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)
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.
Shorter Recruitment Maneuver
Cuff of the endotracheal tube was transiently overinflated to 50 cmH2O. Airway pressure was increased at a rate of 5 cmH2O/s from 10 to 40 cmH2O, which was sustained for 30 .
Most of recruitment was in the first 10 seconds; hemodynamic consequences were after 10 seconds. (Intensive Care Med. 2011 Oct;37(10):1588-94)
Prone Positioning Improves Oxygenation in Post-traumatic Lung InjuryA Prospective Randomized Trial
Voggenreiter, Gregor MD; Aufmkolk, Michael MD; Stiletto, Raphael J. MD; Baacke, Markus G. MD; Waydhas, Christian MD; Ose, Claudia; Bock, Eva; Gotzen, Leo MD; Obertacke, Udo MD; Nast-Kolb, Dieter MD
From the Departments of Trauma Surgery, University Hospital Mannheim, 68135 Mannheim (Drs. Voggenreiter, and Obertacke), University Hospital Essen, 45122 Essen (Drs. Aufmkolk, Waydhas and Nast-Kolb) and Philipps-University Marburg, 35043 Marburg (Drs. Stiletto, Baacke and Gotzen) and the Institute of Medical Informatics, Biometry and Epidemiology (Mrs. Ose and Bock), University Hospital Essen, 45122 Essen, Germany Submitted for publication October 19, 2004. Accepted for publication May 3, 2005. Supported by Deutsche Forschungsgemeinschaft (DFG grant Vo 694/1-1). Requests should be sent to: Dr. Gregor Voggenreiter, Department of Trauma Surgery, University Hospital Mannheim, Ruprecht-Karls University of Heidelberg, 68135 Mannheim, Germany, Tel. 0049-621-383 2335, Fax. 0049-621-383 2009 Abstract
Background: In a prospective randomized trial the effect of prone positioning on the duration of mechanical ventilation was evaluated in multiple trauma patients and was compared with patients ventilated in supine position.
Method: Multiple trauma patients of the intensive care units of two university hospitals were considered eligible if they met the criteria for acute lung injury or the acute respiratory distress syndrome. Patients in the prone group (N = 21) were kept prone for at least eight hours and a maximum of 23 hours per day. Prone positioning was continued until a PaO 2:FiO2 ratio of more than 300 was present in prone as well as supine position over a period of 48 hours. Patients in the supine group (N = 19) were positioned according to standard care guidelines.
Results: The duration of ventilatory support did not differ significantly (30 ± 17 days in the prone group and 33 ± 23 days in the supine group). Worst case analysis (death and deterioration of gas exchange) displayed ventilatory support for 41 ± 29 days in the prone group and 61 ± 35 days in the supine group ( p = 0.06). The PaO2:FiO2 ratio increased significantly more in the prone group in the first four days ( p = 0.03). The prevalence of Acute Respiratory Distress Syndrome (ARDS) following acute lung injury (p = 0.03) and the prevalence of pneumonia (p = 0.048) were reduced also. One patient in the prone and three patients in the supine group died due to multi organ failure (p = 0.27).
Conclusions: Intermittent prone positioning was not able to reduce the duration of mechanical ventilation in this limited number of patients. However the oxygenation improved significantly over the first four days of treatment, and the prevalence of ARDS and pneumonia were reduced. (J Trauma 2005;Volume 59(2):333-343)SR shows decreased mortality with proning (Intensive Care Med (2010) 36:585599)
Meta-analysis of prone positioning (Crit Care Med 2008;36:603)
Anesthesiologists routinely perform such maneuvers in the operating room, albeit in a slightly uncontrolled manner (a tidal volume is delivered through a manual breathing system and held, the airway pressure is not measured). There are many methods of performing sustained inflation maneuvers in intensive care while being in complete control of the airway pressure. Two factors influence whether or not recruitment maneuvers are successful: the pressure applied must be in excess of the current plateau pressure, and the pressure must be sustained, in order to inflate lung units with long time constants. The most effective method of doing this is to apply CPAP to the airway. Amato (1998) applied CPAP at 10cmH2O above the plateau pressure for 30 to 60 seconds to restore alveolar recruitment. Following the period of sustained inflation, the ventilation settings are returned to previous levels. It is not necessary to increase the PEEP, as the lung volumes from the same amount of PEEP as before should be higher. A successful procedure will result in improved oxygenation, reduced end-tidal CO2 and improved compliance.
On occasion, it may be necessary to increase the CPAP further to guarantee recruitment up to 20cmH2O above the pressure limit. Indeed sometimes very high pressures are required to recruit collapsed lung tissue: Medoff (2000) and colleagues have reported a case where 40cmH2O of PEEP and 20cmH2O of pressure control was required to reinflate the lungs of a young woman with Streptococcal sepsis. Interestingly, the PEEP required to prevent derecruitment in this patient was significantly higher than that predicted by Pflex.
Performance of Recruitment Maneuvers:
1. Ensure hemodynamic stability.
2. Set the FiO2 to 1.0
3. Wait 10 minutes.
4. Recruit with 30* cmH2O CPAP for 30-40 seconds (* or 10 cmH2O above the plateau pressure level).
5. If unresponsive, wait 15 minutes and then recruit with 35 cmH2O CPAP for 30 to 40 seconds.
6. If unresponsive, wait 15 minutes and then recruit with 40 cmH2O CPAP for 30 to 40 seconds.
7. If unresponsive, wait 15 minutes and then recruit with 20 cmH2O pressure control and 40 cmH2O CPAP for 2 minutes.
8. If the patient remains unresponsive, consider prone positioning.
Our protocol is to assess “recruitability” to start with. We do this by using high pressures on the Pressure Controlled Mode for a minute – would use a Ppeak of about 40 to 50. If there is any sign of improved saturation within 5 minutes or so, we would do a “sustained inflation” using a pressure of 40 for 40 seconds and crank up the PEEP to 15 to 20. If the initial assessment shows no “recruitability”, ie, no improvement in saturation, we do not to ahead with sustained inflation. Not much of scientific evidence I’m afraid to justify what we do, but seems to work OK. I have also seen a few patients who didn’t seem to recruit at all by any mechanism, going on to improve oxygenation dramatically after proning. Jose
Review article (Brit J Anaes 2006;96(2):156)
prone positioning led to reduced ICU stay and hospital stay and better oxygenation, survival trend was there but study was stopped prior to stat sig (Inten Care Med 2008;34:1487)
| | |