Capnodynamic monitoring of lung volume and blood flow in response to increased positive end-expiratory pressure in moderate to severe COVID-19 pneumonia: an observational study.

BACKGROUND: The optimal level of positive end-expiratory pressure (PEEP) during mechanical ventilation for COVID-19 pneumonia remains debated and should ideally be guided by responses in both lung volume and perfusion. Capnodynamic monitoring allows both end-expiratory lung volume ([Formula: see text]) and effective pulmonary blood flow (EPBF) to be determined at the bedside with ongoing ventilation. METHODS: Patients with COVID-19-related moderate to severe respiratory failure underwent capnodynamic monitoring of [Formula: see text] and EPBF during a step increase in PEEP by 50% above the baseline (PEEPlow to PEEPhigh). The primary outcome was a > 20 mm Hg increase in arterial oxygen tension to inspired fraction of oxygen (P/F) ratio to define responders versus non-responders. Secondary outcomes included changes in physiological dead space and correlations with independently determined recruited lung volume and the recruitment-to-inflation ratio at an instantaneous, single breath decrease in PEEP. Mixed factor ANOVA for group mean differences and correlations by Pearson's correlation coefficient are reported including their 95% confidence intervals. RESULTS: Of 27 patients studied, 15 responders increased the P/F ratio by 55 [24-86] mm Hg compared to 12 non-responders (p < 0.01) as PEEPlow (11 ± 2.7 cm H2O) was increased to PEEPhigh (18 ± 3.0 cm H2O). The [Formula: see text] was 461 [82-839] ml less in responders at PEEPlow (p = 0.02) but not statistically different between groups at PEEPhigh. Responders increased both [Formula: see text] and EPBF at PEEPhigh (r = 0.56 [0.18-0.83], p = 0.03). In contrast, non-responders demonstrated a negative correlation (r = - 0.65 [- 0.12 to - 0.89], p = 0.02) with increased lung volume associated with decreased pulmonary perfusion. Decreased (- 0.06 [- 0.02 to - 0.09] %, p < 0.01) dead space was observed in responders. The change in [Formula: see text] correlated with both the recruited lung volume (r = 0.85 [0.69-0.93], p < 0.01) and the recruitment-to-inflation ratio (r = 0.87 [0.74-0.94], p < 0.01). CONCLUSIONS: In mechanically ventilated patients with moderate to severe COVID-19 respiratory failure, improved oxygenation in response to increased PEEP was associated with increased end-expiratory lung volume and pulmonary perfusion. The change in end-expiratory lung volume was positively correlated with the lung volume recruited and the recruitment-to-inflation ratio. This study demonstrates the feasibility of capnodynamic monitoring to assess physiological responses to PEEP at the bedside to facilitate an individualised setting of PEEP. TRIAL REGISTRATION: NCT05082168 (18th October 2021).

Subglottic secretion drainage for preventing ventilator associated pneumonia: a meta-analysis.

BACKGROUND: Ventilator associated pneumonia (VAP) in the intensive care unit (ICU) has been shown to be associated with significant morbidity and mortality.(1-3) It has been reported to affect between 9 and 27% of intubated patients receiving mechanical ventilation.(4-6) OBJECTIVE: A meta-analysis was undertaken to combine information from published studies of the effect of subglottic drainage of secretions on the incidence of ventilated associated pneumonia in adult ICU patients. DATA SOURCES: Studies were identified by searching MEDLINE (1966 to January 2011), EMBASE (1980-2011), and CINAHL (1982 to January 2011). REVIEW METHODS: Randomized trials of subglottic drainage of secretions compared to usual care in adult mechanically ventilated ICU patients were included in the meta-analysis. RESULTS: Subglottic drainage of secretions was estimated to reduced the risk of VAP by 48% (fixed-effect relative risk (RR)=0.52, 95% confidence interval (CI), 0.42-0.65). When comparing subglottic drainage and control groups, the summary relative risk for ICU mortality was 1.05 (95% CI, 0.86-1.28) and for hospital mortality was 0.96 (95% CI, 0.81-1.12). Overall subglottic drainage effect on days of mechanical ventilation was -1.04 days (95% CI, -2.79-0.71). CONCLUSION: This meta-analysis of published randomized control trials shows that almost one-half of cases of VAP may be prevented with the use of specialized endotracheal tubes designed to drain subglottic secretions. Time on mechanical ventilation may be reduced and time to development of VAP may be increased, but no reduction in ICU or hospital mortality has been observed in published trials.

Tetanus, pneumonia, and malaria in a tsunami victim in Banda Aceh, Indonesia.

On December 26, 2004, a tsunami from the Indian Ocean struck the coastal city of Banda Aceh, Sumatra, Indonesia. This case report describes a 24-year-old woman who presented to the Dr. Zainoel Abidin Hospital in Banda Aceh on January 8, 2005, with a tsunami-related illness. The patient was initially treated for tetanus and aspiration pneumonia with a guarded prognosis. Her recovery was complicated by malaria and recurrent pneumonia. Treatment was hampered by a shortage of medication and equipment, damage to the hospital, and a filthy environment. Morphine, diazepam, and ketamine infusions were used to good effect. This case highlights some of the logistical problems of treating multiple tetanus patients in an austere environment.