Leandro M. de Azeredo

Evaluation of maximal inspiratory pressure, tracheal airway occlusion pressure, and its ratio in the weaning outcome.

PURPOSE The objective of this study is to evaluate the predictive performance of maximal inspiratory pressure (Pimax), airway occlusion pressure (P 0.1), and its ratio (P 0.1/Pimax) in the weaning outcome. MATERIALS AND METHODS Seventy patients on mechanical ventilation for more than 24 hours, who fulfilled weaning criteria, were prospectively evaluated. Pimax less than -25 cm H(2)O, P 0.1 less than 4.2 cm H(2)O, and P 0.1/Pimax less than 0.14 were evaluated in all patients before spontaneous breathing trials. The receiver operating characteristic (ROC) curve was calculated to evaluate the predictive performance of each index. RESULTS Pimax presented the area under the ROC curves smaller than those for P 0.1 and P 0.1/Pimax (0.52 x 0.76 and 0.52 x 0.78; P = .004 and P = .0006, respectively), being the criteria of worst performance. P 0.1/Pimax presented excellent predictive performance in weaned patients, with sensitivity of 98.08, but with the area under the ROC curves only slightly larger than those for P 0.1 (0.78 x 0.76, respectively; P = .69). CONCLUSION In our study, P 0.1 and P 0.1/Pimax ratio were moderately accurate, whereas Pimax was less accurate in predicting the weaning outcome.

Alveolar recruitment maneuver in patients with subarachnoid hemorrhage and acute respiratory distress syndrome: A comparison of 2 approaches☆

PURPOSE The purpose of the study was to compare 2 alveolar recruitment maneuvers (ARMs) approaches in patients with subarachnoid hemorrhage (SAH) and acute respiratory distress syndrome (ARDS). MATERIAL AND METHODS Sixteen SAH patients with ARDS were randomized in 2 similar groups. One received ARM with continuous positive airway pressure (CPAP) of 35 cm H(2)O for 40 seconds (CPAP recruitment), whereas the other received pressure control ventilation with positive-end expiratory pressure of 15 cm H(2)O and pressure control above positive end-expiratory pressure of 35 cm H(2)O for 2 minutes (pressure control recruitment maneuver [PCRM]). Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were measured before and after ARM. The ratio of arterial oxygen tension to fraction of inspired oxygen was measured before and 1 hour after the ARM. RESULTS After ARM, ICP was higher in CPAP recruitment (20.50 ± 4.75 vs 13.13 ± 3.56 mm Hg; P = .003); and CPP was lower in CPAP recruitment (62.38 ± 9.81 vs 79.60 ± 6.8 mm Hg; P = .001). One hour after the ARM, the ratio of arterial oxygen tension to fraction of inspired oxygen increased significantly only in PCRM (108.5 to 203.6; P = .0078). CONCLUSION In SAH patients with ARDS, PCRM did not affect ICP and decreased CPP in safe levels, besides improving oxygenation.

Effects of positive end-expiratory pressure on brain tissue oxygen pressure of severe traumatic brain injury patients with acute respiratory distress syndrome: A pilot study

PURPOSE To verify whether high positive end-expiratory pressure levels can increase brain tissue oxygen pressure, and also their effects on pulse oxygen saturation, intracranial pressure, and cerebral perfusion pressure. MATERIAL AND METHODS Twenty traumatic brain injury patients with acute respiratory distress syndrome were submitted to positive end-expiratory pressure levels of 5, 10, and 15 cm H2O progressively. The 3 positive end-expiratory pressure levels were used during 20 minutes for each one, whereas brain tissue oxygen pressure, oxygen saturation, intracranial pressure, and cerebral perfusion pressure were recorded. RESULTS Brain tissue oxygen pressure and oxygen saturation increased significantly with increasing positive end-expiratory pressure from 5 to 10 and from 10 to 15 cm H2O (P=.0001 and P=.0001 respectively). Intracranial pressure and cerebral perfusion pressure did not differ significantly with increasing positive end-expiratory pressure from 5 to 10 and from 10 to 15 cm H2O (P=.16 and P=.79 respectively). CONCLUSIONS High positive end-expiratory pressure levels increased brain tissue oxygen pressure and oxygen saturation, without increase in intracranial pressure or decrease in cerebral perfusion pressure. High positive end-expiratory pressure levels can be used in severe traumatic brain injury patients with acute respiratory distress syndrome as a safe alternative to improve brain oxygenation.

Applying a new weaning index in ICU older patients

With the increase in life expectation, more admissions to hospital, use of mechanical ventilation (MV) and weaning trials in older patients have been observed.

Effects of expiratory trigger setting on respiratory parameters of nonchronic obstructive pulmonary disease patients

< 40%. Expiratory trigger was set at 1%, 25%, 50% and 70%, for at least 5-minute period each. Respiratory rate, f / Vt ratio, Vt, Ve, SpO2, and Ti / Ttot were measured in each percentage of ET. Analysis of variance for repeated measures was used to analyze variations during the four ET values and to verify variations out of the comfort zone. Bonferroni test was used to identify which values were significantly different among the multiple comparisons. A probability of less than 0.05 was considered significant. Results: Tidal volume, RR and f / Vt ratio presented significant increase in the percentage of patients that showed these parameters out of the comfort zone (p = 0.0025, p = 0.0002 and p = 0.007 respectively). No respiratory parameter presented significant variations when the comparisons were made from 1% to 25% of ET. Conclusions: In non-COPD patients, the use of ET in 1% or 25% has no effect on the respiratory parameters. The increase of ET to 50% or more can worse the respiratory parameters and lead to a rapid shallow breathing, suggesting that these values should be avoided in non-COPD patients.

The Integrative Weaning Index in Elderly ICU Subjects

BACKGROUND: With increasing life expectancy and ICU admission of elderly patients, mechanical ventilation, and weaning trials have increased worldwide. METHODS: We evaluated a cohort with 479 subjects in the ICU. Patients younger than 18 y, tracheostomized, or with neurologic diseases were excluded, resulting in 331 subjects. Subjects ≥70 y old were considered elderly, whereas those <70 y old were considered non-elderly. Besides the conventional weaning indexes, we evaluated the performance of the integrative weaning index (IWI). The probability of successful weaning was investigated using relative risk and logistic regression. The Hosmer-Lemeshow goodness-of-fit test was used to calibrate and the C statistic was calculated to evaluate the association between predicted probabilities and observed proportions in the logistic regression model. RESULTS: Prevalence of successful weaning in the sample was 83.7%. There was no difference in mortality between elderly and non-elderly subjects (P = .16), in days of mechanical ventilation (P = .22) and days of weaning (P = .55). In elderly subjects, the IWI was the only respiratory variable associated with mechanical ventilation weaning in this population (P < .001). CONCLUSIONS: The IWI was the independent variable found in weaning of elderly subjects that may contribute to the critical moment of this population in intensive care.