Excellent - comprehensive content from both sources. Compiling the summary now.
Part 1: Postoperative Pulmonary Complications (PPCs)
Definition & Significance
PPCs are a major cause of postoperative morbidity and mortality, with incidence varying from 5% to 70% depending on the patient population and type of surgery. They include: fever (microatelectasis), atelectasis, pneumonia, pleural effusion, bronchospasm, pneumothorax, hypercapnia, aspiration, ARDS, and respiratory failure.
Pathophysiology
Surgery and anaesthesia impair pulmonary physiology by:
- Reducing functional residual capacity (FRC) - lung volumes fall, particularly after thoracic/upper abdominal surgery
- Diaphragmatic dysfunction - stimulation of GI viscera during surgery alters diaphragmatic movement for days
- Impaired mucociliary clearance - from anaesthesia, pain, opioids → secretion retention
- Reduced cough effort - pain limits deep breathing and coughing
- Net result: V/Q mismatch, shunting, atelectasis, secretion pooling → infection risk
Risk Factors (Bailey & Love / Sabiston)
| Patient Factors | Procedure Factors | Lab Markers |
|---|
| Non-modifiable: Age, male sex, ASA >II, frailty, malignancy, acute URTI within 1 month, impaired cognition, stroke, long-term steroids, weight loss >10% | Non-modifiable: Thoracic/upper abdominal surgery, vascular surgery, emergency surgery, duration >2 hours, reoperation | Raised urea/creatinine |
| Modifiable: Smoking, COPD/asthma, OSA, obesity (BMI <18.5 or >40), hypertension, CCF, chronic liver failure, renal failure, DM, alcohol, GORD, preoperative sepsis | Modifiable: General vs. regional anaesthesia, NMB agents, open vs. laparoscopic, mechanical ventilation strategy, intraoperative transfusion | Low albumin, SpO₂ <96%, abnormal CXR preop, anaemia <10 g/dL, FEV₁/FVC <0.7, FEV₁ <80% |
Highest risk procedures: Upper abdominal and thoracic surgery
Individual Complications
1. Atelectasis (Most Common PPC)
- Partial or complete collapse of alveoli; most common cause of postoperative fever in early period (POD 1-2)
- Features: Fever, tachypnoea, reduced SpO₂, absent/reduced breath sounds; CXR - loss of hemidiaphragm, air bronchograms, volume loss with tracheal deviation toward collapse
- Treatment:
- Early mobilisation (out of bed 3x/day)
- Deep breathing exercises (5 breaths held 5-6 seconds)
- Incentive spirometry (ICOUGH protocol)
- Coughing and chest physiotherapy
- Bronchodilators; hydration; tracheal suctioning if needed
- Optimal analgesia - multimodal (paracetamol + NSAIDs + opioids PRN + regional blocks) to enable deep breathing
- Reversible within 24-48 hours with above measures
2. Pneumonia
- Develops from retained secretions ± aspiration
- Features: fever (typically POD 3-5), productive cough, consolidation on CXR, leukocytosis
- Treatment: antibiotics guided by sputum culture; physiotherapy; adequate analgesia
3. Aspiration
- Aspiration pneumonitis (Mendelson syndrome): Chemical injury from sterile acidic gastric contents (pH <2.5); treat supportively (O₂, CPAP/ventilation)
- Aspiration pneumonia: Infective; from colonised oropharyngeal secretions; requires antibiotics
- Risk factors: emergency surgery, bowel obstruction, impaired consciousness, GLP-1 receptor agonists (delayed gastric emptying), oropharyngeal instrumentation
4. Postoperative Respiratory Failure
- Defined as ventilator dependency >48 hours after surgery
- Causes: ARDS, severe pneumonia, PE, severe atelectasis, bronchospasm, worsening COPD
- Management: escalating respiratory support (NIV → invasive ventilation), ICU admission
5. Bronchospasm
- Especially in asthmatics/COPD patients; triggered by airway manipulation, aspiration, pain
- Treatment: nebulised bronchodilators (salbutamol, ipratropium), IV steroids, correct trigger
6. Pleural Effusion
- Post-thoracic/cardiac/upper abdominal surgery or from hypoalbuminaemia
- Significant effusions: thoracocentesis or chest drain
Prevention (ICOUGH Protocol - Sabiston)
- I - Incentive spirometry
- C - Coughing and deep breathing
- O - Oral care (brushing teeth + mouthwash - reduces VAP risk)
- U - Understanding (patient education)
- G - Getting out of bed (early mobilisation 3x/day)
- H - Head of bed elevation (>30°)
Additional: Smoking cessation ≥8 weeks preop; preoperative chest physiotherapy in high-risk patients; regional anaesthesia where possible; lung-protective ventilation; epidural analgesia for thoracic/upper abdominal surgery
Part 2: Treatment of Perforation Peritonitis
Classification of Peritonitis
| Type | Description | Example |
|---|
| Primary | No GI source; haematogenous spread | SBP in cirrhosis; TB peritonitis |
| Secondary | GI perforation/transmural infection | Perforated appendix, peptic ulcer, colon; most common surgical peritonitis |
| Tertiary | Persistent/recurrent despite treatment; nosocomial organisms | ICU patients; antibiotic-resistant organisms; mortality up to 50% |
Pathophysiology
Perforation of a hollow viscus → GI contents + bacteria → peritoneal cavity → massive inflammatory response → peritonitis → third-space fluid loss (compared to 50% TBSA burn in severity) → hypovolaemia, metabolic acidosis, septic shock → MODS
Diagnosis
Clinical:
- Sudden onset severe abdominal pain; board-like (generalised) rigidity
- Generalised rebound tenderness, guarding
- Absent bowel sounds
- Signs of systemic sepsis: fever, tachycardia, hypotension
- Note: Not all peritonitis requires surgery (e.g. localised diverticular peritonitis may respond to antibiotics)
Investigations:
- FBC (leukocytosis), CRP, LFTs, U&E, lactate, blood cultures
- Erect CXR: Free air under diaphragm (pneumoperitoneum) - limited sensitivity; absence does NOT exclude perforation
- CT abdomen/pelvis (with IV ± oral contrast): Gold standard; much more sensitive than plain films; can identify site of perforation, free air, free fluid, abscesses
- Peritoneal lavage: If CT unavailable or patient too unstable; >500 WBC/mm³, elevated amylase/bilirubin, or +Gram stain = ~90% likelihood of surgical peritonitis
- Diagnostic laparoscopy: Highly accurate; many causes can be dealt with laparoscopically
Treatment - The Three Pillars
1. Resuscitation
- IV access (2 large-bore); aggressive fluid resuscitation (30 mL/kg bolus)
- Guided by: BP (arterial line if shocked), HR, CVP, mixed venous O₂ sat, urine output (target >0.5 mL/kg/hr)
- Monitor: FBC, U&E, glucose, creatinine, blood gases, serum lactate (Surviving Sepsis guidelines)
- Vasopressors only after adequate volume resuscitation fails
- Glucocorticoids only for septic shock refractory to fluids + vasopressors
- O₂ therapy; urinary catheter; NGT (bowel decompression)
- Blood products if anaemic/coagulopathic
2. Antibiotics
Started before, during, and after surgery:
| Setting | Organisms | Antibiotic Choice |
|---|
| Community-acquired | Gram-negative bacilli, anaerobes, enterococci | Broad-spectrum beta-lactam (e.g. piperacillin-tazobactam) OR cephalosporin + metronidazole |
| Hospital-acquired / healthcare-associated | Resistant organisms (MRSA, ESBL, Candida) | Broader cover; discuss with microbiology |
| Colonic source | Gram-negative aerobes + anaerobes | Must cover both; metronidazole essential |
| Candida | Treat only if: septic shock, immunocompromised, or hospital-acquired | Antifungal (fluconazole/echinocandin) |
Duration: STOP-IT trial - short course (4 ±1 days) after source control = equivalent to treatment until fever/WBC resolves (~8 days) → short course now preferred
Antibiotic options (equivalent efficacy in trials):
- Monotherapy: broad-spectrum beta-lactam (e.g. piperacillin-tazobactam) = as effective as beta-lactam + aminoglycoside
- Fluoroquinolone + metronidazole
- Aminoglycosides avoided if possible (nephrotoxicity)
3. Surgical Intervention (Source Control) - Mainstay
Timing: As soon as patient is haemodynamically stable and resuscitated; do not delay unnecessarily
Goals of surgery (Sleisenger & Fordtran):
- Source control - close/resect/exteriorise the perforation
- Peritoneal decontamination - copious washout (lavage) with warm saline
- Prevention of recurrence - drainage of abscesses, fascial closure
Approaches:
- Laparotomy - gold standard for definitive management
- Laparoscopy - increasingly successful for selected cases (perforated peptic ulcer, appendix, selected colonic perforations)
Source control procedures by cause:
| Cause | Procedure |
|---|
| Perforated peptic ulcer | Graham patch (omental patch) ± H. pylori eradication |
| Perforated appendix | Appendicectomy ± lavage |
| Perforated diverticulum | Hartmann's procedure (resection + end colostomy) or primary anastomosis ± defunctioning stoma |
| Free colonic perforation | Resection ± stoma |
| Anastomotic leak | Re-explore; takedown + stoma vs. washout + drain |
Temporary abdominal closure / "damage control" laparotomy:
- Used when source control not possible at first operation
- Reasons for planned re-exploration: tenuous source control, bowel viability assessment, inadequate drainage, haemodynamic instability, fecal peritonitis, reassessment of anastomosis, abdominal compartment syndrome
Abdominal compartment syndrome: Fascia/skin closure raises intra-abdominal pressure → impairs respiration, hepatic, and renal function → leave abdomen open (vacuum dressing)
Nutrition
- Peritonitis = hypermetabolic state comparable to 50% TBSA burn
- 3000-4000 kcal/day may still not achieve positive nitrogen balance
- Enteral preferred over parenteral (maintains gut barrier)
- Feeding jejunostomy tube placed at initial operation in critically ill patients
Prognosis
| Cause | Mortality |
|---|
| Perforated appendix | ~10% |
| Perforated duodenal ulcer | ~10% |
| General secondary peritonitis | Up to 30% |
| Tertiary peritonitis (nosocomial) | Up to 50% |
Mortality highest in: elderly, multi-organ failure before presentation, delayed surgery, hospital-acquired infections
Sources: Bailey & Love's Short Practice of Surgery, 28th Ed.; Sabiston Textbook of Surgery (Atelectasis, Aspiration, PPCs); Sleisenger & Fordtran's GI and Liver Disease (Peritonitis Management)