Description

• Any negative outcome either by surgeon or patient; no consensus on definition
• Multiple classification systems exist based on severity.

Epidemiology

• Mortality rate in general and vascular surgery is 3.5–6.9% (1).
• Overall complication rate in general and vascular surgery is 24.6–26.9% (1).
• Postoperative fever is very common. Incidence ranges (14–91%) (2).
• 2008: 3 venous thromboembolic events/1,000 surgical discharges in the US (3)
• Emergent cases associated with more postop complications vs. nonemergent cases (22.8% vs. 14.2%) and have higher mortality rate (6.5% vs. 1.4%) (4)
• Complications after bariatric surgery: Anastamotic leak (0–5.6%), internal hernia (3–4.5%), marginal ulcer (1–16%), GI bleeding (0.6–4%), acute distention of distal stomach.
• Surgical infection incidence varies with type of operation:
  • 1–2% clean operative site (e.g., hernia repair)
  • 5–15% clean contaminated site (e.g., cholecystectomy)
  • 10–20% contaminated site (e.g., colectomy)
  • 50% dirty operative site

Risk Factors

• People at increased operative risk include those with:
  • Poorly controlled diabetes/obesity
  • Heart disease (especially myocardial infarction [MI] and heart failure)
  • Bleeding disorders
  • Malnutrition
  • Renal failure
  • Liver and pulmonary disease
  • Smoking
  • Immunosuppression
  • Malignancy

• Other risk factors:
  • Prolonged surgery
  • Immobility following surgery
  • Emergency surgery

• Malignant hyperthermia:
  • Incidence: 1/50–100,000; treated with dantrolene
• Pseudocholinesterase deficiency:
  • Inherited enzyme deficiency resulting in abnormally slow degradation of choline ester drugs
  • Causes prolonged respiratory paralysis following administration of standard doses of succinylcholine
  • Incidence: <0.01% of the general population; may have personal or family history of prolonged postanesthesia wake-up time
• Bleeding disorders, including hemophilia

General Prevention

Preventive measures span entire perioperative period:

• Smoking cessation (5)[A]
• Imaging
• Appropriate fluid/blood resuscitation
• Assessment of underlying risk factors
• Preoperative antibiotics, when appropriate
• Sterile technique
• Warming during surgery
• Clip hair instead of shaving preoperatively (6)[B]

Pathophysiology

• Fever caused by pyrogens (mediated by interleukin-1): Bacteria, viruses, antigen-antibody complexes
• Wound dehiscence: Poor wound healing (malnutrition) or increased abdominal pressure
• Deep vein thrombosis: Blood clot formation attributed to 1 of Virchow triad:
  • Hypercoagulability
  • Hemodynamic changes (stasis, turbulence)
  • Endothelial injury/dysfunction
• Renal failure:
  • Drug toxicity (commonly antibiotics)
  • Inadequate resuscitation leading to poor perfusion (catecholamine release during surgery and activation of renin-angiotensin-aldosterone system) results in ATN.
• Respiratory:
  • Decreased vital capacity leads to atelectasis, pneumonitis, and acute respiratory distress syndrome (ARDS).
  • Aspiration can occur at any time. Stomach acid/particulate matter cause an inflammatory reaction, leading to cyanosis or death.
  • Pulmonary edema due to fluid transudation to alveolus from fluid overload or heart failure
  • Pulmonary mechanics are compromised postoperatively. Precipitating factors include pain and altered mental status.
• Cardiac:
  • Postoperative MI occurs within 3 days of surgery; caused by anesthetics and blood loss (loss of as little as 500 mL can cause shock).
  • Arrhythmia is due to destabilization of cardiac membranes or prolongation of conduction.
• Small bowel obstruction: Intra-abdominal adhesive bands can form and constrict the bowel, even decades after surgery.
• Urinary retention: Men more frequently than women, impaired coordination between α-receptors in the bladder neck and parasympathetic stimulation to the bladder

Etiology

• Fever in the first 24 hours is usually due to atelectasis. Consider the 5 Ws:
  • Wind—atelectasis, PNA, aspiration
  • Water—UTI
  • Walking—deep venous thrombosis (DVT)
  • Wound—surgical site infection
  • Wonder drugs—drug fever
• Fever >102°F in the first 48 hours is concerning for necrotizing wound infection.
• Staphylococcus aureus is the most common cause of wound infection. Others include Pseudomonas, Proteus, and Klebsiella.
• Hematoma: Inadequate hemostasis/bleeding
• Seroma: Disruption of lymphatics
• UTI: Related to indwelling catheter
• Dehiscence: Increased abdominal pressure, inadequate fascial closure, malnutrition, contamination, and chemotherapy
• Renal failure: Hypovolemia, drug toxicity (commonly due to antibiotics or IV contrast)
• Respiratory: Volume overload, aspiration, and decreased vital capacity lead to decreased diffusion capacity. Pulmonary embolism formation is another possible postoperative etiology.
• Pulmonary embolism: Generally due to thromboembolism from the deep veins of the legs; more rarely from air, fat, or amniotic fluid.
• Cardiac: Arrhythmia occurs due to electrolyte abnormalities, catecholamine release (from pain), hypercapnia, and digitalis.
• Small bowel obstruction: Adhesive bands form intra-abdominally and can constrict the bowel; occurs remotely after abdominal surgery.
• Fistula/Intestinal leak: Generally occurs at the site of bowel anastomosis due to suture line breakdown
• Stomal complications:
  • More common in obese patients
  • Include fibrosis of bowel at stoma, necrosis, retraction, skin breakdown, and stomal stricture
  • Most complications are due to technical errors at the time of operation.
• Urinary retention: Due to anesthetics

Commonly Associated Conditions

• Adrenal insufficiency when on chronic steroids preoperatively
• Liver failure in patients with pre-existing disease
• Delirium tremens in alcoholics
• Thyroid storm in patients with undiagnosed hyperthyroidism
• Parotitis in the elderly
• Depression

Pediatric Considerations
Operative procedures can lead to severe anxiety in children aged 1–2 years, with lasting emotional disturbance in 20%.

Geriatric Considerations
90% of patients age >65 years experience depression after surgery, with activities of daily living impaired in 50%. Increase human contact to prevent withdrawal and reduce symptoms.