1. Post-Operative Complications
د. صباح نوري السعد
M.B.Ch.B, D.A,
F.I.M.S, C.A.B.A & I.C

2. 1-The Respiratory System:
1. Hypoxia: a common problem in early post-operative period
Causes:
Reduced central drive to ventilation (anaesthetic drugs, CO2 washout).
Residual effect of muscle relaxant
Upper airway obstruction
Bronchospasm
Increased ventilation-perfusion mismatching
Reduced functional residual capacity
Aspiration of blood/stomach contents
Pneumothorax
Pain
Sputum retention
Pulmonary embolism

3. Clinical Diagnosis of hypoxia:
The first and most sensitive organ to hypoxia is the BRAIN.
Effect of hypoxia on cerebral cortex: restlessness, agitation; if not treated → coma and death.
Hypothalamus (which control the function of Autonomic Nervous System): tachycardia, hypertension, and if not treated → bradycardia and cardiac arrest.
Medulla: tachypnoea (shallow rapid respiration), if not treated → bradypnoea and apnoea.

4. Hypercapnia:
Causes:
Reduced central drive to ventilation by anaesthetic drugs, especially opioid anagelsics.
Excessive oxygen administration to chronic bronchitic patient who rely on their hypoxic drive.
Consequences:
Cardiovascular system: tachycardia, hypertension and arrhythmia
Central nervous system: CO2 narcosis → Delayed patient recovery from anaesthesia with delayed return of protective reflexes.

5. 2- The Cardiovascular System:
Hypotension:
Causes
Most common cause is a low blood volume (blood loss often occult, or loss of other fluids, e.g. significant mesenteric oedema after extensive and prolonged abdominal surgery → 3rd space loss).
Residual effect of anaesthetics (especially spinal and epidural)
N.B: Post-operative hypotension is due to hypovolemia until proved otherwise.
Rarely due to a cardiac causes (e.g. fast atrial fibrillation, complete heart block, myocardial ischemia, or myocardial infarction).

6. Management: most causes of hypotension respond well to: Head—down tilt
Administration of intravenous fluid
Oxygen should always be given, because hypotension increases ventilation-perfusion mismatching.

7. Arrhythmias: most commonly occur in:
Hypertension:
Causes:
Most common cause is pain, especially in patients who are already hypertensive.
Hypoxia, hypercapnia, or both.
Sometimes distended bladder
Rarely: metabolic derangement such as malignant hyperthermia, thyroid crisis.
Arrhythmias: most commonly occur in:
Patient with pre-existing cardiac disease
Hypoxia or hypercapnia
Drugs: adrenaline has been infiltrated during surgery, or the volatile anaesthetic halothane.

8. Major cardiac events: such as:
Myocardial infarction
Unstable angina
Pulmonary oedema
Ventricular tachycardia

9. Pre-operative risk factors:
Recent myocardial infarction
Significant heart failure (pulmonary oedema, gallop rhythm, raised jugular venous pressure).
Intra-operative risk factors: abnormality of the haemodynamic state, such as tachycardia, hypotension, and hypertension.
Post-operative risk factors: prolonged post-operative ischemia with tachycardia

10. Pulmonary embolism: Common in patient with:
History of previous pulmonary embolism
Abdominal (mainly pelvic) malignancies
Female on oestrogen - oral contraceptive pills
Prevention:
Prophylactic low molecular weight heparin (LMWH) 2 hours before operation in high risk patients.
Encourage early ambulation
Good hydration
Regional anaesthetic techniques

11. 3-The Gastro-Intestinal System:
Nausea and vomiting:
patients at risk:
Female > male
Young > old
History of motion sickness, and post-operative nausea and vomiting.
Type of surgery; more common in eye, ear, pelvic and laparoscopic surgeries.
Post-operative pain.
Non-smokers

12. Prevention and treatment of post-operative nausea and vomiting:
Prophylactic anti-emetic therapy with a 5-hydroxytryptamine 3 (5HT3) antagonist drugs as: Ondansetron (Zofran®) 8mg intravenously combined with Dexamethasone 8mg intravenously.
The above regimen is superior to a combination of:
Metclopramide 5-10mg and dexamethasone 8 mg.
Generous intravenous hydration
Aggressive pain control with non-opioid analgesic drugs
Post-operative O2 therapy

13. 4-The Urinary System: Oliguiria: Causes:
Pre-renal causes (hypovolemia): are common in the post-operative period (mainly due to inadequate fluid or blood replacement during surgery)
Renal causes:
Mismatch blood transfusion
Precipitation of bile salts in the renal tubules (obstructive jaundice)
Post-renal causes:
Prostatism
Blocked or misplaced urinary catheter

14. Management:
Adequate fluid hydration till we reach a urine output which is >30ml/hour (preferably gauged by central venous pressure).
If no urine inspite of good hydration, then enhanced dieresis with diuretics (furosemide).