ABSTRACT
INTRODUCTION: Ventilatory ratio (VR) is a simple bedside index of carbon dioxide removal. VR correlates well with physiologic dead space fraction (VD/VT) and clinical outcomes in patients with acute respiratory distress syndrome (ARDS). We hypothesized that high VR would identify COVID-19 ARDS patients with higher risk for death and organ failure. METHOD(S): We conducted a retrospective cohort study of patients admitted to a single hospital in New York, NY, USA from March-July 2020 who had PCR-confirmed SARS-CoV-2 infection, met the Berlin criteria for ARDS, and required tracheostomy for prolonged invasive mechanical ventilation (MV). MV parameters were collected 2-8 hours after intubation. Based on prior studies, a VR>2 was considered to be abnormally elevated. Comparisons were performed using the Wilcoxon rank-sum test or z-test for difference in proportions with alpha=0.05. The primary outcome was 30- day mortality and the secondary outcome was a composite endpoint of death or organ failure defined as requiring renal replacement or extracorporeal membrane oxygenation (ECMO) during the hospitalization. RESULT(S): Of 139 subjects enrolled, 67 (48.2%) had a VR>2. Low and high VR groups had similar baseline characteristics, including age (mean 58 years, SD +/-15.2), body mass index (30.1+/-6.69 kg/m2), simplified acute physiology score II (35.4+/-12.4), sequential organ failure assessment (SOFA) score (5.7+/-2.5), and a 19-point review of systemic disease history. High VR was not significantly associated with mortality (OR 0.92, p=0.827). However, high VR was associated with increased risk for the composite endpoint (OR 1.96, p=0.049) and independently identified patients with a higher risk of organ failure (OR 2.03, p=0.047). High VR was also associated with longer hospital length-of-stay for subjects who survived to discharge (52 vs. 43, p=0.035), more MV-free days within the 30 days after intubation (3.2 vs. 1.8, p=0.029), and higher SOFA score at 10+/-4 days post-intubation (6.2 vs. 4.8, p=0.024). CONCLUSION(S): Ventilatory ratio identifies COVID-ARDS ventilated patients with increased risk for organ failure requiring advanced intervention, as well as patients who may require prolonged mechanical ventilation and hospitalization.
ABSTRACT
INTRODUCTION: Mortality and morbidity associated with COVID-19 acute respiratory distress syndrome (ARDS) has been associated with pulmonary vasculopathy, which has been hypothesized to increase pulmonary dead space (VD/ VT). However, VD/VT is rarely measured at the bedside. As a result, multiple proxy estimates have been developed. Our hypothesis was proxy estimates for VD/VT would have differing utilities in prognostication of COVID-19 ARDS. METHOD(S): We conducted a retrospective cohort study of patients admitted to an intensive care unit with SARSCoV- 2 ARDS who required invasive mechanical ventilation. Ventilation parameters were collected 2-8 hours after intubation. The VD/Vt proxies examined were 1) ventilatory ratio (VR), 2) estimation of VD/VT using the Harris-Benedict equation for energy expenditure (VD/VT-HB), 3) direct estimation of VD/VT using Beitler et. al.'s formula (VD/VTDir), and 4) corrected minute ventilation (VECorr). For each proxy, subjects were dichotomized using the median value. Comparisons were performed using the Wilcoxon rank-sum test with alpha=0.05. RESULT(S): For 139 subjects, mean VR was 2.08 (SD+/-0.80), mean VD/VT-HB was 0.614 (+/-0.15), mean VD/VT-Dir was 0.657 (+/-0.08), and mean VECorr was 12.2 (+/-4.6) L/min. All four proxies had strong inter-measure correlation (Pearson's r 0.748-0.881, p< 0.001 for all comparisons). No proxy was predictive of 30-day hospital mortality. High VR and VECorr were associated with increased morbidity using a composite endpoint of death or organ failure (defined as requiring renal dialysis or extracorporeal membrane oxygenation) with both having an odds ratio of 2.20 (95% CI: 1.12-4.33, p=0.022), while VD/VT-HB (p=0.552) and VD/VT-Dir (p=0.554) were not significantly associated. Of all proxies, only VR was significantly associated with increased sequential organ failure assessment (SOFA) score at 10+/-4 days post-intubation (6.2 vs. 4.8, p=0.024) and more ventilatorfree days within the 30 days after intubation (3.2 vs. 1.8, p=0.029). CONCLUSION(S): Ventilatory ratio and corrected minute volume appear to have stronger associations with morbidity in COVID-19 ARDS compared to other VD/VT estimates. Ventilatory ratio is also associated with ventilator-free days and delayed SOFA score.
ABSTRACT
INTRODUCTION: Ventilatory ratio (VR) is a bedside index of impaired ventilation that can be used as a surrogate marker for pulmonary dead space fraction (VD/VT). Vasculopathy is hypothesized to increase VD/VT in patients with acute respiratory distress syndrome (ARDS) due to COVID-19. The purpose of this study was to investigate associations between VR and markers of inflammation in critically ill COVID-ARDS patients. METHOD(S): We conducted a retrospective study of patients admitted to an intensive care unit due to SARS-CoV-2 infection. All subjects required invasive mechanical ventilation and met the Berlin criteria for ARDS. Clinical lab values were collected at two timepoints: 2-8 hours after intubation (T1) and 2-24 hours before tracheostomy (T2). VR was split into high (VR>2) and low (VR< 2) groups. Comparisons were performed using student's t, Mann-Whitney, and z tests for difference in proportions with alpha=0.05. RESULT(S): Of the 139 subjects enrolled at T1, 67 (48%) had high VR (>2), with an overall mean VR of 2.08. High VR was significantly associated with leukocyte count (WBC) (13.3 vs. 10.6 x10
ABSTRACT
CASE: A 51-year-old man without significant past medical history presented to our hospital with dyspnea on exertion. SARS-CoV-2 was detected on routine occupational screening 2 months prior to admission. He subsequently reported a 100lb weight loss, during which time he experienced dysgeusia and ate primarily cereal, sandwiches, and potatoes and consumed nearly no fruits or vegetables. Three weeks prior to admission he developed postprandial nausea and vomiting and anorexia. A week later he developed progressive epigastric pain, lower extremity edema, and dyspnea while walking around the college campus where he worked as a security guard, and sought medical attention. He did not have fever, chills, night sweats, cough, orthopnea, paroxysmal nocturnal dyspnea, rash, or diarrhea. He had not seen a doctor in 20 years and took no medications. He did not drink alcohol, smoke cigarettes, or use illicit substances. Vital signs were T 36.6°F HR 104 BP 149/111 RR 20 and SpO2 97%. Physical examination revealed a cachectic man with bitemporal wasting, sunken orbits, poor dentition, and severe periodontal disease. JVP was 14cm of H2O at 45°. An S3 was present. The abdomen was tender to palpation in the mid epigastrium. The extremities were cool with 3+ pitting edema. Pancreatitis was diagnosed after discovery of markedly elevated lipase levels and peripancreatic fat stranding on abdominal CT. TTE showed biventricular systolic dysfunction with LVEF 15%. He developed cardiogenic shock complicated by oliguric renal failure, congestive hepatopathy and obtundation, requiring ICU transfer for diuresis and inotropic support. Further workup revealed deficiencies of thiamine, zinc, and vitamins A, C, and D. A regadenoson myocardial perfusion PET/CT showed no flow-limiting coronary artery disease, and workup for inflammatory, infectious, and toxic-metabolic causes of heart failure was unrevealing. While COVID myocarditis and multisystem inflammatory syndrome in adults (MIS-A) were considered, ultimately, a diagnosis of wet beriberi was made. After 5 months of aggressive nutritional supplementation via percutaneous gastrostomy tube and initiation of guideline-directed medical therapy, LVEF improved to 53% and weight increased by 35lbs. IMPACT/DISCUSSION: Wet beriberi is a potentially underrecognized cause of dilated cardiomyopathy in resource-rich areas. Within 3 months, thiamine deficiency can cause high-output heart failure due to impaired myocardial energy metabolism and dysautonomia. Risk factors include alcohol use disorder, prolonged vomiting, and history of bariatric surgery. CONCLUSION: The laboratory evaluation of non-ischemic dilated cardiomyopathy should include measurement of serum thiamine, carnitine, and selenium levels in select patients, alongside iron studies, ANA, screening for HIV, Chagas disease, and viral myocarditis, and genetic testing in patients with a suggestive family history. Empiric thiamine repletion should be considered in all critically ill patients with evidence of malnutrition.