Experimental model in pigs: Schematic diagrams of recruiting maneuver (RM) methods tested. SI continuous positive airway pressure (CPAP) held at 45 cm H2O for 40 secs. Incremental positive end-expiratory pressure (PEEP) with a fixed peak pressure (IP), PEEP increased in 5 cm H2O increments (allowing 30 secs\/step) from a baseline PEEP of 8 cm H2O to 35 cm H2O while decreasing tidal volume to limit peak inspiratory pressure to 35 cm H2O. After CPAP of 35 cm H2O was held for 30 secs, PEEP was decremented in 5-cm H2O steps to the post-RM PEEP setting, while increasing tidal volume toward the baseline value of 10 mL\/kg (as the 35 cm H2O peak pressure limit allowed). PCV peak pressure = 45 cm H2O, inspiratory to expiratory ratio = 1:2, and PEEP level = 16 cm H2O for 2 min. (Crit Care Med 2004, Dec)<\/p>\n
<\/p>\n
An effective recruitment strategy that we have found successful is to: Select an appropriate patient Ideal patients for recruitment maneuvers are patients with putative ARDS in the early phase of the disease (before the onset of fibro-proliferation). Patients should be poorly oxygenated on a high FiO2. Pre-existing focal lung disease that may predispose to barotrauma should be regarded as a relative contra-indication to the maneuver (for example extensive apical bullous lung disease). Patients with ‘secondary’ ARDS (following on, for example, abdominal sepsis) are thought to be more likely to respond favourably to the maneuver than patients with ‘primary’ lung disease and acute lung injury. Position the patient prone This is easily done (after some initial resistance from nursing staff)! An important component of prone positioning for recruitment is to have a pillow under the upper chest, and another beneath the pelvic area, so the abdomen hangs down somewhat in between the two pillows. Continue appropriate mechanical ventilation. The patient must be fully monitored Monitoring should include (at least) invasive arterial blood pressure monitoring, pulse oximetry and ECG. The patient must also be completely paralysed with non-depolarising neuromuscular blockade, to prevent attempts at respiration during the maneuver. A baseline arterial blood gas analysis (ABG) should be obtained after the FiO2 has been increased to 100%. Administer 40cm H2O of PEEP for 90s Set the ventilator to an effective rate of zero (with no machine breaths) and then immediately raise the PEEP to 40cm H2O for a carefully timed period of one and a half minutes. Then re-institute ventilation as before. Wait and recheck the ABG Wait for a period of five minutes, leaving the patient in the prone position, and obtain a blood gas analysis. If the PaO2 is under 300mmHg, then consider repeating the maneuver at PEEPs of 45mmHg and (if this fails) 50mmHg, also for ninety seconds. Prevent ‘de-recruitment’ The patient should now be maintained on a PEEP of 15 cmH2O. Often, the patient can be turned back to a supine position without substantial worsening of oxygenation. Ventilation should continue with a strategy that minimises additional alveolar trauma (for example, inverse ratio pressure-control ventilation, with every attempt to keep trans-alveolar pressure to under 35cm H2O). Ventilator tidal volumes should perhaps be limited to approximately 6 ml\/kg.<\/p>\n