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Emergency medicine & critical care > Emergency patient anesthesia > Flashcards

Emergency patient anesthesia Flashcards

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1
Q

A patient with severe trauma can have the following issues: (6)

A

pain

a decline in compensatory
mechanisms and energetic resources
(sudden flare up and decompensation of
previously stable health problems)

shock

tissue hypoxia

electrolyte imbalances

anaerobic metabolism

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2
Q

Effects of trauma on the Cardiovascular system. (5)

A

Excretion of catecholamines

Tachycardia and arrhythmias

Sudden constriction of peripheral blood vessels.

A sudden but short-term increase in blood pressure.

The compensatory effect of the
sympathetic nervous system depends on the body’s energy reserves.

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3
Q

Sympathetic nervous system receptors and chemical mediators.

A

alfa 1 & 2 (heart), beta 1 & 2 (lungs)

norepinephrine and epinephrine

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4
Q

What is “wind-up” syndrome?

A

Long-term stimulation of NMDA receptors
causes acute hyperalgesia and “wind-up”
syndrome.

Secondary hypersensitivity to pain (abnormally increased pain sensitivity in other areas of the body where there is no direct tissue damage).

Adaptive or protective pain turns into maladaptive or pathological pain (continues long after the tissue injury has healed).

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5
Q

What is shock?

A

Shock or circulatory collapse is a clinical
syndrome that occurs as a result of insufficient blood supply to all organs/tissues of the body.

“consumption is higher than delivery”

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6
Q

Name the 4 types of shock.

A

cardiogenic
distributive
hypovolemic
obstructive

(neurogenic, septic, anaphylactic -> these are all distributive shock)

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7
Q

Name 3 types of distributive shock.

A

neurogenic
septic/septicemic
anaphylactic

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8
Q

What type of shock is Pericardial tamponade?

A

obstructive, NOT cardiogenic

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9
Q

What type of shock is severe spinal cord injury?

A

distributive due to blood vessel dilation

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10
Q

What type of shock could pneumothorax be?

A

obstructive

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11
Q

3 types of pneumothorax and describe them

A

open, closed and tension

open (hole to the outside world, new air moves in an out)

closed (hole closed by e.g. fibrin, “old” air stuck in pleural space)

tension (air just keeps coming in but none is leaving, this is the most dire type)

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12
Q

Stabilization of the trauma patient. (5)

A

Most trauma patients primarily need
supplemental oxygen.

Adequate systemic analgesia

Placement of venous catheter and blood sample for hematocrit determination.

If the hematocrit is <22%, anesthesia is
contraindicated before blood transfusion.

Patients with life-threatening active bleeding may be anesthetized without stabilization.

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13
Q

anesthesia is contraindicated before blood transfusion with hematocrit of what %

A

If the hematocrit is <22%, anesthesia is
contraindicated before blood transfusion.

This can be applied to both dogs and cats.

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14
Q

The survival of a patient with multiple trauma in anesthesia is statistically more affected by the…? than what?

A

duration of being in anesthesia than by the choice of anesthetics.

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15
Q

4 general rules for anesthesia.

A

The choice of anesthetics is based
on existing health conditions.

Favor Short-acting drugs, ideally with the
possibility of reversal.

Use Low doses (you can always add on after all)

Intubation is mandatory.

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16
Q

Name 4 types of sedative/anesthetic drugs that are NOT suitable for a hypovolemic patient (bleeding, dehydration, hypovolemia):

A

Alpha-2-adrenomimetics (cause brady)

NSAIDs (causes vasodilation, decreases BP, decreased GFR, risk of AKI)

Acepromazine (causes vasodilation, decreases BP, long duration & cannot be reversed)

Corticosteroids (inhibits healing, stimulates hyperglycemia which is bad for brain traumas)

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17
Q

What state causes dehydration and hyPERvolemia?

A

salt poisoning

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18
Q

Drugs to titrate and use caution in trauma patients. (3)

A

propofol

isoflurane (lowers BP + neg. inotropic effect)

etomidate (decreased adrenal function)

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19
Q

Good sedative drug options for traumas. (3)

A

Benzodiazepines (midazolam, diazepam):
- Sedation
- Minimal effect on the cardiovascular system

Dissociative anesthetics (ketamine):
- Supports the sympathetic nervous system
(But! Use In low doses for head trauma patients)
- Antihyperalgesia (anti “wind-up”)

Systemic lidocaine:
- Lowers the likelihood of ventricular arrhythmias
- Analgesia
- Be careful in cats

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20
Q

Ideal (as opposed to just good) drug choices for traumas. (2)

A

Opioids: fentanyl (minutes) and methadone (4h).

Excellent analgesia. Evidence that they increase survival. You can reverse these with naloxone.

You can combine the above two even, they don’t cancel each other out (butorphanol does).

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21
Q

How to reverse methadone (e.g. in case of overdose)?

A

You can reverse these with naloxone.

Or use butorphanol to compete with methadone and decrease dose in case of overdose because butorphanol is a mixed agonist-antagonist for mu and kappa receptors.

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22
Q

GDV syndrome is characterized by accumulation of air within the stomach with a rapid rise in intraluminal pressure, gastric malpositioning, compression of (2)

A

diaphragm and caudal vena cava,
and impaired respiratory and cardiovascular function. A life threatening condition.

Distention of the stomach limits motion of the diaphragm during respiration and reduces the tidal volume.

Severe cellular hypoxemia and cell death.
Lactic acid production is increased due to
anaerobic metabolism. Multiply organ failure. Death of patient.

Mortality without surgical treatment, 100%.
Mortality after surgical treatment, 10–33%.

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23
Q

Stages of GDV: (4)

A

Stage I: fermentation of gastric contents induces dilation of the stomach.

Stage II: The stomach and sometimes the spleen rotate around the gastrosplenic ligament.

Stage III: severe changes in hemodynamics in portal vein and caudal vena cava; decrease in circulating blood volume.

Stage IV: hypoxia, hypovolemia, toxemia, death.

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24
Q

Pathophysiology of cardiovascular changes in GDV. (5+)

A

Elevation of pressure in the abdominal cavity compresses the portal vein and the caudal vena cava.

Significant reduction of venous return to the heart, causing cardiac output and arterial pressure to fall.

Flow in caudal vena cava in large dog can drop 50 times.

Compression of the portal vein induces edema and congestion of the gastrointestinal system and a reduction in vascular volume.

Elevated portal pressure compromises microcirculation in the viscera and reduces oxygen delivery to GIT.

Severe cellular hypoxemia and cell death.
Lactic acid production is increased due to
anaerobic metabolism. Multiply organ failure. Death of patient.

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25
Q

Under ischemic conditions (GDV) the pancreas produces

A

a myocardial depressant factor (MDF).

Contributes to Myocardial ischemia leading to Reduction of cardiac contractility. Next, Subendocardial ischemia, tachycardia, arrhythmias.

Distention of the stomach limits motion of the diaphragm during respiration and reduces the tidal volume.

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26
Q

Describe toxemia in GDV. (4+)

A

Breakdown in gastrointestinal mucosa allows bacterial translocation from the stomach to abdominal cavity.

The local immune system that controls bacterial translocation is altered by ischemia.

When circulation is restored bacteria and endotoxins are liberated into blood stream.

Production of free oxygen radicals cause direct toxic effect to tissues.

Severe cellular hypoxemia and cell death.
Lactic acid production is increased due to
anaerobic metabolism. Multiply organ failure. Death of patient.

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27
Q

Clinical signs of GDV. (5)

A

Tachycardia

Rapid capillary refill time (compensatory phase in shock)

Bounding femoral pulses

Hypotension
Hypothermia

28
Q

Prognostic test for GDV.

A

Serum lactate: Decreased organ perfusion and cardiovascular
instability is one of the causative factors of the complications of GDV.

A switch from aerobic to anaerobic metabolism produces lactate.

Lactate concentration acts as a prognostic indicator, see image.

If 12 h after surgery the level of serum lactate decreases ≥50%, the prognosis is good. (if it increases, you may have left some necrosing stomach behind)

29
Q

Stabilization of a GDV patient, fluids.

A

Intravenous fluid therapy through one or two large-bore catheters placed in the
cephalic veins (v. cephalica!!, IVs need to be front of the body, not the back).

Ringer-Lac or NaCl 0,9%,

Boluses of ¼ (20 ml/kg) of shock volume of fluids over 15 min.

In a case of severe shock use 90 ml/kg.

Monitor the HR, blood pressure, mucous membrane color, rectal temperature.

30
Q

Stabilization of a GDV patient, blood pressure drugs. (4)

A

Positive inotropes and vasopressors:

Dopamine (3–10 μg/kg per min iv by CRI)

Dobutamine (5–15 μg/kg per min iv by CRI)

Norepinephrine (0,05–0,4 μg/kg per min iv by continuous-rate infusion)

Ephedrine (0,1–0,2 mg/kg i.v.) (old fashioned)

31
Q

What parameters in a GDV patient will tell you whether its responding to fluid bolus? (2)

A

heart rate goes down,
rectal temp. goes up

32
Q

Dobutamine increases

A

cardiac contractility (positive inotrope)

33
Q

Dopamine, in low doses, increases what?

And in high doses it…

A

cardiac contractility as well as heart rate (positive inotrope and chronotrope)

In high doses it also causes vasoconstriction.

34
Q

Best vasopressor in GDV?

A

Dopamine causes vasoconstriction as well so not a first choice.

Norepinephrine also causes vasoconstriction.

Dobutamine is best choice for improving BP via cardiac contractility in GDV.

35
Q

Dobutamine 250 mg/50ml

Dose at 1-2 micrograms/kg

50 ml syringe for CRI pump

You need to dilute the above to 1mg/ml.

How much med and solution for dilution do you need?

A

250 mg/50ml = 5mg/ml (5000 microg/ml)

We want 1mg/ml dilution in our 50 ml CRI so we want to draw 50 mg worth of dobutamine.

50 mg in 10 ml of the drug solution

mixed into 40 ml of physiological solution to get 1 mg/ml.

36
Q

Stabilization of a GDV patient, Antiarrhythmic drugs.

A

Cardiac arrhythmias have been documented in 10 – 42% of dogs with GDV preoperatively. Are Ventricular arrhythmias.

Treatment of arrhythmias must be performed before induction to anesthesia thus all GDV patients should get lidocaine.

Lidocaine (1–2 mg/kg i.v. slowly)

Intraoperatively: lidocaine 50–100 μg/kg per min by CRI).

If they’re on it for a few days it may make them very sleepy (central effects).

37
Q

Stabilization of a GDV patient, analgesia doses. (3)

A

Methadone (0,3 – 0,4 mg/kg IM or i.v.)

Fentanyl (start with 2 μg/kg i.v., following 3 – 7 μg/kg/h)

Do not use morphine due to vomiting!

Intraoperative analgesia: FLK.

38
Q

Stabilization of a GDV patient, antibiotics and the need for them. (2)

A

During GDV, decreased oxygen delivery to the small and large intestine and cellular membrane dysfunction has been associated with bacterial translocation.

Bacteremia occurs in 43% of dogs with GDV.

Broad-spectrum antibiotics in the immediate perioperative period is advised: use first-generation cephalosporin
Cefazolin 22 mg/kg i.v.

39
Q

Main 4 Things to remember about Anesthesia of a GDV patient. (4)

A

Preoxygenation before anesthesia!

Premedication: opioid/benzodiazepines

Avoid α2-agosts
- they Decrease cardiac output
- they Decrease gut motility

Monitor blood pressure, ECG, HR, RR, SpO2,
ETCO2, electrolytes, blood gases.

40
Q

GDV patient anesthetic full protocol.

A

+ paracetamol postop

41
Q

Postoperative management of a GDV patient. (5)

A

Maintain fluid balance and blood pressure.
Intravenous fluids are continued until the patient is eating and drinking.

In critical patients, positive inotropes and
vasopressors may be indicated for maintenance of myocardial contractility, cardiac output and blood pressure.

MAP should be > 60 mmHg

Oxygen by mask

A continuous ECG should be performed to
evaluate for the presence of arrhythmias (2-3 days even).

42
Q

Cardiac arrhythmias should be treated with

A

intravenous antiarrhythmic drugs (usually lidocaine) and care should be exercised in monitoring and maintaining normal serum acid-base and electrolyte status (can affect heart rhythms).

Supplementation with potassium and
magnesium may be necessary for treatment of ventricular arrhythmias.

43
Q
A

ventricular premature complex

wide and bizarre QRS complex, typical to GDV cases and treated with lidocaine. In GDV, they’re caused by myocardial hypoxia and pain.

44
Q

Postoperative analgesia in GDV:

A

FLK CRI first 8 – 12 h

Followed by:
- Methadone (0,2 – 0,3 mg/kg every 4 hours)
- NSAIDs are contraindicated

45
Q

Gastroprotectives to give postoperatively in GDV. (3)

A

Histamine-receptor blockers (ranitidine, famotidine)

Sucralfate (coats the gastric mucosa)

Proton pump inhibitors (esomeprazole)

Indicated especially if gastrotomy or partial
gastrectomy were performed.

Nutrition should be provided within the first 12-24 hours postoperatively.

46
Q

Common Postoperative complications in GDV. (3)

A

Arrhythmias
DIC
Renal insufficiency or failure

47
Q

Physiological changes in the end of pregnancy. (5)

A

Maternal blood volume increases by approximately 40% (but mostly only plasma volume). So, causes a hemodilution and a relative anemia, HCT 30 – 35%.

Lowered BUN and creatinine

Viscosity of the blood and concentration of proteins decrease – decreasing of oncotic pressure (oedemas).

Hypercoagulation of blood

Increase in blood progesterone and endorphins produce a greater sensitivity to inhalation agent.

48
Q

Cardiovascular changes in heavily pregnant animals coming for cesarean. (4)

A

Peripheral vascular resistance decreased

Cardiac output increases

MAP does no change

A serious decrease in venous return due to compression of vena cava by the enlarged uterus.

49
Q

Heavily pregnant animals coming for cesarean section are super prone to what complication?

A

Risk of regurgitation
Risk of aspiration

Due to:
- Gastric emptying slowed
- Intraabdominal pressure is high
- pH of gastric fluids is very low

50
Q

Respiratory system changes in heavily pregnant animals coming for cesarean. (7)

A

Increased oxygen consumption

Decreased functional residual capacity

Increased sensitivity of respiratory center to PaCO2

Increased minute ventilation

Uptake of inhalation agents more rapid

PaO2 decreases more rapidly during decreased ventilation

Onset of hypoxia more rapid during apnea

51
Q

Preparation of a cesarean section patient. (3)

A

Intravenous fluid therapy should begin prior to induction of anesthesia.

Ringer Lac warmed to body temperature (10 ml/kg/h if not dehydrated, 20 ml/kg/h if mildly dehydrated, 30 ml/kg/h if severely dehydrated).

Preoxygenation of dam with a mask giving 3-5 l/min of 100% oxygen prior to induction of anesthesia.

Stress can decrease oxygen transfer to the fetuses as well as decrease uterine blood flow.

There should be as little stress as possible.

52
Q

Minimizing anesthetic time in cesarean sections.

A

The abdomen should be clipped and initial scrub performed prior to induction of anesthesia.

Premedication of the dam can have adverse effects on the fetuses so we avoid its use and instead induce directly.

53
Q

Premedication Drugs to avoid in cesarean sections: (3)

A

Acepromazine (long action >6 h, produces hypotension, no antagonist)

α2-agonists (xylazine, medetomidine,
dexmedetomidine; produce hypotension, significant adverse effects on the fetuses and/or dam, the correlation between using of α2-agonists and mortality of neonates
was described)

Benzodiazepines (drug accumulation and strong sedation of fetuses)

54
Q

All drugs that cross the blood-brain-barrier also cross the

A

placentas.

55
Q

For cesarean sections: Doses of all drugs should be calculated according to

A

body weight of non-pregnant animals.

56
Q

Cholinoblockers that can be used in cesarean section (2).

A

Handling of the uterus stimulates the n.vagus, particularly in queens.

Atropine can be indicated for minimizing bradycardia in the fetus and dam.

HR of dam increases, leading to increased uterine perfusion, increased local temp. and oxygenation and thus increased fetal HR.

Glycopyrrolate (longer onset time) doesn’t cross the placental barrier.

57
Q

How do you know if the fetal heart rate is low?

A

if you can count them, then they’re too low

58
Q

Opioid Premedication options for cesarean section. (2)

A

Opioids Provide analgesia and decrease the doses of anesthetics but they Rapidly cross the placental barrier.

Can cause marked respiratory and central nervous depression.

They Don’t increase the risk of anesthesia.

Butorphanol, fentanyl have minimal adverse effects.

Buprenorphine has a long duration of effects (> 6 h) so is not suited to cesareans.

59
Q

Propofol in cesarean section.

A

Propofol induction is the most commonly used method.

Short acting and Depression of fetus is minimal.

IV-administration produces vascular irritation (pain) so administration of lidocaine IV (0,5 mg/kg) before the propofol is indicated.

Vasodilation in dam can result in decreasing of perfusion of uterus – risk of fetus hypoxia.

60
Q

Ketamine in cesarean sections.

A

Can be used for either induction and
maintenance.

Rapidly crosses the placenta.

Can negatively affect fetuses.

Not the first choice but can be given after fetuses removed.

61
Q

Alfaxalone in cesarean section.

A

Neuroactive steroid with anesthetic properties. Induction is fast and smooth.

Cardiovascular effect is similar to propofol, but less respiratory depression.

Alfaxalone vs propofol
- Less depression of neonates
- Higher Apgar score
- Faster recovery of dam

62
Q

Paracetamol in cesarean section.

A

Paracetamol is an Analgesic, but not anti-inflammatory.

Has no negative effect on neonates.

For dogs only!

63
Q

Anesthetic considerations of Inhalation agents (isoflurane, sevoflurane) in cesarean section.

A

Most common method for anesthesia maintenance for CS.

MAP required in the dam is reduced by 40% for isoflurane in humans and sheep.

Use of inhalation anesthesia ensures (forces) open airways and oxygen supply.

Crosses the placenta

Minimally metabolized

64
Q

Regional and local anesthesia in cesarean section.

A

Infiltration of incision side with 2% lidocaine.

Epidural anesthesia with 2% lidocaine has been used in dogs successfully. Patient needs to be heavily sedated.

65
Q

Semjonov protocol for cesarean section.

A

+ paracetamol post op

66
Q

Intraoperative considerations for cesarean section.

A

Fluid therapy
Monitoring!

In a case of hypotension, dopamine (1–5
μg/kg/min) or dobutamine (1–5 μg/kg/min).

In a case of bradycardia: atropine or glycopyrrolate.

Once fetuses have been removed, more analgesics can be administered (ketamine, fentanyl, NSAIDs).

NB Pain can cause agalactiae!

67
Q

Postoperative analgesia after cesarean.

A

Local infiltration of anesthetics at the surgical incision in the dam is indicated (lidocaine 2% 2 mg/kg or bupivacaine 2 mg/kg).

Systemic analgesia:
Opioids given orally, transdermally, or via injection.

The opioid can be combined with NSAID to reduce the dose of opioids.

Some amounts of NSAID can be transferred to the neonate in the milk. NSAIDs can theoretically damage neonate renal development.

Single dose of meloxicam following CS has been advocated.

Consider paracetamol for multimodal postop. analgesia.

Emergency medicine & critical care (13 decks)

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