Low respiratory quotient correlates with high mortality in patients undergoing mechanical ventilation.

OBJECTIVE: Oxygen consumption (VO2), carbon dioxide generation (VCO2), and respiratory quotient (RQ), which is the ratio of VO2 to VCO2, are critical indicators of human metabolism. To seek a link between the patient's metabolism and pathophysiology of critical illness, we investigated the correlation of these values with mortality in critical care patients. METHODS: This was a prospective, observational study conducted at a suburban, quaternary care teaching hospital. Age 18 years or older healthy volunteers and patients who underwent mechanical ventilation were enrolled. A high-fidelity automation device, which accuracy is equivalent to the gold standard Douglas Bag technique, was used to measure VO2, VCO2, and RQ at a wide range of fraction of inspired oxygen (FIO2). RESULTS: We included a total of 21 subjects including 8 post-cardiothoracic surgery patients, 7 intensive care patients, 3 patients from the emergency room, and 3 healthy volunteers. This study included 10 critical care patients, whose metabolic measurements were performed in the ER and ICU, and 6 died. VO2, VCO2, and RQ of survivors were 282 +/- 95 mL/min, 202 +/- 81 mL/min, and 0.70 +/- 0.10, and those of non-survivors were 240 +/- 87 mL/min, 140 +/- 66 mL/min, and 0.57 +/- 0.08 (p = 0.34, p = 0.10, and p < 0.01), respectively. The difference of RQ was statistically significant (p < 0.01) and it remained significant when the subjects with FIO2 < 0.5 were excluded (p < 0.05). CONCLUSIONS: Low RQ correlated with high mortality, which may potentially indicate a decompensation of the oxygen metabolism in critically ill patients.

Impact of Limited Enhanced Recovery Pathway for Cardiac Surgery: A Single-Institution Experience.

OBJECTIVES: Enhanced recovery pathway (ERP) refers to extensive multidisciplinary, evidence-based pathways used to facilitate recovery after surgery. The authors assessed the impact that limited ERP protocols had on outcomes in patients undergoing cardiac surgery at their institution. DESIGN: A retrospective cohort study. SETTING: This study was a single-institution study conducted at a university hospital. PARTICIPANTS: Patients undergoing open adult cardiac surgery. INTERVENTIONS: Enhanced recovery pathways limited to preoperative, intraoperative, and postoperative management of pain, atrial fibrillation prevention, and nutrition optimization were implemented. MEASUREMENTS AND MAIN RESULTS: A total of 1,058 patients were included in this study. There were 374 patients in each pre- and post-ERP cohort after propensity matching, with no significant baseline differences between the 2 cohorts. Compared to the matched patients in the pre-ERP group, patients in the post-ERP group had decreased total ventilation hours (6.8 v 7.8, p = 0.006), less use of postoperative opioid analgesics as determined by total morphine milligram equivalent (32.5 v 47.5, p < 0.001), and a decreased rate of postoperative atrial fibrillation (23.3% v 30.5%, p = 0.032). Post-ERP patients also experienced less subjective pain and postoperative nausea and drowsiness as compared to their matched pre-ERP cohorts. CONCLUSIONS: Limited ERP implementation resulted in significantly improved perioperative outcomes. Patients additionally experienced less postoperative pain despite decreased opioid use. Implementation of ERP, even in a limited format, is a promising approach to improving outcomes in patients undergoing cardiac surgery.

Continuous and repeat metabolic measurements compared between post-cardiothoracic surgery and critical care patients.

OBJECTIVE: Using a system, which accuracy is equivalent to the gold standard Douglas Bag (DB) technique for measuring oxygen consumption (VO2), carbon dioxide generation (VCO2), and respiratory quotient (RQ), we aimed to continuously measure these metabolic indicators and compare the values between post-cardiothoracic surgery and critical care patients. METHODS: This was a prospective, observational study conducted at a suburban, quaternary care teaching hospital. Age 18 years or older patients who underwent mechanical ventilation were enrolled. RESULTS: We included 4 post-surgery and 6 critical care patients. Of those, 3 critical care patients died. The longest measurement reached to 12 h and 15 min and 50 cycles of repeat measurements were performed. VO2 of the post-surgery patients were 234 ± 14, 262 ± 27, 212 ± 16, and 192 ± 20 mL/min, and those of critical care patients were 122 ± 20, 189 ± 9, 191 ± 7, 191 ± 24, 212 ± 12, and 135 ± 21 mL/min, respectively. The value of VO2 was more variable in the post-surgery patients and the range of each patient was 44, 126, 71, and 67, respectively. SOFA scores were higher in non-survivors and there were negative correlations of RQ with SOFA. CONCLUSIONS: We developed an accurate system that enables continuous and repeat measurements of VO2, VCO2, and RQ. Critical care patients may have less activity in metabolism represented by less variable values of VO2 and VCO2 over time as compared to those of post-cardiothoracic surgery patients. Additionally, an alteration of these values may mean a systemic distinction of the metabolism of critically ill patients.

Passive transfer of SARS-CoV-2 antibodies with platelet transfusions.

BACKGROUND: Although over 5000 platelet transfusions occur daily in the United States, the presence of SARS-CoV-2 antibodies in platelet units is not commonly evaluated for. The effects of platelet transfusions with SARS-CoV-2 antibodies remain largely unknown. We evaluated single-donor (apheresis) platelet units for SARS-CoV-2 antibodies and determined if platelet transfusions passively transferred antibodies to seronegative recipients. STUDY DESIGN AND METHODS: We conducted a retrospective analysis as part of a quality assurance initiative during February to March 2021 at a tertiary referral academic center in suburban New York. Platelet units and platelet recipients were evaluated for the presence of SARS-CoV-2 antibodies using the DiaSorin LIASON SARS-CoV-2 S1/S2 IgG assay. There were 47 platelet recipients eligible for study inclusion. The primary outcome was the presence of SARS-CoV-2 spike protein IgG antibodies in the recipient's blood after platelet transfusion. RESULTS: Twenty-three patients received platelets with SARS-CoV-2 spike protein IgG antibodies; 13 recipients had detection of SARS-COV-2 antibodies (56.5%), and 10 recipients did not. The median antibody titer in the platelet units given to the group with passive antibodies detected was significantly higher compared to the median antibody titer in the platelet units given to the group without antibodies detected (median [interquartile range]: 306 AU/ml [132, 400] vs. 96.1 AU/ml [30.6, 186], p = .027). CONCLUSIONS: Our study demonstrated a significant rate of passive transfer of SARS-CoV-2 spike protein IgG antibodies through platelet transfusions. Considering the volume of daily platelet transfusions, this is something all clinicians should be aware of.

Use of TIMP-2 and IGFBP-7 for prediction of postoperative acute kidney injury after cardiac surgery.

BACKGROUND: The following cell cycle arrest urinary biomarkers, tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP-7), have been used for early detection of acute kidney injury (AKI) in critically ill patients. The purpose of this study is to validate the use of these urinary biomarkers in patients undergoing open heart surgery. MATERIALS AND METHODS: In a single-center prospective observational study, urine samples were collected in 108 consecutive patients who underwent open heart surgery immediately after separation from cardiopulmonary bypass and on postoperative day 1, and were sent for the biomarker [TIMP-2]*[IGFBP7] analysis. Acute kidney injury was defined based on KDIGO criteria, and levels of [TIMP-2]*[IGFBP7] were analyzed for the ability to predict AKI. RESULTS: Of the 108 patients, 19 (17.6%) patients developed postoperative AKI within 48 hours of surgery. At the threshold of > 0.3 (ng/mL)2/1,000, post-cardiopulmonary bypass [TIMP-2]*[IGFBP-7] had a sensitivity of 13% and specificity of 82% for predicting postoperative AKI. Postoperative day-1 [TIMP-2]*[IGFBP-7] had a sensitivity of 47% and a specificity of 59% for predicting postoperative AKI. There were no differences in [TIMP-2]*[IGFBP-7] values at either timepoint between patients who developed postoperative AKI as compared to those who did not. CONCLUSION: Urinary [TIMP-2]*[IGFBP7] was not predictive of the risk of AKI after cardiac surgery in this single-center study population.

Impact of chronic lung disease on quality-of-life outcomes in patients undergoing transcatheter aortic valve replacement.

BACKGROUND: As the symptoms for both chronic lung disease (CLD) and aortic stenosis (AS) frequently overlap, it may be challenging to determine the degree of symptomatic improvement expected for a patient with CLD after correction of AS. Our aim was to determine if patients with CLD have the same degree of quality-of-life improvement following transcatheter aortic valve replacement (TAVR) as patients without CLD. METHODS: A retrospective review of 238 TAVR patients from January 2017 to November 2018 who underwent preoperative pulmonary function tests and completed 30-day follow-up was performed. Patients were identified as having CLD with FEV1 more than 75% predicted. Postoperative outcomes and changes in Kansas City Cardiomyopathy Questionnaire-12 (KCCQ-12) were compared between groups. RESULTS: Of the 238 patients identified, 143 (60.0%) had CLD, 50 (35.0%) of whom had an obstructive disease pattern. Patients with CLD were more likely to be male, had higher rates of peripheral artery disease, and had lower baseline ejection fraction. There was no difference in STS Predicted Risk of Mortality, but patients with CLD were more likely to be designated as high-risk by surgeon evaluation. While initial and follow-up KCCQ-12 was lower for patients with CLD, there was no significant difference in degree of improvement (p = .900). When comparing patients with obstructive lung disease (FEV1/FVC < 0.70) to those without CLD, there was also no significant difference in the change of quality of life (p = .720). CONCLUSION: Although patients with concomitant severe AS and CLD have reduced baseline quality of life compared to patients without CLD, they experience a comparable degree of improvement following TAVR.

Risk stratification for nonagenarians undergoing transcatheter aortic valve replacement.

BACKGROUND: There are disparate data on the outcomes of nonagenarians undergoing transcatheter aortic valve replacement (TAVR) compared with younger patients. The purpose of this study is to determine whether the Society of Thoracic Surgeons (STS) score can be used to identify the subset of nonagenarians that are at a significantly higher risk for poor postoperative outcomes after TAVR. METHODS: A total of 425 patients above the age of 80 underwent elective TAVR between 12/2013 and 2/2018 and were included in this study. Patients were deemed intermediate or high risk based on an STS predicted the risk of surgical mortality score of 3% to 8% and more than 8%, respectively. Differences in postoperative outcomes and/or 6-month mortality between intermediate and high-risk octogenarians and nonagenarians were compared. RESULTS: Of the 425 patients, 112 (26.4%) patients were nonagenarians, and 313 (73.6%) patients were octogenarians. Fifty-four (48.2%) of the nonagenarians were stratified as high-risk, while 78 (24.9%) of the octogenarians were stratified as high-risk. There were no statistically significant differences in the composite outcomes between intermediate-risk nonagenarians and intermediate-risk octogenarians. In contrast, high-risk nonagenarians were significantly more likely to experience the composite outcome of major perioperative complications and/or 6-month mortality as compared to high-risk octogenarians. CONCLUSION: Intermediate-risk nonagenarians undergoing TAVR have similar postoperative outcomes compared to intermediate-risk octogenarians. However, high-risk nonagenarian patients undergoing TAVR experience significantly poorer outcomes compared to their octogenarian counterparts. Judicious patient selection for TAVR in this subgroup of patients is therefore warranted.

Incidence of Acute Kidney Injury in Patients with Chronic Renal Insufficiency: Transcatheter versus Surgical Aortic Valve Replacement.

OBJECTIVES: The objective of this study is to determine incidence of acute kidney injury (AKI) associated with transcatheter aortic valve replacement (TAVR) versus surgical aortic valve replacement (SAVR) in patients with preexisting chronic kidney disease. BACKGROUND: The incidence of AKI in patients with preexisting renal insufficiency undergoing TAVR versus SAVR is not well described. METHODS: All patients with preexisting chronic kidney disease who underwent SAVR for aortic stenosis with or without concomitant coronary artery bypass grafting or TAVR from 5/2008 to 6/2017. Patients requiring preoperative hemodialysis were excluded. Chronic kidney disease was defined as an estimated glomerular filtrate rate (eGFR) of < 60 mL/min/1.73 m2. The incidence of postoperative AKI was compared using the RIFLE classification system for acute kidney injury. RESULTS: A total of 406 SAVR patients and 407 TAVR patients were included in this study. TAVR patients were older and had lower preoperative eGFR as compared to SAVR patients. Covariate adjustment using propensity score between the two groups showed that SAVR patients were more likely to have a more severe degree of postoperative AKI as compared to TAVR patients (OR = 4.75; 95% CI: 3.15, 7.17; p <.001). SAVR patients were more likely to require dialysis postoperatively as compared to TAVR patients (OR = 4.55; 95% CI: 1.29, 15.99; p <.018). CONCLUSION: In patients with preexisting chronic kidney disease, TAVR was associated with significantly less AKI as compared to SAVR.

Predictors of Increased Length of Hospital Stay in Patients with Severe Cardiomyopathy Undergoing Coronary Artery Bypass Grafting.

OBJECTIVE: Predictors of operative outcome in patients with severely depressed left ventricular ejection fraction (LVEF) undergoing coronary artery bypass grafting (CABG) remain poorly defined. This study aims to identify preoperative variables that are associated with increased postoperative length of hospital stay or operative mortality in this patient population. DESIGN: Retrospective study. SETTING: Single tertiary care university hospital. PARTICIPANTS: Patients undergoing isolated CABG between January 2012 and March 2017 with an LVEF ≤ 25%. INTERVENTIONS: Isolated CABG. MEASUREMENTS AND MAIN RESULTS: Primary endpoint was a composite of prolonged length of stay, defined as postoperative length of stay >7 days or operative mortality. Of the 201 patients, 99 (49.3%) met the primary endpoint. Patient comorbidities, clinical presentation, presence of Q-waves on electrocardiogram, and echocardiographic parameters including ventricular dimensions and right heart dysfunction were not associated with the primary endpoint. On multivariable analysis, patients who were not on preoperative beta-blockers, patients with preoperative albumin of <3.5 g/dL, and higher Society of Thoracic Surgeons Predicted Risk of Mortality score were associated with increased prolonged length of stay or death. CONCLUSIONS: More than half of patients with severely depressed LVEF undergoing isolated CABG are able to be discharged within 7 days postoperatively. The absence of preoperative beta-blockers, low preoperative albumin levels, and higher Society of Thoracic Surgeons Predicted Risk of Mortality score are associated with more complicated or slower postoperative recovery after CABG in this patient population.

Impact of novel oral anticoagulants vs warfarin on effusions after coronary artery bypass grafting.

BACKGROUND: Novel oral anticoagulants (NOAC) have been shown to have comparable risk profiles compared with warfarin. However, data on the use of NOACs in cardiac surgery patients is limited. The aim of this study is to compare postoperative effusion rates in patients who were anticoagulated with NOACs vs warfarin after coronary artery bypass grafting (CABG). METHODS: A retrospective review of 2017 patients undergoing isolated CABG from 2014 to 2017 was performed. Of those patients, 246 patients (12.2%) were placed on either a NOAC or warfarin postoperatively. The combined rates of postoperative pericardial and pleural effusions requiring invasive intervention during the index hospitalization and up to 3 months postoperatively were compared between patients who were placed on NOACs vs warfarin. RESULTS: Of the 246 patients placed on oral anticoagulation after isolated CABG, 64 (26.0%) were placed on NOACs, and 182 (74.0%) received warfarin. There were no significant differences in preoperative coagulation profile and use of anticoagulation and antiplatelets preoperatively between the groups. Of the patients anticoagulated with NOACs postoperatively, 17 patients (26.6%) required invasive interventions for effusions compared with 24 patients (13.2%) in the cohort anticoagulated with warfarin (P < 0.014). Of the patients who required interventions for effusions, those on NOACs were more likely to require delayed interventions compared with those on warfarin. CONCLUSIONS: Patients receiving NOACs after CABG are at increased risk of developing effusions requiring invasive interventions compared to patients receiving warfarin. This increased risk should be taken into consideration when choosing the appropriate anticoagulation strategy for postoperative patients with CABG.

Impact of Postoperative Hypothermia on Outcomes in Coronary Artery Bypass Surgery Patients.

OBJECTIVES: To determine the impact of postoperative hypothermia on outcomes in coronary artery bypass graft surgery (CABG) patients. DESIGN: A retrospective study was performed on patients who underwent isolated CABG between 2011 and 2014. SETTING: Single-center study at a university hospital. PARTICIPANTS: All patients who underwent isolated CABG with cardiopulmonary bypass between 2011 and 2014. INTERVENTIONS: Patients underwent isolated CABG on cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: Patients were propensity-score matched based on the likelihood of being hypothermic (<36ºC) or normothermic (≥36ºC) on arrival to the cardiac surgery intensive care unit (ICU) from the operating room. Total transfusion requirements, composite in-hospital morbidity and/or mortality endpoint, total hours in the ICU, and length of hospital stay were compared between the 2 groups. Of the 1,030 patients undergoing isolated CABG, 529 (51.3%) were hypothermic on arrival to the ICU. The hypothermic cohort were older, had more females, had lower body mass indices, had lower starting hematocrit values, were cooled to lower temperatures while on cardiopulmonary bypass, and had longer cardiopulmonary bypass runs compared with the normothermic group. Of the 748 patients who were propensity matched, there were no differences in blood and blood product transfusion requirements, mortality and complication rates, time on the ventilator, length of ICU stay, and length of hospital stay between hypothermic and normothermic patients. CONCLUSIONS: Hypothermia at ICU admission after CABG was not associated with increased adverse outcomes, possibly suggesting that complete rewarming before separation from cardiopulmonary bypass may not be essential in all patients.

Outcomes of Patients With Prolonged Intensive Care Unit Length of Stay After Cardiac Surgery.

OBJECTIVE: To determine in-hospital and post-discharge long-term survival in patients with prolonged intensive care unit (ICU) stays after cardiac surgery. DESIGN: Retrospective, cohort study of cardiac surgery patients from May 2007 to June 2012. SETTING: Single-center cardiac surgery ICU. PARTICIPANTS: Patients were grouped according to length of ICU stay: between 1 and 2 weeks, between 2 and 4 weeks, and>4 weeks. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 4,963 patients, 3.3%, 1.6%, and 2.9% of patients stayed 1 to 2 weeks, 2 to 4 weeks, and>4 weeks in the ICU, respectively. In-hospital mortality was 11.1%, 26.6%, and 31.0% for patients with 1 to 2 weeks, 2 to 4 weeks, and>4 weeks ICU stay, respectively. Patients with ICU stays between 1 and 2 weeks had 6 months, 1 year, and 2 year survival rates of 84.4%, 80.0%, and 75.3% after discharge, respectively. Patients with ICU stay between 2 and 4 weeks had similar 6 months, 1 year, and 2 year survival rates of 84.7%, 79.9%, and 74.1%, respectively. In contrast, patients with>4 week ICU stays had significantly lower postdischarge survival rates of 63.3%, 56.4%, and 41.1% at 6 months, 1 year, and 2 years, respectively. Postoperative stroke conferred the greatest risk of death within 1 year after discharge (odds ratio 7.6, p = 0.0140). CONCLUSIONS: In-hospital mortality rates post-cardiac surgery correlate with length of ICU stay but appear to plateau after 4 weeks. However, a>4 week ICU length of stay confers a worse long-term outcome post-hospital discharge, especially in patients with postoperative stroke.

Utility of Established Risk Models to Predict Surgical Mortality in Acute Type-A Aortic Dissection.

OBJECTIVE: The objective of this study was to determine the predictive value of 2 established risk models for surgical mortality in a contemporary cohort of patients undergoing repair of acute type-A aortic dissection. DESIGN: Retrospective analysis. SETTING: Single tertiary care hospital. PARTICIPANTS: Seventy-nine consecutive patients undergoing emergent repair of acute type-A aortic dissection between 2008 and 2013. INTERVENTION: All patients underwent emergent repair of acute type-A aortic dissection. MEASUREMENTS AND MAIN RESULTS: The receiver operating characteristic curve was compared for each scoring system. Of the 79 patients undergoing emergent repair of acute type-A aortic dissection, 23 (29.1%) were above the age of 70. Seventeen (21.5%) patients presented with hypotension, 25 (31.6%) presented with limb ischemia, and 10 (12.7%) presented with evidence of visceral ischemia. Overall operative mortality was 16.5%. Increasing age was the only preoperative variable associated with increased operative mortality. The areas under the receiver operating characteristic curve for operative mortality was 0.62 and 0.66 for the scoring systems developed by Rampoldi et al and Centofanti et al, respectively. The area under the receiver operating characteristic curve for operative mortality for age was 0.67. The areas under the receiver operating characteristic curve for operative mortality between the 2 scoring systems and for age were not statistically different. CONCLUSIONS: Existing predictive risk models for acute type-A aortic dissection provide moderate discriminatory power for operative mortality. Age as a single variable may provide equivalent discriminatory power for operative mortality as the established risk models.

Propensity-matched analysis of the effect of preoperative intraaortic balloon pump in coronary artery bypass grafting after recent acute myocardial infarction on postoperative outcomes.

INTRODUCTION: There is substantial variability in the preoperative use of intraaortic balloon pumps (IABPs) in patients undergoing coronary artery bypass grafting post myocardial infarction. The objective of this study is to determine the effect of preoperative IABPs on postsurgical outcomes in this subset of patients. METHODS: From 2007 to 2012, 877 patients underwent isolated coronary artery bypass post myocardial infarction. Four hundred and six patients were propensity-score matched based on the likelihood of receiving a preoperative balloon pump. Total blood transfusion requirements, composite in-hospital morbidity and/or mortality end point, total hours in the intensive care unit, and length of hospital stay were compared between the two groups. RESULTS: No significant differences in demographics, preoperative risk factors, intraoperative variables or length of hospital stay were found between patients with and without balloon pumps after propensity score matching. Compared to patients without balloon pumps, a higher percentage of patients with preoperative IABPs required transfusions. Patients with preoperative balloon pumps were more likely to have the composite end point of in-hospital morbidity (24.1% versus 12.8%, P <0.004), and increased hours in the intensive care unit (median hours: 69.0 versus 46.0, P <0.013) as compared to patients without balloon pumps. CONCLUSIONS: The use of preoperative IABPs in patients undergoing isolated coronary artery bypass grafting after myocardial infarction is associated with increased transfusion requirements, increased in-hospital morbidity and longer postoperative intensive care unit stay as compared to patients without IABPs.

Dose-dependent effects of intraoperative low volume red blood cell transfusions on postoperative outcomes in cardiac surgery patients.

OBJECTIVE: To determine the incremental risk associated with each intraoperative red blood cell transfusion in cardiac surgery patients. DESIGN: Retrospective analysis on prospectively collected data. SETTING: Single tertiary care hospital. PARTICIPANTS: Seven hundred forty-five patients undergoing on-pump cardiac surgery between January 2010 and June 2012 who received between 1 and 3 units of red blood cell transfusion intraoperatively. INTERVENTIONS: All patients received between 1 and 3 units of red blood cell transfusions. All transfusions were with leukoreduced blood that had been stored for < 14 days. MEASUREMENTS AND MAIN RESULTS: Postoperative complications and length of intubation were associated with the number of red blood cell units transfused. Transfusion of each additional unit of red blood cells was associated with incrementally worse outcomes. Median length of intubation was 11 hours, 12 hours, and 13 hours in patients receiving 1, 2, and 3 units of red blood cell transfusions, respectively (p < 0.005). Similarly, each additional unit of red blood cell transfusion was associated with increasing postoperative septicemia (0% v 0.35% v 2.29%, p < 0.006) and postoperative pneumonia (0% v 0.70% v 2.29%, p < 0.013). CONCLUSIONS: There is a step-wise increase in length of postoperative intubation with each red blood cell transfusion in patients undergoing cardiac surgery. Each additional unit of intraoperative RBC transfusion also may increase postoperative infectious complications. Thus, even single-unit reductions in red blood cell transfusions may have significant impact on outcomes.

P2Y12 platelet function assay for assessment of bleeding risk in coronary artery bypass grafting.

BACKGROUND: The use of platelet function testing has been advocated to individualize the time needed between discontinuation of P2Y12 inhibitors and coronary artery bypass grafting (CABG). However, the use of specific point-of-care assays to predict bleeding risk in patients on P2Y12 inhibitors prior to CABG has not been fully validated. METHODS: From September 2012 to May 2013, 81 patients on P2Y12 inhibitors underwent isolated CABG. Preoperative level of P2Y12 receptor blockade was measured using the VerifyNow P2Y12 assay. Packed red blood cell (pRBC) and platelet transfusions and postoperative chest tube output were correlated with preoperative P2Y12 reaction units (PRUs). RESULTS: Patients who stopped P2Y12 inhibitors for ≤3 days received significantly more platelet transfusions as compared to those whose inhibitors were stopped for longer (0.71 ± 1.05 units vs. 0.20 ± 0.71 units, p = 0.01). They also had increased postoperative chest tube output (552.5 ± 325.5 mL vs. 399.8 ± 146.5 mL, p = 0.03). There was no significant difference in platelet transfusions and chest tube output between patients whose preoperative PRU value was <250 compared to those whose values were ≥250. pRBC requirements were correlated with preoperative hematocrit and age but not with timing of discontinuation of P2Y12 inhibitors or with PRU levels. CONCLUSIONS: In patients on P2Y12 inhibitors undergoing CABG surgery, discontinuation of P2Y12 inhibitors three days prior to surgery rather than VerifyNow PRU values predicts postoperative bleeding and the need for platelet transfusions. Sole reliance on platelet function testing to determine the timing of surgery for patients on P2Y12 inhibitors should therefore be done with caution.

Acute intramural hematoma of the aorta complicated by spinal cord ischemia.

We present an unusual case of spinal cord ischemia from an acute type B intramural hematoma that was successfully treated with blood pressure elevation and drainage of cerebral spinal fluid.

Assessment of cardiac recovery in patients supported with venoarterial extracorporeal membrane oxygenation.

AIMS: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly being used to support patients in cardiogenic shock (CS). Early determination of disposition is paramount, as longer durations of support have been associated with worse outcomes. We describe a stepwise, bedside weaning protocol to assess cardiopulmonary recovery during VA-ECMO. METHODS AND RESULTS: Over 1 year, we considered all patients on VA-ECMO for CS for the Weaning Protocol (WP) at our centre. During the WP, patients had invasive haemodynamic monitoring, echocardiography, and blood gas analysis while flow was reduced in 1 LPM decrements. Ultimately, the circuit was clamped for 30 min, and final measures were taken. Patients were described as having durable recovery (DR) if they were free of pharmacological and mechanical support at 30 days post-decannulation. Over 12 months, 34 patients had VA-ECMO for CS. Fourteen patients were eligible for the WP at 4-12 days. Ten patients tolerated full flow reduction and were successfully decannulated. Twenty-four per cent of the entire cohort demonstrated DR with no adverse events during the WP. Patients with DR had significantly higher ejection fraction, cardiac index, and smaller left ventricular size at lowest flow during the WP. CONCLUSIONS: We describe a safe, stepwise, bedside weaning protocol to assess cardiac recovery during VA-ECMO. Early identification of patients more likely to recover may improve outcomes during ECMO support.

An Automation System Equivalent to the Douglas Bag Technique Enables Continuous and Repeat Metabolic Measurements in Patients Undergoing Mechanical Ventilation.

PURPOSE: To develop a system that is equivalent to the gold standard Douglas Bag (DB) technique for measuring oxygen consumption (V̇o2), carbon dioxide generation (V̇co2), and respiratory quotient (RQ) and to validate its use in clinical settings. METHODS: This was a prospective, observational study conducted at a suburban, quaternary care teaching hospital. Healthy volunteers and patients 18 years or older who received mechanical ventilation were enrolled. FINDINGS: Data from 3 healthy volunteers and 7 patients were analyzed in this study. The interrater reliability between the automation device and DB methods were 0.999, 0.993, and 0.993 for V̇o2, V̇co2, and RQ, respectively. In healthy volunteers, mean (SD) V̇o2, V̇co2, and RQ measured by DB were 411 (100) mL/min, 288 (79) mL/min, and 0.70 (0.03) at high fraction of inspired oxygen (Fio2) and 323 (46) mL/min, 280 (45) mL/min, and 0.85 (0.05) at normal Fio2, respectively. V̇o2 was significantly higher (P < 0.05) and RQ was lower (P < 0.01) in the high Fio2 group as compared to those in the normal Fio2 group. Values measured by the automation system were 227 (31) mL/min, 141 (18) mL/min, and 0.62 (0.04) at high Fio2 and 209 (25) mL/min, 147 (18) mL/min, and 0.70 (0.06) at normal Fio2, respectively. RQ was significantly lower (P < 0.05) in the high Fio2 group as compared to the normal Fio2 group. We also successfully performed continuous and repeat measurements by using the device. The longest measurement reached 12 hours 15 minutes, including 50 cycles of repeat measurements that are equivalent to the DB technique as described above. IMPLICATIONS: We developed an automation system that enables repeat measurements of V̇o2, V̇co2, and RQ, and the accuracy was equivalent to the DB technique. High Fio2 may decrease RQ because of an increase in V̇o2.

Hypermetabolism in critically ill patients with COVID-19 and the effects of hypothermia: A case series.

BACKGROUND: We have observed that critically ill patients with COVID-19 are in an extreme hypermetabolic state. This may be a major contributing factor to the extraordinary ventilatory and oxygenation demands seen in these patients. We aimed to quantify the extent of the hypermetabolic state and report the clinical effect of the use of hypothermia to decrease the metabolic demand in these patients. METHODS: Mild hypothermia was applied on four critically ill patients with COVID-19 for 48 h. Metabolic rates, carbon dioxide production and oxygen consumption were measured by indirect calorimetry. RESULTS: The average resting energy expenditure (REE) was 299% of predicted. Mild hypothermia decreased the REE on average of 27.0% with resultant declines in CO2 production (VCO2) and oxygen consumption (VO2) by 29.2% and 25.7%, respectively. This decrease in VCO2 and VO2 was clinically manifested as improvements in hypercapnia (average of 19.1% decrease in pCO2 levels) and oxygenation (average of 50.4% increase in pO2). CONCLUSION: Our case series demonstrates the extent of hypermetabolism in COVID-19 critical illness and suggests that mild hypothermia reduces the metabolic rate, improves hypercapnia and hypoxia in critically ill patients with COVID-19.