The effects of carbon monoxide on oxygen-carrying capacity are short-lived. The elimination half-life of CO is approximately 4-6 hours when breathing room air. The p50 of oxygen increases from 22.9 to 26.4 mm Hg after only 12 hours of smoking cessation. Also, the plasma levels of carboxyhemoglobin decrease from 6.5% to approximately 1%. However, despite the decrease in plasma carboxyhemoglobin concentration after a short period of smoking cessation, there has been no proven decrease in the incidence of postoperative pulmonary complications.
Cigarette smoking causes mucus hypersecretion, impairment of mucociliary transport, and narrowing of small airways. Improvement in ciliary and small airway function, as well as decreased sputum production, occurs slowly over a period of weeks after smoking cessation. The optimal timing of smoking cessation before surgery to reduce postoperative pulmonary complications remains unclear. Most suggestions are somewhere between 4-8 weeks.
Despite the clear advantages of long-term smoking cessation, there can be disadvantages to smoking cessation in the immediate preoperative period. These include an increase in sputum production, patient fear of the inability to handle stress, nicotine withdrawal, and symptoms including irritability, restlessness, sleep disturbances, and depression.
- ABA:Smoking cessation – P50 effect
- ABA:Smoking cessation – acute physiology
- Smoking Cessation and Anesthesia
- Stoelting’s Anesthesia and Co-Existing Disease, Chapter 9, 181-217
Defined by: CT Bell, MD