Abstract
Crit Care Sci. 2024;36:e20240005en
DOI 10.62675/2965-2774.20240005-en
To investigate the factors influencing carbon dioxide transfer in a system that integrates an oxygenation membrane in series with high-bicarbonate continuous veno-venous hemodialysis in hypercapnic animals.
In an experimental setting, we induced severe acute kidney injury and hypercapnia in five female Landrace pigs. Subsequently, we initiated high (40mEq/L) bicarbonate continuous veno-venous hemodialysis with an oxygenation membrane in series to maintain a pH above 7.25. At intervals of 1 hour, 6 hours, and 12 hours following the initiation of continuous veno-venous hemodialysis, we performed standardized sweep gas flow titration to quantify carbon dioxide transfer. We evaluated factors associated with carbon dioxide transfer through the membrane lung with a mixed linear model.
A total of 20 sweep gas flow titration procedures were conducted, yielding 84 measurements of carbon dioxide transfer. Multivariate analysis revealed associations among the following (coefficients ± standard errors): core temperature (+7.8 ± 1.6 °C, p < 0.001), premembrane partial pressure of carbon dioxide (+0.2 ± 0.1/mmHg, p < 0.001), hemoglobin level (+3.5 ± 0.6/g/dL, p < 0.001), sweep gas flow (+6.2 ± 0.2/L/minute, p < 0.001), and arterial oxygen saturation (-0.5 ± 0.2%, p = 0.019). Among these variables, and within the physiological ranges evaluated, sweep gas flow was the primary modifiable factor influencing the efficacy of low-blood-flow carbon dioxide removal.
Sweep gas flow is the main carbon dioxide removal-related variable during continuous veno-venous hemodialysis with a high bicarbonate level coupled with an oxygenator. Other carbon dioxide transfer modulating variables included the hemoglobin level, arterial oxygen saturation, partial pressure of carbon dioxide and core temperature. These results should be interpreted as exploratory to inform other well-designed experimental or clinical studies.
Abstract
Crit Care Sci. 2024;36:e20240203en
DOI 10.62675/2965-2774.20240203-en
To assess whether the respiratory oxygenation index (ROX index) measured after the start of high-flow nasal cannula oxygen therapy can help identify the need for intubation in patients with acute respiratory failure due to coronavirus disease 2019.
This retrospective, observational, multicenter study was conducted at the intensive care units of six Brazilian hospitals from March to December 2020. The primary outcome was the need for intubation up to 7 days after starting the high-flow nasal cannula.
A total of 444 patients were included in the study, and 261 (58.7%) were subjected to intubation. An analysis of the area under the receiver operating characteristic curve (AUROC) showed that the ability to discriminate between successful and failed high-flow nasal cannula oxygen therapy within 7 days was greater for the ROX index measured at 24 hours (AUROC 0.80; 95%CI 0.76 - 0.84). The median interval between high-flow nasal cannula initiation and intubation was 24 hours (24 - 72), and the most accurate predictor of intubation obtained before 24 hours was the ROX index measured at 12 hours (AUROC 0.75; 95%CI 0.70 - 0.79). Kaplan-Meier curves revealed a greater probability of intubation within 7 days in patients with a ROX index ≤ 5.54 at 12 hours (hazard ratio 3.07; 95%CI 2.24 - 4.20) and ≤ 5.96 at 24 hours (hazard ratio 5.15; 95%CI 3.65 - 7.27).
The ROX index can aid in the early identification of patients with acute respiratory failure due to COVID-19 who will progress to the failure of high-flow nasal cannula supportive therapy and the need for intubation.
Abstract
Crit Care Sci. 2023;35(3):302-310
DOI 10.5935/2965-2774.20230141-pt
To evaluate the accuracy of the persistent AKI risk index (PARI) in predicting acute kidney injury within 72 hours after admission to the intensive care unit, persistent acute kidney injury, renal replacement therapy, and death within 7 days in patients hospitalized due to acute respiratory failure.
This study was done in a cohort of diagnoses of consecutive adult patients admitted to the intensive care unit of eight hospitals in Curitiba, Brazil, between March and September 2020 due to acute respiratory failure secondary to suspected COVID-19. The COVID-19 diagnosis was confirmed or refuted by RT-PCR for the detection of SARS-CoV-2. The ability of PARI to predict acute kidney injury at 72 hours, persistent acute kidney injury, renal replacement therapy, and death within 7 days was analyzed by ROC curves in comparison to delta creatinine, SOFA, and APACHE II.
Of the 1,001 patients in the cohort, 538 were included in the analysis. The mean age was 62 ± 17 years, 54.8% were men, and the median APACHE II score was 12. At admission, the median SOFA score was 3, and 83.3% had no renal dysfunction. After admission to the intensive care unit, 17.1% had acute kidney injury within 72 hours, and through 7 days, 19.5% had persistent acute kidney injury, 5% underwent renal replacement therapy, and 17.1% died. The PARI had an area under the ROC curve of 0.75 (0.696 - 0.807) for the prediction of acute kidney injury at 72 hours, 0.71 (0.613 - 0.807) for renal replacement therapy, and 0.64 (0.565 - 0.710) for death.
The PARI has acceptable accuracy in predicting acute kidney injury within 72 hours and renal replacement therapy within 7 days of admission to the intensive care unit, but it is not significantly better than the other scores.
Abstract
Crit Care Sci. 2023;35(2):168-176
DOI 10.5935/2965-2774.20230410-pt
We hypothesized that the use of mechanical insufflation-exsufflation can reduce the incidence of acute respiratory failure within the 48-hour post-extubation period in intensive care unit-acquired weakness patients.
This was a prospective randomized controlled open-label trial. Patients diagnosed with intensive care unit-acquired weakness were consecutively enrolled based on a Medical Research Council score ≤ 48/60. The patients randomly received two daily sessions; in the control group, conventional chest physiotherapy was performed, while in the intervention group, chest physiotherapy was associated with mechanical insufflation-exsufflation. The incidence of acute respiratory failure within 48 hours of extubation was evaluated. Similarly, the reintubation rate, intensive care unit length of stay, mortality at 28 days, and survival probability at 90 days were assessed. The study was stopped after futility results in the interim analysis.
We included 122 consecutive patients (n = 61 per group). There was no significant difference in the incidence of acute respiratory failure between treatments (11.5% control group versus 16.4%, intervention group; p = 0.60), the need for reintubation (3.6% versus 10.7%; p = 0.27), mean length of stay (3 versus 4 days; p = 0.33), mortality at Day 28 (9.8% versus 15.0%; p = 0.42), or survival probability at Day 90 (21.3% versus 28.3%; p = 0.41).
Mechanical insufflation-exsufflation combined with chest physiotherapy seems to have no impact in preventing postextubation acute respiratory failure in intensive care unit-acquired weakness patients. Similarly, mortality and survival probability were similar in both groups. Nevertheless, given the early termination of the trial, further clinical investigation is strongly recommended.
Abstract
Rev Bras Ter Intensiva. 2022;34(1):185-196
DOI 10.5935/0103-507X.20220013-en
Although the PaO 2/FiO 2 derived from arterial blood gas analysis remains the gold standard for the diagnosis of acute respiratory failure, the SpO2/FiO2 has been investigated as a potential substitute. The current narrative review presents the state of the preclinical and clinical literature on the SpO2/FiO2 as a possible substitute for PaO2/FiO2 and for use as a diagnostic and prognostic marker; provides an overview of pulse oximetry and its limitations, and assesses the utility of SpO2/ FiO2 as a surrogate for PaO2/FiO2 in COVID-19 patients. Overall, 49 studies comparing SpO2/FiO2 and PaO2/FiO2 were found according to a minimal search strategy. Most were conducted on neonates, some were conducted on adults with acute respiratory distress syndrome, and a few were conducted in other clinical scenarios (including a very few on COVID-19 patients). There is some evidence that the SpO2/ FiO2 criteria can be a surrogate for PaO2/FiO2 in different clinical scenarios. This is reinforced by the fact that unnecessary invasive procedures should be avoided in patients with acute respiratory failure. It is undeniable that pulse oximeters are becoming increasingly widespread and can provide costless monitoring. Hence, replacing PaO2/FiO2 with SpO2/FiO2may allow resourcelimited facilities to objectively diagnose acute respiratory failure.
Abstract
Rev Bras Ter Intensiva. 2021;33(4):544-548
DOI 10.5935/0103-507X.20210082
To evaluate whether there was any impact on the number of pediatric extracorporeal membrane oxygenation runs and survival rates in the years subsequent to the 2009 pandemic.
We studied two different periods of extracorporeal membrane oxygenation support for respiratory failure in children by analyzing datasets from the Extracorporeal Life Support Organization. Autoregressive integrated moving average models were constructed to estimate the effect of the pandemic. The year 2009 was the year of intervention (the H1N1 epidemic) in an interrupted time series model. Data collected from 2001 - 2010 were considered preintervention, and data collected from 2010 - 2017 were considered postintervention.
There was an increase in survival rates in the period 2010 - 2017 compared to 2001 - 2010 (p < 0.0001), with a significant improvement in survival when extracorporeal membrane oxygenation was performed for acute respiratory failure due to viral pneumonia. The autoregressive integrated moving average model shows an increase of 23 extracorporeal membrane oxygenation runs per year, prior to the point of the level effect (2009). In terms of survival, the preslope shows that there was no significant increase in survival rates before 2009 (p = 0.41), but the level effect was nearly significant after two years (p = 0.05), with a 6% increase in survival. In four years, there was an 8% (p = 0.03) increase in survival, and six years after 2009, there was up to a 10% (p = 0.026) increase in survival.
In the years following 2009, there was a significant, global incremental increase in the extracorporeal membrane oxygenation survival rates for all runs, mainly due to improvements in the technology and treatment protocols for acute respiratory failure related to viral pneumonia and other respiratory conditions.
Abstract
Rev Bras Ter Intensiva. 2021;33(3):384-393
DOI 10.5935/0103-507X.20210055
To describe current clinical practices related to the use of high-flow nasal cannula therapy by Brazilian pediatric intensivists and compare them with those in other countries.
A questionnaire was administered to pediatric intensivists in North and South America, Asia, Europe, and Australia/New Zealand for the main study. We compared the Brazilian cohort with cohorts in the United States of America, Canada, the United Kingdom, and India
Overall, 501 physicians responded, 127 of which were in Brazil. Only 63.8% of respondents in Brazil had a high-flow nasal cannula available, in contrast to 100% of respondents in the United Kingdom, Canada, and the United States. The attending physician was responsible for the decision to start a high-flow nasal cannula according to 61.2% respondents in Brazil, 95.5% in the United Kingdom, 96.6% in the United States, 96.8% in Canada, and 84.7% in India. A total of 62% of respondents in Brazil, 96.3% in the United Kingdom, 96.6% in the United States, 96.8% in Canada, and 84.7% in India reported that the attending physician was responsible for the decision to wean or modify the high-flow nasal cannula settings. When high-flow nasal cannula therapy failed due to respiratory distress/failure, 82% of respondents in Brazil would consider a trial of noninvasive ventilation before endotracheal intubation, compared to 93% in the United Kingdom, 88% in the United States, 91.5% in Canada, and 76.8% in India. More Brazilian intensivists (6.5%) than intensivists in the United Kingdom, United States, and India (1.6% for all) affirmed using sedatives frequently with high-flow nasal cannulas.
The availability of high-flow nasal cannulas in Brazil is still not widespread. There are some divergences in clinical practices between Brazilian intensivists and their colleagues abroad, mainly in processes and decision-making about starting and weaning high-flow nasal cannula therapy.