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Background Methods Results Conclusions The vasopressor dose needed is a common measure to assess the severity of cardiovascular failure, but there is no consensus on the ranges of vasopressor doses determining different levels of cardiovascular support. We aimed to identify cutoffs for determining low, intermediate and high doses of noradrenaline (norepinephrine), the primary vasopressor used in intensive care, based on association with hospital mortality.We conducted a binational registry study to determine cutoffs between low, intermediate and high noradrenaline doses. We required the cutoffs to be statistically rational and practical (rounded to the first decimal and easy to remember), and to result in increasing mortality with increasing doses. The highest noradrenaline dose in the first 24 h after intensive care unit (ICU) admission was used. The cutoffs were developed using data from 8079 ICU patients treated in the ICU at Kuopio University Hospital, Finland, between 2013 and 2019. Subsequently, the cutoffs were validated in the eICU database, including 39,007 ICU admissions to 29 ICUs in the United States of America in 2014–2015. The log‐rank statistic, with the Contal and O'Quigley method, was used to determine the cutoffs resulting in the most significant split between the noradrenaline dose groups with regard to hospital mortality.The two most prominent peaks in the log‐rank statistic corresponded to noradrenaline doses 0.20 and 0.44 μg/kg/min. Accordingly, we determined three dose ranges: low (<0.2 μg/kg/min), intermediate (0.2–0.4 μg/kg/min) and high (>0.4 μg/kg/min). Mortality increased, whereas the number of patients decreased consistently with increasing noradrenaline doses in both cohorts. In the development cohort, hospital mortality was 6.5% in the group without noradrenaline administered and 14.0%, 26.4% and 40.2%, respectively, in the low‐dose, intermediate‐dose and high‐dose groups. Compared to patients who received no noradrenaline, the hazard ratio for in‐hospital death was 1.4 for the low‐dose group, 4.0 for the intermediate‐dose group and 7.5 for the high‐dose group in the validation cohort (p < .001).The highest noradrenaline dose is a useful measure for quantifying circulatory failure. Cutoffs 0.2 and 0.4 μg/kg/min seem to be suitable for defining low, intermediate and high doses. [ABSTRACT FROM AUTHOR]

Background: Gastric residual volume (GRV) measurement to detect gastrointestinal (GI) dysfunction is a common diagnostic procedures in critical care, albeit still not well standardized being operator-, patient-, and tube-dependent. Our aim was to describe current practice of GRV measurements and its association with clinical outcomes in critically ill patients., Methods: This was a secondary analysis of an international prospective observational cohort study (intestinal-specific organ function assessment). Eligibility criteria were defined as ≥1 GRV measurement during the 7-day study period. Data collection included GRV measurement practices, tube diameters and volumes, symptoms of GI dysfunction, and clinical outcomes. The primary aim was to describe current practices of GRV measurements, and the secondary aim was to test the association of high (>200 ml) vs. low GRV with symptoms of GI dysfunction and clinical outcomes using generalized linear regression and survival models., Results: Two hundred fifty-eight patients with 2422 GRV measurements on 875 study days were analyzed. GRV was mainly measured via passive drainage twice daily using large diameter tubes. There was no significant association between tube size or measurement technique and high GRV. High GRV occurred in 34% of patients and was associated with other GI symptoms and with increased disease severity but not with 28-day or 90-day mortality, intensive care unit-free and ventilator-free days., Conclusion: There was substantial variability of GRV measurement techniques, but this had no impact on the amount of GRV. High GRV was not associated with mortality or ventilator-free days but may serve as a marker of GI dysfunction and disease severity., (© 2023 The Authors. Journal of Parenteral and Enteral Nutrition published by Wiley Periodicals LLC on behalf of American Society for Parenteral and Enteral Nutrition.)

Assessment of native cardiac output during extracorporeal circulation is challenging. We assessed a modified Fick principle under conditions such as dead space and shunt in 13 anesthetized swine undergoing centrally cannulated veno-arterial extracorporeal membrane oxygenation (V-A ECMO, 308 measurement periods) therapy. We assumed that the ratio of carbon dioxide elimination (V̇co 2 ) or oxygen uptake (V̇o 2 ) between the membrane and native lung corresponds to the ratio of respective blood flows. Unequal ventilation/perfusion (V̇/Q̇) ratios were corrected towards unity. Pulmonary blood flow was calculated and compared to an ultrasonic flow probe on the pulmonary artery with a bias of 99 mL/min (limits of agreement -542 to 741 mL/min) with blood content V̇o 2 and no-shunt, no-dead space conditions, which showed good trending ability (least significant change from 82 to 129 mL). Shunt conditions led to underestimation of native pulmonary blood flow (bias -395, limits of agreement -1,290 to 500 mL/min). Bias and trending further depended on the gas (O 2 , CO 2 ) and measurement approach (blood content vs. gas phase). Measurements in the gas phase increased the bias (253 [LoA -1,357 to 1,863 mL/min] for expired V̇o 2 bias 482 [LoA -760 to 1,724 mL/min] for expired V̇co 2 ) and could be improved by correction of V̇/Q̇ inequalities. Our results show that common assumptions of the Fick principle in two competing circulations give results with adequate accuracy and may offer a clinically applicable tool. Precision depends on specific conditions. This highlights the complexity of gas exchange in membrane lungs and may further deepen the understanding of V-A ECMO.

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is used as rescue therapy for severe cardiopulmonary failure. We tested whether the ratio of CO 2 elimination at the lung and the V-A ECMO (V˙co 2ECMO /V˙co 2Lung ) would reflect the ratio of respective blood flows and could be used to estimate changes in pulmonary blood flow (Q˙ Lung ), i.e., native cardiac output. Four healthy pigs were centrally cannulated for V-A ECMO. We measured blood flows with an ultrasonic flow probe. V˙co 2ECMO and V˙co 2Lung were calculated from sidestream capnographs under constant pulmonary ventilation during V-A ECMO weaning with changing sweep gas and/or V-A ECMO blood flow. If ventilation-to-perfusion ratio (V˙/Q˙) of V-A ECMO was not 1, the V˙co 2ECMO was normalized to V˙/Q˙ = 1 (V˙co 2ECMONorm ). Changes in pulmonary blood flow were calculated using the relationship between changes in CO 2 elimination and V-A ECMO blood flow (Q˙ ECMO ). Q˙ ECMO correlated strongly with V˙co 2ECMONorm ( r 2 0.95-0.99). Q˙ Lung correlated well with V˙co 2Lung ( r 2 0.65-0.89, P < = 0.002). Absolute Q˙ Lung could not be calculated in a nonsteady state. Calculated pulmonary blood flow changes had a bias of 76 (-266 to 418) mL/min and correlated with measured Q˙ Lung ( r 2 0.974-1.000, P = 0.1 to 0.006) for cumulative ECMO flow reductions. In conclusion, V˙co 2 of the lung correlated strongly with pulmonary blood flow. Our model could predict pulmonary blood flow changes within clinically acceptable margins of error. The prediction is made possible with normalization to a V˙/Q˙ of 1 for ECMO. This approach depends on measurements readily available and may allow immediate assessment of the cardiac output response.