Postoperative respiratory complications and perioperative strategies to prevent them: a review

2014/2015 Catarina Sousa Duque Soares Queirós Postoperative respiratory complications and perioperative strategies to prevent them: a review março, 2015 Mestrado Integrado em Medicina Área: Anestesiologia Tipologia: Monografia Trabalho efetuado sob a Orientação de: Professor Doutor Fernando José Abelha Trabalho organizado de acordo com as normas da revista: Revista da Sociedade Portuguesa de Anestesiologia Catarina Sousa Duque Soares Queirós Postoperative respiratory complications and perioperative strategies to prevent them: a review março, 2015 Projeto de Opção do 6º ano - DECLARAÇÃO DE INTEGRIDADE Eu, Catarina Sousa Duque Soares Queirós, abaixo assinado, nº mecanográfico 200907076 estudante do 6º ano do Ciclo de Estudos Integrado em Medicina, na Faculdade de Medicina da Universidade do Porto, declaro ter atuado com absoluta integridade na elaboração deste projeto de opção. Neste sentido, confirmo que NÃO incorri em plágio (ato pelo qual um indivíduo, mesmo por omissão, assume a autoria de um determinado trabalho intelectual, ou partes dele). Mais declaro que todas as frases que retirei de trabalhos anteriores pertencentes a outros autores, foram referenciadas, ou redigidas com novas palavras, tendo colocado, neste caso, a citação da fonte bibliográfica. Faculdade de Medicina da Universidade do Porto, ___/___/______ Assinatura conforme cartão de identificação: ________________________________________________ Projecto de Opção do 6º ano – DECLARAÇÃO DE REPRODUÇÃO NOME Catarina Sousa Duque Soares Queirós CARTÃO DE CIDADÃO OU PASSAPORTE (se estrangeiro) E-MAIL TELEFONE OU TELEMÓVEL 13955344 [email protected] 918263531 NÚMERO DE ESTUDANTE DATA DE CONCLUSÃO 200907076 2015 DESIGNAÇÃO DA ÁREA DO PROJECTO Anestesiologia TÍTULO MONOGRAFIA Postoperative respiratory complications and perioperative strategies to prevent them: a review ORIENTADOR Professor Doutor Fernando José Abelha COORIENTADOR (se aplicável) Não aplicável É autorizada a reprodução integral desta Dissertação/Monografia (riscar o que não interessa) para efeitos de investigação e de divulgação pedagógica, em programas e projectos coordenados pela FMUP. Faculdade de Medicina da Universidade do Porto, ___/___/______ Assinatura conforme cartão de identificação: ______________________________________________ Index Review 1 Abstract/resumo 3 Abbreviations 6 Introduction 7 Methods 9 Pathophysiology of postoperative respiratory complications 10 Common postoperative respiratory complications 12 Prevention of postoperative respiratory complications 15  Preoperative interventions 15  Intraoperative interventions 20  Postoperative interventions 26 Conclusion 35 References 36 Appendices and tables 44 1 Prevention of postoperative respiratory complications: a review Review Postoperative respiratory complications and perioperative strategies to prevent them: a review Trabalho organizado de acordo com as normas da revista: Revista da Sociedade Portuguesa de Anestesiologia 2 Prevention of postoperative respiratory complications: a review Title in English: Postoperative respiratory complications and perioperative strategies to prevent them: a review Title in Portuguese: Complicações respiratórias no pós-operatório e estratégias perioperatórias para a sua prevenção: uma revisão Authors Catarina Sousa Duque Soares Queirós – medical student Faculdade de Medicina da Universidade do Porto, Portugal Fernando José Pereira Alves Abelha – PhD* Faculdade de Medicina da Universidade do Porto, Portugal Serviço de Anestesiologia – Hospital de São João, Porto, Portugal * Corresponding author Adress for reprints: Fernando José Abelha Alameda da República, 731, 4405-696 – Vila Nova de Gaia, Portugal Telephone: 00351917304213; Fax: 00351967599051 E-mail address: fernando[email protected] Name of the department where the work was performed: Post-Anaesthesia Care Unit at Hospital de São João, Porto, Portugal Department of Anaesthesiology - Hospital de São João, Porto, Portugal Brief title for a heading: Prevention of postoperative respiratory complications: a review 3 Prevention of postoperative respiratory complications: a review Abstract/Resumo Postoperative respiratory complications and perioperative strategies to prevent them: a review Background: Postoperative respiratory complications are the most frequent postoperative complications following thoracic and upper abdominal surgery, playing an important role in the risk for patients undergoing noncardiothoracic surgery. These complications, defined as any pulmonary abnormality occurring in the postoperative period that adversely influences outcomes after surgery, are as prevalent as cardiac complications and contribute similarly to adverse outcomes. Given the high clinical and economical impact of postoperative pulmonary complications, prevention and treatment are issues of major importance for the healthcare team. Objective: In this study, we aim to review the most recent literature about postoperative pulmonary complications, focusing on their pathophysiology and suggesting perioperative strategies to prevent them. Methods: This review was performed using the PubMed database, focusing on the literature of the last 5 years. Results: As far as postoperative respiratory complications are concerned, several strategies of prevention have been used in the last years, with varying degrees of success. These include preoperative, intraoperative and postoperative interventions, some of them really simple and inexpensive. Recent studies suggest that the most effective strategy may be a combined approach, including preoperative assessment and education, evidence based practice in anesthesia, minimally invasive procedures, effective analgesia and early feeding and ambulation. 4 Prevention of postoperative respiratory complications: a review Conclusions: Due to its enormous impact on postoperative outcomes, morbidity, mortality and healthcare resources consumption, PPC are definitely an issue where efficient prevention is needed and must be implemented. This kind of combined approach seems an interesting area for future research, with a great potential of improving patient care and helping healthcare systems. Keywords: postoperative complications; risk factors; prevention; perioperative period; anesthesiolology; outcomes assessment. Complicações respiratórias no pós-operatório e estratégias perioperatórias para a sua prevenção: uma revisão Introdução: As complicações respiratórias pós-operatórias são as complicações mais frequentes após cirurgia torácica ou abdominal superior, desempenhando um papel determinante no risco dos doentes submetidos a cirurgia não-cardiotorácica. Estas complicações, definidas como qualquer alteração pulmonar que ocorra no período pósoperatório e que resulte em efeitos adversos, são tão prevalentes como as complicações cardíacas, contribuindo de forma semelhante para eventos adversos. Tendo em conta o significativo impacto clínico e económico das complicações repiratórias pós-operatórias, a sua prevenção e tratamento são aspetos da maior relevância para os profissionais de saúde. Objetivo: Com este artigo, pretende-se rever a literatura mais recente relativamente às complicações respiratórias pós-operatórias, com destaque para a sua fisiopatologia e estratégias para a sua prevenção. 11 Prevention of postoperative respiratory complications: a review of consciousness), postoperative residual curarization (with increased risk of colapse of upper airway dilators), systemic inflammation, mechanical ventilation 21 and patient related factors (age 22, obesity, obstrutive sleep apnea (OSA), obstructive respiratory pathology and smoking). This dysfunction leads to a difficulty in increasing postoperative lung volumes. 18  Postoperative pain: Postoperative pain also contributes to PRC 4,13,22 due to its effects in impairing lung expansion 9 and in difficulting increases in lung volumes. 18  Decreased lung and chestwall compliance 1,23 All these factors lead to a reduction in FRC and total lung capacity, with a resultant restrictive syndrome 24, failure of the cough mechanisms 25 and ventilation-perfusion mismatch 1,9. This leads to shunt, dead space, hypoxemia 13,19,25,26 and atelectasis 19,27, with subsequent increased risk of other PRC. 12 Prevention of postoperative respiratory complications: a review Common postoperative respiratory complications Atelectasis Atelectasis are the most common PRC 11, occuring in more than 90% of anesthetized patients immediately after induction 28, during either spontaneous breathing or positive pressure ventilation 27, and are predominantly located in dependent lungs (aproximately 15-20% of the parenquima) 1,9,28,29. Three mechanisms contribute to the generation of atelectasis: compression of lung tissue 30 (due to supine positioning 4,18 and surgical material 31), absorption of alveolar air 30, and impairment of surfactant function. 13 In many instances atelectasis do not have a great clinical impact, as they may be transient and self-resolving; however, they cannot be ignored due to its associated increased work of breathing 30 and therefore increased risk of PRC 9,15,18,25,27,30-32. This risk can be even higher if several perioperative factors are presente, such as excessive fluids, transfusion-related acute lung injury, inflammation, sepsis, and aspiration. 26 Hypoxemia Hypoxemia is a common intra and postoperative finding, and one of the most feared events in these settings 33, with a reported incidence of 19% in the Post Anaesthesia Care Unit (PACU). 34 In fact, it is the major problem associated with intraoperative atelectasis and consequent V/Q mismatch 30; other contributing factors include hypoventilation due to pain or residual anesthetics, lung edema due to fluid overload, exacerbation of chronic obstructive pulmonary disease, laryngospasm or bronchospasm. This condition can have a serious impact on outcome, as it can be responsible for complications in other systems beside the respiratory. 27 13 Prevention of postoperative respiratory complications: a review Pneumonia Pneumonia is effectively one of the most frequent PRC, responsible for the highest morbidity and mortality rates 3, along with ARF 12. Pneumonia occurs when bacteria reach the lower respiratory tract, which should be sterile. This colonization is facilitated not only by impaired host defenses secondary to anesthesia-induced respiratory changes but also by the presence of invasive devices, medications altering gastric emptying and pH, contaminated water and respiratory therapy equipment 3. Postoperative pneumonia can be further classified in hospitalacquired or ventilator-associated 3,27. Once it is diagnosed, empirical therapy should be readily instituted while awayting results from cultures, and possible resistant agents should be adequately covered. When these results are available, therapy can be tailored to the agent in an effort to avoid excessive medication. 3 Acute respiratory failure Postoperative ARF is commonly defined as failure to wean from mechanical ventilation within 48 hours of surgery or unplanned reintubation in the postoperative period, and is significantly associated with increased 30-day mortality after surgery. 35 The severity of this condition can range from transient hypoxemia in the early postoperative period to the life-threatening acute respiratory disease syndrome (ARDS). Thus, it can be classified based on the PaO2/FiO2 relationship (partial pressure of oxygen in arterial blood divided by the fraction of inspired oxygen) as mild (PaO2/FiO2 < 300mmHg but >200mmHg), moderate (PaO2/FiO2 < 200mmHg but > 100mmHg), or severe (PaO2/FiO2 < 100mmHg) 12. ARF in the postoperative setting can be caused by failure to oxygenate (hypoxemic respiratory failure, type 1) or failure to ventilate (hypercapnic respiratory failure, type 2). Hypoxemic respiratory failure is more common and occurs when there is a problem at the pulmonary capillary/alveolar interface, usually associated with fluid filling or colapse of alveolar units. Hypercapnic respiratory failure can be due to a 14 Prevention of postoperative respiratory complications: a review central loss of ventilation, decreased activity of the diaphragm or accessory muscle after mechanical injury to the chest, or obesity. 3 In this setting, ARF occurs usually as a consequence of several other PRC such as large atelectasis, pneumonia, ARDS and diaphragmatic paralysis. 18,26 Ventilator-associated lung injury Postoperatively ventilator-associated lung injury (VALI) leads to local and systemic adverse effects 36 and may present as ALI or ARDS 27. These pathophysiological changes occur from the direct effect of high pressure on the lung (barotrauma), damage caused by lung overdistension (volutrauma) and the shear stress of repetitive opening and closing of alveoli (atelectotrauma) 36,37. All these factors lead to the release of proinflammatory mediators with activation of circulating neutrophils that alter endovascular permeability. 27,36,38 If a PRC is suspected, arterial blood gas assessment, sputum culture, chest x-rays and an electrocardiogram should be ordered. Aggressive treatment should readily be instituted, including the combination of antibiotics, physical therapy and ventilatory support. 13 15 Prevention of postoperative respiratory complications: a review Prevention of postoperative respiratory complications Taking into account the high impact of PRC on morbidity, mortality and economics, it is essential to implement all the possible measures to prevent them. In recent years, the management of the surgical patient has changed and a multi-modal effort to enhance postoperative recovery has been adopted, combining the preoperative preparation, intraoperative period and postoperative care. 39 Reduction of the incidence of PRC will require a multifaceted approach involving many clinical disciplines operating at different moments. 1 1. Preoperative interventions: a) Identifying patients with a higher risk of PRC In the preoperative period, the first strategy to prevent PRC should be stratifying the individual risk of the patient, to allow a correct allocation of resources and treatment. 40 A detailed clinical history (with focus on preexisting respiratory diseases, smoking, respiratory symptoms and medications) and a physical examination seem to be the best strategies to predict the risk of PRC 13. Spirometry findings do not correlate well with the risk of PRC in individual patients, so it is not routinely recommended and should be used only in specific settings 14. The same is true for cough tests 13. Pulmonary function tests are also not useful as a general screening tests to assess risk the of PRC 17, being important only in patients undergoing lung resection surgery 13,14. Currently, evidence suggests that chest radiograph only rarely provides new information that influences preoperative management, and therefore it should not be routinely ordered 13,14. 16 Prevention of postoperative respiratory complications: a review Therefore, the identification of patients at an higher risk of PRC remains largely dependent on the presence of certain risk factors, which permit a quick assessment and subsequent planning of the possible optimization 3.  Patient factors: advanced age 4,18,31,41, obesity 18,31,41, lung disease 4,13,18,31,41-44, smoking history (as it leads to reduced lung capacity, increased inflammation, reduced mucus and reduced ciliary function) 4,6,18,41, congestive heart failure 4,13, OSA 4,42,45, obesityhypoventilation syndrome 42, functional dependence 4, renal insufficiency (due to impaired excretion of anaesthetic agents with a subsequent longer duration of action) and hypoalbuminaemia (a marker of poor metabolic reserve) 44 may all be associated with an increased risk of PRC. Preoperative smokers, in particular, can have up to 2.5 times the risk of developing PRC when compared to nonsmokers, along with a significantly increased risk of admission to an ICU. 46  Surgery: type of surgery (higher risk for open and agressive procedures such as thoracoabdominal surgery 4,13,18,22,44,47 and non-midline incisions 40; in general, risk increases with increases in the proximity to the diaphragm 48), duration of the procedure 4,13,31,44, emergency cases 44 and situations associated with great blood losses 13 may also increase the risk of PRC.  Anesthesia: neuromuscular blockers (particularly long acting 22,49 and aminosteroid derivatives 44) are known to increase the risk of PRC, as well as an higher ASA physical status (III or more) 4,41,44. Moreover, a recent study has sugested a higher impairment on postoperative respiratory function from total intravenous anaesthesia when compared to balanced anaesthesia with sevoflurane. 50 17 Prevention of postoperative respiratory complications: a review A study from Canet et al. 51 included 2464 patients and identified seven independent predictors of PRC: age (particularly if older than 80 years), low preoperative SpO2, preoperative anemia, acute respiratory infection in the previous month, intrathoracic or upper abdominal surgery, longer duration of procedure, and emergency surgery. With these seven variables, the authors developed a score to assess the PRC risk of an individual patient. Alcohol intake, snoring, obesity, diabetes, immunosuppression, intraoperative fluid therapy, and postoperative pain did not show any correlation with PRC in this study. In a recent study from Brueckmann et al. 52, the authors investigated risk factors for PRC and developed a 11 point score to predict severe PRC with need of reintubation. The variables used in this score are ASA class (3 points if ≥ III), need for emergency surgery (3 points), staying in a high-risk surgical service (2 points), history of congestive heart failure (2 points) and chronic pulmonary disease (1 point). These models may be useful in assessing which patients are at a higher risk of PRC, so that they can be adequately informed and specific preventive strategies can be implemented, including modifying or postponning the procedure if necessary. Finally, a recent review from Canet J. and Gallart L. 5 on prediction of PRC in the general population ilustrated the miriad of possible risk factors, suggesting that several ones may be important although they are not included in the American College of Physicians guidelines. Specific risk calculators: In the specific setting of postoperative pneumonia, a recent retrospective study 7 developed a risk calculator for this outcome based on seven risk factors: dependent functional status, age, ASA class, COPD, preoperative sepsis, smoking history within 1 year before operation, and type of surgery. Although some of these risk factores are not modifiable, there are some in which it is possible to intervene, for exemple by advising smoking cessation, optimizing COPD patients and lowering ASA class if possible. 7,13 The same is true for postoperative ARF, for 18 Prevention of postoperative respiratory complications: a review which Gupta et al. 35 developed a risk calculator based on several preoperative variables: ASA physical status classification, dependent functional status, emergency procedure, preoperative sepsis, and type of surgery (brain, foregut/hepatopancreatobiliary and aortic surgeries associated with the highest risk). b) General measures Several easy strategies can be adopted in the preoperative period in order to reduce the risk of PRC. Smoking cessation is a well documented way of preventing not only PRC but also other types of postoperative complications 14,46,48, showing more benefit as the period of smoking abstinence increases 53,54. Some previous studies suggested that quitting smoking is effective only if done at least 8 weeks before surgery 3,39, because of a possible greater risk of PRC due to increases in cough and mucous production in the first weeks after cessation 55. However, recent studies have not confirmed this hypothesis: a systematic review and methanalysis of 9 studies with 889 patients 56 concluded that stopping smoking within 8 weeks before surgery does not lead to poorer postoperative outcomes when compared to continuous smoking; and another systematic review and methanalysis from Wong et al. 54 included 25 studies and showed a reduction of 23% in the risk of PRC when cessation occurred more than 4 weeks before surgery and of 47% when cessation occurred more than 8 weeks before surgery. The authors confirmed previous findings that smokers have an increased risk of PRC but did not find any evidence that abstinence from smoking for a period shorter than four weeks before surgery increases or decreases the risk of PRC. Patients with previous pulmonary disease should be managed accordingly, as they have an higher risk of PRC due to an increased susceptibility to sudden changes in arterial oxygen concentration; therefore, the preoperative evaluation of these patients is of major importance17. 19 Prevention of postoperative respiratory complications: a review Therefore, in COPD patients the pulmonary function should be optimized by using combinations of bronchodilators, antibiotics and systemic glucocorticoids 14,57; in the case of asthma, the patient should be evaluated about the need of a step-up in the therapy 57, of an eventual postponing of the surgery or of special considerations concerning anesthetic management 49. c) Physiotherapy The benefits of preoperative physiotherapy remain largely unknown, with most of the studies in this subject refering to patients awayting thoracic surgery 57. In this setting, Pehlivan et al. 58 demonstrated that preoperative physiotherapy with breathing, coughing exercises and treadmill walking reduced the incidence of PRC and length of hospital stay when compared to no physiotherapy. In another article from Nagarajan et al. 59, the authors concluded that preoperative physiotherapy is useful in optimising exercise capacity in patients with lung cancer with eventual impact in reducing PRC. Altough some studies suggest a benefit from this intervention, such services are actually offered by very few hospitals 60, and these benefits have not been confirmed in other settings 61. Therefore, a review from Canet et al. 13 concluded that currently there is no clinical evidence supporting routine preoperative physiotherapy, although it may be useful in some settings 14,62. d) Inspiratory muscle training Inspiratory muscle training (IMT) aims to increase inspiratory muscle strength and endurance by applying an increased load to inspiration 63. IMT has proved to be useful in increasing inspiratory muscle strength in healthy volunteers 64 and several patient populations, including 20 Prevention of postoperative respiratory complications: a review patients weaning from mechanical ventilation 65, patients undergoing bariatric surgery 66 and patients awaiting for elective surgery 67. Two meta-analysis have also demonstrated the utility of preoperative IMT in reducing the incidence of PRC after major abdominal or thoracic surgery63,68. Thereby, IMT in patients at high risk for PRC is recommended 57 and defering surgery in order to allow for a short period of IMT seems perhaps a good strategy for this group67. e) Exercise training Currently, there is substantial evidence of the association between physical fitness and outcome following major surgery, with less fit patients having poorer outcomes than well fit patients69,70. Cardiopulmonary exercise testing (CPET) is a clinical tool used to evaluate the performance of the cardiorespiratory system and to assess the individual’s functional capacity. CPET has been increasingly adopted as a preoperative risk stratification tool, helping in decisions related to the type of surgery, perioperative management and postoperative care 69. Preoperative exercise training has shown benefits in terms of reducing PRC after abdominal surgery 71, with a metaanalysis from Valkenet et al. suggesting that this technique can be helpful in decreasing PRC rates and length of hospital stay after cardiac or abdominal surgery 68. However, the beneficial effects of these strategies on postoperative outcomes have not been confirmed in other studies72,73. Moreover, more studies are needed in order to establish the optimal duration and type of exercises. 2. Intraoperative interventions a) General measures 27 Prevention of postoperative respiratory complications: a review tracheal extubation should be antecipated, so that patients at risk can be correctly managed in order to reduce the risk of injury or death due to anesthesia 95. Oxygen suplemmentation during transport to the PACU is also a controversial topic, due to the heterogeneity of the literature published on this topic and lack of established guidelines. However, a recent study evaluating episodes of dessaturation in the PACU found that the most important predictors of this situation were transport without supplemental oxygen, low respiratory rate and sedation score. Therefore, the use of supplemental oxygen during transport to the PACU seems a simple and effective strategy of preventing postoperative hypoxemia 34. After that, postoperative oxygen therapy should not be used routinely. Routine continuous pulse oximetry during the first postoperative hours is an important tool to monitorize patients 13, as it is useful to detect hypoxemia and early pulmonary events; this strategy is even more important in patients with an increased risk of PRC, like those with OSA 42,45. However, its effect on improving outcomes remains unknown 33. High-flow nasal cannula has been sugested as a better strategy than conventional postoperative oxygen therapy to reduce the risk of PRC in cardiac surgery patients 96, but more evidence is needed before its recommendation as a routine measure. Post-oxygenation with high inspired fractions of oxygen and suctioning of the airways at the end of surgery has been suggested as a routine strategy to improve postoperative oxygenation, but recent evidence suggests that it can have more deleterious effects than benefits and should therefore be avoided 19, possibly due to oxygen toxicity 29. Postoperative nausea and vomiting are significant risk factors for postoperative complications, namely aspiration pneumonitis, and therefore should be prevented as far as possible 39. Postoperatively, when the airway is unprotected and mainly in patients at higher risk of aspiration, it is recommended to carefully monitor administration of sedation and to avoid oral alimentation 22. Nasogastric tubes should not be routinely used as they may increase the risk of pneumonia 13, and when needed they should be removed as soon as possible. Conversely, there 28 Prevention of postoperative respiratory complications: a review is some evidence that routine nasogastric decompression after abdominal surgery may be of benefit in reducing the incidence of postoperative vomits and PRC 14,49. Therefore, more evidence is needed in this setting 49. Effective pain control is also extremely important, as it permits earlier mobilization 97 and contributes to adequate pulmonary toilet, thereby reducing the risk of pneumonia 3 and ARF 12. Opioids can affect respiratory function through several mechanisms: direct depression of the central respiratory drive, sedation and depression of consciousness, and reduction of upper airway muscle tone. This ventilatory dysfunction usually occurs when initial doses are too high, when titration is too fast or when opioids are combined with other depressing agentes 98, and particularly in patients with ASA physical status of IV-V 97. The avoidance of these agents as analgesics, for exemple through the implementation of an epidural catheter, seems a useful way of reducing the impact of opioids on respiratory function and thereby reducing the incidence of PRC 49,62,99, and is of greatest importance in patients at higher risk, such as those with OSA42,45. Residual paralysis after emergence from anesthesia (defined as a train-of-four ratio < 0.9 100) is a common problem, with incidences ranging from 5 to 85% depending on the centres 101, and occurs mainly when long-acting agentes are used 102. The most common adverse outcome associated with this situation is the ocurrence of PRC 100 due to its association with muscular weakness and subsequent airway colapse 100,102, oxygen desaturation, respiratory impairment and ARF, thereby increasing postoperative morbidity and mortality 100,101. These findings ilustrate the importance of careful patient monitoring in order to avoid residual paralysis with all its adverse consequences 12,49,101,102; in adittion, reversal agents such as neostigmine or sugammadex can be used in more severe cases 49,102. In the specific setting of pneumonia, several preventive strategies have been suggested; in a study from Wren et al. 103, the authors achieved a 81% reduction in postoperative hospitalacquired pneumonia by implementing measures such as education of health profissionals, 29 Prevention of postoperative respiratory complications: a review postoperative incentive spirometer, chlorhexidine oral hygiene, early ambulation, and head-of- bed elevation. As far as ventilator-associated pneumonia is concerned, the most important preventive measure is avoidance of intubation or reduction of the duration of mechanical ventilation 3. Noninvasive ventilation may be an effective way to achieve this if evidence exists to support its use 26, with the aditional benefit of decreasing atelectasis 27. Besides this strategy, usual infection-control principles should be instituted 12, as well as specific measures aimed at reducing bacterial colonization of the respiratory tract and decreasing the incidence of aspiration 3. These measures include adoption of a semirecumbent position or eventually a lateral-horizontal position 104, implementation of intermitent aspiration of subglottic secretions 105 and use of oral chlorhexidine gluconate 103. Multistrategy programs including several of these measures may be of greater effectiveness in this setting 106. b) Incentive Spirometry Incentive spirometry is a commonly used strategy 107 in which the patient performs slow, deep breathings and sustain maximal inspiration 108 through a device that offers visual feedback, with the aims of mobilizing secretions and re-expanding areas of postoperatively collapsed lung by stretching the tissue 109. It has the potential of decreasing pleural pressure and promoting lung expansion and better gas exchange, so it has been proposed as a way of preventing or reversing perioperative atelectasis with repetitive treatment on a regular basis 48. There is not much evidence on the use of incentive spirometry during the preoperative period, and in general this strategy is not recommended due to a lack of benefits 108. Conversely, several studies have adressed the effects of incentive spirometry in the postoperative period. As far as thoracic surgery is concerned, postoperative incentive spirometry does not seem to improve respiratory function or outcomes when compared to conventional thoracic expansion exercises 109 or to 30 Prevention of postoperative respiratory complications: a review cough and deep-breathing regimens; the same is true for abdominal surgery 110. Similar findings have been demonstrated in three recent systematic reviews evaluating the effects of incentive spirometry after upper abdominal 111 and cardiac/thoracic surgery 11,112, and therefore its routine use in these settings is not recommended 4,107. Current guidelines 113 confirm that routine incentive spirometry alone is not recommended for prevention of PRC, either pre or postoperatively. c) Postoperative physiotherapy In the past, chest physiotherapy with percussion, postural drainage, coughing, deep breathing exercises and mechanical devices was used as a preventive strategy to decrease the risk of PRC, based on its effects in increasing lung volumes and mobilizing secretions 4,107. Chest physiotherapy is also routine in the management of ICU patients, with different combinations of the various techniques, depending on the physiotherapist 114. As far as the postoperative period is concerned, chest physiotherapy has proved to be better than conventional care in improving outcomes in several settings 114,115. Conversely, oposing results have been found in other studies 60,116. Breathing exercises are one of the most commonly used strategies, and this techique in particular has proved to be beneficial in improving pulmonary function tests when used after upper abdominal surgery; however, its effects on postoperative outcomes remain unknown 117. Therefore, based on the available evidence, which is mostly old, there is currently no indication for the postoperative routine use of chest physiotherapy 112, except probably in case of retained secretions 4,118. The availability of several techniques and the lack of evidence in favour of one over another dictates that this approach should be tailored to the individual patient according to experience of the professional 25. 31 Prevention of postoperative respiratory complications: a review d) Early mobilization Several studies have shown that postoperative bed rest can be detrimental to patient recovery 62 and that early patient mobilization can reduce the incidence of PRC 20,39,40,103,119,120, so this strategy is generally recommended to reduce them and to promote airway clearance in the postoperative period 57,107. The benefits may be evident even with once daily mobilization, if a moderate level of exertion is achieved, and this strategy should be implemented as early as possible 120. Early mobilization may also be of benefit even in mechanicaly ventilated patients as a mean of preventing weakness and improving patients’ status at the time of discharge, although more evidence is needed in this setting 62. The addition of breathing exercises to early mobilization does not seem to be essential to improve postoperative outcomes 120. e) Exercise training Postoperative pulmonary rehabilitation with exercise training has been shown to be beneficial following some surgical procedures 121 and in some special populations like COPD patients 49, but these benefits have not been systematically confirmed 122. Currently, there is insufficient evidence to conclude that exercise training is definitely of benefit prior to or after surgery. However, there is encouraging evidence that physical capacity and quality of life can be improved with prehabilitation and post-rehabilitation, so more studies are needed to establish if this will translate into a real improvement in outcomes 121. f) Multistrategy approaches 32 Prevention of postoperative respiratory complications: a review Lung expansion modalities such as chest physiotherapy, deep breathing exercises and incentive spirometry may be helpful in the postoperative setting, but evidence is insufficient to recommend them in a systematic way 13,22. However, when the benefits of a specific intervention are small, there is a chance of combinig different strategies in order to improve an outcome 57. In the case of PRC, Cassidy et al. 119 proposed a system called I COUGH (incentive spirometry, coughing and deep breathing, oral care, understanding, getting out of bed, and head of bed elevation) as a way of reducing PRC. The results showed a reduction in the incidence of postoperative pneumonia and unplanned intubations. Although these were not statistically significant, they suggest a possible benefit from the combination of simple measures and thereby incentivate future trials with strategies like this in order to find effective ways of preventing or treating PRC 4. Incentive spirometry plus positive expiratory airway pressure is another combination that has shown benefits over conventional care after cardiac surgery 123, further supporting more investigation in multistrategy approaches (see tables 1 and 2, on the appendices section). g) Noninvasive ventilation When ARF develops, there is a need of maintaining adequate oxygenation by using external ventilation. Traditionally, invasive endotracheal ventilation has been the prefered approach, but it has also been associated with some complications such as ventilator-associated pneumonia 3. Therefore, in recent years the interest in the use of noninvasive ventilation (NIV) has increased 10, specially in patients presenting with COPD exacerbations or with acute cardiogenic pulmonary edema 18,124. NIV has also shown eficiency in several other situations such as allowance of earlier extubation in patients with COPD 124,125, discontinuation of mechanical ventilation in patients with resolving hypoxemic respiratory failure, management of 33 Prevention of postoperative respiratory complications: a review immunocompromised patients who develop ARF and management of obesity-hypoventilation syndrome, some cases of acute asthma and some of comunity-acquired pneumonia 124. The use of NIV as a facilitator to weaning from mechanical ventilation is controversial, as different conclusions have resulted from several studies 125. As far as anesthesia and surgery are concerned, postoperative NIV has proved to be useful in preventing or treating hypoxemia, thereby improving postoperative gas exchange and outcome 9,24,95, and permits an increase in lung volumes without requiring effort from patient, thereby reducing atelectasis 18,24. It is also a useful strategy to improve respiratory function by improving alveolar ventilation, reducing the work of breathing and reducing left ventricular afterload, with subsequent improvements in hemodynamics 26. Moreover, NIV has the potential of decreasing the use of sedatives and endotracheal tubes, thereby reducing the number of pneumonias and improving patient comunication and functional status 24. NIV as a prophylatic strategy is specially important in high-risk patients (elderly, obese, COPD, and heart disease) 9,26,30 and has been demonstrated as a useful way of improving postoperative lung function in obese patients and in patients undergoing cardiac 126, abdominal 127, and several other types of surgery 10. It also seems a beneficial approach once postoperative ARF has developed 10,126, which occurs mainly after upper abdominal, cardiac, thoracic, and bariatric surgery 30, and with a potential benefit over traditional mechanical ventilation 9,26,30. However, when ARF develops, the first approach should be treating the cause (obstruction, central respiratory depression, residual neuromuscular blockade, ventilation-perfusion mismatch due to retained secretions and/or atelectasis, pulmonary embolism or obstruction). Then, if still needed, NIV should be considered 30. In the specific setting of cardiothoracic surgery, the use of NIV has proved to be useful both as a preventive and as a therapeutic tool for ARF, with improved respiratory function and postoperative outcomes 18,126,128-131. Hemodynamic changes induced by NIV may be of benefit in this setting 126, as they lead to a reduced myocardial 34 Prevention of postoperative respiratory complications: a review oxygen consumption 130 and improved pump function of the heart 129. Postoperative NIV also appears to improve oxygenation in morbidly obese patients who undergo bariatric surgery 132, with greater benefits if instituted immediately after extubation 133. In a systematic review from Chiumello et al., the authors included 29 articles and concluded that NIV should be used postoperatively both as a preventive and as a therapeutic approach to improve gas exchange after several types of surgery 9. The decision to use NIV in the postoperative period as a prophylactic measure for high-risk patients should be taken taken preoperatively 30. Currently, there is no evidence that BiPAP is superior to CPAP in these setting 30. Studies of NIV as a treatment for ARF in the postoperative setting have also shown favorable results for both NIV types 26. Studies have also demonstrated that NIV is more effective if instituted as early as possible 133 and in a continuous way, not in an intermitent approach 10. Although a variety of interfaces are available, the oronasal mask is considered by some authors as the best initial interface in terms of leak prevention and patient confort 124. The most important issue in this setting is to choose the best interface for the individual patient, even if that requires trying various types 9,24,26. Improved comfort is associated with adequate synchrony and increased success of NIV 124. 35 Prevention of postoperative respiratory complications: a review Conclusion Due to its enormous impact on outcomes after surgery, morbidity, mortality and healthcare resources consumption, PRC are definitely an issue where efficient prevention is needed and must be implemented. Several strategies have been proposed with this goal, some of them with promising results, others still needing more studies to provide sufficient evidence of their benefits. However, it is certain that prevention of PRC should not rely on one specific measure, but should instead be considered as a whole process combining pre, intra and postoperative interventions, taking advantage of all the possible strategies for that individual patient. In this sense, fast-track programs have gained increased interest in the last years. These kind of approaches usually combine preoperative assessment and education, evidence based practice in anesthesia, minimally invasive procedures, effective analgesia and early feeding and ambulation; the goals are enhancing and accelerating postoperative recovery, thereby reducing morbidity. Currently, they have been adopted in several types of surgery with promising results 57,62, and therefore this seems an interesting area for future research, with a great potential of improving patient care and helping healthcare systems. 36 Prevention of postoperative respiratory complications: a review References 1. Shander A, Fleisher LA, Barie PS, Bigatello LM, Sladen RN, Watson CB. Clinical and economic burden of postoperative pulmonary complications: patient safety summit on definition, risk-reducing interventions, and preventive strategies. Critical care medicine. 2011;39(9):2163-2172. 2. Sigl JC, Bloom JD, Hansell DM, Sessler DI. Scientific Abstracts: Post‐Operative Pulmonary Complications & Age: Mortality, Length‐of‐Stay & Readmission. 2010;5– 6. 3. Sachdev G, Napolitano LM. Postoperative pulmonary complications: pneumonia and acute respiratory failure. The Surgical clinics of North America. 2012;92(2):321-344. 4. Branson RD. The scientific basis for postoperative respiratory care. Respiratory care. 2013;58(11):1974-1984. 5. Canet J, Gallart L. Predicting postoperative pulmonary complications in the general population. Current opinion in anaesthesiology. 2013;26(2):107-115. 6. Kamath AS, Vaughan Sarrazin M, Vander Weg MW, Cai X, Cullen J, Katz DA. Hospital costs associated with smoking in veterans undergoing general surgery. Journal of the American College of Surgeons. 2012;214(6):901-908. 7. Gupta H, Gupta PK, Schuller D, et al. Development and validation of a risk calculator for predicting postoperative pneumonia. Mayo Clinic proceedings. 2013;88(11):1241- 1249. 8. Linde-Zwirble W, Bloom J, Mecca R, Hansell D. Postoperative pulmonary complications in adult elective surgery patients in the US: severity, outcomes and resources use. Critical care medicine. 2010;14(Suppl 1):210. 9. Chiumello D, Chevallard G, Gregoretti C. Non-invasive ventilation in postoperative patients: a systematic review. Intensive care medicine. 2011;37(6):918-929. 10. Cereda M, Neligan PJ, Reed AJ. Noninvasive respiratory support in the perioperative period. Current opinion in anaesthesiology. 2013;26(2):134-140. 11. Carvalho CR, Paisani DM, Lunardi AC. Incentive spirometry in major surgeries: a systematic review. Revista brasileira de fisioterapia. 2011;15(5):343-350. 12. Canet J, Gallart L. Postoperative respiratory failure: pathogenesis, prediction, and prevention. Current opinion in critical care. 2014;20(1):56-62. 13. Canet J, Mazo V. Postoperative pulmonary complications. Minerva anestesiologica. 2010;76(2):138-143. 14. Duggan M, Kavanagh BP. Perioperative modifications of respiratory function. Best practice & research. Clinical anaesthesiology. 2010;24(2):145-155. 15. Mans CM, Reeve JC, Gasparini CA, Elkins MR. Postoperative outcomes following preoperative inspiratory muscle training in patients undergoing open cardiothoracic or upper abdominal surgery: protocol for a systematic review. Systematic reviews. 2012;1:63. 16. Futier E, Paugam-Burtz C, Constantin JM, Pereira B, Jaber S. The OPERA trial - comparison of early nasal high flow oxygen therapy with standard care for prevention of postoperative hypoxemia after abdominal surgery: study protocol for a multicenter randomized controlled trial. Trials. 2013;14:341. 17. Hong CM, Galvagno SM, Jr. Patients with chronic pulmonary disease. The Medical clinics of North America. 2013;97(6):1095-1107. 43 Prevention of postoperative respiratory complications: a review quality of life, muscle strength and exercise tolerance: randomised controlled trial. Lung cancer. 2011;71(2):229-234. 123. Ferreira GM, Haeffner MP, Barreto SS, Dall'Ago P. [Incentive spirometry with expiratory positive airway pressure brings benefits after myocardial revascularization]. Arquivos brasileiros de cardiologia. 2010;94(2):230-235, 246-251, 233-238. 124. Hess DR. Noninvasive ventilation for acute respiratory failure. Respiratory care. 2013;58(6):950-972. 125. Ferreyra G, Fanelli V, Del Sorbo L, Ranieri VM. Are guidelines for non-invasive ventilation during weaning still valid? Minerva anestesiologica. 2011;77(9):921-926. 126. Zhu GF, Wang DJ, Liu S, Jia M, Jia SJ. Efficacy and safety of noninvasive positive pressure ventilation in the treatment of acute respiratory failure after cardiac surgery. Chinese medical journal. 2013;126(23):4463-4469. 127. Ireland CJ, Chapman TM, Mathew SF, Herbison GP, Zacharias M. Continuous positive airway pressure (CPAP) during the postoperative period for prevention of postoperative morbidity and mortality following major abdominal surgery. The Cochrane database of systematic reviews. 2014;8:CD008930. 128. Barbagallo M, Ortu A, Spadini E, et al. Prophylactic use of helmet CPAP after pulmonary lobectomy: a prospective randomized controlled study. Respiratory care. 2012;57(9):1418-1424. 129. Ferreira LL, Souza NM, Vitor AL, Bernardo AF, Valenti VE, Vanderlei LC. Noninvasive mechanical ventilation in the postoperative cardiac surgery period: update of the literature. Revista brasileira de cirurgia cardiovascular. 2012;27(3):446-452. 130. Guarracino F, Ambrosino N. Non invasive ventilation in cardio-surgical patients. Minerva anestesiologica. 2011;77(7):734-741. 131. Olper L, Cabrini L, Landoni G, et al. Non-invasive ventilation after cardiac surgery outside the Intensive Care Unit. Minerva anestesiologica. 2011;77(1):40-45. 132. Pessoa KC, Araujo GF, Pinheiro AN, Ramos MR, Maia SC. Noninvasive ventilation in the immediate postoperative of gastrojejunal derivation with Roux-en-Y gastric bypass. Revista brasileira de fisioterapia. 2010;14(4):290-295. 133. Neligan PJ, Malhotra G, Fraser M, et al. Noninvasive ventilation immediately after extubation improves lung function in morbidly obese patients with obstructive sleep apnea undergoing laparoscopic bariatric surgery. Anesthesia and analgesia. 2010;110(5):1360-1365. 44 Prevention of postoperative respiratory complications: a review Appendices and tables Appendix 1: query used in our research. ("postoperative complications"[All Fields] AND ("respiratory"[All Fields] OR "pulmonary"[All Fields] OR "acute lung injury"[All Fields] OR "aspiration pneumonitis"[All Fields] OR "pneumothorax "[All Fields] OR "pneumonia"[All Fields] OR "bronchospasm"[All Fields] OR "pulmonary edema"[All Fields] OR "atelectasis"[All Fields] OR "respiratory failure"[All Fields]) AND ("prevention"[All Fields] OR "risk factors"[All Fields] OR "ventilation"[All Fields])) AND ((Clinical Trial[ptyp] OR Review[ptyp] OR systematic[sb]) AND "humans"[MeSH Terms] AND (English[lang] OR Portuguese[lang]) AND ("2010/01/01"[PDAT] : "2014/12/31"[PDAT])) 45 Prevention of postoperative respiratory complications: a review Appendix 2: selection strategy (see text for details). 657 articles identified from our literature research 187 articles after first selection 470 articles excluded by screening the titles 41 articles excluded after reading the summaries 61 articles excluded after reading the full text 146 articles after second selection 85 articles after third selection 48 articles included from the references of selected articles 133 articles for inclusion in our review 46 Prevention of postoperative respiratory complications: a review Table 1. Proposed combination strategies to keep the lungs open during the perioperative period. - Pre-oxygenation with a FiO2 of 100% (eventually 80% followed by a gentle inflation of the lung in nonobese patients with healthy lungs and no anticipated difficulty in airway management); - Perform a LRM or, alternatively, use CPAP/PEEP during the induction phase; after the first LRM, repeat it at every 30 minutes or use a PEEP of 7 to 10 cmH2O during maintenance of anesthesia; - If possible, maintain a low FiO2 during surgery, ideally 30 to 40% or even less; - Do not use post-oxygenation and airway suctioning as routine strategies. 19 - Induction of anesthesia using a preoxygenation with a FiO2 of 80 to 100% to allow for a longer safety time in case of a difficult intubation; - Perform an early LRM increasing the airway pressure to 40 cmH2O during 10 seconds; - During surgery, keep the FiO2 around 30 to 40%; if there is any oxygen problem, repeat a LRM with following PEEP of 7 to 10 cmH2O; - Before extubation, consider performing another LRM and decide about postoxygenation according to the individual patient, as this may promote atelectasis formation with persistence into the postoperative period. 28 47 Prevention of postoperative respiratory complications: a review Table 2. Example of a multiapproach strategy to reduce PRC. 27 Preoperative 1. Preoperative respiratory muscle training Intraoperative 2. Application of CPAP during anesthesia induction 3. Reversal of anesthesia-induced atelectasis after intubation by a recruitment maneuver in combination with sufficient levels of PEEP and a low FiO2 4. Repeating recruitment maneuvers as indicted by decrease in oxygenation and respiratory system compliance 5. Tracheal extubation using low FiO2 and CPAP during emergence from anestesia 6. Use of CPAP and low FiO2 immediately after extubation Postoperative 7. Promotion of lung expansion through early mobilization, frequent changes in body position and coughing and support for the expectoration of mucus by sighs in conjunction with chest physiotherapy Anexos Anexo 1 - Revista da Sociedade Portuguesa de Anestesiologia - Guia para autores: Autoria - cada manuscrito deve ter um “Autor Correspondente”. Língua - os artigos devem ser redigidos em português (de acordo com o novo acordo ortográfico) ou em inglês. Instruções aos Autores - o texto deverá ser escrito a dois espaços, com letra tamanho 12, Times New Roman e com margens não inferiores a 2,5 cm, em Word para Windows. Todas as páginas devem ser numeradas. Os Autores devem categorizar o “artigo” submetido como Artigo Original, de Educação Médica Contínua, de Revisão, de Consenso, Caso Clínico, Carta ao Editor, Editorial, Perspetiva ou Imagem em Anestesiologia. Estrutura – os textos submetidos para publicação devem ser organizados da seguinte forma: Primeira página: a) Título em português e inglês, conciso e informativo. Se necessário, pode ser usado um complemento de título. b) Nome dos Autores com os títulos académicos e/ou profissionais e respectiva afiliação (departamento, instituição, cidade, país) c) Subsídio(s) ou bolsa(s) que contribuíram para a realização do trabalho d) Morada e correio electrónico do Autor responsável pela correspondência relativa ao manuscrito e) Título breve para rodapé Segunda página: a) Título (sem autores) b) Resumo em português e inglês - deve ser estruturado da seguinte forma: Introdução, Material e Métodos, Resultados, Discussão e Conclusões. Não deve exceder as 250 palavras. c) Palavras-chave em português e em inglês (Keywords). Um máximo de 10 palavraschave, utilizando a terminologia que consta no Medical Subject Headings (MeSH), deve seguir-se ao resumo. Na terceira página e seguintes: Nos artigos de revisão narrativa, o texto deverá incluir as seguintes secções: Introdução (incluindo Objetivos), Material e Métodos, Resultados, Discussão e Conclusões, Agradecimentos (se aplicável), Referências, Tabelas e Figuras. A secção Métodos deve ser utilizada para descrever como foi feita a revisão da literatura. Contagem de palavras: até 6 000. Resumo estruturado: até 400 palavras. Tabelas/figuras: até 10. Referências: até 100. Informações complementares - a partir da segunda página, inclusive, todas as páginas devem ter em rodapé o título breve indicado na página 1. Abreviaturas - abreviaturas ou acrónimos não devem ser utilizados no título e no resumo, mas apenas no texto e de forma limitada. Abreviaturas não consagradas devem ser definidas na primeira utilização, por extenso, logo seguido pela abreviatura entre parenteses. Tabelas, Figuras ou Fotografias - as Tabelas/Quadros/Figuras devem ser numerados de acordo com ordem em que são citadas no texto e assinaladas em numeração árabe e com identificação, Tabela/Quadro/Figura. Toda a Tabela/Quadro ou Figura incluída no artigo têm de ser referida no texto: as Figuras quando referidas no texto são abreviadas para Fig., enquanto as Tabelas/Quadros não são abreviadas. Nas legendas ambas as palavras são escritas por extenso. As Tabelas e Figuras devem ter legenda e são numerados com numeração árabe independente e na sequência em que são referidas no texto. As legendas devem ser autoexplicativas (sem necessidade de recorrer ao texto para as entender) – é uma declaração descritiva. Legenda das Tabelas: Colocada por cima do corpo da tabela e justificada à esquerda. Na parte inferior serão colocadas todas as notas informativas – notas de rodapé (abreviaturas, significado estatístico, etc.). Legenda das Figuras: Colocada por baixo da figura, gráfico e justificada à esquerda. Referências - as referências bibliográficas devem ser classificadas e numeradas por ordem de entrada no texto. Devem ser identificadas no texto com algarismos árabes em expoente. As citações completas devem ser listadas por ordem numérica no final do texto. Anexo 2 - Cópia do e-mail recebido por parte da Equipa Editorial da Revista da Sociedade Portuguesa de Anestesiologia, aquando da submissão do trabalho para publicação Catarina Soares Queirós, Agradecemos a submissão do seu manuscrito "Postoperative pulmonary complications and strategies to prevent them in the perioperative period: a review" para a revista Revista da Sociedade Portuguesa de Anestesiologia. Através da interface de administração do sistema, utilizado para a submissão, será possível acompanhar o progresso do documento dentro do processo editorial, bastando ligar-se ao sistema disponível em: URL do Manuscrito: http://revistas.rcaap.pt/anestesiologia/author/submission/6541 Nome de utilizador: catarina_sq Em caso de dúvidas, entre em contacto através deste email. Agradecemos mais uma vez considerar a nossa revista como meio de transmitir ao público o seu trabalho científico. António Augusto Martins Revista da Sociedade Portuguesa de Anestesiologia http://revistas.rcaap.pt/anestesiologia