This Invited Commentary accompanies the following original article:
Canet J, Sabaté S, Mazo V, et al. Development and validation of a score to predict postoperative respiratory failure in a multicentre European cohort. A prospective, observational study. Eur J Anaesthesiol 2015; 32:458–470.
Pulmonary complications, including postoperative respiratory failure, represent the second most frequent form of postoperative complications after surgical site infections, with an incidence estimated to range from 2.0 to 7.9%, depending on the definitions and patients studied.1 Postoperative respiratory failure is a severe complication, which leads to a longer hospital stay, higher financial cost and increases the in-hospital death rate by as much as 90-fold.2,3
It is clinically important to identify patients at high risk of postoperative respiratory failure because early prediction of risk allows for preoperative triage and better healthcare resource allocation. In the present issue of the European Journal of Anaesthesiology, Canet et al.4 – supported by the European Society of Anaesthesiology – provide meaningful information that may change clinical practice in perioperative medicine.
In a prospective, international, multicentre trial the authors evaluated 27 possible risk factors for the development of postoperative respiratory failure. They identified the following independent predictors: low preoperative SpO2, at least one preoperative respiratory symptom, preoperative chronic liver disease, history of congestive heart failure, open intrathoracic or upper abdominal surgery, surgical procedures lasting at least 2 h, and emergency surgery. The study is a secondary analysis of data from the PERISCOPE study, a prospective observational study of a European cohort of 5384 patients undergoing surgery with general or regional anaesthesia during a 7-day recruitment period.1
In recent years, several different scores based on data on file have been proposed to predict postoperative respiratory failure.2,5,6 Interestingly, the prospective study of Canet et al.4 validates the results of the published quantitative effectiveness trials by arriving at very similar predictors:2,5,6 preexisting heart and respiratory failure, emergency procedures of long duration, surgery of high-risk anatomical areas such as the abdomen and thorax, and vascular surgery. In these high-risk surgical specialties a procedure is frequently associated with diaphragmatic muscle dysfunction and increased vulnerability to low volume lung injury.
The good news is that we can prevent such pulmonary respiratory complications if we allocate our resources properly. Recently, obstructive sleep apnoea (OSA) – a disease with high vulnerability to postoperative pulmonary complications – was independently associated with a significant reduction in length of hospital stay, total charges and in-hospital mortality after surgery, despite an increased use of postoperative mechanical ventilation.7,8 The ‘beneficial’ effects of OSA on postoperative respiratory outcome may be because these high-risk patients are allocated to more experienced anaesthetists, who can offer the optimum intraoperative treatment and also make full use of the range of resources available in the hospital setting for their postoperative monitoring and treatment.
How can we develop clinical pathways that provide all patients at risk with the best treatment to prevent postoperative respiratory complications?
Preoperatively, not only do we need to screen patients to identify those at a high risk of postoperative respiratory failure but also our screening tools need to be based on disease-entity and procedure-specific aspects as described by Canet et al.4
There are also intraoperative considerations. So far, data suggest that protective intraoperative mechanical ventilation9,10 and restrictive fluid management during surgery11 improves postoperative outcomes, probably by causing less barotrauma, volutrauma and atalectrauma to the lung (Fig. 1). Also, appropriate use of quantitative neuromuscular monitoring and reversal agents are associated with patient comfort and safety.12 Quantitative effectiveness research will identify additional intraoperative strategies, including those related to the prevention of surgery-associated lung injury, which will help minimise the risk of postoperative failure.
Finally, postoperative treatment must take into account the preoperative screening results as well as the respiratory consequences of intraoperative events. Proper monitoring on the surgical floor has been associated with reduced ICU transfers as the early detection of signs and symptoms of respiratory failure improves outcome13 However, in order to interpret postoperative oxygen saturation values correctly, the clinician needs to consider a patient's preoperative oxygen saturation status. Patients with sleep apnoea, for instance, show predictable nocturnal desaturations, which do not necessarily need to be treated by ICU admission. The clinician should consider that noninvasive mechanical ventilation,14 pulmonary physiotherapy,15 early mobilisation15 and opioid-sparing analgesia are key aspects of protective postoperative treatment for patients at a high risk of respiratory complications.
Future research will identify procedure-specific risk factors of postoperative respiratory failure, similar to the well established procedure-specific postoperative pain therapy. In addition, in order to eliminate postoperative respiratory complications, more research is needed to evaluate how best to implement expert recommendations into clinical practice. The evidence suggests that clinicians do not rigorously apply recommended standards, inevitably leading to an increased incidence of postoperative respiratory complications.12
In conclusion, the development of the new score to predict the risk of respiratory failure following surgery is an important step towards the goal of developing clinical pathways that define an individualised perioperative treatment plan for patients at risk of postoperative respiratory failure.
Acknowledgements relating to this article
Assistance with the Invited Commentary: none.
Financial support and sponsorship: this work was supported by the University of Copenhagen, Denmark, and by the Department of Anesthesia, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.
Conflicts of interest: none.
Comment from the editor: this invited commentary was checked and accepted by the editors but was not sent for external peer review.
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