Does smoking on the day of surgery increase the risk of anaesthetic complications?

Smoking on the Day of Surgery and Anesthetic Risk

Yes, smoking on the day of surgery increases anesthetic risk, but the acute risks are primarily related to carbon monoxide and nicotine effects on cardiopulmonary function rather than respiratory complications, which require 4-8 weeks of cessation to reduce. 1, 2

Immediate Physiological Effects (Same-Day Smoking)

Smoking within 24 hours of surgery causes acute cardiopulmonary changes that directly impact anesthetic safety:

• Carbon monoxide elevation reduces oxygen-carrying capacity by forming carboxyhemoglobin, impairing oxygen delivery to tissues during a period when oxygen demand is critical 3, 4
• Nicotine-mediated cardiovascular effects include increased blood pressure, heart rate, and systemic vascular resistance, which compromise myocardial oxygen balance during anesthesia 3, 4
• Monitoring difficulties occur because pulse oximeters give falsely elevated readings in the presence of carboxyhemoglobin, potentially masking hypoxemia 3
• Increased arterial to end-tidal CO2 gradient makes ventilation monitoring less reliable 3

Critical Distinction: Acute vs. Chronic Risks

The evidence clearly separates two timeframes for smoking-related surgical risk:

Same-Day to 24-Hour Cessation

• Reduces acute cardiopulmonary stress from carbon monoxide and nicotine 3, 4
• Does NOT reduce respiratory complications like pneumonia, atelectasis, or wound infections 1, 2
• May be beneficial even if surgery cannot be delayed 3

4-8 Week Cessation

• Required to significantly reduce postoperative respiratory complications, wound infections, and mortality 5, 1, 2
• Optimal timing is 6-8 weeks for maximal cardiopulmonary benefit 2, 6
• Shorter periods (<4 weeks) show unclear or potentially paradoxical effects on respiratory complications due to temporarily increased mucous production 5, 1

Clinical Algorithm for Day-of-Surgery Smokers

For patients who smoked on the day of surgery:

1. Proceed with surgery if indicated—do not delay urgent or necessary procedures 1, 2

2. Anticipate increased anesthetic requirements:

   • Plan for deeper anesthesia during induction and maintenance 3
   • Expect potential altered responses to muscle relaxants 3

3. Enhance intraoperative monitoring:

   • Recognize pulse oximetry may overestimate oxygen saturation 3
   • Monitor arterial blood gases if concerned about oxygenation 3
   • Consider processed EEG monitoring for depth of anesthesia 5

4. Prepare for postoperative complications:

   • Plan for supplemental oxygen therapy in recovery 3
   • Anticipate higher analgesic requirements 3
   • Maintain vigilance for respiratory complications despite same-day cessation not reducing this risk 1

Important Caveats

The paradox of short-term cessation: Evidence shows that stopping smoking less than 4 weeks before surgery may not reduce—and could theoretically increase—respiratory complications due to transiently increased mucous production and impaired ciliary clearance 5, 1. However, even 24 hours of abstinence eliminates acute carbon monoxide effects 3, 4, 7.

Surgery should never be delayed for smoking cessation in urgent cases, as disease progression risk outweighs potential cessation benefits 1, 2.

Postoperative nausea and vomiting is paradoxically less common in smokers than nonsmokers, so aggressive PONV prophylaxis may not be as critical as in non-smokers 3.

Practical Recommendation

For same-day smokers: Accept the increased acute cardiopulmonary risk, optimize anesthetic technique with deeper anesthesia and enhanced monitoring, and counsel that while proceeding is appropriate, they face substantially elevated risks of respiratory complications, wound infections, and cardiovascular events that could only have been reduced by 4-8 weeks of preoperative cessation 1, 2, 6.