Jonathan Elmer

Lung-Protective Ventilation With Low Tidal Volumes and the Occurrence of Pulmonary Complications in Patients Without Acute Respiratory Distress Syndrome: A Systematic Review and Individual Patient Data Analysis.

Objective:Protective mechanical ventilation with low tidal volumes is standard of care for patients with acute respiratory distress syndrome. The aim of this individual patient data analysis was to determine the association between tidal volume and the occurrence of pulmonary complications in ICU patients without acute respiratory distress syndrome and the association between occurrence of pulmonary complications and outcome in these patients. Design:Individual patient data analysis. Patients:ICU patients not fulfilling the consensus criteria for acute respiratory distress syndrome at the onset of ventilation. Interventions:Mechanical ventilation with low tidal volume. Measurements and Main Results:The primary endpoint was development of a composite of acute respiratory distress syndrome and pneumonia during hospital stay. Based on the tertiles of tidal volume size in the first 2 days of ventilation, patients were assigned to a “low tidal volume group” (tidal volumes⩽ 7 mL/kg predicted body weight), an “intermediate tidal volume group” (> 7 and < 10 mL/kg predicted body weight), and a “high tidal volume group” (≥ 10 mL/kg predicted body weight). Seven investigations (2,184 patients) were included. Acute respiratory distress syndrome or pneumonia occurred in 23% of patients in the low tidal volume group, in 28% of patients in the intermediate tidal volume group, and in 31% of the patients in the high tidal volume group (adjusted odds ratio [low vs high tidal volume group], 0.72; 95% CI, 0.52–0.98; p = 0.042). Occurrence of pulmonary complications was associated with a lower number of ICU-free and hospital-free days and alive at day 28 (10.0 ± 10.9 vs 13.8 ± 11.6 d; p < 0.01 and 6.1 ± 8.1 vs 8.9 ± 9.4 d; p < 0.01) and an increased hospital mortality (49.5% vs 35.6%; p < 0.01). Conclusions:Ventilation with low tidal volumes is associated with a lower risk of development of pulmonary complications in patients without acute respiratory distress syndrome.

Neuromuscular blocking agent administration for emergent tracheal intubation is associated with decreased prevalence of procedure-related complications.

Background:Emergent intubation is associated with a high rate of complications. Neuromuscular blocking agents are routinely used in the operating room and emergency department to facilitate intubation. However, use of neuromuscular blocking agents during emergent airway management outside of the operating room and emergency department is controversial. We hypothesized that the use of neuromuscular blocking agents is associated with a decreased prevalence of hypoxemia and reduced rate of procedure-related complications. Methods:Five hundred sixty-six patients undergoing emergent intubations in two tertiary care centers, Massachusetts General Hospital, Boston, MA, and the University of California Los Angeles, Ronald Reagan Medical Center, Los Angeles, CA, were enrolled in a prospective, observational study. The 112 patients intubated during cardiopulmonary resuscitation were excluded, leaving 454 patients for analysis. All intubations were supervised by attendings trained in Critical Care Medicine. We measured intubating conditions, oxygen saturation during and 5 mins following intubation. We assessed the prevalence of procedure-related complications defined as esophageal intubation, traumatic intubation, aspiration, dental injury, and endobronchial intubation. Results:The use of neuromuscular blocking agents was associated with a lower prevalence of hypoxemia (10.1% vs. 17.4%, p = .022) and a lower prevalence of procedure-related complications (3.1% vs. 8.3%, p = .012). This association persisted in a multivariate analysis, which controlled for airway grade, sedation, and institution. Use of neuromuscular blocking agents was associated with significantly improved intubating conditions (laryngeal view, p = .014; number of intubation attempts, p = .049). After controlling for the number of intubation attempts and laryngoscopic view, muscle relaxant use is an independent predictor of complications associated with emergency intubation (p = .037), and there is a trend towards improvement of oxygenation (p = .07). Conclusion:The use of neuromuscular blocking agents, when used by intensivists with a high level of training and experience, is associated with a decrease in procedure-related complications.

Association of early withdrawal of life-sustaining therapy for perceived neurological prognosis with mortality after cardiac arrest

BACKGROUND Withdrawing life-sustaining therapy because of perceived poor neurological prognosis (WLST-N) is a common cause of hospital death after out-of-hospital cardiac arrest (OHCA). Although current guidelines recommend against WLST-N before 72h (WLST-N<72), this practice is common and may increase mortality. We sought to quantify these effects. METHODS In a secondary analysis of a multicenter OHCA trial, we evaluated survival to hospital discharge and survival with favorable functional status (modified Rankin Score ≤3) in adults alive >1h after hospital admission. Propensity score modeling the probability of exposure to WLST-N<72 based on pre-exposure covariates was used to match unexposed subjects with those exposed to WLST-N<72. We determined the probability of survival and functionally favorable survival in the unexposed matched cohort, fit adjusted logistic regression models to predict outcomes in this group, and then used these models to predict outcomes in the exposed cohort. Combining these findings with current epidemiologic statistics we estimated mortality nationally that is associated with WLST-N<72. RESULTS Of 16,875 OHCA subjects, 4265 (25%) met inclusion criteria. WLST-N<72 occurred in one-third of subjects who died in-hospital. Adjusted analyses predicted that exposed subjects would have 26% survival and 16% functionally favorable survival if WLST-N<72 did not occur. Extrapolated nationally, WLST-N<72 may be associated with mortality in approximately 2300 Americans each year of whom nearly 1500 (64%) might have had functional recovery. CONCLUSIONS After OHCA, death following WLST-N<72 may be common and is potentially avoidable. Reducing WLST-N<72 has national public health implications and may afford an opportunity to decrease mortality after OHCA.

Cardiopulmonary resuscitation feedback improves the quality of chest compression provided by hospital health care professionals

STUDY OBJECTIVE High-quality chest compressions (CCs) are an important component of successful resuscitation. Suboptimal in-hospital CC are commonly reported. Skill degradation and fatigue have been implicated. We assessed the effect of a handheld feedback device on the measured and perceived quality of CC and rescuer physiologic response. METHODS This is a nonblinded randomized controlled study of nurses at an academic medical center. Participants performed CC on a mannequin either with or without a feedback device. Compression rate (CR) and compression depth (CD), heart rate, and oxygen saturation were documented. Perceived quality of CC, fatigue, and ease of use of the device were obtained. RESULTS Twelve nurses were in the feedback group (FG) and 13 were controls. Mean CD was significantly higher in the FG (1.99 ± 0.37 in vs 1.52 ± 0.36 in; P = .005) and mean CR significantly lower in the FG (127 ± 13.8 per min vs 101 ± 9.7 per min; P ≤ .0001). Using a CD of more than 1.5 in and a CR of 90 to 100 as a composite measure of high-quality CC, the FG performed significantly better (81.4% ± 22.0% vs 10.4% ± 21.9%; P < .0001). Perceived CD, CR, and fatigue did not differ between groups; however, participants overestimated depth and underestimated rate. The FG rated the design as user-friendly (85% + 26%) helpful in maintaining correct CR (83% + 26%). CONCLUSION A handheld accelerometer-based audiovisual cardiopulmonary resuscitation (CPR) feedback device significantly improved the quality of CCs provided by experienced hospital nurses in a simulated setting, with no perceived or measured difference in fatigue between the 2 groups. The CPR feedback provides an effective means to monitor and improve CPR performance.

Validation of the Pittsburgh Cardiac Arrest Category illness severity score

BACKGROUND The purpose of this study was to validate the ability of an early post-cardiac arrest illness severity classification to predict patient outcomes. METHODS The Pittsburgh Cardiac Arrest Category (PCAC) is a 4-level illness severity score that was found to be strongly predictive of outcomes in the initial derivation study. We assigned PCAC scores to consecutive in and out-of-hospital cardiac arrest subjects treated at two tertiary care centers between January 2011 and September 2013. We made assignments prospectively at Site 1 and retrospectively at Site 2. Our primary outcome was survival to hospital discharge. Inter-rater reliability of retrospective PCAC assessments was assessed. Secondary outcomes were favorable discharge disposition (home or acute rehabilitation), Cerebral Performance Category (CPC) and modified Rankin Scale (mRS) at hospital discharge. We tested the association of PCAC with each outcome using unadjusted and multivariable logistic regression. RESULTS We included 607 cardiac arrest patients during the study (393 at Site 1 and 214 at Site 2). Site populations differed in age, arrest location, rhythm, use of hypothermia and distribution of PCAC. Inter-rater reliability of retrospective PCAC assignments was excellent (κ=0.81). PCAC was associated with survival (unadjusted odds ratio (OR) for Site 1: 0.33 (95% confidence interval (CI) 0.27-0.41)) Site 2: 0.32 (95% CI 0.24-0.43) even after adjustment for other clinical variables (adjusted OR Site 1: 0.32 (95% CI 0.25-0.41) Site 2: 0.31 (95% CI 0.22-0.44)). PCAC was predictive of secondary outcomes. CONCLUSIONS Our results confirm that PCAC is strongly predictive of survival and good functional outcome after cardiac arrest.

Massive Transfusion in Traumatic Shock

BACKGROUND Hemorrhage after trauma is a common cause of death in the United States and globally. The primary goals when managing traumatic shock are the restoration of oxygen delivery to end organs, maintenance of circulatory volume, and prevention of ongoing bleeding through source control and correction of coagulopathy. Achieving these goals may require massive transfusion of blood products. Although use of blood products may be lifesaving, dose-related adverse effects are well described. DISCUSSION Complications of massive transfusion include interdependent derangements such as coagulopathy, hypothermia, acidosis, and electrolyte abnormalities, as well as infectious and immunomodulatory phenomena. This article explores the pathogenesis, implications, prevention, and treatment of these complications through the use of massive transfusion protocols. Particular attention is given to the optimal ratio of blood products transfused in large volume resuscitation and prevention of secondary coagulopathy. CONCLUSIONS Observational data indicate that the development and use of a massive transfusion protocol may reduce the morbidity and mortality associated with large-volume resuscitation of patients with hemorrhagic shock. Such protocols should include a pre-defined ratio of packed red blood cells, fresh frozen plasma, and platelets transfused; most commonly, the ratio used is 1:1:1. Additionally, such protocols should monitor for and correct hypothermia, hypofibrinogenemia, and electrolyte disturbances such as hypocalcemia and hyperkalemia.

Clinically distinct electroencephalographic phenotypes of early myoclonus after cardiac arrest

We tested the hypothesis that there are readily classifiable electroencephalographic (EEG) phenotypes of early postanoxic multifocal myoclonus (PAMM) that develop after cardiac arrest.

Acute Respiratory Distress Syndrome After Spontaneous Intracerebral Hemorrhage

Objectives:Acute respiratory distress syndrome develops commonly in critically ill patients in response to an injurious stimulus. The prevalence and risk factors for development of acute respiratory distress syndrome after spontaneous intracerebral hemorrhage have not been reported. We sought to determine the prevalence of acute respiratory distress syndrome after intracerebral hemorrhage, characterize risk factors for its development, and assess its impact on patient outcomes. Design:Retrospective cohort study at two academic centers. Patients:We included consecutive patients presenting from June 1, 2000, to November 1, 2010, with intracerebral hemorrhage requiring mechanical ventilation. We excluded patients with age less than 18 years, intracerebral hemorrhage secondary to trauma, tumor, ischemic stroke, or structural lesion; if they required intubation only during surgery; if they were admitted for comfort measures; or for a history of immunodeficiency. Interventions:None. Measurements and Main Results:Data were collected both prospectively as part of an ongoing cohort study and by retrospective chart review. Of 1,665 patients identified by database query, 697 met inclusion criteria. The prevalence of acute respiratory distress syndrome was 27%. In unadjusted analysis, high tidal volume ventilation was associated with an increased risk of acute respiratory distress syndrome (hazard ratio, 1.79 [95% CI, 1.13–2.83]), as were male sex, RBC and plasma transfusion, higher fluid balance, obesity, hypoxemia, acidosis, tobacco use, emergent hematoma evacuation, and vasopressor dependence. In multivariable modeling, high tidal volume ventilation was the strongest risk factor for acute respiratory distress syndrome development (hazard ratio, 1.74 [95% CI, 1.08–2.81]) and for inhospital mortality (hazard ratio, 2.52 [95% CI, 1.46–4.34]). Conclusions:Development of acute respiratory distress syndrome is common after intubation for intracerebral hemorrhage. Modifiable risk factors, including high tidal volume ventilation, are associated with its development and in-patient mortality.

Association between hospital post-resuscitative performance and clinical outcomes after out-of-hospital cardiac arrest

BACKGROUND Survival varies among those resuscitated from out-of-hospital cardiac arrest (OHCA). Evidence-based performance measures have been used to describe hospital quality of care in conditions such as acute coronary syndrome and major trauma. It remains unclear if adherence to performance measures is associated with better outcome in patients hospitalized after OHCA. OBJECTIVES To assess whether a composite performance score based on evidence-based guidelines for care of patients resuscitated from OHCA was independently associated with clinical outcomes. METHODS Included were 3252 patients with OHCA who received care at 111 U.S. and Canadian hospitals participating in the Resuscitation Outcomes Consortium (ROC-PRIMED) study between June 2007 and October 2009. We calculated composite performance scores for all patients, aggregated these at the hospital level, then associated them with patient mortality and favorable neurological status at discharge. RESULTS Composite performance scores varied widely (median [IQR] scores from lowest to highest hospital quartiles, 21% [20%, 25%] vs. 59% [55%, 64%]. Adjusted survival to discharge increased with each quartile of performance score (from lowest to highest: 16.2%, 20.8%, 28.5%, 34.8%, P<0.01), with similar findings for adjusted rates of good neurologic status. Hospital score was significantly associated with outcome after risk adjustment for established baseline factors (highest vs. lowest adherence quartile: adjusted OR of survival 1.64; 95% CI 1.13, 2.38). CONCLUSIONS Greater survival and favorable neurologic status at discharge were associated with greater adherence to recommended hospital based post-resuscitative care guidelines. Consideration should be given to measuring, reporting and improving hospital adherence to guideline-based performance measures, which could improve outcomes following OHCA.

Hemoglobin-based oxygen carriers for hemorrhagic shock

Hemorrhagic shock is a pathologic state in which intravascular volume and tissue oxygen delivery are impaired, leading to circulatory collapse and cellular ischemia. Resuscitation with hemoglobin-based oxygen carriers (HBOCs) is appealing in that their use can both restore intravascular volume and tissue oxygenation, without the limitations in supply and immunomodulatory effects of packed red blood cells. However, the development of safe and effective agents has been elusive. In this article, we briefly discuss the major limitations of traditional resuscitative fluids which have driven the continued interest in HBOCs. We then review the history of early HBOC development and the modern understanding of their mechanisms of toxicity, which has informed the rational design of second-generation agents. Finally, we provide an overview of these second-generation HBOCs that are under active investigation or have recently completed phase 3 clinical trials.