Smokers and smoking in Anesthesia

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Smokers and Smoking in Anesthesia

Smoking is one of the most common and consequential comorbidities encountered in anesthetic practice. It affects every organ system relevant to the perioperative period and requires specific management across all phases of care.

1. Pathophysiological Effects of Smoking Relevant to Anesthesia

Respiratory System

Mucociliary dysfunction: Decreased tracheal ciliary function leads to impaired mucus clearance and increased sputum production, predisposing to atelectasis and infection.
Airway irritability and bronchospasm: Smokers show increased airway reactivity under general anesthesia. Preoperative pulmonary function testing has limited predictive value for postoperative complications, but it may predict postoperative bronchospasm in smokers specifically.
Increased secretions: Bronchial irritation causes excessive airway secretions that can obstruct the airway postoperatively.
Underlying COPD: Many smokers have varying degrees of obstructive lung disease, ranging from subclinical to severe, that impairs reserve and recovery.

Cardiovascular System

Nicotine effects: Nicotine stimulates the sympathetic nervous system, causing tachycardia, hypertension, and increased myocardial oxygen demand.
Carboxyhemoglobin (COHb): Carbon monoxide from cigarette smoke binds hemoglobin with ~240x greater affinity than oxygen, reducing oxygen-carrying capacity and impairing tissue oxygen utilization. COHb levels in heavy smokers can reach 10-15%.
Vasoconstriction: Nicotine causes cutaneous vasoconstriction, reducing skin and wound blood flow.

Oxygen Delivery and Wound Healing

The impairment in arterial oxygenation during anesthesia is more marked with increased age, obesity, and smoking (Miller's Anesthesia, 10e). Mechanisms contributing to poor wound healing include:

Reduced oxygen-carrying capacity (elevated COHb)
Cutaneous vasoconstriction and local thrombosis
Impaired collagen synthesis
Altered immune function and impaired secretion clearance
Effects of comorbid COPD and cardiovascular disease

2. Perioperative Risks: Quantified

A meta-analysis of 107 studies found that smoking within 30 days of operation significantly increased complications (Murray & Nadel's Respiratory Medicine):

Complication	Relative Risk
General morbidity	1.5
Wound complications	2.2
Infections	1.5
Pulmonary complications	1.7
Neurologic complications	1.4
ICU admission	1.6

In ambulatory surgery patients specifically, respiratory complications were 32.8% in smokers vs. 25.9% in nonsmokers, and wound infections were 3.6% vs. 0.6%. Heavy smoking, along with obesity, sleep apnea, severe asthma, and COPD, increases the risk of postoperative ventilatory events (Barash's Clinical Anesthesia, 9e).

Smoking also independently increases perioperative pulmonary risk beyond COPD severity - it is not merely a surrogate marker for lung disease (Fishman's Pulmonary Diseases).

3. Preoperative Assessment of Smokers

Key elements to evaluate:

Pack-year history and duration of smoking
Symptom review: cough, sputum, dyspnea, wheeze (suggesting COPD, chronic bronchitis, or asthma overlap)
Exercise tolerance as a functional capacity surrogate
Spirometry: Not mandated for most noncardiothoracic surgery, but indicated when symptoms or exam suggest significant airflow obstruction
Chest X-ray: Identifies structural abnormalities but has limited perioperative predictive value for most patients
Exhaled CO levels: Can be measured preoperatively to confirm smoking status and assess COHb burden
ASA physical status classification: Smoking contributes to ASA II or higher classification

4. Smoking Cessation Before Surgery

This is one of the most evidence-based and impactful preoperative optimisation interventions.

Timeline of Benefits

Time After Quitting	Benefit
12-24 hours	COHb levels fall; oxygen delivery improves
2 days	COHb decreases, nicotine effects abolished, mucociliary clearance begins to improve
1-2 weeks	Cyanide levels fall; mitochondrial oxidative metabolism improves; vasodilatation improves
4-8 weeks	Reduction in postoperative pulmonary complications; wound healing benefits; considered the minimum optimal window
>8 weeks	Near-maximal reduction in postoperative respiratory complications

The landmark randomised controlled trial by Moller et al. (hip and knee surgery) found overall complication rates of 18% in the smoking cessation arm vs. 52% in controls, with wound complications 5% vs. 31% respectively (Murray & Nadel's).

A meta-analysis of six trials found that smoking cessation:

Reduced postoperative complications by 41% overall
Each week of cessation increased the magnitude of benefit by 19%

There is no evidence that quitting within 8 weeks of surgery increases perioperative risk (a concern from older studies). Motivated patients should be encouraged to quit at any point before surgery (Miller's Anesthesia, 10e).

Pharmacological Aids for Cessation

Nicotine Replacement Therapy (NRT): Patches, gum, lozenges - first-line recommended approach
Varenicline: Should be started at least one week before the quit date; recommended for perioperative cessation
Bupropion / e-cigarettes: Role in the perioperative setting remains unclear; not strongly recommended
Brief preoperative interventions alone are less effective than intensive multi-component programs (health professional visits + psychoeducational support + pharmacotherapy)

The preoperative evaluation clinic represents a key "teachable moment" - population-based survey data confirm significantly higher smoking cessation rates after major surgery (Miller's Anesthesia, 10e).

5. Intraoperative Management

Airway Management

Smokers should be considered at higher risk for bronchospasm during airway manipulation
Preoperative inhaled bronchodilators (e.g., salbutamol) are beneficial and should be given to smokers with significant airway reactivity before intubation
Consider deeper plane of anesthesia before intubation or use of a supraglottic airway device where appropriate to reduce stimulation of hyperreactive airways
Increased secretions may necessitate more suctioning intraoperatively

Oxygenation

Smokers have higher baseline COHb; supplemental oxygen delivery is critical throughout
Impaired oxygen delivery from COHb must be considered when interpreting SpO₂ - standard pulse oximetry cannot distinguish COHb from oxyhaemoglobin; co-oximetry may be needed in heavy smokers
Risk of intraoperative atelectasis is increased; adequate PEEP and lung-protective ventilation strategies apply

Volatile Anesthetics

Volatile agents inhibit mucociliary clearance and can increase alveolar-capillary permeability
They can blunt the ventilatory response to hypoxia at subanesthetic concentrations - a particular concern in the context of already impaired oxygen delivery from COHb

6. Postoperative Management

PACU monitoring: Smokers are at higher risk for respiratory complications including bronchospasm, retained secretions, and desaturation
Postoperative bronchospasm: Especially in heavy smokers; treat with nebulised bronchodilators
Pulmonary toilet: Encourage coughing, deep breathing exercises, early mobilisation, and incentive spirometry - critical in smokers who already have impaired ciliary function
Analgesia: Adequate analgesia is essential to enable deep breathing; regional techniques where feasible reduce splinting from pain
Supplemental oxygen: Continue until SpO₂ is consistently maintained on room air
Wound surveillance: Heightened vigilance for wound infection and breakdown
Patients with COPD who are CO₂ retainers need careful oxygen titration to avoid abolishing hypoxic drive

7. Vaping and E-cigarettes

Vaping is increasingly prevalent, especially among young adults. While large trials are lacking, case reports and series describe increased airway reactivity and anesthetic complications due to pulmonary interstitial changes from e-cigarette use (vaping-associated lung injury, EVALI). These patients warrant the same heightened airway precautions as traditional smokers (Barash's Clinical Anesthesia, 9e).

Summary Table

Phase	Key Consideration
Preoperative	COHb elevation, airway reactivity, mucociliary dysfunction, COPD assessment, cessation counselling
Induction	Increased risk of bronchospasm; pretreat with bronchodilators
Intraoperative	Impaired oxygenation, secretions, volatile agents worsen mucociliary clearance
PACU	Bronchospasm, desaturation, retained secretions, bronchopneumonia risk
Postoperative	Wound complications (RR 2.2), infections, pulmonary complications, delayed healing
Cessation counselling	Best at 4-8 weeks before surgery; NRT + varenicline + behavioural support; any cessation is beneficial

Sources:

Barash, Cullen, and Stoelting's Clinical Anesthesia, 9e - [Smoking section, p. 1775-1776]
Miller's Anesthesia, 10e - [Perioperative smoking cessation, p. 3955-3956]
Morgan and Mikhail's Clinical Anesthesiology, 7e - [Smoking & Alcohol Cessation, p. 2101-2102]
Murray & Nadel's Textbook of Respiratory Medicine - [Wound Healing/Postoperative Complications; Measures to Reduce Risk]
Fishman's Pulmonary Diseases and Disorders - [Measures to Reduce Risk, p. 1835]

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