Anesthetic considerations in patients with chronic pulmonary diseases

MINERVA ANESTESIOL 2004;70:279-84

Anesthetic considerations in patients with chronic pulmonary diseases D. HENZLER, R. DEMBINSKI, R. KUHLEN, R. ROSSAINT

Aim. Increasing age and co-morbidities of patients admitted for surgery impose new challenges on the anesthesiologist. Methods. Review of current literature regarding the perioperative management of patients with chronic pulmonary disease. Results. If patients are treated adequately, surgery can be safely performed under regional and general anaesthesia. Major risk factors include type of surgery, type and duration of anesthesia, general health status and smoking history, but not certain lung function parameters. Regional anesthesia remains the first choice for intra- and postoperative care, and if general anesthesia is necessary, early extubation should be achieved. Non-invasive ventilation could be a possible alternative in weaning failure. Conclusion. Assessing the functional status of patients admitted to surgery remains a difficult task, and in patients identified at risk by clinical examination additional spirometry and blood gases may be helpful. If there are signs of respiratory failure, the anaesthe tist should monitor the patient closely and invasively, yet there is no reason to deny any patient a substantially beneficial operation. Key words: Pulmonary disease, chronic obstructive - Intraoperative complications - Perioperative care - Postoperative care-anesthesia, conduction

Department of Anesthesiology, University Hospital, RWTH Aachen, Aachen, Germany

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nesthesiologists are increasingly confronted with patients admitted for elective and emergency surgery, who present with more co-morbidities than those considered to be inoperableonly a few years ago. Especially chronic pulmonary disease has developed to a major burden of civilisation with increasing prevalence. Expressed as disability adjusted life years (DALY) lost, which is the sum of years lost due to severe disability and premature mortality, chronic pulmonary disease has ranked 12th in 1990 and is predicted to rank 5th in 20201 of all diseases world-wide. Constant advances in anesthetic techniques have shown that safe conduction of anesthesia is possible under a variety of pathologic conditions, and this has led to abandon classical contraindications against anesthesia, for example a certain lung function parameter2,3. This article presents a review on recent published studies and recommendations for practical use. Preoperative risk assessment and preparation

Address reprint requests to: Dr. Dietrich Henzler, MD, Deparment of Anesthesiology, University Hospital, RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany. E-mail [email protected].

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For safe conduction of anesthesia it is necessary to assess the risk for perioperative

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ANESTHETIC CONSIDERATIONS IN PATIENTS WITH CHRONIC PULMONARY DISEASES

TABLE I. — Clinical symptoms of chronic pulmonary diseases. Symptom

Clinical correlate

Orthopnoea, dyspnoea

Pulmonary and cardiac impairment ”happy wheezer”, ”pink puffer” COPD Cyanosis Right-left shunt, severe restriction ”barrel chest”, decreased breath Emphysema sounds Prolonged expiration, wheeze Asthma Rough breath sounds Pulmonary oedema, pneumonia, secretion retention Fine crackels Pneumonia, atelectasis, fibrosis Friction sounds Pleuritis Inspiratory stridor Interstitial oedema Expiratory stridor COPD, asthma

complications given the specific disease and operation, the method of choice for anaesthetic technique and the specific advantages/risks for certain surgical procedures (e.g., minimal invasive techniques). Therefore, subtle questioning and a throughout clinical examination should stand before performing any anesthetic procedure. Common symptoms and clinical findings with the concordant diagnosis are summarised in Table I. In the absence of clear cut guidelines the American Society of Anesthesiologists (ASA) has conducted a survey on preoperative lung function testing4, which showed that routine testing for all patients was not considered, but 98% of anesthesiologists ordered lung function tests in specific patients. Of these, in 68% asthma, 80% COPD and 53% significant scoliosis were present. Still the Task Force believed that “there is insufficient evidence to identify explicit decision parameters or rules for ordering preoperative tests on the basis of specific clinical characteristics...”. A review on preoperative evaluation of lung function was given previously5, which did not reveal specific parameters of lung function predictive of postoperative complications. Just the existence of COPD incorporated an increased risk, as it would be represented in general assessment scores, like the ASA physical health score, anyway. The highest predictive

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parameter was upper abdominal or thoracic surgery. Fisher et al.6 have done a systematic review on blinded studies, but of a total of 16 singular parameters reported (one of them COPD), only duration of anaesthesia and postoperative placement of a nasogastric tube were independently associated with increased risk of postoperative pulmonary complications. Arozullah et al.7,8 have published the largest single study investigating a newly developed risk index for postoperative respiratory failure (181 109 patients) or postoperative pneumonia (316 071 patients) in nonthoracic surgery. COPD was a major predictor of complications in both studies (respiratory failure: RR(CI) 1.81(1.66-1.98); pneumonia 1.72(1.55-1.91), but was outweighed by far from type of surgery (upper abdominal: respiratory failure: 4.21(3.8-4.67); pneumonia 4.29(3.34-5.5). Unfortunately, no risk adjustment had been calculated for COPD, and no spirometry data had been evaluated. More concise data is reported from a very recent series of 272 patients undergoing noncardiothoracic surgery9. Clinical preoperative assessment and postoperative complications were collected independently and analysed for predictors. Besides age >65 and history of >40 pack years of smoking, COPD, asthma, productive cough and exercise intolerance of less than 1 flight of stairs was associated with significantly increased risk of postoperative pulmonary complications. More interestingly, physical examination with symptoms of airflow obstruction [e.g. expiratory time ≥ 9 sec.: OR 5.7 (2.3-14.2)] were strong predictors, but type of surgery were not. Reduced FEV1 7.9(1.7-37)), hypercarbia 61 (3.8-986) and hypoxia 13.4 (1.3-14.1) also indicated precisely the occurrence of postoperative pulmonary complications. A summary of risk factors is given in Table II. The role of nicotine cessation before anesthesia in reducing pulmonary complications has been investigated by Warner et al.10,11, showing an increased complication rate if patients quit smoking for less that 8 weeks before operation, but less complications if they quit smoking for more that 8 weeks as compared to active smokers. Lung exercise of several weeks can be effective in increasing


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TABLE II. — Risk factors for postoperative pulmonary complications. Patient dependent factors

Surgery dependent factors

Current smoker

Abdominal surgery (open > minimal invasive) Thoracic surgery

Reduced health status (ASA grade >2) Old age (>70 years in pts. Long duration of with COPD) surgery (> 3h) COPD with exercise intolerance General anesthesia (vs. regional anesthesia)

lung function12, and those patients without postoperative pulmonary complications exhibited improvements in lung function, while those with complications were unresponsive to exercises. Oral premedication on the ward should be cautioned, since benzodiazepines have shown to reduce respiratory strength13. In patients with borderline respiratory function, this might just be enough to cause decompensation, and i.v. premedication in the operating theatre just before induction should be considered instead. Intraoperative management During general anesthesia, patients with pulmonary disease are threatened by various unphysiologic conditions. Supine position and positive pressure ventilation can hamper borderline respiratory function by a reduction in FRC and an increase in atelectasis14. This can be reversed in part by application of PEEP15, which per se is not contraindicated in patients with COPD. Especially in COPD patients potential dynamic hyperinflation can lead to life-threatening hypotension16 and should first be treated by disconnecting the patient from the ventilator17. Dynamic hyperinflation can easily be detected by measurement of intrinsic PEEP (PEEPi) by endexpiratory occlusion. PEEPi is the difference of alveolar to ventilator airway expiratory pressure (external PEEP). From simple mathematical calculation, PEEPi can be reduced by increasing external PEEP.

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Importantly, this does not reduce hyperinflation, which can be done only by prolongation of expiratory time18 or reversal of bronchoconstriction, and external PEEP should be set below PEEPi. General anaesthesia has been associated with increased risk for bronchoconstriction and postoperative complications, although there really is no data to support this view. Usually, general anaesthesia can be applied safely2,19. Volatile anaesthetics are even used for rescue therapy in very severe status asthmaticus, due to their bronchodilative properties20. However, induction of anaesthesia should be undertaken with caution, since histamin liberating induction agents, light anaesthesia and mechanical irritation can induce bronchoconstriction. If problems are going to be anticipated, for example in asthmatic children or in awake fiberoptic intubation, pre-treatment with salbutamol might prevent deleterious complications21,22. The addition of lignocaine might be able to enhance the effect. Most modern sedatives and opioids23 can be used safely, even though all (including propofol)24,25 have the potential to trigger bronchoconstriction. However, it must be stressed that deep anaesthesia still is a major prophylactic against bronchoconstriction, in healthy as well as COPD patients. Theoretically, the avoidance of mechanical irritation of the trachea by usage of a laryngeal mask (LMA) might improve lung function. It was indeed demonstrated in healthy patients26 that FEV1, FVC and peak expiratory flow (PEF) postoperatively were higher, if a LMA was used. To reproduce these results in lung diseased patients remains an interesting task for future investigations. In contrast to general anesthesia, regional anaesthesia has the advantage of otherwise unimpaired lung function. However, patients are often unable to lie strictly supine or get progressively uncooperative with worsening hypoxia. Vanek et al.27 have reported a series of 10 patients having undergone off-pump CABG in high thoracic epidural anaesthesia (TEA) without intubation. Another three patients with partial respiratory failure and FEV1 12 hours of mechanical ventilation has been shown to be as high as 31%35, of which 11% presented with chronic pulmonary disease. Mortality of those admitted postoperatively (21% of all patients) was lower (22%) than overall mortality (OR 0.67, 0.59-0.76 95%CI) and was equal to those with COPD (22%). Even if partial respiratory failure persists, early extubation followed by non-invasive ventilation (NIV) could be beneficial. However, so far only medical patients have been evaluated in randomised trials. Ferrer et al.36 have reported shorter mechanical ventilation and length of stay, lower incidence of complications and improved survival in patients with weaning failure if NIV was used as com-


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pared to conventional weaning approach. This was confirmed by a meta-analysis37, showing a positive effect of NIV as a weaning strategy on survival in patients with respiratory failure, most of whom had COPD. Conclusions Assessing the functional status of patients admitted to surgery remains a difficult task, and in patients identified at risk by clinical examination additional spirometry and blood gases may be helpful. Still it is hard to predict, whether the patients condition could be improved, which has to rely on the adequacy of current treatment. Function tests like stairclimbing or the ATS 6-minute-walk-test38 have been proposed, but they lack data of association of a given value with a specific outcome. If there is flow limitation and signs of respiratory failure, the anesthetist should be highly alarmed and monitor the patient closely and invasively, yet there is no reason to deny any patient a substantial beneficial operation. If it is possible, regional anesthesia with preserved spontaneous breathing should be applied. Intubation has also proven to be safe, but fast extubation should be the aim like in any of our patients. The other striking perception is that non-invasive ventilation as a weaning strategy can be effective in improving outcome in patients with chronic pulmonary disease, if the airways can be protected and cleared adequately. The validation for patients with postoperative respiratory failure however has yet to be done in future research. Riassunto Considerazioni di natura anestesiologica nei pazienti affetti da patologie polmonari croniche Obiettivo. L’aumento dell’età e del numero di patologie in comorbilità nei pazienti ricoverati per essere sottoposti a un intervento chirurgico pone nuove sfide per l’anestesista. Metodi. È stata condotta una review aggiornata della letteratura medica riguardante il trattamento perioperatorio dei pazienti affetti da patologia polmonare cronica.

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Risultati. Se i pazienti sono adeguatamente trattati, l’intervento chirurgico può essere eseguito in condizioni di sicurezza sotto anestesia regionale e generale. I principali fattori di rischio comprendono il tipo di intervento chirurgico, il tipo e la durata dell’anestesia, lo stato generale di salute e l’anamnesi positiva per fumo, ma non certi parametri di funzionalità respiratoria. L’anestesia regionale costituisce tuttora la prima scelta durnate l’intevento chirurgico e nel periodo postoperatorio, e qualora sia necessaria l’anestesia generale, bisogna procedere con l’estubazione precoce. La ventilazione non invasiva potrebbe rappresentare una valida alternativa in caso di mancato svezzamento. Conclusioni. La valutazione dello stato funzionale dei pazienti ricoverati per intervento chirurgico rimane un obiettivo di difficile realizzazione; nei pazienti identificati a rischio sulla base dell’esame clinico si possono rivelare utili una spirometria aggiuntiva e un’emogasanalisi. Se ci sono segni di insufficienza respiratoria, l’anestesista deve monitorare attentamente e in modo invasivo il paziente, tuttavia non c’è ragione di impedire al paziente di sottoporsi a un intervento chirurgico in grado di procurare importanti benefici. Parole chiave: Broncopneumopatia cronica ostruttiva Complicanze operatorie - Trattamento perioperatorio Trattamento postoperatorio - Anestesia regionale.

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