Postoperative Complications Flashcards
What is the most common cause of immediate postoperative fever?
Malignant hyperthermia.
What is the underlying genetic mutation in malignant hyperthermia?
Ryanodine receptor (RYR1) gene mutation; autosomal dominant inheritance.
What are the key clinical features of malignant hyperthermia?
Acute muscle rigidity, hypercapnia (elevated CO2), tachycardia, hyperthermia, and rhabdomyolysis.
How is malignant hyperthermia treated?
100% oxygen and dantrolene.
What is the most common cause of early postoperative fever (within 1-3 days)?
Nosocomial infections such as pneumonia or catheter-related infections (CLABSI).
What is the most common bacterial cause of catheter-related bloodstream infections (CLABSI)?
Staphylococcus aureus and coagulase-negative staphylococci.
What is the diagnostic approach for nosocomial pneumonia in postoperative patients?
Urinalysis, chest X-ray, and checking catheter sites for infection.
What are the most common causes of late postoperative fever (>3 days)?
Surgical site infections, intra-abdominal abscess, deep venous thrombosis (DVT), and Clostridium difficile colitis.
Which organisms are most commonly associated with early surgical site infections?
Group A Streptococcus and Clostridium perfringens.
Which organisms are most commonly associated with late surgical site infections?
Staphylococcus aureus and other gram-negative bacteria.
What is the best initial diagnostic test for suspected postoperative deep vein thrombosis (DVT)?
Doppler ultrasound of the lower extremities.
What is the difference between dehiscence and evisceration of a surgical wound?
Dehiscence: disruption of sutures without organ protrusion. Evisceration: complete opening with organ protrusion.
What is the first-line treatment for evisceration?
Emergency surgery.
What is a fistula and what conditions increase its risk postoperatively?
An abnormal connection between two organs, commonly seen in Crohn’s disease, radiation, and infections.
What is Ogilvie’s syndrome, and how is it diagnosed?
Acute pseudo-obstruction of the colon, diagnosed via abdominal X-ray or CT scan.
What is the treatment for Ogilvie’s syndrome?
Supportive care and neostigmine if severe dilation is present.
What are the major causes of decreased urine output in postoperative patients?
Pre-renal (hypovolemia), intrinsic renal (acute tubular necrosis), and post-renal (obstruction).
What is the minimum urine output required in adults postoperatively?
0.5 mL/kg/hr.
What is the minimum urine output required in children postoperatively?
≥1 mL/kg/hr.
How is a suspected postoperative myocardial infarction diagnosed?
ECG and troponin levels.
How is postoperative bleeding managed?
Assess vitals, CBC, coagulation panel, and surgical site for signs of hemorrhage; transfuse if necessary.
What are the most common causes of hypoxemia in postoperative patients?
- Residual anesthesia effect
- Airway obstruction and edema
- Bronchospasm
- Atelectasis
- Pneumonia
- Pulmonary embolism
- Aspiration
- Heart failure
What are the earliest causes for postoperative hypoxia?
Residual anesthesia effect, airway obstruction and edema, as well as bronchospasm.
What form of postoperative hypoxia is associated with wheezing?
Bronchospasm is a potential cause of early postoperative hypoxemia. Patients will experience wheezing on physical examination. This tends to occur early postoperatively.
Who are at greatest risk for hypercapnic, hypoxic, respiratory failure, seen in postoperative hypoxia (secondary to residual anesthesia effect)?
Postoperative hypercapnic and hypoxic respiratory failure, most likely due to residual anesthesia effect, has a predilection for patients with underlying obstructive sleep apnea. These patients are at further risk due to sedation and neuromuscular blockers causing decreased pharyngeal muscle dilator tone and a higher propensity for obstructive apneic or hypopneic events. These factors can lead to severe hypoventilation and respiratory failure immediately following or shortly after surgery due to the effects of sedation, opioid analgesia, and anesthesia, which place patients at risk for respiratory failure due to decreased central respiratory drive and a depressed state of arousal.
How do both the respiratory rates and tidal volumes impact patient’s ABGs and Aa gradient if they have respiratory failure due to residual anesthesia?
Patients with respiratory failure due to residual anesthesia effect are typically somnolent with decreased respiratory rate and tidal volume, and will have hypoinflation on chest x-ray. Arterial blood gas will demonstrate respiratory acidosis with a normal alveolar-arterial (A-a) gradient. Because the hypoxemia is due to hypoventilation and A-a gas exchange is intact, the hypoxemia typically corrects with supplemental oxygen.
A patient has stridor and hypoxemia postoperatively, what is the likely underlying cause?
Upper airway (laryngeal) edema is a potential complication early in the postoperative period. There is an increased risk of airway obstruction and edema following endotracheal intubation that presents in the early postoperative period. Patients usually have stridor with tachypnea and increased work of breathing.
Is Atelectasis a common finding immediately after surgery?
Atelectasis is a common cause of postoperative hypoxemia that can occur 2-5 days following surgery; however, it is uncommon immediately following surgery.
Does atelectasis tend to cause fever?
No.
What is the classic ABG finding in postoperative atelectasis?
Atelectasis causes hypoxemia due to intrapulmonary shunting, the hypoxemia fails to correct with supplemental oxygen and the A-a gradient is typically elevated. Patients have respiratory alkalosis with low PaO2 and low PaCO2.
How is postoperative atelectasis typically managed?
Encourage incentive spirometry, early ambulation, deep breathing exercises, and adequate pain control.
When does postoperative pneumonia tend to occur?
Within the first week postoperatively (1 to 5 days)
When does postoperative pulmonary embolism tend to occur?
Usually anytime after 3 days. Postoperative patients are at increased risk of pulmonary embolism (PE); however, PE in the immediate postoperative period is rare. In addition, acute PE usually presents with respiratory alkalosis due to hyperventilation, and an elevated A-a gradient is expected due to ventilation/perfusion mismatch.
