Haemolysis in prehospital blood samples.

The increasing use of Point Of Care Testing (POCT) in the prehospital setting demands a high and consistent quality of blood samples. We have investigated the degree of haemolysis in 779 prehospital blood samples and found a significant increase in haemolysis compared to intrahospital samples. The degree of haemolysis was within acceptable limits for current analyses. However, haemolysis should be taken into account when implementing future analyses in the prehospital field.

A low end-tidal CO2/arterial CO2 ratio during cardiopulmonary resuscitation suggests pulmonary embolism.

INTRODUCTION: Identifying reversible causes of cardiac arrest is challenging. The diagnosis of pulmonary embolism is often missed. Pulmonary embolism increases alveolar dead space resulting in low end-tidal CO2 (EtCO2) relative to arterial CO2 (PaCO2) tension. Thus, a low EtCO2/PaCO2 ratio during resuscitation may be a sign of pulmonary embolism. METHODS: Post hoc analysis of data from two porcine studies comparing ultrasonographic measurements of right ventricular diameter during resuscitation from cardiac arrest of different causes. Pigs were grouped according to cause of arrest (pulmonary embolism, hypovolemia, primary arrhythmia, hypoxia, or hyperkalaemia) and EtCO2/PaCO2 ratios were compared. RESULTS: Data from 54 pigs were analysed. EtCO2 levels at the third rhythm analysis were significantly lower when cardiac arrest was caused by pulmonary embolism than by primary arrhythmia, hypoxia and hyperkalaemia, but there was no significant difference between pulmonary embolism and hypovolemia. In contrast, PaCO2 levels were higher in cardiac arrest caused by pulmonary embolism than in the other causes of cardiac arrest. Consequently, the EtCO2/PaCO2 ratio was lower in pulmonary embolism 0.2 (95%CI 0.1-0.4), than in hypovolaemia 0.5 (95%CI 0.3-0.6), primary arrhythmia 0.7 (95%CI 0.7-0.8), hypoxia 0.5 (95%CI 0.4-0.6), and hyperkalaemia 0.6 (95%CI 0.6-0.7). CONCLUSION: A low EtCO2/PaCO2 ratio during cardiopulmonary resuscitation suggests pulmonary embolism.

Prehospital triage of patients suffering severe dyspnoea using N-terminal pro-brain natriuretic peptide, the PreBNP trial: a randomised controlled clinical trial.

PURPOSE: The purpose of this study was to examine whether the addition of brain natriuretic peptide measurement to the routine diagnostic work-up by prehospital critical care team physicians improves triage in patients with severe dyspnoea. METHODS: Prehospital critical care team physicians randomly assigned patients older than 18 years with severe dyspnoea to routine diagnostic work-up or diagnostic work-up with incorporated point-of-care N-terminal pro-brain natriuretic peptide (NT-proBNP) measurement. The primary endpoint was the proportion of patients with dyspnoea of primary cardiac origin triaged directly to a department of cardiology. RESULTS: A total of 747 patients were randomly assigned and 711 patients consented to participate, 350 were randomly assigned to the NT-proBNP group and 361 to the routine work-up group. NT-proBNP was measured in 90% (315/350) of patients in the NT-proBNP group and in 19% (70/361) of patients in the routine work-up group. There was no difference in the proportion of patients with dyspnoea of primary cardiac origin triaged directly to a department of cardiology between the NT-proBNP group and the routine work-up group (75% vs. 69%, P=0.22) in the intention-to-treat analysis. Sensitivity analysis according to the de facto diagnostics performed showed results consistent with this. No differences in hospital length of stay, intensive care unit admission rates or mortality between the NT-proBNP group and the routine work-up group were observed. CONCLUSION: Routine supplementary point-of-care measurement of NT-proBNP in patients with severe dyspnoea did not improve triage of patients with dyspnoea primarily caused by heart disease. ClinicalTrials.gov identifier NCT02050282.

Telemedicine-based physician consultation results in more patients treated and released by ambulance personnel.

OBJECTIVE: We examined whether teleconsultation from ambulances to a physician at an emergency medical communication center (EMCC) would increase the proportion of patients with nonurgent conditions being treated and released on site. METHODS: This research was a before-after pilot study. In the intervention period, the EMCC was manned 24/7 with physicians experienced in emergency care. Eligible participants included all patients with nonurgent conditions receiving an ambulance after a medical emergency call. Ambulance personnel assessed patients and subsequently performed a telephone consultation from the ambulance with the physician. The primary outcome was the proportion of patients treated and released on site. Secondary outcomes were the number of hospital admissions, mortality, and patient satisfaction. The intervention period was compared with a corresponding control period from the previous year. RESULTS: We observed an increase in the proportion of patients treated and released in the intervention period in 2014 compared with the control period in 2013, up from 21% (n=137) to 29% (n=221) (odds ratio=1.46; 95% confidence interval=1.14-1.89, P=0.002). The follow-up rate was 100%. There was no observable increase in hospital admissions or mortality among patients treated and released from 2013 to 2014. A telephone survey of patients treated and released showed that 98.4% (95% confidence interval=91.3-99.9) were very satisfied or satisfied with their treatment. CONCLUSION: Teleconsultation between a physician at the EMCC and ambulance personnel and noncritically ill 1-1-2 patients results in an increased rate of patients treated and released with high satisfaction. The approach does not seem to compromise patient safety.

Timing of focused cardiac ultrasound during advanced life support - A prospective clinical study.

INTRODUCTION: Focused cardiac ultrasound can potentially identify reversible causes of cardiac arrest during advanced life support (ALS), but data on the timing of image acquisition are lacking. This study aimed to compare the quality of images obtained during rhythm analysis, bag-mask ventilations, and chest compressions. METHODS: Adult patients in cardiac arrest were prospectively included during 23 months at a Danish community hospital. Physicians who had completed basic ultrasound training performed subcostal focused cardiac ultrasound during rhythm analysis, bag-mask ventilations, and chest compressions. Image quality was categorised as either useful for interpretation or not. Two echocardiography experts rated images useful for interpretation if all the following characteristics could be determined: 1) right ventricle larger than left ventricle, 2) pericardial fluid, and 3) collapsing ventricles. RESULTS: Images were obtained from 60 of 114 patients undergoing ALS. A higher proportion of the images obtained during rhythm analysis and bag-mask ventilations were useful for interpretation when compared with chest compressions (rhythm analysis vs chest compressions: OR 2.2 (95%CI 1.3-3.8), P = 0.005; bag mask ventilations vs chest compressions: OR 2.0 (95%CI 1.1-3.7), P = 0.03). There was no difference between images obtained during rhythm analysis and bag-mask ventilations (OR 1.1 (95%CI 0.6-2.0), P = 0.74). CONCLUSION: The quality of focused cardiac ultrasound images obtained during rhythm analysis and bag-mask ventilations was superior to that of images obtained during chest compressions. There was no difference in the quality of images obtained during rhythm analysis and bag-mask ventilations. Bag-mask ventilations may constitute an overlooked opportunity for image acquisition during ALS.

The Right Ventricle Is Dilated During Resuscitation From Cardiac Arrest Caused by Hypovolemia: A Porcine Ultrasound Study.

OBJECTIVES: Dilation of the right ventricle during cardiac arrest and resuscitation may be inherent to cardiac arrest rather than being associated with certain causes of arrest such as pulmonary embolism. This study aimed to compare right ventricle diameter during resuscitation from cardiac arrest caused by hypovolemia, hyperkalemia, or primary arrhythmia (i.e., ventricular fibrillation). DESIGN: Thirty pigs were anesthetized and then randomized to cardiac arrest induced by three diffrent methods. Seven minutes of untreated arrest was followed by resuscitation. Cardiac ultrasonographic images were obtained during induction of cardiac arrest, untreated cardiac arrest, and resuscitation. The right ventricle diameter was measured. Primary endpoint was the right ventricular diameter at the third rhythm analysis. SETTING: University hospital animal laboratory. SUBJECTS: Female crossbred Landrace/Yorkshire/Duroc pigs (27-32 kg). INTERVENTIONS: Pigs were randomly assigned to cardiac arrest caused by either hypovolemia, hyperkalemia, or primary arrhythmia. MEASUREMENTS AND MAIN RESULTS: At the third rhythm analysis during resuscitation, the right ventricle diameter was 32 mm (95% CI, 29-35) in the hypovolemia group, 29 mm (95% CI, 26-32) in the hyperkalemia group, and 25 mm (95% CI, 22-28) in the primary arrhythmia group. This was larger than baseline for all groups (p = 0.03). When comparing groups at the third rhythm analysis, the right ventricle was larger for hypovolemia than for primary arrhythmia (p < 0.001). CONCLUSIONS: The right ventricle was dilated during resuscitation from cardiac arrest caused by hypovolemia, hyperkalemia, and primary arrhythmia. These findings indicate that right ventricle dilation may be inherent to cardiac arrest, rather than being associated with certain causes of arrest. This contradicts a widespread clinical assumption that in hypovolemic cardiac arrest, the ventricles are collapsed rather than dilated.

Detection of Pulmonary Embolism During Cardiac Arrest-Ultrasonographic Findings Should Be Interpreted With Caution.

OBJECTIVES: The aim of this study was to test the hypothesis that the right ventricle is more dilated during resuscitation from cardiac arrest caused by pulmonary embolism, compared with hypoxia and primary arrhythmia. DESIGN: Twenty-four pigs were anesthetized and cardiac arrest was induced using three different methods. Pigs were resuscitated after 7 minutes of untreated cardiac arrest. Ultrasonographic images were obtained and the right ventricular diameter was measured. SETTING: University hospital animal laboratory. SUBJECTS: Female crossbred Landrace/Yorkshire/Duroc pigs (27-32 kg). INTERVENTIONS: Pigs were randomly assigned to cardiac arrest induced by pulmonary embolism, hypoxia, or primary arrhythmia. MEASUREMENTS AND MAIN RESULTS: There was no difference at baseline. During induction of cardiac arrest, the right ventricle dilated in all groups (p < 0.01 for all). The primary endpoint was right ventricle diameter at the third rhythm analysis: 32 mm (95% CI, 29-36) for pulmonary embolism which was significantly larger than both hypoxia: 23 mm (95% CI, 20-27) and primary arrhythmia: 25 mm (95% CI, 22-28)-the absolute difference was 7-9 mm. Physicians with basic training in focused cardiac ultrasonography were able to detect a difference in right ventricle diameter of approximately 10 mm with a sensitivity of 79% (95% CI, 64-94) and a specificity of 68% (95% CI, 56-80). CONCLUSIONS: The right ventricle was more dilated during resuscitation when cardiac arrest was caused by pulmonary embolism compared with hypoxia and primary arrhythmia. However, the right ventricle was dilated, irrespective of the cause of arrest, and diagnostic accuracy by physicians with basic training in focused cardiac ultrasonography was modest. These findings challenge the paradigm that right ventricular dilatation on ultrasound during cardiopulmonary resuscitation is particularly associated with pulmonary embolism.

Long-Term Mortality of Emergency Medical Services Patients.

STUDY OBJECTIVE: Emergency medical services (EMS) provides out-of-hospital care to patients with life-threatening conditions, but the long-term outcomes of EMS patients are unknown. We seek to determine the long-term mortality of EMS patients in Denmark. METHODS: We analyzed linked EMS, hospital, and vital status data from 3 of 5 geographic regions in Denmark. We included events from July 1, 2011, to December 31, 2012. We classified EMS events according to primary dispatch category (unconsciousness/cardiac arrest, accidents/trauma, chest pain, dyspnea, neurologic symptoms, and other EMS patients). The primary outcome was 1-year mortality adjusted for age, sex, and Charlson comorbidity index. RESULTS: Among 142,125 EMS events, primary dispatch categories were unconsciousness or cardiac arrest 5,563 (3.9%), accidents or trauma 40,784 (28.7%), chest pain 20,945 (14.7%), dyspnea 9,607 (6.8%), neurologic symptoms 17,804 (12.5%), and other EMS patients 47,422 (33.4%). One-year mortality rates were unconscious or cardiac arrest 54.7% (95% confidence interval [CI] 53.4% to 56.1%), accidents or trauma 7.8 (95% CI 7.5% to 8.1%), chest pain 8.5% (95% CI 8.1% to 9.0%), dyspnea 27.7% (95% CI 26.7% to 28.7%), neurologic symptoms 14.1% (95% CI 13.6% to 14.7%), and other EMS patients 11.1% (95% CI 10.8% to 11.4%). Compared with other EMS conditions, adjusted 1-year mortality was higher in unconsciousness or cardiac arrest (risk ratio [RR] 2.6; 95% CI 2.5 to 2.7), dyspnea (RR 1.5; 95% CI 1.4 to 1.5), and in neurologic symptoms (RR 1.1; 95% CI 1.0 to 1.1), but lower in chest pain (RR 0.6; 95% CI 0.6 to 0.7) and accidents or trauma (RR 0.8; 95% CI 0.8 to 0.8). CONCLUSION: EMS patients with unconsciousness or cardiac arrest, dyspnea, and neurologic symptoms are at highest risk of long-term mortality. Our results suggest a potential for outcome improvement in these patients.

Continuous positive airway pressure and noninvasive ventilation in prehospital treatment of patients with acute respiratory failure: a systematic review of controlled studies.

Continuous positive airway pressure (CPAP) and noninvasive ventilation (NIV) are frequently used inhospital for treating respiratory failure, especially in treatment of acute cardiogenic pulmonary edema and exacerbation of chronic obstructive pulmonary disease. Early initiation of treatment is important for success and introduction already in the prehospital setting may be beneficial. Our goal was to assess the evidence for an effect of prehospital CPAP or NIV as a supplement to standard medical treatment alone on the following outcome measures; mortality, hospital length of stay, intensive care unit length of stay, and intubation rate. We undertook a systematic review based on a search in the three databases: PubMed, EMBASE, and Cochrane. We included 12 studies in our review, but only four of these were of acceptable size and quality to conclude on our endpoints of interest. All four studies examine prehospital CPAP. Of these, only one small, randomized controlled trial shows a reduced mortality rate and a reduced intubation rate with supplemental CPAP. The other three studies have neutral findings, but in two of these a trend toward lower intubation rate is found. The effect of supplemental NIV has only been evaluated in smaller studies with insufficient power to conclude on our endpoints. None of these studies have shown an effect on neither mortality nor intubation rate, but two small, randomized controlled trials show a reduction in intensive care unit length of stay and a trend toward lower intubation rate. The risk of both type two errors and publication bias is evident, and the findings are not consistent enough to make solid conclusion on supplemental prehospital NIV. Large, randomized controlled trials regarding the effect of NIV and CPAP as supplement to standard medical treatment alone, in the prehospital setting, are needed.

A systematic review of controlled studies: do physicians increase survival with prehospital treatment?

BACKGROUND: The scientific evidence of a beneficial effect of physicians in prehospital treatment is scarce. The objective of this systematic review of controlled studies was to examine whether physicians, as opposed to paramedical personnel, increase patient survival in prehospital treatment and if so, to identify the patient groups that gain benefit. METHODS: A systematic review of studies published in the databases PubMed, EMBASE and Cochrane from January 1, 1990 to November 24, 2008. Controlled studies comparing patient survival with prehospital physician treatment vs. treatment by paramedical personnel in trauma patients or patients with any acute illness were included. RESULTS: We identified 1.359 studies of which 26 met our inclusion criteria. In nine of 19 studies including between 25 and 14.702 trauma patients in the intervention group, physician treatment increased survival compared to paramedical treatment. In four of five studies including between nine and 85 patients with out of hospital cardiac arrest, physician treatment increased survival. Only two studies including 211 and 2.869 patients examined unselected, broader patient groups. Overall, they demonstrated no survival difference between physician and paramedical treatment but one found increased survival with physician treatment in subgroups of patients with acute myocardial infarction and respiratory diseases. CONCLUSION: Our systematic review revealed only few controlled studies of variable quality and strength examining survival with prehospital physician treatment. Increased survival with physician treatment was found in trauma and, based on more limited evidence, cardiac arrest. Indications of increased survival were found in respiratory diseases and acute myocardial infarction. Many conditions seen in the prehospital setting remain unexamined.