Could CPAP Devices Be Used to Ventilate Cardiac Arrest Patients? A Bench Study

To investigate the potential efficacy of a commercial continuous positive airway pressure (CPAP) ventilator to provide effective respiratory support in a simulated scenario of out-of-hospital cardiac arrest (OHCA). The study was conducted on a high-fidelity manikin (SimMan 3 GTM, Laerdal, NOR) connected to the ASL 5000TM Lung Simulator (IngMar Medical, USA). To simulate OHCA, we set no spontaneous respiratory acts and physiological respiratory system resistance (13 cmH2O/L.sec) and compliance (50 mL/cmH2O). The Respironics BiPAP A40 ventilatorI (Philips, NL) was used to provide ventilatory support while operating in CPAP mode. Tests were performed at different values of positive pressure of the CPAP ventilator (PCPAP: 5, 7.5, 10, 12.5 and 15 cmH2O) and the intrapulmonary volume (tidal volume, Vt) measured via the simulator software computer interface. A trained physician performed the tests. Our primary outcome was a VT of ≈500-600 mL with an intermittent maneuver simulating cardiopulmonary resuscitation (CPR)-like ventilatory support practice according to international guideline-based target (1-sec ventilation followed by 1-sec pause). In intermittent ventilatory support tests, PCPAP levels of 12.5, and 15 cmH2O resulted in a VT equal to 508 ± 13 mL, and 557 ± 44 mL respectively (p = 0.04), thus approaching the VT target. We provide preliminary evidence of the potential efficacy of CPAP ventilators designed for home use to provide effective respiratory support to a simulated respiratory arrest patient.</p

Secondary Outcomes.

<p>Dex: dexmedetomidine; RR: relative risk; CI: confidence interval; P: p-value.</p

Sensitivity analyses of intensive care unit stay and time to extubation.

<p>The overall analyses using weighted mean differences showed a reduction in intensive care unit stay of −0.79 [−1.17 to −0.40] days and a reduction in time to extubation of −2.74 [−3.80 to −1.65] hours in the dexmedetomidine group. It should be noted that the standard mean differences used in this table is not expressed in days or hours.</p><p>Dex: dexmedetomidine; SMD: standardized mean difference; CI: confidence interval; P: p-value; CABG: coronary artery bypass grafting; ICU: intensive care unit; NIV: non invasive ventilation.</p><p>duration of mechanical ventilation from randomization until patients were free of mechanical ventilation(including noninvasive).</p

Forest plot for the length of ICU stay.

<p>Overall analysis showed that the use of dexmedetomidine was associated with a significant reduction in length of ICU stay (SMD = −0.48 [−0.78 to −0.18] , p for effect = 0.002, p for heterogeneity <0.001, I2 = 91% with 17 studies and 2,424 patients included). ICU = intensive care unit; CI = confidence interval; SMD = standardized mean difference; N = number; SD = standard deviation; Dex = dexmedetomidine.</p

Funnel plot for the length of ICU stay.

<p>Visual inspection of funnel plots did not identify a skewed or asymmetrical shape for the co-primary endpoints. Quantitative evaluation did not suggest a presence of publication bias, as measured by the Egger's test (p = 0.4) and Peters' test (p = 0.6). ICU = intensive care unit; SE = standard error; SMD = standardized mean difference.</p

Doses, sedation scales and target sedation levels.

<p>ICU: Intensive Care Unit; CPB: cardiopulmonary bypass; NA: not available.</p

Dexmedetomidine as a Sedative Agent in Critically Ill Patients: A Meta-Analysis of Randomized Controlled Trials

<div><p>Introduction</p><p>The effect of dexmedetomidine on length of intensive care unit (ICU) stay and time to extubation is still unclear.</p><p>Materials and Methods</p><p>Pertinent studies were independently searched in BioMedCentral, PubMed, Embase, and the Cochrane Central Register of clinical trials (updated February first 2013). Randomized studies (dexmedetomidine versus any comparator) were included if including patients mechanically ventilated in an intensive care unit (ICU). Co-primary endpoints were the length of ICU stay (days) and time to extubation (hours). Secondary endpoint was mortality rate at the longest follow-up available.</p><p>Results</p><p>The 27 included manuscripts (28 trials) randomized 3,648 patients (1,870 to dexmedetomidine and 1,778 to control). Overall analysis showed that the use of dexmedetomidine was associated with a significant reduction in length of ICU stay (weighted mean difference (WMD) = −0.79 [−1.17 to −0.40] days, p for effect <0.001) and of time to extubation (WMD = −2.74 [−3.80 to −1.65] hours, p for effect <0.001). Mortality was not different between dexmedetomidine and controls (risk ratio = 1.00 [0.84 to 1.21], p for effect = 0.9). High heterogeneity between included studies was found.</p><p>Conclusions</p><p>This meta-analysis of randomized controlled studies suggests that dexmedetomidine could help to reduce ICU stay and time to extubation, in critically ill patients even if high heterogeneity between studies might confound the interpretation of these results.</p></div

Forest plot for the time to extubation.

<p>Overall analysis showed that the use of dexmedetomidine was associated with a significant reduction of time to extubation (SMD = −0.39 [−0.66 to −0.11], p for effect = 0.005, p for heterogeneity <0.001, I2 = 93% with 24 studies and 3,478 patients included). CI = confidence interval; SMD = standardized mean difference; N = number; SD = standard deviation; Dex = dexmedetomidine.</p

Description of the 28 trials included in the meta-analysis.

<p>Dex: dexmedetomidine; ICU: Intensive Care Unit; NA: not available; RASS: Richmond Agitation Sedation Scale; BIS: BispectralIndex ; MAAS: Motor Activity Assessment Scale.</p

Sensitivity analyses of mortality.

<p>RR: Risk Ratio; CI: confidence interval; P: statistical p-value; I²: I square.</p