Perioperative Abstinence from Cigarettes : Physiologic and Clinical Consequences

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Perioperative Abstinence from Cigarettes
Physiologic and Clinical Consequences

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• Smoking status can affect many perioperative
  outcomes
• by contributing to the pathophysiology of
  diseases such as chronic obstructive pulmonary
  disease and atherosclerosis
• via the acute pharmacologic actions of smoke
  constituents such as carbon monoxide and nicotine
• All smokers requiring surgery are abstinent from
  tobacco for at least some period of time.
• These information is of practical importance to
  anesthesiologists ?
• Clinically relevant effects on anesthetic
  management and periop. outocome

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Mechanisms by which exposure to cigarette smoke
may affect responses of patients undergoing
anesthesia
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• Cardiovascular function
• Respiratory function
• Wound and bone healing
• Nervous system function
• Implications for periop. smoking interventions

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Cardiovascular functionMechanisms of Injury and
Recovery

• Nicotine
• Myocardial work ?
• Sympathetic tone catecholamines ?
• HR, BP, myocardial contractility ?
• Coronary vasoconstriction in pts. with coronary
  a. dz.
• Carbon monoxide
• Carboxy hemoglobin ? O2 carrying capacity ?
• Oxyhemoglobin dissociation cure shifting to Lt.
• ? Exercise-induced angina in smokers with
  coronary a. dz. and frequency of
  ventricular arrhythmias ?
• Cytochrome C oxidase inhibition ? mitochondrial
  respiration ?
• Cyanide

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Cardiovascular functionMechanisms of Injury and
Recovery

• Promotion of atherosclerosis
• endothelial injury, oxidant injury, enhanced
  thrombosis, and adverse effects on blood lipids.
• Abstinence from cigarettes decreases
  cardiovascular risk.
• the risk for all-cause mortality in smokers with
  coronary a. dz. by 1/3
• the time needed to fully realize this benefit is
  estimated to be at least several months.
• Nicotine and carboxyhemoglobin
• relatively brief half-lives (1h and 4h,
  respectively)
• even brief cessation(i.e., over a few hours) is
  plausible.
• Improvement in smoking related dz. such as
  atherosclerosis may occur more slowly.

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Cardiovascular functionPerioperative Risk

• Smoking may contributes to perioperative cardiac
  risk.
• It is not clear whether status as an active
  smoker itselt (apart from the presence of
  smoking-related cardiac dz.) increases the
  periop. risk of cardiac events.
• Most studies have been unable to identify preop.
  smoking status as an independent risk factor for
  major cardiac events during and after either
  cardiac or noncardiac surgery.

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Cardiovascular Risk of NRT (Nicotine Replacement
Therypy)

• NRT is a valuable therapy for tobacco dependence.
• The safety of therapeutic nicotine in pts. with
  cardiovascular dz.
• Overwhelming evidence now supports the safety of
  NRT in pts. with cardiac disease.
• NRT does not affect the patency of experimental
  coronary a. bypass grafts.
• The benefits of NRT to aid pts. with coronary
  heart dz. stop smoking far outweigh the risk of
  continued smoking or NRT itself.
• Other components of cigarette smoke contribute to
  adverse effects.
• The serum concentrations of nicotine produced by
  NRT are less than the peak concentrations
  produced by cigarettes.

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Respiratory FunctionMechanisms of Injury and
Recovery

• Smoking induces an inflammatory state in the
  lung.
• Alveolar macrophage function is impaired in
  smokers compared with nonsmokers.
• Impaired ability to mount an effective response
  to infection.
• Airway epithelial structure and function are
  altered.
• Goblet cell hyperplasia and other structural
  epithelial abnormalities
• Increased airway smooth m. and fibrosis
• Accelerated age-related decline in FEV1
• Response to inhaled bronchoconstrictors is
  increased, but the ability of inhaled
  irritants(eg. capsaicin and citric acid) to
  produce cough is diminished in helthy smokers.
• Depletion of neuropeptides from sensory nn.
  responsible for cough.
• Smokers become more tolerant to inhaled
  irritants.

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Respiratory FunctionMechanisms of Injury and
Recovery

• Recovery process of lung with abstinence.
• Symptoms of cough and wheezing decrease within
  weeks.
• Abstinence slows the accelerated decline in FEV1
  obseved.
• Goblet cell hyperplasia and mucus production
  decreases with cessation.
• Inflammatory markers decrease.
• But, fibrosis, alveolar destruction and smoth m.
  hyperplasia may be permanent.
• Mucociliary clearance seems to at least partially
  improve in smokers, requiring at least 1 week to
  show improvement.

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Respiratory FunctionPerioperative Risk

• Smoking status is a consistent univariate risk
  factor for several periop. pulmonary
  complications (PPCs)
• Respiratory failure, unanticipated ICU admission,
  pneumonia, airway events during induction(cough,
  laryngospasm)
• Excessive production of mucus itself seems to be
  a risk factor for PPCs.
• The sensitivity of upper airway reflexes to
  chemical stimulants(eg. Desflurane) is increased.
• Bronchial mucus transport during general
  anesthesia is slowed compared with nonsmokers.

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Respiratory FunctionEffects of Abstinence on Risk

• Prolonged abstinence from smoking decreases the
  risk of many PPCs.
• At least 12 weeks of abstinence was needed for
  full benefit.
• In terms of reducing PPCs, the longer the
  duration of abstinence is, the better, at least
  within the first few months of cessation.

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Wound and Bone HealingPerioperative Risk and
Mechanism of Injury

• Smokers are more likely to have development of
  postop. wound-related complications.
• Factors decreasing tissue oxygenation
• Nicotine and corbon monoxide
• via pph. vasoconstriction and impaired carrying
  capacity of Hb, respectively
• Function of cells such as fibroblasts and immune
  cells
• Most of these cells express nicotinic Ach
  receptor
• Nicotine could directly inhibit cellular
  responses to injury.
• The healing of bone may also be impaired in
  smokers.
• Significant effects on bone metabolism
• A major risk factor for osteoporosis

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Wound and Bone HealingEffects of Abstinence on
Risk

• Preop. smoking cessation can reduce wound-related
  complications.
• Smoking intervention goup, beginning 6-8 weeks
  preoperatively, has dramatically reduced relative
  risk for wound-related complications.
• Wound infection rate were similar in the
  abstinence group and nonsmoker group.
• Postop. Smoking behavior may also affect the risk
  of complication.
• The rate of nonunion was approximately twice as
  high in pts. who continued smoking after surgery
  compared with non-smokers.
• For smokers who quit postoperatively, their
  nonunion rate approached that of the non-smokers.
  

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Risk of NRT to Wound Healing

• NRT would not contribute to wound-related
  complications.
• During NRT and smoking cessation, microvascular
  responses were significantly improved with before
  cessation.
• The infection rate was not different between
  abstinent smokers who did or did not receive NRT.
• NRT can decrease exposure to higher nicotine
  doses and other smoke constituents.

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Nervous System FunctionMechanisms of Action and
Recovery

• Nicotine activates several subtypes of nicotinic
  acetylcholine receptors (nAChRs).
• Withdrawal symptoms
• When nicotine intake is reduced or eliminated.
• Somatic complaint
• GI Sx. Increased appetite
• Affective symptoms
• craving for cigarettes, depressed mood, anxiety,
  dysphoria
• They may be manifest within hours of abstinence
  from nicotine and may last for several weeks.
• Prevention of these Sx. may be an important
  motivational factor in the maintenance of smoking
  behavior.
• Neuronal nAChRs modulate pain.
• Depending on location and dose, nAChRs in CNS can
  have either pronociceptive or antinociceptive
  effects.

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Nervous System FunctionPerioperative Consequences

• Neuronal nAChRs are inhibited by isoflurane and
  propofol at clinically relevant concentrations.
• The acute administration of nicotine produces a
  small decrease in MAC in mice.
• Cigarette smoking increases both tolerance and
  threshold to painful stimulation.
• Cigarettes is a stress management tool?
• No effect of active nicotine patches on stress or
  nicotine withdrawal compared with placebo
  patches.
• Withdrawal Sx. may be lessened under stressful
  situations that demand forced abstinence, such as
  military training or prisoners.

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Implications for Perioperative Smoking
Interventions

• Chronic exposure to cigarette smoke produces
  profound changes in the physiology of many organ
  systems.
• The periop. period may present unique
  opportunities for smokers to attempt prolonged
  postop. abstinenc.
• NRT has proven to be both safe and effective in
  treating tobacco dependence, even in pts. with
  smoking-related dz.
• The longer the duration of preop. abstinence is,
  the better, especially with regard to pulmonary
  complications.
• Sustained abstinence produces tremendous benefits
  to the long-term health of the surgical pt.(or
  anyone) who smoke.

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