M. Racagni

INTRODUCTION: This study sought to assess whether the use of thoraco-pelvic supports during prone positioning in patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS) improves, deteriorates or leaves unmodified gas exchange, hemodynamics and respiratory mechanics. METHODS: We studied 11 patients with ALI/ARDS, sedated and paralyzed, mechanically ventilated in volume control ventilation. Prone positioning with or without thoraco-pelvic supports was applied in a random sequence and maintained for a 1-hour period without changing the ventilation setting. In four healthy subjects the pressures between the body and the contact surface were measured with and without thoraco-pelvic supports. Oxygenation variables (arterial and central venous), physiologic dead space, end-expiratory lung volume (helium dilution technique) and respiratory mechanics (partitioned between lung and chest wall) were measured after 60 minutes in each condition. RESULTS: With thoraco-pelvic supports, the contact pressures almost doubled in comparison with those measured without supports (19.1 +/- 15.2 versus 10.8 +/- 7.0 cmH2O, p < or = 0.05; means +/- SD). The oxygenation-related variables were not different in the prone position, with or without thoraco-pelvic supports; neither were the CO2-related variables. The lung volumes were similar in the prone position with and without thoraco-pelvic supports. The use of thoraco-pelvic supports, however, did lead to a significant decrease in chest wall compliance from 158.1 +/- 77.8 to 102.5 +/- 38.0 ml/cmH2O and a significantly increased pleural pressure from 4.3 +/- 1.9 to 6.1 +/- 1.8 cmH2O, in comparison with the prone position without supports. Moreover, when thoraco-pelvic supports were added, heart rate increased significantly from 82.1 +/- 17.9 to 86.7 +/- 16.7 beats/minute and stroke volume index decreased significantly from 37.8 +/- 6.8 to 34.9 +/- 5.4 ml/m2. The increase in pleural pressure change was associated with a significant increase in heart rate (p = 0.0003) and decrease in stroke volume index (p = 0.0241). CONCLUSION: The application of thoraco-pelvic supports decreases chest wall compliance, increases pleural pressure and slightly deteriorates hemodynamics without any advantage in gas exchange. Consequently, we stopped their use in clinical practice.

BACKGROUND: Constipation is frequent in critically ill patients, and potentially related to adverse outcomes. Peripherally-active mu-opioid receptor antagonists (PAMORAs) are approved for opioid-induced constipation, but information on their efficacy and safety in critically ill patients is limited. We present a single-center, retrospective, case-series of the use of naldemedine for opioid-associated constipation, and we systematically reviewed the use of PAMORAs in critically ill patients. METHODS: Case-series included consecutive mechanically-ventilated patients; constipation was defined as absence of bowel movements for >3 days. Naldemedine was administered after failure of the local laxation protocol. Systematic review: PubMed was searched for studies of PAMORAs to treat opioid-induced constipation in adult critically ill patients. PRIMARY OUTCOMES: time to laxation, and number of patients laxating at the shortest follow-up. SECONDARY OUTCOMES: gastric residual volumes and adverse events. KEY RESULTS: A total of 13 patients were included in the case-series; the most common diagnosis was COVID-19 ARDS. Patients had their first bowel movement 1 [0;2] day after naldemedine. Daily gastric residual volume was 725 [405;1805] before vs. 250 [45;1090] mL after naldemedine, p = 0.0078. Systematic review identified nine studies (two RCTs, one prospective case-series, three retrospective case-series and three case-reports). Outcomes were similar between groups, with a trend toward a lower gastric residual volume in PAMORAs group. CONCLUSIONS & INFERENCES: In a highly-selected case-series of patients with refractory, opioid-associated constipation, naldemedine was safe and associated to reduced gastric residuals and promoting laxation. In the systematic review and meta-analysis, the use of PAMORAs (mainly methylnaltrexone) was safe and associated with a reduced intolerance to enteral feeding but no difference in the time to laxation.

Mechanical ventilation (MV) is the principle supportive care in ALI/ARDS patients. MV can be associated with several negative side effects and lung injury (VILI). In recent years several randomized trials tried to focus the optimal ventilatory strategy in ALI/ARDS patients aimed to avoid or minimize the VILI [1-3]. In this study we evaluated how MV has been employed in recent years in ALI/ARDS patients in our intensive care unit (eight beds). We retrospectively collected data of all ALI/ARDS patients, from 2001 to August 2004. To be included in the study the patient must to be ventilated for at least 48 hours without an unfavorable short-term prognosis. Sixty-two patients were enrolled; the mean age and the body mass index were not different between the years (54 ± 17, 62 ± 12, 56 ± 16 and 55 ± 20 years and 24 ± 3, 24 ± 2, 25 ± 6 and 25 ± 4 kg/m2, respectively). The variables in Table ​Table11 were not different at day 3 and day 7 between the four years. We did not find any difference in our 'local' lung ventilatory setting through the years regarding level of PEEP or tidal volume. Instead, to set the tidal volume based on body weight we prefer to set taking into account the airway plateau pressure. Table 1

The use of computed tomography (CT) in the management of ALI/ARDS patients is quite common, due to the possible additional clinical information and the influence on the patient's treatment. With the new spiral CT scan it is possible to measure the total lung volume, the percentage of lung tissue and gas, there being a linear correlation between the physical density and the CT coefficient of attenuation. The aim of this study was to evaluate in vitro the new computer program 'Maluna' (University of Mannheim, Germany) dedicated to measuring the lung volume, weight and gas/tissue ratio. A series of different known volumes of water (100, 500, 1500 and 2000 ml) were studied. In addition, the contrast material was diluted with water to obtain solutions of increasing concentrations (0, 0.5, 1, 1.5, 2.5 and 5%). The spiral CT was performed at 120 KV and 240 mA. Each CT section was manually delineated by a physician. The total volume was computed as the total number of voxels present in a given region times the volume of the voxels, while the CT number was directly related to the physical density. Figure ​Figure11 shows the Bland–Altman analysis between the known volumes of water and the measured volumes by 'Maluna'; Fig. ​Fig.22 shows the linear regression between the CT attenuation coefficient with increasing concentrations of contrast material in the solution. These data show that 'Maluna' is able to correctly compute the volumes and CT number. Figure 1 Figure 2