RESUMEN

Alveolar recruitment manoeuvres may mitigate ventilation and perfusion mismatch after cardiac surgery. Monitoring the efficacy of recruitment manoeuvres should provide concurrent information on pulmonary and cardiac changes. This study in postoperative cardiac patients applied capnodynamic monitoring of changes in end-expiratory lung volume and effective pulmonary blood flow. Alveolar recruitment was performed by incremental increases in positive end-expiratory pressure (PEEP) to a maximum of 15 cmH2O from a baseline of 5 cmH2O over 30 min. The change in systemic oxygen delivery index after the recruitment manoeuvre was used to identify responders (> 10% increase) with all other changes (≤ 10%) denoting non-responders. Mixed factor ANOVA using Bonferroni correction for multiple comparisons was used to denote significant changes (p < 0.05) reported as mean differences and 95% CI. Changes in end-expiratory lung volume and effective pulmonary blood flow were correlated using Pearson's regression. Twenty-seven (42%) of 64 patients were responders increasing oxygen delivery index by 172 (95% CI 61-2984) mL min-1 m-2 (p < 0.001). End-expiratory lung volume increased by 549 (95% CI 220-1116) mL (p = 0.042) in responders associated with an increase in effective pulmonary blood flow of 1140 (95% CI 435-2146) mL min-1 (p = 0.012) compared to non-responders. A positive correlation (r = 0.79, 95% CI 0.5-0.90, p < 0.001) between increased end-expiratory lung volume and effective pulmonary blood flow was only observed in responders. Changes in oxygen delivery index after lung recruitment were correlated to changes in end-expiratory lung volume (r = 0.39, 95% CI 0.16-0.59, p = 0.002) and effective pulmonary blood flow (r = 0.60, 95% CI 0.41-0.74, p < 0.001). Capnodynamic monitoring of end-expiratory lung volume and effective pulmonary blood flow early in postoperative cardiac patients identified a characteristic parallel increase in both lung volume and perfusion after the recruitment manoeuvre in patients with a significant increase in oxygen delivery.Trial registration This study was registered on ClinicalTrials.gov (NCT05082168, 18th of October 2021).

Asunto(s)

Pulmón , Circulación Pulmonar , Humanos , Mediciones del Volumen Pulmonar , Oxígeno , Respiración con Presión Positiva , Estudios Prospectivos

RESUMEN

Aims We sought to evaluate the clinical impact of a 6 month transthoracic echocardiography (TTE) teaching programme in a critical care unit. Methods An observational single centre study. Four critical care doctors, 2 fellows and 2 consultants were trained to use TTE. The study was conducted over 2 six month study periods; period 1 before echocardiography training and period 2 following echocardiography training. Results An increased number of TTE examinations were performed following echocardiography training, 47 TTE studies during period 1 and 144 TTE studies during period 2. The commonest indications for TTE examination were assessment of ventricular function, wall motion abnormalities and cardiac tamponade. The percentage of TTE studies leading to a change in clinical management were similar during both periods, 30% period 1 and 34% period 2. During period 2 the majority of TTE's leading to management change were performed by critical care doctors who frequently manipulated vasoactive medications and administered fluid therapy. Conclusions A 6 month echocardiography training programme led to an increase number of TTE studies independently performed by critical care doctors with resultant clinical impact in one third of cases.