1. Preoperative pulmonary risk assessment

A. Identify risk factors

• Age over 60 years
• Current smoking
• COPD or poorly controlled asthma
• Recent respiratory infection, increased cough or purulent sputum
• Obstructive sleep apnea (OSA)
• Heart failure, pulmonary hypertension
• Poor functional capacity or functional dependence
• ASA class 2 or higher
• Hypoalbuminemia, malnutrition, weight loss
• Abnormal chest examination or low baseline oxygen saturation
• Impaired sensorium, alcohol use

• Emergency surgery
• Prolonged surgery, especially more than 3 to 4 hours
• Upper abdominal, thoracic, aortic, vascular, head and neck, neurosurgical procedures
• General anesthesia, especially with prolonged neuromuscular blockade
• Surgery close to the diaphragm carries greater risk. The Washington Manual of Medical Therapeutics, pp. 35-36.

B. Clinical assessment

1. History
   • Dyspnea, cough, sputum, wheeze, exercise tolerance
   • Previous pulmonary disease, exacerbations, hospitalizations, home oxygen
   • Smoking history and cessation attempts
   • Symptoms of respiratory infection
   • Symptoms or known diagnosis of OSA, using a tool such as STOP-Bang
   • Prior anesthesia or ventilatory problems
2. Examination
   • Respiratory rate, oxygen saturation, BMI
   • Wheeze, crackles, reduced air entry, signs of chronic lung disease
   • Signs of heart failure or pulmonary hypertension
   • Airway evaluation and OSA features
3. Risk prediction
   • Use a validated calculator when appropriate, such as ARISCAT for PPC risk or the Arozullah respiratory-failure index.
   • Risk estimates support counseling, anesthetic planning, postoperative level-of-care decisions, and optimization. The Arozullah index stratifies postoperative respiratory-failure risk from approximately 0.5% to 26.6%. The Washington Manual of Medical Therapeutics, p. 35.

C. Investigations

D. Risk reduction and optimization

• Stop smoking: advise cessation for all smokers. Ideally stop at least 4 weeks before elective surgery, but cessation should be encouraged even if surgery is sooner. Do not delay advice because of the outdated concern that short-term cessation increases sputum-related complications.
• Treat active disease before elective surgery: defer if feasible for acute COPD/asthma exacerbation or significant respiratory infection.
• Optimize COPD/asthma: continue inhaled bronchodilators and inhaled corticosteroids; treat infection only when clinically present; give systemic corticosteroids when indicated for an exacerbation, not routinely.
• OSA: ensure the patient brings/uses their usual CPAP device; use opioid-sparing analgesia and appropriate postoperative monitoring.
• Correct reversible factors: treat heart failure, improve nutrition when possible, correct anemia if relevant, and encourage preoperative activity/physiotherapy.
• Choose perioperative strategies: regional/neuraxial anesthesia where suitable, lung-protective ventilation, complete reversal of neuromuscular blockade, multimodal opioid-sparing analgesia.
• Postoperative pulmonary care: early mobilization, upright posture, effective analgesia, coughing/deep-breathing exercises, chest physiotherapy where indicated, and CPAP/non-invasive support for selected high-risk patients.

2. Perioperative prophylaxis of venous thromboembolism (VTE)

A. Assess both VTE risk and bleeding risk

• Previous VTE or known thrombophilia
• Cancer, particularly abdominal/pelvic cancer
• Major surgery, prolonged operation, emergency surgery
• Age, obesity, immobility, paralysis
• Acute infection/inflammation, heart or respiratory failure
• Pregnancy/postpartum state or estrogen therapy
• Central venous catheter
• Major lower-limb orthopedic surgery, trauma, spinal-cord injury

• Active bleeding
• Severe thrombocytopenia or coagulopathy
• Recent intracranial/spinal surgery or hemorrhage
• Uncontrolled hypertension
• Planned neuraxial catheter procedures when anticoagulant timing is not safe
• Major hepatic failure or other operation-specific bleeding concern

B. General preventive measures for nearly all surgical patients

• Early postoperative mobilization
• Adequate hydration, avoiding unnecessary immobility
• Minimize central venous catheter duration when possible
• Mechanical prophylaxis when pharmacologic prophylaxis is contraindicated

• Intermittent pneumatic compression (IPC) is preferred.
• Graduated compression stockings can be used when IPC is unavailable or unsuitable, but should be correctly fitted and avoided with significant peripheral arterial disease, severe leg edema, or skin compromise.

C. Risk-stratified approach in general and abdominal-pelvic surgery

D. Pharmacologic prophylaxis

• LMWH: generally preferred for many general surgical patients.
• Low-dose unfractionated heparin (UFH): useful when renal function is severely impaired or when shorter effect duration is desirable.
• Fondaparinux: an alternative in selected patients, but avoid or use cautiously in renal impairment and when neuraxial anesthesia is planned.
• DOACs or aspirin: used in selected orthopedic pathways, not as universal prophylaxis for all operations.

E. Extended-duration prophylaxis

• Major abdominal or pelvic surgery for cancer: usually extended LMWH prophylaxis for about 4 weeks.
• Selected high-risk orthopedic procedures: duration depends on the procedure-specific guideline and local protocol.
• Some high-risk inflammatory bowel disease or other specialty populations may also need extended prophylaxis.

F. Special points

• Do not use prophylactic IVC filters routinely. They do not replace anticoagulant or mechanical prophylaxis and carry thrombosis, migration, fracture, and penetration risks.
• Mechanical prophylaxis alone is appropriate temporarily if anticoagulation is unsafe.
• Reassess daily: when bleeding risk decreases, initiate or restart pharmacologic prophylaxis if indicated.
• Ensure clear discharge documentation: prophylaxis agent, intended duration, injection teaching if relevant, and symptoms requiring urgent review such as unilateral leg swelling, pleuritic chest pain, syncope, or sudden dyspnea.

Practical summary

1. Assess pulmonary and VTE risks early.
2. Optimize modifiable pulmonary factors: smoking, infection/exacerbation, COPD/asthma, OSA, nutrition, mobility.
3. Avoid indiscriminate preoperative CXR, ABG, and spirometry.
4. Use early mobilization and IPC broadly.
5. Add LMWH or UFH when VTE risk outweighs bleeding risk.
6. Use combined IPC plus pharmacologic prophylaxis for high-VTE-risk, low-bleeding-risk patients.
7. Continue extended prophylaxis for selected high-risk surgery, particularly major abdominopelvic cancer surgery.