Makindo Medical Notes

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Post-operative complications are events that adversely affect recovery after surgery. They can occur immediately (within 24 h), early (days–weeks), or late (weeks–months). Understanding the physiology of the surgical stress response, risk factors, and timing helps clinicians anticipate, prevent, and manage complications effectively.

🧬 Physiology of the Surgical Stress Response

• Tissue injury → cytokine release (IL-1, IL-6, TNF-α), ↑ cortisol and catecholamines.
• Results in catabolism (muscle breakdown, hyperglycaemia), immunosuppression, and hypercoagulability.
• This increases susceptibility to infection, thromboembolism, ileus, and metabolic derangements.
• Anaesthesia and immobility further exacerbate these risks.

🗂️ Classification of Post-Operative Complications

• ⏱️ By timing: Immediate (0–24 h), Early (1–7 days), Late (>7 days).
• 🫀 By system: Respiratory, Cardiovascular, GI, Renal, Neurological, Wound/Surgical site, Thromboembolic, Infective.
• ⚖️ By severity: Minor (nausea/vomiting) vs Major (MI, sepsis, anastomotic leak).

🌡️ Infective Complications

• Wound infection: Redness, swelling, pus, dehiscence. Occurs Day 5–7. Prevention: sterile technique, prophylactic antibiotics.
• Pneumonia: Often hospital-acquired, esp. in immobile or ventilated patients. Atelectasis predisposes.
• Urinary tract infection: Especially with catheterisation. Presents Day 3–5.
• Line sepsis: Indwelling IV cannulae, CVCs. Suspect with unexplained fever.
• Deep abscess/anastomotic leak: Persistent fever, abdominal pain, ileus, tachycardia. Requires imaging and often surgical drainage.

💨 Respiratory Complications

• Atelectasis: Most common early cause of pyrexia; prevent with physio and mobilisation.
• Pneumonia: Lobar or aspiration. Presents with cough, fever, desaturation.
• Pulmonary embolism (PE): Dyspnoea, pleuritic pain, hypoxia. Prevention with VTE prophylaxis.
• Respiratory depression: Due to opiates, residual anaesthesia. Monitor SpO₂, use naloxone if severe.
• Pneumothorax: Post thoracic/central line procedures; acute dyspnoea, ↓ breath sounds.

❤️ Cardiovascular Complications

• Myocardial infarction: Peri-operative MI due to stress and demand–supply mismatch. Monitor ECG/troponin if chest pain.
• Arrhythmias: AF common after thoracic/cardiac surgery; electrolyte imbalance contributes.
• Hypotension: Causes include hypovolaemia, sepsis, anaesthetic effect, bleeding.
• Hypertension: Pain, anxiety, urinary retention, or pre-existing disease.
• Shock: Hypovolaemic, septic, cardiogenic, or anaphylactic.

🩸 Haemorrhage & Thromboembolism

• Primary haemorrhage: Intra-op or immediately post-op due to poor haemostasis.
• Reactive haemorrhage: When BP rises after anaesthesia wears off.
• Secondary haemorrhage: Infection eroding a vessel (day 7–10).
• DVT: Leg swelling, pain; prevent with LMWH, stockings, mobilisation.
• PE: As above; may be fatal if massive.

🍽️ Gastrointestinal Complications

• Ileus: Functional bowel obstruction post-op; distension, vomiting. NG tube + fluids.
• Anastomotic leak: Fever, tachycardia, peritonitis. CT and urgent surgical review.
• Intra-abdominal abscess: Persistent fever, pain, ileus. Requires imaging and drainage.
• GI bleeding: Stress ulcers, anastomotic sites. Consider PPI prophylaxis in high risk.
• Constipation: Common with opiates; prevent with laxatives.

🧪 Renal & Metabolic Complications

• Acute Kidney Injury (AKI): Pre-renal (dehydration, bleeding), intrinsic (ATN, nephrotoxins), or post-renal (retention, obstruction).
• Electrolyte imbalances: Hypokalaemia, hyponatraemia, hypomagnesaemia. Can cause arrhythmias and ileus.
• SIADH: Post neuro/pituitary surgery. Hyponatraemia with low plasma osmolality.
• Hyperglycaemia: Common with stress response and steroids. Monitor and use insulin if needed.

🧠 Neurological Complications

• Delirium: Especially in elderly; causes include hypoxia, sepsis, drugs, metabolic derangements.
• Stroke/TIA: Peri-operative embolism, AF, carotid disease.
• Post-op cognitive dysfunction: Long-term decline in elderly patients, mechanism unclear.
• Seizures: Secondary to electrolyte imbalance, CNS infection, withdrawal syndromes.

🪡 Wound & Surgical Site Complications

• Infection: Local erythema, pus, dehiscence.
• Wound dehiscence ("burst abdomen"): Surgical emergency with high mortality.
• Incisional hernia: Late complication, often months–years later.
• Fistula formation: May follow bowel surgery or infection.
• Scarring/keloid: Cosmetic but can be functionally significant.

⚠️ Other Important Complications

• Nausea & Vomiting: Anaesthetic drugs, opioids, ileus.
• Pressure sores: Due to immobility, especially in frail patients.
• Drug reactions: “Wonder drugs” causing pyrexia, rash, eosinophilia.
• Sepsis: Any source – treat with “Sepsis Six”.
• Late adhesions: Leading to small bowel obstruction months–years after surgery.

🔎 Approach to a Post-Operative Patient with Deterioration

• ABCDE assessment; escalate if unstable.
• Check vitals, fluid balance, drains, wound, catheters, chest.
• Investigations: Bloods (FBC, CRP, U&E, LFTs, cultures), ECG, CXR, CT as indicated.
• Always consider sepsis; initiate antibiotics promptly if suspected.
• Early involvement of surgical and critical care teams is vital.

🛡️ Prevention Principles

• Prophylactic antibiotics where indicated.
• VTE prophylaxis (LMWH, stockings, mobilisation).
• Adequate pain control to allow chest expansion/mobilisation.
• Strict catheter and line care; remove early.
• Close monitoring in high-risk patients (elderly, comorbidities, long operations).

📚 Case Example

👨‍🦳 A 72-year-old man, POD 6 after sigmoidectomy, develops fever (38.7 °C), tachycardia, and abdominal pain. Exam: distended tender abdomen, absent bowel sounds. CRP 280, WCC 16. ✅ Diagnosis: Anastomotic leak with sepsis. 🛠️ Management: Sepsis Six, urgent CT abdomen, broad-spectrum IV antibiotics, early surgical review (possible reoperation).

📝 Summary

Post-operative complications range from minor to life-threatening. Always consider timing, system affected, and risk factors. Prevention through good peri-operative care, early recognition of deterioration, and multidisciplinary management are essential to improve outcomes.