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* From the Department of Anesthesiology and
Division of Pulmonary and Critical Care Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
Address correspondence to: Dr. Juraj Sprung, Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. Phone: 507-255-3298; Fax: 507-255-6463; E-mail: sprung.juraj{at}mayo.edu
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Abstract |
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 TOP Abstract IntroductionAGE-RELATED CHANGES IN PULMONARY...AGING LUNGS AND PERIOPERATIVE...MINIMIZING PULMONARY...References |
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Source: A MEDLINE-based English-language literature search was undertaken for the period 1966–2006, and an EMBASE search covered the overlapping period 1988–2006. Selected articles were limited to those applying to elderly subjects/patients.
Principal findings: Age-related loss of the lung static recoil forces, stiffening of the chest wall and diminished alveolar surface area lead to a decrease in vital capacity, an increase in residual volume, decrease in expiratory flows and increased ventilation-perfusion heterogeneity. Respiratory muscle strength consistently declines with age further increasing the work of breathing. While gas exchange may be well preserved at rest and during exertion, pulmonary reserve is diminished, and under conditions of positive fluid balance, positioning for surgery, and increased metabolic demand, postoperative respiratory failure can occur. Increased sensitivity to respiratory depressants and muscle weakness pose additional risks for the development of postoperative respiratory complications in elderly patients. Regional anesthetic techniques provide for superior postoperative analgesia, without necessarily altering the frequency of postoperative pulmonary complications in the older surgical population.
Conclusion: Alterations in respiratory physiology associated with aging must be appreciated to anticipate and minimize potential complications associated with surgery and anesthesia in the elderly. Individualized care to optimize preoperative cardiorespiratory function, minimize intraoperative respiratory pertubations, and to gently restore postoperative pulmonary function are essential anesthetic goals for elderly patients who require surgery.
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Introduction |
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TOPAbstractIntroductionAGE-RELATED CHANGES IN PULMONARY...AGING LUNGS AND PERIOPERATIVE...MINIMIZING PULMONARY...References |
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).
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This review will describe the fundamental changes in respiratory structure and function associated with aging, and how these changes may affect the perioperative course of elderly patients. A MEDLINE-based English-language literature search was undertaken for the period 1966–2006, and an EMBASE search covered the overlapping period 1988–2006. The initial search was performed using the following keywords and terms: "pulmonary function", "surgery", "geriatric an(a)esthesia", "anesthetic agents", "respiratory insufficiency", "respiratory failure", "airway resistance", "respiratory system (lung, chest wall) compliance", "perioperative period", "intraoperative complications", and "perioperative care". Bibliographies of retrieved publications were scanned for additional sources, and selected articles were limited to those applying to elderly subjects/patients.
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AGE-RELATED CHANGES IN PULMONARY FUNCTION |
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TOPAbstractIntroductionAGE-RELATED CHANGES IN PULMONARY...AGING LUNGS AND PERIOPERATIVE...MINIMIZING PULMONARY...References |
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, lower panel).5
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, lower panel).5 The "remodelling" of the chest wall with aging flattens the curvature of the diaphragm, which leads to a reduction in maximal transdiaphragmatic pressure (Pdi).4 Reductions in respiratory muscle mass may also contribute to a decrease in the force produced by respiratory muscle activity. A reduction of skeletal muscle electromyographic activity by as much as 50% in the 70-yr-old individual is attributed to the loss of type II fast-twitch muscle fibres.10 Indeed, in an electrophysiologic study, the electromyographic signal produced by twitch stimulation of the phenic nerve was modestly reduced in the elderly (mean age 73) compared to younger subjects (mean age of 29).11 As a result, during voluntary maximal inspiratory effort Pdi is lower in elderly than in younger patients and this may predispose to diaphragmatic fatigue;12 in clinical settings this may translate into difficulties in weaning a patient from the ventilator.
Age-related changes in pulmonary mechanics, gas exchange and respiratory control
Static lung volumes
The overall effect of loss of inward elastic recoil of the lung with aging is somewhat balanced by the decline in chest wall outward force such that the total lung capacity (TLC) remains unchanged. However, at relaxed end-expiration, the rate of decrease in lung recoil with aging exceeds that of the chest wall, such that functional residual capacity (FRC) increases by 1 to 3% per decade (Figure 2). Because TLC remains unchanged, an increase in residual volume (5 to 10% per decade) results in a decrease in vital capacity (VC). After age 20, VC decreases 20 to 30 mL per year. The ratio of RV to TLC increases from 25% at 20 yr to 40% in a 70-yr-old subject.
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).13 After age 65, the decrease of FEV1 is on average 38 mL per year.14 Chronic smoking dramatically intensifies these age-related changes.15 In healthy elderly subjects from 65 to 85 yr of age, the normal FEV1/FVC ratio may be as low as 65% to 55%, and the rule of thumb that 70% represents the lower limit of the normal range for the FEV1/FVC ratio is not applicable.16 Lung function gradually deteriorates with aging even in individuals who attempt to maintain aerobic capacity over the sixth and seventh decades of life.2,3 Surprisingly, in these individuals a greater decrease in FVC compared to FEV1 results in a significant increase in the FEV1/FVC ratio.2
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).18
Maximal expiratory air-flow
Both peak expiratory flow and maximal inspiratory flow rates decrease with aging. The decrease in maximal expiratory flow is attributed to the loss of static lung elastic recoil pressure. These changes lead to an increase in the critical transmural pressure causing a dynamic compression of airways leading to increased upstream resistance, i.e., to expiratory airflow limitation. 19–21 This expiratory airflow limitation in elderly subjects causes significant alteration of the ventilatory response to exercise compared to younger adults.22 Figure 4 shows a maximal flow-volume loop and two tidal flow-volume loops (the first measured during rest and the second during maximal exercise) for subjects aged 39, 70 and 88 yr. It is evident that older subjects have less ventilatory reserve to accommodate the increased ventilatory demand of heavy to maximal exercise due to marked airflow limitation.22 The only strategy to increase minute ventilation in elderly subjects is by increasing the frequency of breathing. At the same time, the expiratory flow rates available to elderly subjects may increase the time required to exhale a given volume, which places further constraints on respiratory rate. Despite these limitations in the response to exercise in aged individuals, carbon dioxide and arterial oxygen homeostasis are generally well-maintained even during maximal exercise.23
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Several factors contribute to this age-related decline in PaO2. In young seated subjects breathing air at rest the alveolar-arterial pressure difference for oxygen (A-aDO2) is between 5 and 10 mmHg. An increase in the A-aDO2 with age (Figure 5A) occurs because of an increase in ventilation/perfusion heterogeneity, thought to be caused by a decrease in alveolar surface area and the above mentioned premature closure of the small airways.27 In addition, increased body mass index (i.e., obesity), which frequently accompanies aging, can contribute to widening of the A-aDO2.
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Regulation of breathing
The breathing pattern changes with age, such that an elderly subject at rest has a lower tidal volume and a higher respiratory rate than a younger subject.31 The mechanism responsible is not known, but it may represent an adaptation to decreases in chest wall compliance.32 In addition, there may be changes in the function of both central chemoreceptors and peripheral mechanoreceptors in the chest wall and lung parenchyma. Compared to younger subjects, elderly individuals have an approximately 50% decrease in their ventilatory responses to hypoxia and hypercapnia.33 Responses to isocapnic hypoxemia during sleep can be even more depressed, and elderly individuals may not arouse from the rapid eye movement phase of sleep until their oxyhemoglobin saturation decreases below 70%. Although in elderly subjects the ventilatory response to hypercapnia is less pronounced than in younger subjects, the ventilatory response to exercise is actually increased. This cannot be explained by either oxyhemoglobin desaturation or increased anaerobiosis.34 Rather, it appears that increased ventilation compensates for increased efficiency of gas exchange, permitting the maintenance of isocapnia during exercise.34
Alterations in respiratory control mechanisms may also contribute to the finding that elderly patients may be less efficient at distinguishing different respiratory stimuli. Thus, a diminished perception of added resistive or elastic ventilatory loads with aging is attributed to altered integration of perception within the central nervous system.35–37 Aging is also associated with a decline in the ability to perceive methacholine-induced bronchoconstriction when compared with younger subjects.28 Blunting of the response to hypoxia and hypercapnia, as well as a lower ability to perceive respiratory sensations such as bronchoconstriction, represent a loss of important protective mechanisms which may result in lesser awareness of the disease and its delayed diagnosis in elderly patients.
Upper airway dysfunction
Loss of muscular pharyngeal support with aging predisposes elderly subjects to upper airway obstruction. In addition, respiratory effort in response to upper airway occlusion in obstructive sleep apnea (OSA) patients (as measured by swings in esophageal pressure) decreases with increasing age,38 and this may impair the ability of the elderly OSA patients to open their airways. Repetitive episodes of upper airway obstruction during sleep occur in 24 to 75% of elderly individuals.39 As measured by the apnea-hypopnea index, the prevalence of sleep-disordered breathing increases with age.40 Chronic hypoxemia may lead to cognitive impairment, and OSA patients who experience frequent oxyhemoglobin desaturation may be more cognitively impaired than OSA patients who do not have similar episodes.39
A deterioration of protective mechanisms of cough and swallowing in the elderly may lead to ineffective clearance of secretions and increased susceptibility to aspiration. Loss of protective upper-airway reflexes is presumably due to an age-related peripheral deafferentation together with a decreased central nervous system reflex activity.41 In addition, an increased prevalence of cerebrovascular and neurologic diseases in the elderly may be associated with dysphagia and an impaired cough reflex leading to the increased likelihood of pulmonary aspiration.41 All the above factors may have significant perioperative implications and contribute to postoperative pneumonia in elderly individuals.42
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AGING LUNGS AND PERIOPERATIVE PULMONARY COMPLICATIONS |
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Mechanisms of postoperative pulmonary complications
Although the causes of postoperative pulmonary complications are multifactorial, current thought emphasizes the importance of changes in chest wall function, which is reflected by the fact that thoracic and upper abdominal surgeries are associated with the higher rates of postoperative pulmonary complications.43 Changes in chest wall function lead to atelectasis, which forms within minutes after the induction of anesthesia, and is an important cause of intraoperative gas exchange abnormalities. Alterations in chest wall function that develop during anesthesia and surgery can persist into the postoperative period for several reasons. First, pain may limit the voluntary actions of the chest wall muscles. Second, surgery in the thoracic and abdominal cavities stimulates afferent nerves that innervate these structures and may result in a reflex inhibition of the respiratory muscles. Third, mechanical disruption of respiratory muscles may directly affect their ability to generate chest wall motion. Although laparoscopic surgical techniques may reduce these effects, they still cause stimulation of visceral afferents that significantly affect respiratory control. The net result of these changes is a decrease in the FRC, an impairment of VC, and a pattern of rapid and shallow breathing.
In addition to the above effects, which pertain to patients of all ages, other considerations apply to the elderly. Awake older non-anesthetized patients have less efficient gas exchange compared to younger subjects, as shown by the increase in both A-aDO2 and physiologic pulmonary shunt (Figure 5A). Supine positioning for anesthesia induces a further decrease in FRC (Figure 2),24 and the arterial oxygenation appears to be related to the relationship between preoperative closing capacity and intraoperative FRC.44 Alveolar gas exchange during anesthesia is less efficient in the elderly (Figure 5B) and an inverse relationship exists between the increased age and arterial oxygenation in spontaneously breathing patients.27,45 On the other hand, changes in chest wall and lung properties that accompany aging may actually help protect the elderly from anesthesia-induced changes in gas exchange. For example, atelectasis in dependent lung regions usually develops after induction of anesthesia. However, Gunnarsson et al.46 found that atelectasis is not a prominent feature in elderly patients with healthy lungs during general anesthesia. Similarly, elderly patients with chronic obstructive pulmonary disease tend to show, at least initially following induction of anesthesia, less formation of atelectasis and less shunting compared with normal patients, due to their chronic lung hyperinflation.47
Risk factors for pulmonary complications
Several factors related to changes in aging respiratory system may contribute to pulmonary complications, as listed in Table I. Decreases in chest wall compliance may increase the work of breathing and increase risk for respiratory failure. Changes in lung mechanics, including an increased tendency for small airway closure, may impair gas exchange and promote atelectasis. Alterations in the control of breathing and increased sensitivity to anesthetic agents in the elderly may increase the incidence of postoperative sleep apnea episodes.
Age
Several studies find age to be a significant independent predictor of risk for perioperative pulmonary complications.42,48,49 For example, in a recent study48 significant multivariate predictors of pulmonary complications after non-thoracic surgery were age > 65 yr, and a smoking history of more than 40 yr. Pedersen et al.50 found that risk factors for perioperative pulmonary complications included patient age older than 70 yr, chronic obstructive lung disease, major surgery, and the use of muscle relaxants during anesthesia. A recent literature review confirmed that advanced age is a risk factor for postoperative pulmonary complications, even after adjustment for other comorbid conditions. 51
General health and cardiopulmonary status
General health status, as assessed by factors such as an American Society of Anesthesiologists physical status classification > 2, poor exercise capacity, and congestive heart failure may be associated with increased pulmonary risk in the elderly.52–54 Gerson et al.55 demonstrated that inability to perform two-minute supine bicycle exercise and increase the heart rate to values > 99 beats·min–1 was the best predictor of perioperative cardiopulmonary complications in patients older than 65 yr undergoing elective abdominal or noncardiac thoracic surgery. Among patients who were able to achieve these exercise criteria, complications occurred in 9.3%, with death in 0.9%. Among those unable to exercise satisfactorily, cardiac or pulmonary complications occurred in 42% with a mortality rate of 7.2%. Similarly, another study found that patients with better exercise tolerance by self-report, walking distance, or cardiovascular classification had lower rates of postoperative pulmonary complications.56 A recent meta-analysis confirmed that congestive heart failure, more prevalent in elderly, represents a significant risk factor for postoperative pulmonary complications.54
Obesity
As in all other age groups, the prevalence of obesity is increasing in the elderly. Aging is associated with weight gain, and 75% of Americans who are clinically obese are between the ages of 51 and 69. Obesity itself does not appear to be a consistent independent risk factor for pulmonary complications after surgery.54,57 However, respiratory system mechanics are abnormal in the obese (e.g., reduced chest wall compliance), which leads to a lower PaO2 both while awake and while anesthetized.26,58 (http://ihcrp.georgetown.edu/agingsociety/pubhtml/obesity2/obesity2.html, accessed May 20, 2006). The effects of obesity on arterial oxygenation may be compounded by advanced age, although this remains to be examined.
Swallowing and aspiration risk
Decreased respiratory muscle strength combined with diminished cough and swallowing reflexes may diminish secretion clearance and increase the risk of aspiration. The elderly frequently receive poor oral care, resulting in oropharyngeal colonization by potential respiratory tract pathogens.59 Regarding aspiration risk, the loss of cough reflex or muscle strength secondary to neurologic disorders, combined with swallowing dysfunction, may predispose the patient to aspiration-induced lung infections.59 For example, in patients with stroke, the prevalence of swallowing dysfunction ranges from 40 to 70% and many of these patients have silent aspiration.59 The risk of aspiration is relatively high in the elderly because of the increased incidence of dysphagia and gastroesophageal reflux. Selective nasogastric tube decompression after abdominal surgery may reduce the risk of postoperative pulmonary complications.60
Anesthesia related factors
Inadequate reversal of muscle relaxation may be an important factor for postoperative complications in the elderly. Beard et al.61 found a fourfold increase in postoperative pulmonary complications among patients who received intraoperative neuromuscular blockers. In general, pulmonary complications were three times higher among patients receiving a long-acting neuromuscular blocker than among those receiving shorter-acting relaxants.62 The rate of postoperative pulmonary complications may be further increased in elderly patients who are overly narcotized, as hypoventilation leading to respiratory acidosis may potentiate the effects of residual neuromuscular blockade. To avoid these problems in the older patient, shorter acting neuromuscular blocking agents should be selected and the adequacy of reversal of neuromuscular block should be tested before tracheal extubation. A recent meta-analysis suggested that the use of short-acting neuromuscular blockers may be of "probable benefit" for reducing postoperative pulmonary complications.60
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MINIMIZING PULMONARY COMPLICATIONS |
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TOPAbstractIntroductionAGE-RELATED CHANGES IN PULMONARY...AGING LUNGS AND PERIOPERATIVE...MINIMIZING PULMONARY...References |
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To minimize perioperative pulmonary complications in the elderly, it is of utmost importance to optimize preoperative respiratory function. This begins with a careful assessment of the patient’s general physical status, with particular attention to the cardiovascular and respiratory system (Table II). Tests such as spirometry, chest radiograms, and arterial blood gases should be obtained as indicated from the history and physical examination as a part of this evaluation, but should not be routinely ordered.51 Specific treatment of any disorder identified should be instituted preoperatively if such treatment is likely to result in improved functional status, so long as the benefit outweighs any risk from surgical delay. For example, any patient with a reversible component of airway obstruction must be treated with bronchodilators and/or corticosteroids while those with pulmonary infection must receive antibiotics. Patients who smoke should be given assistance to quit65,66 and patients with OSA should have their status evaluated and properly treated with measures such as continuous positive airway pressure (CPAP). More intensive postoperative monitoring of oxygenation and ventilation may be required in such patients.
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Conduct of anesthesia/surgery
Surgical techniques
When surgically feasible, laparoscopic techniques should be considered in elderly patients with pulmonary compromise. However, significant changes in postoperative respiratory function can also occur following laparoscopic surgery so that their use does not guarantee a postoperative course free of complications. 60
General vs regional anesthesia
In considering pulmonary complications, there are no convincing data to suggest that pulmonary outcomes differ between general and regional anesthetic techniques, therefore, this should not be the basis for anesthetic choice.60 In particular, regional anesthesia may not necessarily be safer for the lungs of the elderly patient, as techniques such as subarachnoid block may be associated with alterations in chest wall muscle tone that may be poorly tolerated in the elderly, especially individuals with chronic obstructive pulmonary disease.
Intraoperative and postoperative analgesia
As in all patients, appropriate planning for postoperative pain control is necessary. There is a long-standing debate as to whether neuraxial techniques such as epidural analgesia reduce the frequency of postoperative pulmonary complications. Although there is no doubt that regional techniques provide excellent analgesia, their specific benefits with respect to pulmonary outcomes are much less clear.43 A meta-analysis conducted by Rodgers et al.69 concluded that regional techniques may confer a functional benefit, however many of the studies used in this and other meta-analyses have methodological limitations. More recent large clinical trials (not blinded) found few differences in outcomes between those receiving and not receiving epidural analgesia, with the exceptions that: 1) respiratory failure was less frequent for some types of operations, and 2) postoperative pain control was improved by epidural analgesia.70 In a blinded trial, Jayr et al.71 demonstrated that epidural techniques provide superior postoperative analgesia, but do not affect the frequency of postoperative pulmonary complications. In another blinded trial, Norris et al.72 was unable to demonstrate a major outcome benefit of an epidural anesthetic technique, other than slightly shorter times to tracheal extubation. The above findings should not discourage the use of these valuable techniques in the elderly, but the evidence does not support their use to minimize pulmonary complications. The use of a full range of adjunctive analgesia techniques, such as infiltration with local anesthetics, peripheral nerve blocks, non-steroidal anti-inflammatory agents, and others as part of a "multi-modal" approach is appropriate.
Anesthetic drugs and adjuvants
The dosing of all anesthetic drugs should reflect differences in pharmacokinetics and pharmacodynamics that accompany aging. Opioids represent a class of drugs with particular significance to respiratory function in the elderly. As elderly patients may be particularly sensitive to opioid analgesics,73,74 they should be titrated carefully in order to avoid postoperative respiratory depression.
Airway and ventilatory management
As discussed above, elderly patients may have altered upper oropharyngeal reflexes, and in such cases it may be desirable to conduct rapid sequence anesthetic induction in order to prevent pulmonary aspiration. Preoxygenation by performing only four deep breaths prior to induction of anesthesia may be insufficient in the elderly patients, who require a full three minutes of 100% oxygen breathing to avoid oxyhemoglobin desaturation during rapid sequence induction.75 In patients with intact oropharyngeal reflexes but significant reactive airway disease, avoidance of endotracheal intubation by use of devices such as the laryngeal mask airway may be preferable.
As discussed above, atelectasis may be a less important cause of intraoperative hypoxemia during general anesthesia in elderly patients,46 however, in elderly obese patients atelectasis may play a significant role in deterioration of postoperative oxygenation.76 There has been considerable recent interest in maneuvers designed to recruit atelectatic lung regions. A variety of studies have shown that the isolated application of positive end-expiratory pressure (PEEP) does not predictably reverse atelectasis or increase arterial oxygenation.77 To reexpand the atelectatic lung, it is necessary to employ a prolonged VC maneuver with high inflation pressures,78 referred to as a "recruitment maneuver". This maneuver should be followed by sufficient PEEP to maintain the alveolar units open.78,79 A peak opening inspiratory pressure of at least 40 cm H2O is needed to fully reverse anesthesia-induced collapse of healthy lungs,80 and even higher if the patient is grossly obese.58 During a recruitment maneuver, as with application of PEEP, arterial blood pressure needs to be closely monitored, particularly in the dehydrated elderly patient because of its potential to reduce preload and induce hypotension.
Postoperative management
Reversal of drug effects
During the immediate postoperative period it is important to carefully manage all drugs that may weaken the respiratory muscles or affect the drive to breathe. Thus, treatment of pain with opioids, sedation with benzodiazepines, and incomplete elimination of residual inhalational anesthetics may reduce the respiratory response to chemical (hypoxemia, hypercapnia) and mechanical load (increased airway resistance), and may result in hypoventilation and hypoxemia. The same concerns apply to patients who have their muscle relaxation inadequately reversed. The elderly may be especially sensitive to these considerations, not only because of altered pharmacokinetics and pharmacodynamics, 74 but because of the diminished functional reserve of their respiratory system.
Lung expansion maneuvers (incentive spirometry, intermittent positive-pressure breathing)
These maneuvers are the mainstay for postoperative prevention of pulmonary complications in the elderly. Presumably, lung expansion maneuvers lower the risk of atelectasis by increasing the mean lung volume, although the exact mechanism of benefit remains unclear. When effectively performed, these techniques may reduce the risk of pulmonary complications by approximately half.81 In addition to these maneuvers, postoperative care of elderly patients should always include early mobilization, as well as the liberal use of more upright positions that increase FRC and may significantly improve gas exchange.24
Non-invasive ventilation
Elderly patients with altered respiratory function may need support to maintain ventilation after extubation in the immediate postoperative period. To avoid tracheal reintubation in patients recovering from acute respiratory failure, some have tried to use non-invasive positive-pressure ventilation through a tightly fitting nasal mask with bilevel positive airway pressure (BiPAP). With BiPAP, inspiratory positive airway pressure (used to provide inspiratory assistance) and expiratory positive airway pressure (used to prevent alveolar closure) can be adjusted independently. Bilevel positive airway pressure delivers CPAP but also senses when an inspiratory effort is being made and delivers a higher pressure during inspiration, therefore it is more efficient in supporting breathing. There is considerable variation amongst studies reporting the outcome of BiPAP in the setting of acute respiratory failure.82–84 In theory, BiPAP should minimize the decline in lung volume after surgery and may reduce pulmonary complications, but this possibility has not been studied. It has been shown that the use of CPAP may decrease the incidence of tracheal reintubation and other severe complications in patients who develop hypoxemia after elective major abdominal surgery.85
Prolonged postoperative mechanical ventilation in the elderly
An increasing number of elderly patients receive intensive care treatment after surgery. Because of underlying pulmonary disease, loss of muscle mass, and other comorbid conditions, older persons have increased risk of developing respiratory failure requiring mechanical ventilation86 in response to a variety of physiologic insults, including surgery. In patients with adult respiratory distress syndrome older age is clearly associated with higher mortality rates.87,88 Similar data specific to mechanical ventilation made necessary by postoperative pulmonary complications are not available. Ely et al.89 prospectively studied whether age represents an independent effect on the outcomes of patients requiring mechanical ventilation after admission to an intensive care unit. After adjustment for severity of illness, elderly patients spent a similar amount of time on mechanical ventilation and in the intensive care unit. This suggests that chronologic age should not be a restriction for mechanical ventilation in elderly patients with respiratory failure.89 Nonetheless, age-related alterations of the respiratory system may impact respiratory fitness and may, at least theoretically, contribute to failure to wean from the ventilator.90 Factors known to affect weaning include a decrease in lung elasticity, reduction in FVC, decreased respiratory muscle strength, and decreased chest wall compliance. Long-term ventilator dependence (defined as need for mechanical ventilation for more than six hours per day for more than 21 days) complicates up to 20% of the episodes of mechanical ventilation treated in the intensive care units. Long-term ventilator dependence falls disproportionately to patients aged 70 yr or older.91
Conclusion
Progressive changes in lung and chest wall compliance and the changes in lung morphometry lead to ventilation perfusion mismatching and diminished efficiency of gas exchange in the elderly. Respiratory muscle strength consistently declines with age in a setting where reduced chest wall compliance may increase the work of breathing. Increased sensitivity to respiratory depressants, diminished protective airway reflexes and altered response to hypoxemia with increasing age may pose additional risks for the development of postoperative respiratory complications. Anesthesiologists must be aware of these factors and provide close monitoring and vigorous respiratory care to elderly patients undergoing surgery and anesthesia.
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Acknowledgments |
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Accepted for publication July 21, 2006. Revision accepted September 12, 2006.
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2 Pollock ML, Mengelkoch LJ, Graves JE, et al. Twenty-year follow-up of aerobic power and body composition of older track athletes. J Appl Physiol 1997; 82: 1508–16.
3 McClaran SR, Babcock MA, Pegelow DF, Reddan WG, Dempsey JA. Longitudinal effects of aging on lung function at rest and exercise in healthy active fit elderly adults. J Appl Physiol 1995; 78: 1957–68.
4 Zaugg M, Lucchinetti E. Respiratory function in the elderly. Anesthesiol Clin North America 2000; 18: 47–58.[Medline]
5 Turner JM, Mead J, Wohl ME. Elasticity of human lungs in relation to age. J Appl Physiol 1968; 25: 664– 71.
6 Crapo RO. The aging lung. In: Mahler DA (Ed.). Pulmonary Disease in the Elderly Patient. NY: Marcel Dekker; 1993: 1–21.
7 Campbell EJ, Lefrak SS. How aging affects the structure and function of the respiratory system. Geriatrics 1978; 33: 68–74.[Medline]
8 Verbeken E, Cauberghs M, Mertens I, Clement J, Lauweryns JM, Van de Woestijne KP. The senile lung. Comparison with normal and emphysematous lungs. 2. Functional aspects. Chest 1992; 101: 800–9.
9 Murray JF. Aging. In: Murray JF (Ed.). The Normal Lung. PA: W.B. Saunders: 1986: 339–60.
10 Larsson L. Histochemical characteristics of human skeletal muscle during aging. Acta Physiol Scand 1983; 117: 469–71.[Medline]
11 Polkey MI, Harris ML, Hughes PD, et al. The contractile properties of the elderly human diaphragm. Am J Respir Crit Care Med 1997; 155: 1560–4.[Abstract]
12 Tolep K, Higgins N, Muza S, Criner G, Kelsen SG. Comparison of diaphragm strength between healthy adult elderly and young men. Am J Respir Crit Care Med 1995; 152: 677–82.[Abstract]
13 Knudson RJ, Slatin RC, Lebowitz MD, Burrows B. The maximal expiratory flow-volume curve. Normal standards, variability, and effects of age. Am Rev Respir Dis 1976; 113: 587–600.[Medline]
14 Brandstetter RD, Kazemi H. Aging and the respiratory system. Med Clin North Am 1983; 67: 419–31.[Medline]
15 Griffith KA, Sherrill DL, Siegel EM, Manolio TA, Bonekat HW, Enright PL. Predictors of loss of lung function in the elderly: the Cardiovascular Health Study. Am J Respir Crit Care Med 2001; 163: 61–8.
16 Enright PL, Kronmal RA, Higgins M, Schenker M, Haponik EF. Spirometry reference values for women and men 65 to 85 years of age. Cardiovascular health study. Am Rev Respir Dis 1993; 147: 125–33.[Medline]
17 Niewoehner DE, Kleinerman J. Morphologic basis of pulmonary resistance in human lung and effects of aging. J Appl Physiol 1974; 36: 412–8.
18 Fowler RW, Pluck RA, Hetzel MR. Maximal expiratory flow-volume curves in Londoners aged 60 years and over. Thorax 1987; 42: 173–82.[Abstract]
19 Hyatt RE, Flath RE. Influence of lung parenchyma on pressure-diameter behavior of dog bronchi. J Appl Physiol 1966; 21: 1448–52.
20 Hyatt RE. Expiratory flow limitation. J Appl Physiol 1983; 55(1 Pt 1): 1–7.
21 Babb TG, Rodarte JR. Mechanism of reduced maximal expiratory flow with aging. J Appl Physiol 2000; 89: 505–11.
22 DeLorey DS, Babb TG. Progressive mechanical ventilatory constraints with aging. Am J Respir Crit Care Med 1999; 160: 169–77.
23 Johnson BD, Badr MS, Dempsey JA. Impact of the aging pulmonary system on the response to exercise. Clin Chest Med 1994; 15: 229–46.[Medline]
24 Craig DB, Wahba WM, Don HF, Couture JG, Becklake MR. "Closing volume" and its relationship to gas exchange in seated and supine positions. J Appl Physiol 1971; 31: 717–21.
25 Raine JM, Bishop JM. A-a difference in O2 tension and physiological dead space in normal man. J Appl Physiol 1963; 18: 284–8.[Medline]
26 Cerveri I, Zoia MC, Fanfulla F, et al. Reference values of arterial oxygen tension in the middle-aged and elderly. Am J Respir Crit Care Med 1995; 152: 934– 41.[Abstract]
27 Wahba WM. Influence of aging on lung function--clinical significance of changes from age twenty. Anesth Analg 1983; 62: 764–76.
28 Guenard H, Marthan R. Pulmonary gas exchange in elderly subjects. Eur Respir J 1996; 9: 2573–7.[Abstract]
29 Neas LM, Schwartz J. The determinants of pulmonary diffusing capacity in a national sample of U.S. adults. Am J Respir Crit Care Med 1996; 153: 656–64.[Abstract]
30 Thurlbeck WM, Angus GE. Growth and aging of the normal human lung. Chest 1975; 67(2 Suppl): 3S–6S.
31 Krumpe PE, Knudson RJ, Parsons G, Reiser K. The aging respiratory system. Clin Geriatr Med 1985; 1: 143–75.[Medline]
32 Mahler DA, Rosiello RA, Loke J. The aging lung. Clin Geriatr Med 1986; 2: 215–25.[Medline]
33 Peterson DD, Pack AI, Silage DA, Fishman AP. Effects of aging on ventilatory and occlusion pressure responses to hypoxia and hypercapnia. Am Rev Respir Dis 1981; 124: 387–91.[Medline]
34 Brischetto MJ, Millman RP, Peterson DD, Silage DA, Pack AI. Effect of aging on ventilatory response to exercise and CO2. J Appl Physiol 1984; 56: 1143–50.
35 Tack M, Altose MD, Cherniack NS. Effect of aging on respiratory sensations produced by elastic loads. J Appl Physiol 1981; 50: 844–50.
36 Tack M, Altose MD, Cherniack NS. Effect of aging on the perception of resistive ventilatory loads. Am Rev Respir Dis 1982; 126: 463–7.[Medline]
37 Manning H, Mahler D, Harver A. Dyspnea in the elderly. In: Mahler D (Ed.). Pulmonary Disease in the Elderly Patient. NY: Marcel Dekker; 1993: 81–111.
38 Krieger J, Sforza E, Boudewijns A, Zamagni M, Petiau C. Respiratory effort during obstructive sleep apnea: role of age and sleep state. Chest 1997; 112: 875–84.
39 Ancoli-Israel S, Coy T. Are breathing disturbances in elderly equivalent to sleep apnea syndrome? Sleep 1994; 17: 77–83.[Medline]
40 Hoch CC, Reynolds CF 3rd, Monk TH, et al. Comparison of sleep-disordered breathing among healthy elderly in the seventh, eighth, and ninth decades of life. Sleep 1990; 13: 502–11.[Medline]
41 Marik PE, Kaplan D. Aspiration pneumonia and dysphagia in the elderly. Chest 2003; 124: 328–36.
42 Rosenthal RA, Kavic SM. Assessment and management of the geriatric patient. Crit Care Med 2004; 32(4 Suppl): S92–105.[Medline]
43 Warner DO. Preventing postoperative pulmonary complications: the role of the anesthesiologist. Anesthesiology 2000; 92: 1467–72.[Medline]
44 Weenig CS, Pietak S, Hickey RF, Fairley HB. Relationship of preoperative closing volume to functional residual capacity and alveolar-arterial oxygen difference during anesthesia with controlled ventilation. Anesthesiology 1974; 41: 3–7.[Medline]
45 Sorbini CA, Grassi V, Solinas E, Muiesan G. Arterial oxygen tension in relation to age in healthy subjects. Respiration 1968; 25: 3–13.[Medline]
46 Gunnarsson L, Tokics L, Gustavsson H, Hedenstierna G. Influence of age on atelectasis formation and gas exchange impairment during general anaesthesia. Br J Anaesth 1991; 66: 423–32.
47 Gunnarsson L, Tokics L, Lundquist H, et al. Chronic obstructive pulmonary disease and anaesthesia: formation of atelectasis and gas exchange impairment. Eur Respir J 1991; 4: 1106–16.[Abstract]
48 McAlister FA, Khan NA, Straus SE, et al. Accuracy of the preoperative assessment in predicting pulmonary risk after nonthoracic surgery. Am J Respir Crit Care Med 2003; 167: 741–4.
49 Arozullah AM, Daley J, Henderson WG, Khuri SF. Multifactorial risk index for predicting postoperative respiratory failure in men after major noncardiac surgery. The National Veterans Administration Surgical Quality Improvement Program. Ann Surg 2000; 232: 242–53.[Medline]
50 Pedersen T, Eliasen K, Henriksen E. A prospective study of risk factors and cardiopulmonary complications associated with anaesthesia and surgery: risk indicators of cardiopulmonary morbidity. Acta Anaesthesiol Scand 1990; 34: 144–55.[Medline]
51 Qaseem A, Snow V, Fitterman N, et al.; Clinical Efficacy Assessment Subcommittee of the American College of Physicians. Risk assessment for and strategies to reduce perioperative pulmonary complications for patients undergoing noncardiothoracic surgery: a guideline from the American College of Physicians. Ann Intern Med 2006; 144: 575–80.
52 Smetana GW. Preoperative pulmonary evaluation. N Engl J Med 1999; 340: 937–44.
53 Wong DH, Weber EC, Schell MJ, Wong AB, Anderson CT, Barker SJ. Factors associated with postoperative pulmonary complications in patients with severe chronic obstructive pulmonary disease. Anesth Analg 1995; 80: 276–84.[Abstract]
54 Smetana GW, Lawrence VA, Cornell JE; American College of Physicians. Preoperative pulmonary risk stratification for noncardiothoracic surgery: systematic review for the American College of Physicians. Ann Intern Med 2006; 144: 581–95.
55 Gerson MC, Hurst JM, Hertzberg VS, Baughman R, Rouan GW, Ellis K. Prediction of cardiac and pulmonary complications related to elective abdominal and noncardiac thoracic surgery in geriatric patients. Am J Med 1990; 88: 101–7.[Medline]
56 Williams-Russo P, Charlson ME, MacKenzie CR, Gold JP, Shires GT. Predicting postoperative pulmonary complications. Is it a real problem? Arch Int Med 1992; 152: 1209–13.[Abstract]
57 Moulton MJ, Creswell LL, Mackey ME, Cox JL, Rosenbloom M. Obesity is not a risk factor for significant adverse outcomes after cardiac surgery. Circulation 1996; 94(9 Suppl): II87–92.
58 Whalen FX, Gajic O, Thompson GB, et al. The effects of the alveolar recruitment maneuver and positive end-expiratory pressure on arterial oxygenation during laparoscopic bariatric surgery. Anesth Analg 2006; 102: 298–305.
59 Marik PE. Aspiration pneumonitis and aspiration pneumonia. N Engl J Med 2001; 344: 665–71.
60 Lawrence VA, Cornell JE, Smetana GW; American College of Physicians. Strategies to reduce postoperative pulmonary complications after noncardiothoracic surgery: systematic review for the American College of Physicians. Ann Intern Med 2006; 144: 596–608.
61 Beard K, Jick H, Walker AM. Adverse respiratory events occurring in the recovery room after general anesthesia. Anesthesiology 1986; 64: 269–72.[Medline]
62 Berg H, Roed J, Viby-Mogensen J, et al. Residual neuromuscular block is a risk factor for postoperative pulmonary complications. A prospective, randomised, and blinded study of postoperative pulmonary complications after atracurium, vecuronium and pancuronium. Acta Anaesthesiol Scand 1997; 41: 1095–103.[Medline]
63 Lawrence VA, Page CP, Harris GD. Preoperative spirometry before abdominal operations. A critical appraisal of its predictive value. Arch Intern Med 1989; 149: 280–5.[Abstract]
64 Warner DO, Warner MA, Offord KP, Schroeder DR, Maxson P, Scanlon PD. Airway obstruction and perioperative complications in smokers undergoing abdominal surgery. Anesthesiology 1999; 90: 372–9.[Medline]
65 Warner DO. Helping surgical patients quit smoking: why, when, and how. Anesth Analg 2005; 101: 481–7.
66 Warner DO. Perioperative abstinence from cigarettes: physiologic and clinical consequences. Anesthesiology 2006; 104: 356–67.[Medline]
67 Celli BR, Rodriguez KS, Snider GL. A controlled trial of intermittent positive pressure breathing, incentive spirometry, and deep breathing exercises in preventing pulmonary complications after abdominal surgery. Am Rev Respir Dis 1984; 130: 12–5.[Medline]
68 Castillo R, Haas A. Chest physical therapy: comparative efficacy of preoperative and postoperative in the elderly. Arch Phys Med Rehabil 1985; 66: 376–9.[Medline]
69 Rodgers A, Walker N, Schug S, et al. Reduction of postoperative mortality and morbidity with epidural or spinal anaesthesia: results from overview of randomised trials. BMJ 2000; 321: 1493.
70 Myles PS, Power I, Jamrozik K. Epidural block and outcome after major surgery (Editorial). Med J Aust 2002; 177: 536–7.[Medline]
71 Jayr C, Thomas H, Rey A, Farhat F, Lasser P, Bourgain JL. Postoperative pulmonary complications. Epidural analgesia using bupivacaine and opioids versus parenteral opioids. Anesthesiology 1993; 78: 666–76; discussion 22A.[Medline]
72 Norris EJ, Beattie C, Perler BA, et al. Double-masked randomized trial comparing alternate combinations of intraoperative anesthesia and postoperative analgesia in abdominal aortic surgery. Anesthesiology 2001; 95: 1054–67.[Medline]
73 Freye E, Levy JV. Use of opioids in the elderly -- pharmacokinetic and pharmacodynamic considerations (German). Anasthesiol Intensivmed Notfallmed Schmerzther 2004; 39: 527–37.[Medline]
74 Turnheim K. When drug therapy gets old: pharmacokinetics and pharmacodynamics in the elderly. Exp Gerontol 2003; 38: 843–53.[Medline]
75 Valentine SJ, Marjot R, Monk CR. Preoxygenation in the elderly: a comparison of the four-maximal-breath and three-minute techniques. Anesth Analg 1990; 71: 516–9.
76 Eichenberger A, Proietti S, Wicky S, et al. Morbid obesity and postoperative pulmonary atelectasis: an underestimated problem. Anesth Analg 2002; 95: 1788–92.
77 Bindslev L, Hedenstierna G, Santesson J, Norlander O, Gram I. Airway closure during anaesthesia, and its prevention by positive end expiratory pressure. Acta Anaesthesiol Scand 1980; 24: 199–205.[Medline]
78 Lachmann B. Open up the lung and keep the lung open. Intensive Care Med 1992; 18: 319–21.[Medline]
79 Rothen HU, Sporre B, Engberg G, Wegenius G, Hedenstierna G. Reexpansion of atelectasis during general anaesthesia may have a prolonged effect. Acta Anaesthesiol Scand 1995; 39: 118–25.[Medline]
80 Rothen HU, Sporre B, Engberg G, Wegenius G, Hedenstierna G. Re-expansion of atelectasis during general anaesthesia: a computed tomography study. Br J Anaesth 1993; 71: 788–95.
81 Brooks-Brunn JA. Postoperative atelectasis and pneumonia. Heart Lung 1995; 24: 94–115.[Medline]
82 Esteban A, Frutos-Vivar F, Ferguson ND, et al. Noninvasive positive-pressure ventilation for respiratory failure after extubation. N Engl J Med 2004; 350: 2452–60.
83 Brochard L, Mancebo J, Wysocki M, et al. Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease. N Engl J Med 1995; 333: 817–22.
84 Pennock BE, Kaplan PD, Carlin BW, Sabangan JS, Magovern JA. Pressure support ventilation with a simplified ventilatory support system administered with a nasal mask in patients with respiratory failure. Chest 1991; 100: 1371–6.
85 Squadrone V, Coha M, Cerutti E, et al. Continuous positive airway pressure for treatment of postoperative hypoxemia: a randomized controlled trial. JAMA 2005; 293: 589–95.
86 Sevransky JE, Haponik EF. Respiratory failure in elderly patients. Clin Geriatr Med 2003; 19: 205–24.[Medline]
87 Sloane PJ, Gee MH, Gottlieb JE, et al. A multicenter registry of patients with acute respiratory distress syndrome. Physiology and outcome. Am Rev Respir Dis 1992; 146: 419–26.[Medline]
88 Luhr OR, Karlsson M, Thorsteinsson A, Rylander C, Frostell CG. The impact of respiratory variables on mortality in non-ARDS and ARDS patients requiring mechanical ventilation. Intensive Care Med 2000; 26: 508–17.[Medline]
89 Ely EW, Evans GW, Haponik EF. Mechanical ventilation in a cohort of elderly patients admitted to an intensive care unit. Ann Intern Med 1999; 131: 96–104.
90 Thompson LF. Failure to wean: exploring the influence of age-related pulmonary changes. Crit Care Nurs Clin North Am 1996; 8: 7–16.[Medline]
91 Kleinhenz ME, Lewis CY. Chronic ventilator dependence in elderly patients. Clin Geriatr Med 2000; 16: 735–56.[Medline]
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