Several studies investigated the role of NPPV as a preventive measure, namely, routinely administered to all patients after thoracic surgery, in order to decrease the incidence of respiratory events and to improve clinical outcome. Table 12.1 resumes the findings of the most relevant studies.

Several small randomized trials found an improvement in gas exchange [17, 19, 35, 37], and two of them also observed a reduction in hospital length of stay [17, 37]. A single study investigated NPPV also preoperatively [37]. In a randomized trial on 50 patients [41], NPPV improved lung re-expansion, assessed by computed tomography, but no clinical advantage was found; in particular the incidence of PPCs was not lower compared to the control group. In a study using helmets for CPAP delivery [19], the advantages in gas exchange improvement were found to be transient, rapidly returning to the baseline values after the interruption of the CPAP administration.

In the largest randomized trial [42] in 360 COPD patients undergoing major lung resection surgery, NPPV did not reduce the incidence of acute respiratory events nor affected any of the secondary clinical endpoints, including ICU length of stay, intubation rate and mortality. Even if a single middle-sized randomized trial should not be considered definitive, these data suggest that administration of preventive NPPV should not be considered as a standard approach for all patients undergoing lung resectional surgery. It is difficult to aggregate the results from other small studies, due to the heterogeneity of NPPV modes used, interfaces and clinical outcomes. Further studies are necessary to identify subgroups of patients at high risk that could potentially benefit from preventive NPPV.

Several studies investigated the role of NPPV as a therapeutic measure, namely, administered to treat patients which developed ARF postoperatively. Table 12.1 resumes the findings of the most relevant studies. In a pilot study on 20 patients meeting criteria for re-intubation after abdominal and thoracic surgery, nasal CPAP was used as a method to avoid invasive ventilation [43]. In lung transplant recipients, NPPV through face mask avoided intubation in most of the patients that developed ARF postoperatively [44]. NPPV decreased mortality compared to standard oxygen therapy in a randomized trial involving 24 patients in ARF after lung resection [45]. The feasibility of NPPV in ARF following thoracic surgery was further assessed in two prospective observational trials on a larger cohort of patients [46, 47] (Table 12.2).

NPPV should be administered in the right cases in the right time window. Indeed, NPPV should be considered a measure to support the respiratory function while the underlying reversible condition is treated. Further studies are warranted to help the clinician in individuating thresholds and clinical scores to identify patients that can benefit from preventive or curative NPPV.

It is a matter of debate whether postoperative NPPV for ARF should be administered only in the ICU setting [48]. As a general principle, administration of NPPV should be accompanied by adequate respiratory monitoring [49]. In many hospitals ventilators are not available in the medical ward, but this issue could be circumvented by the use of small portable ventilators. In a feasibility study of NPPV in the recovery room of the general surgery, the use of NIV-dedicated small ventilators was proposed and found to be a viable option for relieving ARF in the immediate postoperative period [50]. A recent study in the United States [51] found that most NPPV treatments for ARF were initiated in the ICU or in the emergency department and general wards. NPPV feasibility and efficacy were found to be comparable in different age groups [52].