Perioperative Pulmonary Management |
Several published studies included complications that had no clinical significance. However, the recent studies defined postoperative pulmonary complications as the events influencing outcome following surgery. These include complications either known to prolong the hospital stay or responsible for morbidity and mortality.
PERIOPERATIVE PULMONARY PHYSIOLOGY
Respiratory effects of general anesthesia
Postoperative respiratory physiology in upper abdominal and thoracic surgery
PATIENT AND PROCEDURE RELATED RISK FACTORS
Patient-related risk factors
In severe cases, obesity is associated with pulmonary hypertension, cor pulmonale, and hypercapnic respiratory failure (Pickwickian syndrome). Obesity causes a reduction in lung volume, ventilation-perfusion mismatch, and relative hypoxemia, which are accentuated after surgery. Obesity (ie, body mass index of more than 27 kg/m2) increases the risk of postoperative pulmonary complications and respiratory failure in patients undergoing abdominal surgery, but may not be a risk factor in thoracic surgery.
A recent review article (Smetana GW, 1999), the risk of postoperative pulmonary complications was not excessive in seven studies of obese patients, who underwent abdominal or peripheral procedures. Several other studies have reported no association between obesity and postoperative pulmonary complications as well. Another recent study (Phillips EH, 1994) did not report excessive pulmonary complications in obese individuals following laparoscopic cholecystectomy.
Postoperative morbidity was not decreased in patients who quit smoking for less than 8 weeks. The beneficial effects of smoking cessation including improvement in ciliary and small airway function, and decrease in sputum production, occur gradually over several weeks. The increased incidence of postoperative complications in patients who recently stopped smoking has not been shown in other studies. The likely mechanism is that abrupt absence of the irritant effect of cigarette smoke in postoperative period, inhibits coughing and leads to retention of secretions and small airway obstruction.
In patients with known or suspected sleep apnea, the intraoperative and postoperative use of sedatives and narcotics should be minimized. Careful monitoring in postoperative period is required for worsening of sleep apnea, development of airway obstruction or CO2 retention. In patients suspected to have sleep apnea, the diagnosis should be confirmed and severity should be assessed preoperatively, with a formal polysomnographic sleep study. The severity of sleep apnea is judged based on apnea-hypopnea index (AHI) and the lowest oxygen saturation during sleep. Whenever possible, patients should be adequately treated with nasal CPAP preoperatively. Furthermore, patients with sleep apnea often benefit from regional anesthesia rather than general anesthesia.
Procedure-related risk factors
PREOPERATIVE RISK ASSESSMENT
History
Perform a complete history and physical examination to identify risk factors. Seek any history of smoking, exercise intolerance, unexplained dyspnea, or cough. Note evidence for COPD, such as decreased breath sounds, wheezes, crackles, or a prolonged expiratory phase.
Workup
Risk indices
PREOPERATIVE EVALUATION: THORACIC SURGERY
Preoperative Evaluation - Lung Resection
Preoperative pulmonary function
Exercise testing
Preoperative evaluation - Cardiac surgery
PREPARATION FOR SURGERY
Smoking cessation
Chronic obstructive pulmonary disease
Asthma
Preoperative antibiotics
Patient education
INTRAOPERATIVE STRATEGIES
Type of anesthesia
Type of neuromuscular blockade
Duration and type of surgery
POSTOPERATIVE STRATEGIES
Lung expansion maneuvers
Pain control
Prevention of Thromboembolism
Table: Prophylaxis Against Venous Thromboembolism
Condition | Risk(%)* | Recommendation |
---|---|---|
General Surgery | ||
Low risk | 3 | Early ambulation |
Moderate risk | 29 | Unfractionated heparin: 5000 U SC given 2 h preoperatively and q12h
postoperatively or LMWH: Dalteparin, 2500 U 1-2 hr before surgery, then once daily Enoxaparin, 2000 U before surgery, then once daily Nadroparin 3100 U 2 hr before surgery, then once daily Tinzaparin 3500 U 2 hr before surgery, then once daily |
High risk | 39 | Unfractionated heparin: 5000 U SC given 2 h preoperatively and q8h
postoperatively; or Dalteparin, 5000 U 10-12 before surgery, then once daily Enoxaparin, 4000 U 10-12 hr before surgery, then once daily |
Very high risk | 80 | (1) Unfractionated heparin: 5000 U SC given 2 h preoperatively and
q8h postoperatively; dalteparin: 2500 U given 2 h preoperatively and qd;
plus, intermittent pneumatic compression applied intraoperatively (2) Dalteparin, 5000 U 10-12 before surgery, then once daily Enoxaparin, 4000 U 10-12 hr before surgery, then once daily (3)Perioperative warfarin (INR, 2.0-3.0) |
Orthopedic Surgery/Neurological Surgery/Trauma | ||
Total hip replacement | 51 | (1) Dalteparin, 5000 U 1-2 hr before surgery, then once
daily Enoxaparin, 3000 U 10-12 hr before surgery, then once daily Nadroparin 40 U/kg U 2 hr before surgery, then once daily Tinzaparin 50 U/kg 2 hr before surgery, then 75 U/kg once daily (2) Warfarin: preoperatively and adjusted to INR of 2.0-3.0 postoperatively, continue up to 4 wk after surgery |
Total knee replacement | 61 | (1) Dalteparin, 5000 U 1-2 hr before surgery, then once
daily Enoxaparin, 3000 U 10-12 hr before surgery, then once daily Nadroparin 40 U/kg U 2 hr before surgery, then once daily Tinzaparin 50 U/kg 2 hr before surgery, then 75 U/kg once daily (2) Warfarin: preoperatively and adjusted to INR of 2.0-3.0 postoperatively, continue up to 4 wk after surgery |
Hip fracture surgery | 48 | (1) Dalteparin, 5000 U 1-2 hr before surgery, then once
daily Enoxaparin, 3000 U 10-12 hr before surgery, then once daily Nadroparin 40 U/kg U 2 hr before surgery, then once daily Tinzaparin 50 U/kg 2 hr before surgery, then 75 U/kg once daily (2) Warfarin: preoperatively and adjusted to INR of 2.0-3.0 postoperatively, continue up to 4 wk after surgery |
Neurosurgery | 24 | (1) Intermittent pneumatic compression or (2) unfractionated heparin: 5000 U SC q12h and intermittent pneumatic compression for high-risk patients |
Acute spinal cord injury with leg paralysis | 40 | (1) Unfractionated heparin: SC in doses adjusted to paralysis
produce APTT=1.5 X control 6 h after dose (2) Enoxaparin 3000 U twice daily (3) Warfarin adjusted to INR of 2.0-3.0 in rehabilitation phase (4) Intermittent pneumatic compression plus unfractionated heparin: 5000 U SC q12h |
Multiple trauma | 53 | Intermittent pneumatic compression until further bleeding is
unlikely; then, give (1) enoxaparin: 30 mg SC q12h or (2) warfarin: adjusted to INR of 2.0-3.0 |
Medical Conditions | ||
Acute Myocardial infarction | 24 | Unfractionated heparin: 5000 U SC q12h unless therapeutic anticoagulation used |
Ischemic stroke with paralysis | 42 | Unfractionated heparin: 5000 U SC q12h |
Medical patients (cancer, bedrest, CHF, severe lung disease) | 20 | Unfractionated heparin: 5000 U SC q12h; Dalteparin 2500 U once daily, Enoxaparin 2000 U once daily |
Complications:
Prognosis:
Medical/Legal Pitfalls:
Special Concerns:
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Constructed by Dr N.A. Nematallah Consultant in perioperative medicine and intensive therapy, Al Razi Orthopedic Hospital , State of Kuwait, email : razianesth@freeservers.com