Christian Rylander

Targeted Temperature Management at 33°C versus 36°C after Cardiac Arrest

BACKGROUND Unconscious survivors of out-of-hospital cardiac arrest have a high risk of death or poor neurologic function. Therapeutic hypothermia is recommended by international guidelines, but the supporting evidence is limited, and the target temperature associated with the best outcome is unknown. Our objective was to compare two target temperatures, both intended to prevent fever. METHODS In an international trial, we randomly assigned 950 unconscious adults after out-of-hospital cardiac arrest of presumed cardiac cause to targeted temperature management at either 33°C or 36°C. The primary outcome was all-cause mortality through the end of the trial. Secondary outcomes included a composite of poor neurologic function or death at 180 days, as evaluated with the Cerebral Performance Category (CPC) scale and the modified Rankin scale. 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.).

Intensive care diaries reduce new onset post traumatic stress disorder following critical illness: a randomised, controlled trial

IntroductionPatients recovering from critical illness have been shown to be at risk of developing Post Traumatic Stress disorder (PTSD). This study was to evaluate whether a prospectively collected diary of a patients intensive care unit (ICU) stay when used during convalescence following critical illness will reduce the development of new onset PTSD.MethodsIntensive care patients with an ICU stay of more than 72 hours were recruited to a randomised controlled trial examining the effect of a diary outlining the details of the patients ICU stay on the development of acute PTSD. The intervention patients received their ICU diary at 1 month following critical care discharge and the final assessment of the development of acute PTSD was made at 3 months.Results352 patients were randomised to the study at 1 month. The incidence of new cases of PTSD was reduced in the intervention group compared to the control patients (5% versus 13%, P = 0.02).ConclusionsThe provision of an ICU diary is effective in aiding psychological recovery and reducing the incidence of new PTSD.Trial registrationNCT00912613.

Neurological prognostication after cardiac arrest—Recommendations from the Swedish Resuscitation Council

Cardiopulmonary resuscitation is started in 5000 victims of out-of-hospital cardiac arrest in Sweden each year and the survival rate is approximately 10%. The subsequent development of a global ischaemic brain injury is the major determinant of the neurological prognosis for those patients who reach the hospital alive. Induced hypothermia is a recommended treatment after cardiac arrest and has been implemented in most Swedish hospitals. Recent studies indicate that induced hypothermia may affect neurological prognostication and previous international recommendations are therefore no longer valid when hypothermia is applied. An expert group from the Swedish Resuscitation Council has reviewed the literature and made recommendations taking into account the effects of induced hypothermia and concomitant sedation. A delayed neurological evaluation at 72 h after rewarming is recommended for hypothermia treated patients. This evaluation should be based on several independent methods and the possibility of lingering pharmacological effects should be considered.

The impact of respiratory variables on mortality in non-ARDS and ARDS patients requiring mechanical ventilation

Objectives: Primarily, to determine if respiratory variables, assessed on a daily basis on days 1–6 after ICU admission, were associated with mortality in non-ARDS and ARDS patients with respiratory failure requiring mechanical ventilation. Secondarily, to determine non-respiratory factors associated with mortality in ARDS and non-ARDS patients. Design: Prospective multicentre clinical study. Setting: Seventy-eight intensive care units in Sweden and Iceland. Patients: Five hundred twenty non-ARDS and 95 ARDS patients. Measurements and results: Potentially prognostic factors present at inclusion were tested against 90-day mortality using a Cox regression model. Respiratory variables (PaO2/FIO2, PEEP, mean airway pressure (MAP) and base excess (BE)) were tested against mortality using the model. Primary aim: in non-ARDS a low PaO2/FIO2 on day 1, RR (risk ratio) = 1.17, CI (95 % confidence interval) (1.00; 1.36), day 4, 1.24 (1.02; 1.50), day 5, 1.25 (1.02; 1.53) and a low MAP at baseline, 1.18 (1.00; 1.39), day 2, 1.24 (1.02; 1.52), day 3, 1.33 (1.06; 1.67), day 6, 2.38 (1.11; 5.73) were significantly associated with 90-day death. Secondary aim: in non-ARDS a low age, RR = 0.77 (0.67; 0.89), female gender, 0.85 (0.74; 0.98), and low APS (acute physiologic score), 0.85 (0.73; 0.99), were associated with survival; chronic disease, 1.31 (1.12; 1.52), and non-pulmonary origin to the respiratory failure, 1.27 (1.10; 1.47), with death. In ARDS low age, RR = 0.65 CI (0.46; 0.91), and low APS, 0.65 (0.46; 0.90), were associated with survival. Conclusions: No independent significant association was seen between 90-day mortality and degree of hypoxaemia, PEEP, MAP or BE for the first full week of ICU care in either ARDS or non-ARDS. In a sub-group of non-ARDS a lower PaO2/FIO2 and MAP tended to influence mortality where a significant association was seen for 3 of 7 study days. Age, gender, APS, presence of a chronic disease and a pulmonary/non-pulmonary reason for the respiratory failure were associated with mortality in non-ARDS, while only age and APS showed a similar association in ARDS.

Cognitive Function in Survivors of Out-of-Hospital Cardiac Arrest After Target Temperature Management at 33°C Versus 36°C

Background— Target temperature management is recommended as a neuroprotective strategy after out-of-hospital cardiac arrest. Potential effects of different target temperatures on cognitive impairment commonly described in survivors have not been investigated sufficiently. The primary aim of this study was to evaluate whether a target temperature of 33°C compared with 36°C was favorable for cognitive function; the secondary aim was to describe cognitive impairment in cardiac arrest survivors in general. Methods and Results— Study sites included 652 cardiac arrest survivors originally randomized and stratified for site to temperature control at 33°C or 36°C within the Target Temperature Management trial. Survival until 180 days after the arrest was 52% (33°C, n=178/328; 36°C, n=164/324). Survivors were invited to a face-to-face follow-up, and 287 cardiac arrest survivors (33°C, n=148/36°C, n=139) were assessed with tests for memory (Rivermead Behavioural Memory Test), executive functions (Frontal Assessment Battery), and attention/mental speed (Symbol Digit Modalities Test). A control group of 119 matched patients hospitalized for acute ST-segment–elevation myocardial infarction without cardiac arrest performed the same assessments. Half of the cardiac arrest survivors had cognitive impairment, which was mostly mild. Cognitive outcome did not differ (P>0.30) between the 2 temperature groups (33°C/36°C). Compared with control subjects with ST-segment–elevation myocardial infarction, attention/mental speed was more affected among cardiac arrest patients, but results for memory and executive functioning were similar. Conclusions— Cognitive function was comparable in survivors of out-of-hospital cardiac arrest when a temperature of 33°C and 36°C was targeted. Cognitive impairment detected in cardiac arrest survivors was also common in matched control subjects with ST-segment–elevation myocardial infarction not having had a cardiac arrest. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01946932.

Uneven distribution of ventilation in acute respiratory distress syndrome

IntroductionThe aim of this study was to assess the volume of gas being poorly ventilated or non-ventilated within the lungs of patients treated with mechanical ventilation and suffering from acute respiratory distress syndrome (ARDS).MethodsA prospective, descriptive study was performed of 25 sedated and paralysed ARDS patients, mechanically ventilated with a positive end-expiratory pressure (PEEP) of 5 cmH2O in a multidisciplinary intensive care unit of a tertiary university hospital. The volume of poorly ventilated or non-ventilated gas was assumed to correspond to a difference between the ventilated gas volume, determined as the end-expiratory lung volume by rebreathing of sulphur hexafluoride (EELVSF6), and the total gas volume, calculated from computed tomography images in the end-expiratory position (EELVCT). The methods used were validated by similar measurements in 20 healthy subjects in whom no poorly ventilated or non-ventilated gas is expected to be found.ResultsEELVSF6 was 66% of EELVCT, corresponding to a mean difference of 0.71 litre. EELVSF6 and EELVCT were significantly correlated (r2 = 0.72; P < 0.001). In the healthy subjects, the two methods yielded almost identical results.ConclusionAbout one-third of the total pulmonary gas volume seems poorly ventilated or non-ventilated in sedated and paralysed ARDS patients when mechanically ventilated with a PEEP of 5 cmH2O. Uneven distribution of ventilation due to airway closure and/or obstruction is likely to be involved.

Shiga Toxin–Induced Complement-Mediated Hemolysis and Release of Complement-Coated Red Blood Cell–Derived Microvesicles in Hemolytic Uremic Syndrome

Shiga toxin (Stx)-producing Escherichia coli (STEC) cause hemolytic uremic syndrome (HUS). This study investigated whether Stx2 induces hemolysis and whether complement is involved in the hemolytic process. RBCs and/or RBC-derived microvesicles from patients with STEC-HUS (n = 25) were investigated for the presence of C3 and C9 by flow cytometry. Patients exhibited increased C3 deposition on RBCs compared with controls (p < 0.001), as well as high levels of C3- and C9-bearing RBC-derived microvesicles during the acute phase, which decreased after recovery. Stx2 bound to P1k and P2k phenotype RBCs, expressing high levels of the Pk Ag (globotriaosylceramide), the known Stx receptor. Stx2 induced the release of hemoglobin and lactate dehydrogenase in whole blood, indicating hemolysis. Stx2-induced hemolysis was not demonstrated in the absence of plasma and was inhibited by heat inactivation, as well as by the terminal complement pathway Ab eculizumab, the purinergic P2 receptor antagonist suramin, and EDTA. In the presence of whole blood or plasma/serum, Stx2 induced the release of RBC-derived microvesicles coated with C5b-9, a process that was inhibited by EDTA, in the absence of factor B, and by purinergic P2 receptor antagonists. Thus, complement-coated RBC-derived microvesicles are elevated in HUS patients and induced in vitro by incubation of RBCs with Stx2, which also induced hemolysis. The role of complement in Stx2-mediated hemolysis was demonstrated by its occurrence only in the presence of plasma and its abrogation by heat inactivation, EDTA, and eculizumab. Complement activation on RBCs could play a role in the hemolytic process occurring during STEC-HUS.

Lung regional stress and strain as a function of posture and ventilatory mode

During positive-pressure ventilation parenchymal deformation can be assessed as strain (volume increase above functional residual capacity) in response to stress (transpulmonary pressure). The aim of this study was to explore the relationship between stress and strain on the regional level using computed tomography in anesthetized healthy pigs in two postures and two patterns of breathing. Airway opening and esophageal pressures were used to calculate stress; change of gas content as assessed from computed tomography was used to calculate strain. Static stress-strain curves and dynamic strain-time curves were constructed, the latter during the inspiratory phase of volume and pressure-controlled ventilation, both in supine and prone position. The lung was divided into nondependent, intermediate, dependent, and central regions: their curves were modeled by exponential regression and examined for statistically significant differences. In all the examined regions, there were strong but different exponential relations between stress and strain. During mechanical ventilation, the end-inspiratory strain was higher in the dependent than in the nondependent regions. No differences between volume- and pressure-controlled ventilation were found. However, during volume control ventilation, prone positioning decreased the end-inspiratory strain of dependent regions and increased it in nondependent regions, resulting in reduced strain gradient. Strain is inhomogeneously distributed within the healthy lung. Prone positioning attenuates differences between dependent and nondependent regions. The regional effects of ventilatory mode and body positioning should be further explored in patients with acute lung injury.

Oleic acid lung injury: a morphometric analysis using computed tomography.

Background:  The oleic acid‐induced lung injury (OAI) model is considered to represent the early phase of acute respiratory distress syndrome (ARDS). Its inherent properties are important for the design and the interpretation of interventional studies. The aim of this study was to describe the evolution of morphometric lung changes during OAI using computed tomography (CT) analysis. Furthermore, the effect of a temporary change in positive end‐expiratory pressure (PEEP) was evaluated.

Glucocorticoid receptor function is decreased in neutrophils during endotoxic shock

OBJECTIVES It remains unclear whether glucocorticoid treatment can improve the outcome of sepsis. The aim of the present study was to investigate if glucocorticoid receptor (GR) expression and function is impaired in lipopolysaccharide (LPS) induced shock, and whether the time point for start of glucocorticoid treatment affects the outcome. METHODS Male C57BL/6J mice were administered LPS i.p. and GR expression and binding ability in blood and spleen leukocytes were analysed by flow cytometry. GR translocation was analysed using Image Stream technique. The effect of dexamethasone treatment started 2 h before or 2, 12 or 36 h after LPS administration on survival was studied. RESULTS Despite increased GR expression in neutrophils after LPS administration, the GR binding capacity was reduced. In addition, GR translocation was decreased in neutrophils and T lymphocytes from endotoxic mice at 12 h compared to control animals. Dexamethasone treatment improved survival only when started early (2 h) after LPS administration. CONCLUSION The decreased glucocorticoid responsiveness displayed by neutrophils, in combination with their increased numbers, may explain why survival is increased only when dexamethasone treatment is given early during LPS induced shock.