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Anesthesia > Complications > Flashcards

Complications Flashcards

1
Q

What is believed to be the reason for the increased teratogenicity of N2O when compared to other inhaled and intravenous anesthetics?

A

oxidation of vitamin B12 and inactivation of methionine synthase.

Methionine synthase - methyltetrahydrofolate and homocysteine –> tetrahydrofolate (THF) and methionine.

Without THF and methionine –>reduced thymidine synthesis - essential nucleosides for DNA synthesis, its absence damages the genome and could theoretically induce cancer.

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2
Q

True or false: desflurane can cause an increased risk for infertility.

A

False

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3
Q

List three risk factors for teratogenesis under anesthesia.

A

◾The procedure being performed.
◾The proximity of the surgical site to the uterus.
◾The underlying maternal condition that necessitated the surgery

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4
Q

What are the JCAHO limits for environmental exposure to volatile anesthetic agents?

A

less than 2 ppm for volatile anesthetic when used alone, and less than 0.5 ppm when used with N2O.

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5
Q

What are the two major causes of waste gas contamination in the operating room?

A

operator issues (e.g. poorly fitting masks, filling anesthetic vaporizers, flushing the circuit)

equipment issues (e.g. punctured hoses, circuit leaks).

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6
Q

During which trimester is a fetus at highest risk for death associated with anesthesia and surgery?

A

1st

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7
Q

Describe the factors that contribute to trauma associated with airway management.

A

management of a difficult airway –> commonly multiple attempts at laryngoscopy

insertion of adjunctive airway devices - oropharyngeal or nasopharyngeal airways

Inexperience and poor technique increase the risk of airway complications.

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8
Q

Name two nerves that can be injured during bag mask ventilation.

A

mandibular branch of the facial nerve –> transient facial palsy

mental nerves –> lower lip numbness

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9
Q

List three common symptoms related to airway trauma.

A

sore throat
cough
dysphagia and odynophagia

usually self-limited but can progress –> retropharyngeal abscess in the case of a pharyngeal laceration.

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10
Q

What two things should you do if a tooth becomes dislodged?

A

identified and retrieved

CXR if necessary ensure tooth not aspirated or swallowed

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11
Q

What is the most common complication of nasotracheal intubation?

A

Epistaxis

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12
Q

A patient presents with hoarseness and unilateral vocal cord paralysis after an uneventful endotracheal intubation. What is the most likely reason?

A

endotracheal cuff compression of the recurrent laryngeal nerve

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13
Q

How can you decrease the risk of recurrent laryngeal injury during endotracheal intubation?

A

Avoiding overinflation and inappropriate placement of the endotracheal cuff

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14
Q

After a difficult intubation a patient develops subcutaneous emphysema, hypotension, increased airway pressures and a mediastinal shift. What is the most likely cause?

A

tension pneumothorax - after airway perforation

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15
Q

What are some signs and symptoms of esophageal perforation?

A

subcutaneous emphysema, neck pain, odynophagia, dysphagia, fever, cellulitis, empyema, and mediastinitis

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16
Q

What is the normal intrathoracic pressure range?

A

-3 to -10 cm of H2O

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17
Q

What are the four common risk factors for Negative Pressure Pulmonary Edema stated in the chapter?

A

◾Airway lesions.
◾Upper airway surgery.
◾Obesity.
◾Obstructive sleep apnea

postextubation laryngospasm, foreign body, hanging, strangulation, croup, and epiglottitis

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18
Q

How does Post-obstructive/negative pressure pulmonary edema occur?

A

significant upper airway obstruction – for example, biting the endotracheal tube during emergence from anesthesia

Inspiratory effort to overcome the obstruction –> highly negative intrapleural and alveolar pressures –> large pressure gradient that causes fluid to move out of the pulmonary capillaries and into the interstitial and alveolar spaces

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19
Q

How many hours should a patient be NPO after a light meal? After clear fluids?

A

6 hours after a light meal

2 hours after clear fluids

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20
Q

Aspirated material is likely to contaminate which bronchus more often?

A

right main bronchus

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21
Q

What are some risk factors for regurgitation, vomiting, and aspiration?

A

◾Pregnancy after the first trimester.
◾Acute gastrointestinal disease (esophageal or gastric disease, small bowel obstruction, ileus).
◾GI stasis (trauma, diabetes, obesity, drugs that inhibit gastrointestinal function),
◾The head-down and lithotomy positions.
◾Neurologic conditions that impair protective reflexes (Parkinson’s disease, bulbar palsy, myotonia dystrophica, stroke).
◾Decreased level of consciousness (traumatic brain injury, alcohol intoxication, general anesthesia, and drug overdose).

22
Q

With what force should cricoid pressure be applied when the patient of unconscious?

A

10 N (a weight of about 1 kg, which is tolerable) when the patient is awake and then increasing to 30 N (about 3 kg) when asleep

23
Q

True or false: All patients presenting for surgery should have anti-reflux prophylaxis.

A

False

24
Q

When aspiration is suspected, how should the patient be positioned?

A

semi-prone and tilted to a 30° head-down position

Suction –> secure airway –> NG tube
Always suction before giving PVV

25
Q

Aspiration pneumonitis is likely to occur if the volume of aspirate is _____ and the pH is ___.

A

0.3 mL per kilogram of body weight (20-25 mL in adults) with a pH

26
Q

Antibiotics should be started in a patient who has aspirated and showed signs of pneumonitis for more than ____ hours after the event

A

48 hours

27
Q

What is the reported occurrence of corneal injury in the perioperative period?

A

near 0% with adequate protective precautions, and up to 44% with no protective intervention

28
Q

How does general anesthesia interfere with the eye’s natural reflexes to protect the cornea?

A

masking of pain perception
decreased tear production
lagopthalmos (failure of eyelid to close)
abolishment of Bell’s phenomenon (the upward rotation of the eyeball normally observed during sleep to protect the cornea behind the upper eyelid)

29
Q

Name six risk factors for corneal abrasion.

A 
general anesthesia
prone (and possibly lateral) positioning
prolonged anesthesia/surgery
lower ASA physical status
advanced patient age
less experienced anesthesia care providers
30
Q

How does a corneal injury typically present?

A

foreign-body sensation
photophobia
pain with blinking or eye movement

31
Q

What is the best preventive measure to avoid corneal abrasion in the perioperative period?

A

Taping the eyelid closed immediately after induction

Water-based methylcellulose eye ointment

32
Q

Name three different mechanisms for post-operative visual loss.

A

retinal ischemia
anterior ischemic optic neuropathy (AION)
posterior ischemic optic neuropathy (PION) - more likely to be related to surgery than AION
cortical blindness

33
Q

Describe the fundoscopic exam of central retinal artery occlusion.

A

normal optic disc, pale retina, and cherry-red macula.

34
Q

What type of retinal ischemia most often occurs due to embolic phenomenon?

A

Branch retinal artery occlusion

35
Q

A severe head trauma patient complains of post-operative visual loss. What will the fundoscopic exam most likely reveal?

A

Purtscher retinopathy (cotton wool exudates) = retinal bleeding

Also seen in:
abdominal trauma
acute pancreatitis
fat or amniotic fluid embolism

36
Q

What is the prognosis of retinal ischemia visual loss?

A

most patients sustain permanent visual loss

37
Q

Name the two types of ischemic optic neuropathy and describe the anatomic location of the vascular compromise.

A

Anterior ischemic optic neuropathy (AION) - at the head of the optic nerve as it passes through the lamina cribrosa to enter the globe; AION acutely affects the optic disc.

Posterior ischemic optic neuropathy (PION) - in the retrobulbar portion of the optic nerve.

38
Q

List three high-risk surgeries for AION

A

cardiac surgery, especially CABG
bilateral radical neck procedures
spine, or other orthopedic surgeries

Other risk factors:
head-down positions (prone or steep Trendelenburg)
lower nadir [Hbg] (8.0 g/dL)
large volumes of crystalloid
lower MAP
prolonged surgical time (>500 minutes)
possibly, pressor support
39
Q

Describe ophthalmic exam findings of AION in the immediate postoperative period.

A

optic disc edema
pale

NO pupillary light reflex

40
Q

Describe ophthalmic exam findings of PION in the immediate postoperative period.

A

initially normal –> pale in following weeks to months

Most commonly in spinal fusions

41
Q

List six risk factors for post-operative cortical blindness

A 
cardiac and vascular surgeries - emboli
cardiac arrest
profound hypotension
thrombosis
vascular occlusion

normal optic disc + intact pupillary reflex

Prognosis is quite good (unlike ischemic neuropathy)

42
Q

How can pressure injuries from tourniquets be prevented?

A

Using wider and contoured cuffs
lower inflation pressures
limiting tourniquet times

43
Q

How can the brachial plexus be injured during a median sternotomy?

A

compressed against the clavicle during retraction

44
Q

What are signs of possible intraneural injection of local anesthetic during peripheral nerve blockade?

A

pain on injection
low stimulation current
abnormal resistance during injection

45
Q

Name the four types of heat transfer that occur in the operating room.

A

Evaporative - sweating and moisture losses from the airway. (~10%)

Conductive - transfer between two adjacent surfaces.

Radiation - transfer of heat from one object (the patient) to another (the room), with no contact between the objects. (MAJOR)

Convection - heat loss as a result of air currents. (#2)

46
Q

What causes the initial decrease in temperature that occurs during the first hour of surgery?

A

general anesthesia –> vasodilation –> heat transfer from core to periphery

47
Q

How can hypothermia result in wound infections?

A

directly impairing immune function

thermoregulatory vasoconstriction –> reduce tissue oxygen delivery = further predisposing patients to wound infection

48
Q

What is the most commonly used medication to treat post-operative shivering?

A

Meperidine

49
Q

What is the most effective means of maintaining normothermia during longer operations?

A

Forced-air warming

50
Q

What are the mechanisms by which humans preserve body temperature in warm environments?

A

sweating - cools the skin through evaporation

increased respiration - eliminates heat through the excretion of warm gas from the lungs

51
Q

List 4 consequences of untreated hyperthermia perioperatively.

A

tissue destruction –> myoglobinuria
coagulopathy - damage to hepatocytes
arrhythmias –> cardiac arrest
increases the MAC of most anesthetics

52
Q

List 4 potential causes of elevated temperature in an anesthetized patient with an unknown medical history.

A
  1. Infection
  2. Metabolic - thyrotoxicosis, pheochromocytoma, status epilepticus, carcinoid syndrome, and malignant hyperthermia
  3. Traumatic brain injury
  4. Meds - anti-cholinergic, TCAs, MAOIs

Anesthesia (25 decks)

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