Smoking Flashcards
What are the respiratory effects of smoking?
• Airway hyper-reactivity, especially small airways
• Reduced mucociliary clearance
• Increased mucus secretion
• A change in epithelial permeability
• Altered surfactant and hence compliance
• Small airway narrowing • V/Q mismatch
What are the cardiovascular effects of smoking?
include: • Hypertension (due to chronic nicotine exposure and atherosclerotic change). • Increased catecholamine levels (15–50 ng/L). • Reduced oxygen uptake and shift in the oxygen dissociation curve to the left caused by carboxyhaemoglobin. • Increased haemoglobin values in long-standing smokers secondary to relative hypoxaemia and carboxyhaemoglobin. • A predisposition to thrombosis due to the increased haemoglobin together with damage to vascular endothelium. Endothelin is released resulting in a negative effect on nitric oxide dynamics and altering superoxide production. It acutely affects clot dynamics and thrombin structure and thus is thrombogenic. Curiously, cigarette smoke may have a synergistic effect with clopidogrel reducing platelet aggregation but in general should be considered thrombogenic.
The immunological effects of smoking are diverse but include reduced phagocytic and cytotoxic T-cell activity. There is som
Smoking is associated with enzyme induction so there may be an altered response to some drugs although the clinic
In the postoperative phase, smokers are more prone to hypoxaemia, have slightly higher PCO2 , have more change in pulmonary function tests, with a reduction in FEV1 /FVC ratio suggesting greater small airway obstruction. Pulmonary complications were doubled in one series and in major surgery time to extubation, ICU stay and hospital stay were all increased.
What are the benefits of stopping smoking preoperatively?
Which preoperative investigations would be appropriate?
How does smoking affect pulse oximetry?
Oxygen saturation monitor may overestimate SaO2 if there is significant carboxyhaemoglobin content.
Smoking greater than 20 cigarettes a day is associated with a carboxyhaemoglobin <4% and this will fall fairly rapidly after stopping smoking, so the P50 will be returning to normal at 12 hours, or faster if receiving an increased inspired oxygen concentration. T
Choice of anesthetic?
regional technique may be preferred where feasible and may allow more effective physiotherapy postoperatively.
GA concerns
irritable airways and there may be a nicotine-mediated exaggerated pressor response to intubation. This may be obtunded with lidocaine applied locally. Spontaneous breathing, unless deep, may be problematic with coughing.
Postoperative concerns
Early active physiotherapy should be instigated if there are chronic lung problems.
○ The risk of secondary infection is increased as is the likelihood of postoperative complications generally.
○ It is wise to continue enhanced oxygen by mask for 24 hours minimum.
The incidence of postoperative nausea and vomiting is reduced amongst smokers.
