Utility of thromboelastography to guide blood product transfusion in surgical settings.

Selby R. “TEG talk”: expanding clinical roles for thromboelastography and rotational thromboelastometry. Hematology Am Soc Hematol Educ Program. 2020 Dec 4;2020(1): 67-75.

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“Viscoelastic assays (VEAs) that include thromboelastography and rotational thromboelastometry add value to the investigation of coagulopathies and goal-directed management of bleeding by providing a complete picture of clot formation, strength, and lysis in whole blood that includes the contribution of platelets, fibrinogen, and coagulation factors. Conventional coagulation assays have several limitations, such as their lack of correlation with bleeding and hypercoagulability; their inability to reflect the contribution of platelets, factor XIII, and plasmin during clot formation and lysis; and their slow turnaround times. VEA-guided transfusion algorithms may reduce allogeneic blood exposure during and after cardiac surgery and in the emergency management of trauma-induced coagulopathy and hemorrhage. However, the popularity of VEAs for other indications is driven largely by extrapolation of evidence from cardiac surgery, by the drawbacks of conventional coagulation assays, and by institution-specific preferences. Robust diagnostic studies validating and standardizing diagnostic cutoffs for VEA parameters and randomized trials comparing VEA-guided algorithms with standard care on clinical outcomes are urgently needed. Lack of such studies represents the biggest barrier to defining the role and impact of VEA in clinical care.”

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Temperature Management After Cardiac Arrest

Nielsen N, Wetterslev J, Cronberg T, et al.; TTM Trial Investigators. Targeted temperature management at 33°C versus 36°C after cardiac arrest. N Engl J Med. 2013 Dec 5;369(23):2197-206. doi: 10.1056/NEJMoa1310519. Epub 2013 Nov 17. PMID: 24237006.

Results: In total, 939 patients were included in the primary analysis. At the end of the trial, 50% of the patients in the 33°C group (235 of 473 patients) had died, as compared with 48% of the patients in the 36°C group (225 of 466 patients) (hazard ratio with a temperature of 33°C, 1.06; 95% confidence interval [CI], 0.89 to 1.28; P=0.51). At the 180-day follow-up, 54% of the patients in the 33°C group had died or had poor neurologic function according to the CPC, as compared with 52% of patients in the 36°C group (risk ratio, 1.02; 95% CI, 0.88 to 1.16; P=0.78). In the analysis using the modified Rankin scale, the comparable rate was 52% in both groups (risk ratio, 1.01; 95% CI, 0.89 to 1.14; P=0.87). The results of analyses adjusted for known prognostic factors were similar.

Conclusions: In unconscious survivors of out-of-hospital cardiac arrest of presumed cardiac cause, hypothermia at a targeted temperature of 33°C did not confer a benefit as compared with a targeted temperature of 36°C. (Funded by the Swedish Heart-Lung Foundation and others; TTM ClinicalTrials.gov number, NCT01020916.).

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The use of balanced crystalloids versus saline in sepsis

Brown RM, et al. Balanced Crystalloids versus Saline in Sepsis. A Secondary Analysis of the SMART Clinical Trial. Am J Respir Crit Care Med. 2019 Dec 15;200(12):1487-1495.

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Measurements and Main Results: Of 15,802 patients enrolled in SMART, 1,641 patients were admitted to the medical ICU with a diagnosis of sepsis. A total of 217 patients (26.3%) in the balanced crystalloids group experienced 30-day in-hospital morality compared with 255 patients (31.2%) in the saline group (adjusted odds ratio [aOR], 0.74; 95% confidence interval [CI], 0.59-0.93; P = 0.01). Patients in the balanced group experienced a lower incidence of major adverse kidney events within 30 days (35.4% vs. 40.1%; aOR, 0.78; 95% CI, 0.63-0.97) and a greater number of vasopressor-free days (20 ± 12 vs. 19 ± 13; aOR, 1.25; 95% CI, 1.02-1.54) and renal replacement therapy-free days (20 ± 12 vs. 19 ± 13; aOR, 1.35; 95% CI, 1.08-1.69) compared with the saline group.

Conclusions: Among patients with sepsis in a large randomized trial, use of balanced crystalloids was associated with a lower 30-day in-hospital mortality compared with use of saline.

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Intraoperative cardiac arrest: Resuscitation and Management

One discussion this week included intraoperative cardiac arrest.

Reference: Moitra VK, et al. Cardiac arrest in the operating room: resuscitation and management for the anesthesiologist: part 1. Anesthesia & Analgesia. 2018 Mar;126(3):876-888. doi: 10.1213/ANE.0000000000002596.

Summary: Cardiac arrest in the operating room and procedural areas has a different spectrum of causes (ie, hypovolemia, gas embolism, and hyperkalemia), and rapid and appropriate evaluation and management of these causes require modification of traditional cardiac arrest algorithms. There is a small but growing body of literature describing the incidence, causes, treatments, and outcomes of circulatory crisis and perioperative cardiac arrest. These events are almost always witnessed, frequently known, and involve rescuer providers with knowledge of the patient and their procedure.

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Will there be positive neurological outcomes after ECMO resuscitation?

One discussion this week involved neurological outcomes following ECMO resuscitation.

Reference: Ryu JA, et al. Predictors of neurological outcomes after successful extracorporeal cardiopulmonary resuscitation. BMC Anesthesiology. 2015 Mar 8;15:26. doi: 10.1186/s12871-015-0002-3

Summary: Extracorporeal membrane oxygenation (ECMO) is a useful intervention for refractory cardiogenic shock and respiratory failure. Because ECMO implementation can rapidly normalize circulation in patients under cardiac arrest, it has been used to assist cardiopulmonary resuscitation (CPR). Using traditional chest compression is less effective than using ECMO with CPR (known as extracorporeal CPR or ECPR). ECPR can achieve more effective recovery of spontaneous circulation (ROSC) than conventional CPR.

Since the brain is the organ most vulnerable to hypoxia and inadequate perfusion, ECPR can result in severe neurologic deficits if ECMO is not performed promptly. In addition to delay, several factors may lead to poor neurological outcomes after ECPR. Achieving good neurological outcomes and successful resuscitation are important, so the authors investigated predictors of favorable neurological outcomes rather than survival after ECPR.

The study’s primary endpoint was neurological outcome at hospital discharge, assessed with the Glasgow-Pittsburgh Cerebral Performance Categories (CPC) scale (1 to 5, as shown in Table 1). CPC 1 and 2 were classified as good neurological outcomes. CPC 3, 4, and 5 were considered poor neurological outcomes.

Of 115 patients, 68 (59%) had good neurological outcomes but 47 (41%) did not (Figure 2). Therapeutic hypothermia was performed in 10 patients (5%). Mean duration of ECMO support was 47.5 (range 18.5–101) hours. Total length of stay in intensive care unit (ICU) was 11 (range 7–22.5) days and 24 patients died from brain death.

Univariate analysis showed no differences between the good and poor neurological outcome groups for age, comorbidities, bystander CPR, therapeutic hypothermia, total bilirubin, creatinine, 24-hour lactic acid clearance, ROSC before ECMO, or ROSC time (Table 2).

Multivariate analysis revealed neurological outcomes were affected by hemoglobin level, serum lactic acid before ECMO insertion, and interval from cardiac arrest to ECMO (Figure 3). However, age, gender, cardiac arrest out of the hospital, hemoglobin level after ECMO, acute coronary syndrome, initial shockable rhythm, and CPR duration were not independent predictors of neurological outcomes (Table 3).