Smoking and anesthesia

This topic can come as what are the pulmonary complications in a patient who is a chronic smoker?
Or smoking and the anaesthetist

Smokers and Those Exposed to Second-Hand Smoke with Exposure to tobacco have increased risk for many perioperative complications. 

Smoking affects pulmonary function in many ways 

The irritant smoke causes the following          >decreases ciliary motility 

                                                                        >increases sputum production. 

                                                                      
 which in turn cause increased airway reactivity and development of obstructive disease

Exposure to smoke  1) increases synthesis and release of elastolytic enzymes from alveolar macrophages.

                                 2) damage to the lung tissue is caused by reactive metabolites of oxygen, such as hydroxyl radicals and hydrogen peroxide, which are usually used by the macrophages to kill micro-organisms. 

                                 3)The immunoregulatory function of the macrophages is also changed by cigarette smoking, with changes occurring in the presentation of antigens and interaction with T lymphocytes.

                                  4) direct effects on lung tissue caused by smoking include increased epithelial permeability and changed pulmonary surfactant.

Smokers are more likely to experience 

1) wound infections, 

2) respiratory or airway complications (including oxygen desaturation)

3) severe coughing.

4) Smoking decreases macrophage function,

5) negatively affects coronary flow reserve 

6)causes vascular endothelial dysfunction, hypertension, and ischemia.

Soon after a patient quits smoking, 

1) carbon monoxide levels decrease, which improves oxygen delivery and utilization. 

2) Cyanide levels decrease, which benefits mitochondrial oxidative metabolism. 

3) Lower nicotine levels improve vasodilation, and many toxic substances that impair wound healing decrease.
Pathophysiology of smoking: Early in the disease, 
mild [V with dot above]A/[Q with dot above] mismatch, bronchitic disease, and airway hyperactivity 
  leads to gas trapping + flattened diaphragmatic configuration +and barrel-chest deformity. 
Lung compliance increases significantly so limited elastic recoil prevents complete passive emptying. As a result, many patients exhale forcibly to reduce gas trapping.

• With gas trapping, ventilation and perfusion become increasingly mismatched. 
• Large areas of deadspace ventilation and venous admixture occur. 
• Carbon dioxide elimination is inefficient becauseof dead space ventilation. 
• The typical minute ventilation for patients with advanced obstructive lung disease can be 1.5 to 2 times normal.
• venous admixture produces arterial hypoxemia that is exquisitely sensitive to low concentrations of supplemental oxygen. Gas exchange is further impaired by the increased carboxyhemoglobin concentration that results from inspiring smoke. Normal carboxyhemoglobin concentration in nonsmokers is approximately 1%; in smokers, however, it can be as high as 8 to 10%. Cessation of smoking, even for 12 to 24 hours preoperatively, can decrease CO concentration to near normal.

Smoking is one of the main and most prevalent risk factors associated with postoperative morbidity.COPD patients who smoke have a two- to sixfold risk of developing postoperative pneumonia compared with nonsmokers.

These data further demonstrated that those who quit smoking <8 weeks preoperatively had a higher rate of complication than those who continued to smoke. Normalization of mucociliary function requires 2 to 3 weeks of abstinence from smoking, during which time sputum increases. 

Effective interventions include medical advice and pharmacotherapy, such as nicotine replacement therapy, which is safe in the perioperative period .Nicotine patches, gum, and lozenges are available without a prescription; nasal spray and buproprion (Wellbutrin) require prescriptions. Clonidine is also effective. Buproprion or clonidine should be started 1 to 2 weeks before an attempt at quitting; nicotine replacement therapy 

If patients cannot stop smoking for 4 to 8 weeks preoperatively, it is controversial whether they should be advised to stop smoking 24 hours preoperatively. A 24-hour smoking abstinence would allow carboxyhemoglobin levels to fall to normal .