In patients with acute respiratory distress syndrome (ARDS), the lung comprises areas of aeration and areas of alveolar collapse, the latter producing intrapulmonary shunt and hypoxemia. The currently suggested strategy of ventilation with low lung volumes can aggravate lung collapse and potentially produce lung injury through shear stress at the interface between aerated and collapsed lung, and as a result of repetitive opening and closing of alveoli. An 'open lung strategy' focused on alveolar patency has therefore been recommended. While positive end-expiratory pressure prevents alveolar collapse, recruitment maneuvers can be used to achieve alveolar recruitment. Various recruitment maneuvers exist, including sustained inflation to high pressures, intermittent sighs, and stepwise increases in positive end-expiratory pressure or peak inspiratory pressure. In animal studies, recruitment maneuvers clearly reverse the derecruitment associated with low tidal volume ventilation, improve gas exchange, and reduce lung injury. Data regarding the use of recruitment maneuvers in patients with ARDS show mixed results, with increased efficacy in those with short duration of ARDS, good compliance of the chest wall, and in extrapulmonary ARDS. In this review we discuss the pathophysiologic basis for the use of recruitment maneuvers and recent evidence, as well as the practical application of the technique.
BACKGROUND:Alveolar recruitment is a physiological process that denotes the reopening of previously gasless lung units exposed to positive pressure ventilation. The current study was aimed to compare two recruitment maneuvers, a high continuous positive airway pressure (CPAP), and an extended sigh in patients with ARDS. MATERIALS AND METHODS:
Forty patients with acute respiratory distress syndrome were randomly divided into two groups, 20 patients each. Group I received a CPAP of 40 cm H(2)O for 40 seconds and group II received extended sigh (providing a sufficient recruiting pressure × time). In our study, we assessed the effects of both recruitment maneuvers on respiratory mechanics, gas exchange, and hemodynamics. These data were analyzed using two-way analysis of variance (ANOVA) followed by a Student--Newman--Keuls post hoc comparison test. P < 0.05 was considered statistically significant. RESULTS: Both methods improved the compliance, increased arterial oxygenation (PaO(2)), increased the PaO(2)/FiO(2) ratio, and reduced the pulmonary shunt fraction (Q(s)/Q(t)). However, the extended sigh improved both PaO(2) and PaO(2)/FiO(2) ratios more than continuous positive airway pressure. Also the hemodynamic parameters were better maintained during the extended sigh. CONCLUSION: Alveolar recruitment maneuvers are effective in management of mechanically ventilated ARDS patients. We conclude that extended sigh is more effective than continuous positive airway pressure as a recruitment maneuver.
Crit Care. 2008;12(3):159. doi: 10.1186/cc6910. Epub 2008 Jun 20.
Sustained re-opening of collapsed lung tissue (recruitment) requires the application of airway pressures that exceed those of the tidal cycle. The post-maneuver PEEP as well as the duration of high pressure application are also key factors in its success, with their accompanying potential for hemodynamic compromise. Although a wide variety of recruiting maneuvers have been described, the technique that strikes the best balance between efficacy and risk may well vary among patients with differing right heart loading status and lung properties.
Maniobras de reclutamiento pulmonar con o sin albuterol nebulizado en daño pulmonar agudo. Estudio aleatorizado y controlado
Lung recruitment maneuver with and without nebulized albuterol for acute lung injury: a randomized, controlled study.
Asida SM, Badawy MS.
Res Opin Anesth Intensive Care 2015;2:126-31
Background. β2-Adrenoceptor agonists accelerate the resolution of pulmonary edema in experimental and clinical studies. We tested the hypothesis that combining nebulized albuterol with lung recruitment maneuver (RM) during mechanical ventilation would improve oxygenation and accelerate the resolution of pulmonary edema more than would RM alone in patients with acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS). Materials and methods. In this randomized, controlled, single-blinded study, 60 patients admitted to the ICU of Qena University Hospitals and suffering from ALI and/or ARDS were recruited. All patients were subjected to the lung RM. They were assigned to two equal groups: the albuterol group (30 patients), in which patients were medicated with nebulized albuterol 1 mg diluted in 10 ml saline; and the control group (30 patients), in which patients were given 10 ml nebulized saline instead of albuterol. This regimen was repeated every 8 h for 3 days. Alveolar fluid samples were withdrawn before and 1 h after the lung recruitment for protein concentration measurement in the alveolar fluid. Results. We found a significant difference between the two groups regarding PaO2 (P = 0.003) and PaO2/FiO2 (P = 0.023) before and after RM ± albuterol. No significant difference between the two groups was found regarding alveolar fluid clearance and alveolar protein concentration. Conclusion. RM with nebulized albuterol improved oxygenation but the addition of albuterol was not beneficial regarding alveolar fluid clearance in terms of lowering alveolar protein concentration in ALI/ARDS patients. Keywords: acute lung injury, albuterol, recruitment maneuver