Benefits and risks of manual hyperinflation in intubated and mechanically ventilated intensive care unit patients: a systematic review

Abstract

IntroductionManual hyperinflation (MH), a frequently applied maneuver in critically ill intubated and mechanically ventilated patients, is suggested to mimic a cough so that airway secretions are mobilized toward the larger airways, where they can easily be removed. As such, MH could prevent plugging of the airways.MethodsWe performed a search in the databases of Medline, Embase, and the Cochrane Library from January 1990 to April 2012. We systematically reviewed the literature on evidence for postulated benefits and risks of MH in critically ill intubated and mechanically ventilated patients.ResultsThe search identified 50 articles, of which 19 were considered relevant. We included 13 interventional studies and six observational studies. The number of studies evaluating physiological effects of MH is limited. Trials differed too much to permit meta-analysis. It is uncertain whether MH was applied similarly in the retrieved studies. Finally, most studies are underpowered to show clinical benefit of MH. Use of MH is associated with short-term improvements in lung compliance, oxygenation, and secretion clearance, without changes in outcomes. MH has been reported to be associated with short-term and probably clinically insignificant side effects, including decreases in cardiac output, alterations of heart rates, and increased central venous pressures.ConclusionsStudies have failed to show that MH benefits critically ill intubated and mechanically ventilated patients. MH is infrequently associated with short-term side effects.

Effect of Inspiratory Time and Lung Compliance on Flow Bias Generated During Manual Hyperinflation: A Bench Study

“…This agrees with a recent bench study that achieved similar expiratory flow bias thresholds with 2 s of inspiratory time and ideally 3 s of inspiratory time using pressure-controlled ventilator hyperinflation. 32 Although manual hyperinflation may be commonly delivered with short inspiratory times, 6,7,18 there may be additional factors that facilitate mucus movement under these conditions. It is likely that alterations in V T , 32 airway resistance and airway pressure, 17 manual hyperinflation circuit design, [23][24][25][26] and inclusion of an inspiratory hold 17 may also interact with the expiratory flow bias and alter whether the expiratory flow bias thresholds can be exceeded.…”

“…5 The existing evidence for manual hyperinflation demonstrates only some shortterm improvements in lung function without any benefits in major patient outcomes, 6 and this may account for its limited practice in other regions. 7 There is also the potential for harm with circuit disconnection (loss of PEEP), the tidal volume (V T ) values and airway pressures generated, and the potential impact on cardiac output and blood pres-sure.…”

“…7 There is also the potential for harm with circuit disconnection (loss of PEEP), the tidal volume (V T ) values and airway pressures generated, and the potential impact on cardiac output and blood pres-sure. 6 Retained mucus in the lower respiratory tract is associated with the development of nosocomial pneumonia 8 and may increase mortality in the ICU. 9 Administration of manual hyperinflation requires that the patient be disconnected from the mechanical ventilator and connected to a circuit where the physiotherapist can manually administer breaths to the patient by squeezing and releasing a reservoir bag.…”

“…Peak inspiratory pressures are recommended to be Ͻ40 cm H 2 O to avoid risks of barotrauma. 22 No limits have been recommended for V T during manual hyperinflation, but large V T values may impede venous return 6 and could contribute to lung injury via volutrauma.…”

Alveolar Recruitment Maneuvers Under General Anesthesia: A Systematic Review of the Literature

“…Study outcomes range from improving arterial oxygenation, to no effect, to decreases in cardiac output and blood pressure. 19,25 A thorough and focused systematic review regarding alveolar recruitment maneuvers is necessary to delineate their usefulness in improving patient outcomes both during and after general anesthesia.…”