientsshould be adequately hydrated prior to anesthesia

• total body water (TBW)

= 60% or 50% of total body weight for an adult male or female, respectively

(e.g.for a 70 kg adult male TBW = 70 x 0.6 = 42 L)

• total Na '

content determines ECE volume; [ Na ' ] determines ICE volume

• hypovolemia due to volume contraction

extra-renal Na floss

« Gl: vomiting, NG suction, drainage, fistulae, diarrhea

skin/respiratory:insensible losses (fever),sweating, burns

vascular: hemorrhage

renal Na ’

and H:0loss

diuretics

osmotic diuresis

hypoaldosteronism

salt-wasting nephropathies

renal H’

O loss

diabetes insipidus (central or nephrogenic)

hypovolemia with normal or expanded ECE volume

decreased CO

redistribution

• hypoalbuminemia:cirrhosis, nephrotic syndrome

• capillary leakage: acute pancreatitis,rhabdomyolysis, ischemic bowel,sepsis, anaphylaxis

• replace water and electrolytes as determined by patient’s needs

• with chronic hyponatremia, correction must be done gradually over >48 h to avoid central pontine

myelinolysis

TBW (42 U

I

1

23 1 3

ICFI28 L) ECFI14 L1

1

i i

3/4 1/4

Interstitial (10.5 L) Intravascular (3.5 L)

(Starting's forces maintain balance)

Figure 10. Total body water division

in a 70 kg adult

Table 4. Signs and Symptoms of Dehydration

Percentage of

Body Water Loss

Severity Signs and Symptoms

3% Decreased skin turgor,sunken eyes, dry mucous membranes, dry tongue,reduced sweating

Oliguria, orthostatic hypotension,tachycardia,low volume pulse, cool extremities,reduced

filling of peripheral veins and CVP, hemoconcentration,apathy

Profound oliguria or anuria and compromised CNS function with or without altered sensorium

Mild

6% Moderate

9% Severe

What are the Ongoing Losses?

• traditionally thought that fluid loss during surgery resulted from blood loss, losses from Eoley

catheter, NG,surgical drains, and minor losses due to sequestration of fluid into other body

compartments

• fluid therapy accounting for these losses often resulted in excess crystalloid administration

• goal-directed fluid regimens associated with lower rate of postoperative complications compared to

predetermined calculations, these can be done using point of care ultrasound ( HOCUS), esophageal

doppler, or pulse or pressure variation available either using arterial line monitoring or certain pulse

oximetry

n

J

+

A15 Anesthesia Toronto Notes 2023

IV Fluids

Colloids»s.Crystalloids lor Floid Resuscitationin

Critically IIIPeople

tncteare 06 Syst ter 20t8:C0000567

Purpose:lo assesseftect of colloids vs.crystal cIs

incnticaly illpatients on mortality,need for

transfusions or renal replacement therapy,and

adverse events.

Methods Systematic ev enof tCTs and qsasi-RCTs

irvolvmg trauma,boms,or medical conditons (i.e.

sepsis).Searched CENTRAL.MEDLINE.andEmdase.

Outcomes:65 studes.30020 pancipants.Serenes,

dertrans.aibsmm or FfP (moderate-certainty

erdence).or gelatins (ton-certainty evidence) vs.

crystalloids has no difference onmortality.Starches

slightly increase the need for bindtransfusion

(moderate-certairty evidence),and a bumin or FFP

may make littleor no difference to the need for

renalreplacement therapy (lorn-certainty erdencel.

Evdence for blood transfusions for deifans.and

aSummorfFP.isaittrtain.

• replacement fluids include crystalloid and colloid solutions

• IV fluids improve perfusion but NOT O’

carrying capacity of blood

Initial Distribution of IV Fluids

• H’

O follows ions/molecules to their respective compartments

Crystalloid Infusion

• salt-containing solutions that distribute only within ECF

• consensus guidelines recommend use of balanced crystalloid (i.e. Ringer’

s lactate) over NS for routine

replacement and resuscitation

• maintain euvolemia in patient with blood loss: 3 mL crystalloid infusion per 1 mL of blood loss for

volume replacement (i.e. 3:1 replacement)

• best practice is to use goal-directed therapy

• if large volumes are to be given, use balanced fluids such as Ringer’s lactate or Plasmalyte’, as too

much NS may lead to hyperchloremic metabolic acidosis

Colloid Infusion

« includes protein colloids (albumin and gelatin solutions) and non-protein colloids (dextrans and

starches, (e.g. hydroxyethyl starch) (HES))

• distributes within intravascular volume

• 1:1 ratio (infusiomblood loss) only in terms of replacing intravascular volume

• the use of HES solutions is controversial because of recent RCl'

s and meta-analyses highlighting

their renal (especially in septic patients) and coagulopathic side effects, as well as a lack of specific

indications for their use

colloids are being used based on mechanistic and experimental evidence but there is a paucity of

definitive studies investigating theirsafety and efficacy;routine use of colloids should be avoided

Calculating Acceptable Blood Losses

(ABL)

• Blood volume

term infant

adult male

adult female

80 mL/kg

70 mL

'

kg

60mL/kg

• Calculate estimated blood volume

(EBV) (e g.in a 70 kg male,approx.

70 mL'kg)

EBV - 70 kg x 70 mL'

kg- 4900 mL

• Decide on a transfusion trigger.i.e.

the Hb level at which you would

begin transfusion (e.g.70 g/Lfor

a person with Hb(initial) ~150 g/L)

Hb(final) =70 g/L

• Calculate

ABL -Hb(i) -HbfflxEBV

Table 5. IV Fluid Solutions

ECF Ringer’s

Lactate

0.9% NS 0.45% NS D5W

in D5W

2/3 D5W Plasmalyte

1/3 NS

mEq/L Na‘ 142 130 1S4 77 51 140

K 4 4 5

Ca:" 4 3

Mg Hb(i)

'

'

3 3

-150 - 70 x 4900

ct- 103 109 154 77 51 98 150

-2613 mL

• Therefore,in order to keep the Hb

level above 70 g/L.FtBCs would have

to be given after approximately 2.6 L

of blood has been lost

HC03- 27 28’ 27

mOsm/L 280-310 273 308 154 252 269 294

pH 7.4 6.5 5.0 4.5 4.0 4.3 7.4

’ConvertedIrom lactate

Table 6. Colloid HES Solutions

Concentration Plasma Volume

Expansion

Duration (h) Maximum Daily Dose

(mL/kg)

Transfusion Infection Risks

Virus Risk per1unit

pRBCs

Voluven 6% 4-6 33-50 3

Pentaspan1

1:1

10% 1:1.24.5 18-24 28

HIV 1in 21million

Hepatitis C virus

Hepatitis Bvirus

1in13 million

Blood Products 1in25 million

HTLV 1m1-1.3 million

• see Hematology, H54

Symptomatic

Bacterial Sepsis

1in 40.000 from

platelets and1in

250.000 from SBC

West Nile virus No cases since 2003

Source:C4kimJL Pidkertce PR Bloody Easy Fourth

E&ticoed.Tor onto:Snnrytrcok and Women's Coftege

HeatttiScience Centre:2016

+

A16 Anesthesia Toronto Notes 2023

Induction

toenroniinis.Secdsykhorne for Sapid

Sepaer.ee InducticnIntubation

C ochraae 06 SrstIn20«:C0002788

Pirpoie:Ine“

et raciroums treetesursbatug

conditions comparable to“ose of soctnylcbofse

during RSJ iJrtsi«tio- s.

Methods:Systematic rer ew of ICTs or CCIs wi'a

dose of at least 0.6opt)for rotaroseaasd1erg ng

for SiCtnr'

tfOlire.

lesolts:S0tr.-ai.it51berttrperis.SotccySci-a me

was super®.'to rocaroaeafor actiering eiceBest

rt*

atso ro-dtoa(M0.86.95% Cl 0.810 52) ard

dinically acceptable nrtubaboucosdtiocs {IS057.

95% Cl 055-055).

Conclusion:SutanjictKPtcse treated Superior

irtabatoa coed-toss tomaroonra aacberng

excellent andctacatj acteptePe istsPatng

conditions.

Routine Induction vs. Rapid Sequence Induction

• routine induction is the standard in general anesthesia; however, an RSI is indicated in patients at risk

of regurgitation/aspiration (see Aspiration, A5 )

• RSI uses

1. pre-determined doses of induction drugs given in rapid succession to minimize the time patient is

at risk for aspiration (e.g. from the time svhen they are unconscious without an HIT until the time

when the HIT is inserted and the cuff inflated)

2. no bag mask ventilation

3. cricoid pressure may be applied (although there are some exceptions, e.g. trauma to upper airway)

4. use of rapid onset muscle relaxant (i.e. SCh)

Table 7. Comparison of Routine Induction vs. RSI

Steps Routine Induction RSI

Equipment Preparation Check equipment,drugs,suction,and monitors;prepare an alternative laryngoscope blade and a second ETT tube

one size smaller,suction on

100% 02for 3minor 4-8 vital capacity breaths:reduce risk of hypoxemia during apneic period following induction

Most

Soluble

Haiothare

Pre-Oxygenationl

Denitrogenation

Pre-Treatment Agents

Iscriurane

Use agent of choice to blunt physiologic Use agent of choice to blunt physiologic responses to airway

responses to airway manipulation 3 min prior manipulation:if possible,give 3 min prior to laryngoscopy,but

can skip this step inan emergentsituation

Use IV or inhalation induction agent of choice Use pre-determined dose of fast acting induebon agentof choice

Muscle relaxant of choice given after the onset Predetermined dose of fast acting muscle relaxant (SCh or high

dose rocuronium) given IMMEDIATELY after induction agent

DO NOT bag ventilate - can increase risk of aspirabon

Cricoid pressure (Sellick Maneuver) toprevent regurgitation

Sevo;jrsne

to laryngoscopy

Induction Agents Desflurane

Muscle Relaxants Least

of the induction agent Soluble Nitrous Oxide

Ventilation

Additional Helpful

Maneuvers

Bag-mask ventilation

External Laryngeal Manipulation using

Backwards.Upwards.Rightward Pressure

(BURP)

Intubate,inflate cuff,confirm ETT position Intubate once paralyzed (

“

45 s after SCh given),inflate cuff.

confirm ETT position:cricoid pressure maintained untilETT cuff

inflated and placement confirmed

Secure ETT.and begin manual/machine ventilation

Figure 11. Solubility of volatile

anesthetics in blood

Intubation

Effects of CricoidPresssre Compared with a Sfaaa

Procedurein the Sapid SeqaenceInduction of

A nesthesia:TheIrisBaadoaizedClinicalTrial

JAMA Sarg 2015:154|T|5-17

Purpose:To determne :f cricoidress.'

c nqaets

Dulmocary £sp-

'ction pec

-? e.ndergoi-grapid

seq.e:ce sdaction (SSI)of aKSlftesa.

Methods:Jrtozedc

*d c Jtelio

assess3472 patiatsnotary!tugrapidsetjsoce

induction of aresttesia at W academe centers.

Results:ResritsdesMStratedthatOctets

_nde:go;-g anesfesic asirgRSI eper.erce

ncreasedpmeriaaof palaonary aspiration

using ocodpressure»aes compared to thessaa

condition.

Conclusion:This stsdy prordeseiiJe:eto show

tre:ie:g5tof cmdp*ess^

*e -iRSI ard^3indthat

iissuper.or to tSe sham procedine inprevoSag

asptratkuL

Secure

Induction Agents

•induction of general anesthesia may be achieved with intravenous agents and/or volatile inhalational

agents

Intravenous Agents

•IV induction agents are non-opioid drugs used to provide hypnosis, amnesia, and blunt reflexes to

laryngoscopy

•these are initially used to establish the plane of anesthesia rapidly and smoothly

most commonly used is propofol or ketamine

a continuous propofol infusion may be used as an alternative to inhalational volatile agents

during the maintenance phase of general anesthesia. An indication would be malignant

hyperthermia

Table 8. Intravenous Induction Agents

Propofol

(Diprivan:

)

Thiopental (sodium

thiopental, sodium

thiopentone)'

Ketamine (Ketalar 1,

Ketaject )

Benzodiazepines (midazolam Etomidate

(Versed (.diazepam (Valium ),

lorazepam (Ativan ))

Methohexital

(Brevital )

Alkylphenol- hypnotic Short acting thiobarbiturate Phencyclidine (PCP) derivative -