Postanesthesia Recovery

Question 1

Which are the most common complications in the PACU?

Answer 1

Nausea and vomiting
Need for upper airway support
Hypotension

Question 2

Most frequent cause of airway obstruction in the PACU

Answer 2

Loss of pharyngeal muscle tone in a sedated or obtunded patient

Question 3

Most reliable clinical evaluation of residual NMB and indicator of pharyngeal muscle tone in the PACU

Answer 3

The ability to strongly oppose the incisor teeth against a tongue depressor

Correlates with an average TOF of 0,85

Question 4

Causes of prolonged nondepolarizing neuromuscular blockade

Answer 4

1) drugs
- Inhaled Anesthetics
- Local anesthetics
- Cardiac Antiarrhythmics (procrainamide)
- Antibiotics (polymixins, aminoglycosides, lincosamides, metronidazole, tetecyclines)
- Corticosteroids
- Calcium Chanel blockers
- Danteolene
- Furosemide

2) Metabolic and physiologic states
- Hypermagnesemia
- Hypocalcemia
- Hypothermia
- Respiratory Acidosis
- Hepatic/renal failure
- Myasthenia syndromes

Question 5

Causes of prolonged depolarizing NMB

Answer 5

1) Excessive dose of succinylcholine

2) Reduced plasma cholinesterase activity
- Decreased levels
- Extremes of age (newborn, old age)
- Disease states (hepatic, uremia, malnutrition, plasmapheresis
- Hormonal changes
- Pregnancy
- Contraceptives
- Glucocorticoids

3) Inhibited activity
- Irreversible (echothiophate)
- Reversible (edrophonium, neostigmine, pyridostigmine)

4) Genetic variant (atypical plasma cholinesterase)

Question 6

Treatment of laryngospasm

Answer 6

1- Suctioning
2- Jaw thrust + CPAP up to 40 cm/h2o

If this fails

3- Succinylcholine (0,1 - 1 mg/kg IV or 4 mg/kg IM)

If this fails

4- Intubation with full dose of induction agent and NMBA

Question 7

If airway edema is deemed significant enough to preclude extubation, which measures can facilitate resolution of edema?

Answer 7

1- sitting the patient upright to ensure venous drainage

2- diuretic administration

3- IV dexamethasone

Question 8

Factors contributing to postoperative arterial hipoxemia by mechanism of hypoxemia

Answer 8

1) Right to left intrapulmonary shunt or ventilation perfusion mismatch
- Atelectasis
- Pulmonary Edema
- Aspiration of gastric content
- Pneumothorax
- Pulmonary embolus

2) Alveolar hypoventilation
- Residual effects of anesthetics and/or neuromuscular blocking drugs

3) Venous admixture
- Reduced cardiac output
- Congestive heart failure

4) Diffusion hypoxia
- From NO2 administration

5) Increase O2 consumption
- Shivering

6) Decrease O2 delivery
- Unrecognized disconnection of O2 source
- Empty O2 tank

Question 9

Most common causes of transient postoperative arterial hypoxemia

Answer 9

Atelectasis

Alveolar hypoventilation

Question 10

Cause, manifestations and treatment of Negative Pressure Postoperative Edema

Answer 10

Is a rare consequence of laryngospasm (or, less commonly, other upper airway obstruction). The etiology is multi factorial, but is clearly correlated with the generation of exaggerated negative intrathoracic pressure during inspiration against a closed glottis. The resulting negative pressure augments venous return, which in turn increases pulmonary hydrostatic pressures, promoting the movement of fluid into the intertitial and alveolar spaces.

The resulting arterial hypoxemia develops quickly (usually within 90 min) and is accompanied by dyspnea, pink frothy sputum, and bilateral fluffy infiltrates in the chest X ray.

Treatment is generally supportive and includes O2 supplementation, diuresis, and, in severe cases, positive pressure ventilation.

When treated, NPPE typically resolves in 12 to 48 hours

Question 11

Brief description of TRALI

Answer 11

Transfusion-Related Acute Lung Injury usually manifests within 2 to 4 hours after the transfusion of plasma-containing blood products, including packed red blood cells, whole blood, fresh frozen plasma, or platelets. TRALI occurs when recipient neutrophils become activated by donor plasma and then release inflammatory mediators which cause increased pulmonary vascular permeability resulting in pulmonary edema. Clinical manifestations include fever, pulmonary infiltrates on chest radiograph, cyanosis, and systemic hypotension. The sudden onset of hypoxemic respiratory failure can occur up to 6 hours after the conclusion of the transfusion, and TRALI may first present when the patient is in the PACU.
Treatment is supportive and includes supplemental oxygen and diuresis. Approximately 80% of patients will recover within 48 to 96 hours. Mechanical ventilation may be needed to support hypoxemia and respiratory failure, and vasopressors may be required to treat refractory hypotension.

Question 12

Factors associated with postoperative hypertension

Answer 12

1) Cardiovascular
Preoperative hypertension
Hypervolemia

2) Respiratory
Arterial hypoxemia
Hypercapnia

3) Neurologic
Pain
Emergence agitation
Shivering
Nausea/vomiting
Increased intracranial pressure
Increased sympathetic nervous system activity

4) Drug-related
Withdrawal from β-blocker, clonidine
Withdrawal from opioids, benzodiazepines
Alcohol withdrawal
Substance use (e.g., cocaine, methamphetamine, phencyclidine)

5) Gastrointestinal/genitourinary
Bowel distention
Urinary retention

Question 13

Diferencial diagnosis of hypotension in the PACU

Answer 13

1) Hypovolemic
Intravascular volume depletion
Persistent fluid losses
Ongoing third-space translocation of fluid
Bowel preparation
Gastrointestinal losses
Surgical bleeding
Increased capillary permeability

2) Distributive
Sepsis
Burns
Decreased vascular tone
Allergic reactions (anaphylactic)
Spinal shock (cord injury, iatrogenic high spinal)
Adrenal insufficiency

3) Cardiogenic
Myocardial ischemia or infarction
Cardiomyopathy
Valvular disease
Cardiac arrhythmias
Drug induced (β-blockers, calcium channel blockers, local anesthetic systemic toxicity)

4) Extracardiac/Obstructive
Pulmonary embolus
Pericardial disease
Cardiac tamponade
Tension pneumothorax

Question 14

Pharmacologic treatments of hypotension caused by sympathetic nervous system blockade

Answer 14

Vasopressors, including ephedrine and phenylephrine

Question 15

In one study of patients over 45 years of age undergoing noncardiac surgery 85% of patients with postoperative myocardial infarction complained of typical chest pain

(Characteristics and short-term prognosis of perioperative myocardial infarction in patients undergoing noncardiac surgery: a cohort study. P J Devereaux et Al)

T or F

Answer 15

F

In one study of patients over 45 years of age undergoing noncardiac surgery only 35% of patients with postoperative myocardial infarction complained of typical chest pain

Question 16

ST-segment changes on the electrocardiogram (ECG) in the PACU should be interpreted in light of the patient’s cardiac history and risk index. In low-risk patients (<45 years of age, no known cardiac disease, only one risk factor), postoperative ST-segment changes on the ECG do not usually indicate myocardial ischemia. Relatively benign causes of ST-segment changes in these low-risk patients include…

In general, low-risk patients require only routine PACU observation unless associated signs and symptoms warrant further clinical evaluation

Answer 16

anxiety, esophageal reflux, hyperventilation, and hypokalemia

Question 17

Causes of postoperative renal dysfunction

Answer 17

1) Prerenal
Hypovolemia (bleeding, sepsis, third-space fluid loss, inadequate volume resuscitation)
Hepatorenal syndrome
Low cardiac output
Renal vascular obstruction or disruption
Intra-abdominal hypertension

2) Renal
Ischemia (acute tubular necrosis)
Radiographic contrast dyes
Rhabdomyolysis
Tumor lysis
Hemolysis

3) Postrenal
Surgical injury to the ureters
Obstruction of the ureters with clots or stones
Mechanical (urinary catheter obstruction or malposition)

Question 18

urinary retention is generally defined as

Answer 18

bladder volume greater than 600 mL in conjunction with an inability to void within 30 minutes.

Question 19

Intraabdominal hypertension (IAH) is defined as a sustained IAP greater than …, with abdominal compartment syndrome (ACS) defined as a sustained IAP greater than …

Answer 19

12 mm/Hg

20 mmHg associated with new organ dysfunction/failure

Question 20

Mild to moderate hypothermia (33°C to 35°C) …

(consequences)

Answer 20

inhibits platelet function, coagulation factor activity, and drug metabolism. Hypothermia may also exacerbate postoperative bleeding, prolong neuromuscular blockade, and delay awakening

Question 21

Mild to moderate hypothermia (33°C to 35°C) …

(consequences)

Answer 21

inhibits platelet function, coagulation factor activity, and drug metabolism. Hypothermia may also exacerbate postoperative bleeding, prolong neuromuscular blockade, and delay awakening

Question 22

Why normothermic patients can present shivering in the PACU

Answer 22

Although thermoregulatory mechanisms can explain shivering in the hypothermic patient, a
number of different mechanisms have been proposed to explain shivering in normothermic patients. One proposed mechanism is based on the observation that the brain and spinal cord do not recover simultaneously from general anesthesia. The more rapid recovery of spinal cord function is thought to result in uninhibited spinal reflexes manifested as clonic activity. This theory is supported by the fact that doxapram, a central nervous system stimulant, is somewhat effective in abolishing postoperative shivering

Question 23

Commonly use drug to stop shivering in the PACU

Answer 23

A number of opioids and α2-adrenergic agonists have been shown to be effective in abolishing shivering once it has started. Of those, meperidine (12.5–25 mg IV) is the most commonly used agent in adults

Question 24

Risk factors of PONV

Answer 24

These factors can be divided into patient-related, anesthesia-related, and surgery-related risk factors.

1) Patient-related risk factors; female gender, nonsmoking status, history of PONV and/or motion sickness, the need for postoperative opioids, and young age (<50 years);

2) Anesthesia-related risk factors: use of volatile anesthetics and nitrous oxide, in addition to the administration of higher doses of perioperative opioids and neostigmine for reversal of neuromuscular blockade

3) Surgery-related risk factors: the length of surgery and certain surgical procedures (cholecystectomy, laparoscopy, gynecologic surgery)

Question 25

Medications that can be use to prevent PONV

Answer 25

1) Anticholinergics
Scopolamine: transdermal patch, 1.5 mg
Apply to a hairless area behind the ear before surgery; remove 24 hours postoperatively

2) Antihistamines
Hydroxyzine: 12.5–25 mg IM

3) Phenothiazines
Promethazine: 6.25–12.5 mg IV/IM
Prochlorperazine: 2.5–10 mg IV/IM

4) Butyrophenones
Droperidol: 0.625–1.25 mg IV
See black box warning regarding torsades de pointes: monitor the ECG for prolongation of the QT interval for 2–3 hs after administration—preoperative 12-lead ECG recommended
Haloperidol: 0.5 to <2 mg IM/IV
Use with caution if prolonged QT interval present in ECG

5) Nk-1 Receptor Antagonists
Aprepitant: 40 mg PO before induction of anesthesia
Casopitant: 150 mg PO before induction of anesthesia

6) Prokinetic
Metoclopramide: 10–20 mg IV
Minimal antiemetic properties, avoid in patients with any possibility of gastrointestinal obstruction

7) Serotonin Receptor Antagonists
Ondansetron: 4 mg IV 30 minutes before conclusion of surgery
Granisetron: 0.35–3 mg IV near the conclusion of surgery Tropisetron: 2 mg IV near the conclusion of surgery Ramosetron: 0.3 mg IV near the conclusion of surgery
Palonosetron: 0.075 mg IV with induction of anesthesia
Dolasetron: 12.5 mg IV 15–30 minutes before conclusion of surgery (no longer marketed in the United States because of risk of QTc prolongation and torsades de pointes)

8) Corticosteroids
Dexamethasone: 4–8 mg IV with induction of anesthesia
Methylprednisolone: 40 mg IV with induction of anesthesia

Question 26

Strategies for prevention and treatment of PONV

Answer 26

Two antiemetic agents to all patients with one or two risk factors;

Three to four antiemetic agents to all patients with more than two risk factors;

If an adequate number and dose of antiemetic drugs given at the appropriate time are ineffective, simply giving more of the same class of drug in the PACU is unlikely to produce any significant benefit. It is not recommended to redose any medication of the same class within 6 hours after the initial dose. Therefore a drug from another class that has not previously been administered should be chosen for treatment of PONV in the PACU.

Question 27

Risk factors of postoperative delirium

Answer 27

1) Predisposing (Baseline)
Cognitive impairment (e.g., dementia)
Age >65 years
Sensory impairment (vision, hearing)
Severe illness (e.g., requiring ICU admission) Presence of infection
Poor functional status (e.g., frailty, limited mobility) Alcohol abuse
Malnutrition

2) Precipitating
Medications or medication withdrawal: Psychotropic medications (antidepressants, antiepileptics, antipsychotics, benzodiazepines), anticholinergics, muscle relaxants, antihistamines, GI antispasmodics, opioid analgesics, antiarrhythmics, corticosteroids, more than six total medications, more than three new inpatient medications
Pain
Hypoxemia
Hypoglycemia
Electrolyte abnormalities
Malnutrition
Dehydration
Environmental change (e.g., ICU admission)
Sleep–wake cycle disturbances
Urinary catheter use
Restraint use
Infection

Question 28

How PÓ delirium can be prevented?

Answer 28

Simple measures, such as frequent reorientation, sensory enhancement (ensuring glasses,
hearing aids, or listening amplifiers are available upon arrival in the PACU), pain control, cognitive stimulation, simple communication standards and approaches to prevent the escalation of behaviors, and keeping the patients in their circadian rhythm can decrease the incidence of developing POD by 30% to 40%

Question 29

Even after prolonged surgery and anesthesia, a response to stimulation should occur within

Answer 29

60 to 90 minutes

Question 30

Causes of delayed emergence from general anesthesia

Answer 30

1) Residual anesthetic drug effects

2) Substance use (alcohol, others)

3) Central anticholinergic syndrome

4) Serotonin syndrome

4) Neurologic disorders
Cerebral hypoxia
Acute stroke (embolic, ischemic, hemorrhagic)
Seizures (with postictal state)
Elevated intracranial pressure

6) Metabolic disturbances
Hypothermia
Electrolyte imbalances (especially sodium disorders)
Hypoglycemia
Liver dysfunction (causing hepatic encephalopathy)

Question 31

For a patient in the PACU with delayed emergence, the initial management includes the following steps:

Answer 31

(1) con- firm airway, breathing, and circulatory status;

(2) ensure that all anesthetic agents have been discontinued;

(3) check core temperature and begin rewarming if necessary;

(4) perform a neurologic examination to detect focal findings;

(5) evaluate for residual neuromuscular blockade and treat if required;

(6) consider laboratory tests with rapid turnaround such as glucose (to rule out hypoglycemia) and arterial blood gas with electrolytes (to evaluate for hypercarbia, sodium disorders)

The fol-lowing reversal medications can be considered depending on clinical context:
(1) naloxone 40 mcg every 2 minutes up to 200 mcg (for suspected residual opioid effect);
(2) flumazenil 0.1 to 0.2 mg every 1 minute up to 1 mg (for suspected residual benzodiazepine effect);
(3) physostig- mine 1 to 4 mg (for suspected central anticholinergic syndrome).

If there is concern for acute stroke, consider “code stroke” activation with a neurologist, which will require a stat brain computed tomography (CT). If the patient remains unresponsive despite these management steps, admission to the ICU for further neurologic monitoring and evaluation is indicated.

Question 32

Como diferenciar uma síndrome serotoninergica de uma síndrome neuroléptica maligna?

Answer 32

Entre os pacientes com hipertermia, estado mental alterado, hiperatividade autonômica e rigidez muscular, os fatores que favorecem a síndrome serotoninérgica em detrimento da síndrome neuroléptica maligna incluem o uso de fármacos serotoninérgicos, o início nas últimas 24 horas e a hiperreflexia

• referencia MSD manual

Question 33

Describe the Criteria for Determining Release From the Postanesthesia Care Unit: The Modified Aldrete Score

Answer 33

Variable Evaluated

Activity
Able to move four extremities on command: 2
Able to move two extremities on command: 1
Able to move no extremities on command: 0

Breathing
Able to breathe deeply and cough freely: 2
Dyspnea: 1
Apnea: 0

Circulation (systemic blood pressure)
Within 20% of the preanesthetic level: 2
20%–49% of the preanesthetic level: 1
≥50% of the preanesthetic level: 0

Consciousness
Fully awake: 2
Arousable: 1
Not responding: 0

Oxygen Saturation (pulse oximetry)
>92% while breathing room air: 2
Needs supplemental oxygen to maintain saturation >90%: 1
<90% even with supplemental oxygen: 0

Score ≥ 9 required for discharge