Dominik Roth

Accuracy of Noninvasive Multiwave Pulse Oximetry Compared With Carboxyhemoglobin From Blood Gas Analysis in Unselected Emergency Department Patients

STUDY OBJECTIVE Accurate and timely diagnosis of carbon monoxide (CO) poisoning is difficult because of nonspecific symptoms. Multiwave pulse oximetry might facilitate the screening for occult poisoning by noninvasive measurement of carboxyhemoglobin (COHb), but its reliability is still unknown. We assess bias and precision of COHb oximetry compared with the criterion standard blood gas analysis. METHODS This was a prospective diagnostic accuracy study according to STARD (Standards for the Reporting of Diagnostic accuracy studies) criteria, performed at a tertiary care hospital emergency department. We included all patients for whom both invasive and noninvasive measurement within 60 minutes was available, regardless of their complaints, during a 1-year period. RESULTS One thousand five hundred seventy-eight subjects were studied, of whom 17 (1.1%) received a diagnosis of CO poisoning. In accordance with this limited patient cohort, we found a bias of 2.99% COHb (1.50% for smokers, 4.33% for nonsmokers) and a precision of 3.27% COHb (2.90% for smokers, 2.98% for nonsmokers), limits of agreement from -3.55% to 9.53% COHb (-4.30% to 7.30% for smokers, -1.63% to 10.29% for nonsmokers). Upper limit of normal cutoff of 6.6% COHb had the highest sensitivity in screening for CO poisoning. Smoking status and COHb level had the most influence on the deviation between measurements. CONCLUSION Multiwave pulse oximetry was found to measure COHb with an acceptable bias and precision. These results suggest it can be used to screen large numbers of patients for occult CO poisoning.

Evaluation of airway management associated hands-off time during cardiopulmonary resuscitation: a randomised manikin follow-up study

IntroductionAirway management is an important component of cardiopulmonary resuscitation (CPR). Recent guidelines recommend keeping any interruptions of chest compressions as short as possible and not lasting more than 10 seconds. Endotracheal intubation seems to be the ideal method for establishing a secure airway by experienced providers, but emergency medical technicians (EMT) often lack training and practice. For the EMTs supraglottic devices might serve as alternatives.Methods40 EMTs were trained in a 1-hour standardised audio-visual lesson to handle six different airway devices including endotracheal intubation, Combitube, EasyTube, I-Gel, Laryngeal Mask Airway and Laryngeal tube. EMTs performances were evaluated immediately after a brief practical demonstration, as well as after 1 and 3 months without any practice in between, in a randomised order. Hands-off time was pair-wise compared between airway devices using a repeated-measures mixed-effects model.ResultsOverall mean hands-off time was significantly (p<0.01) lower for Laryngeal tube (6.1s; confidence interval 5.2-6.9s), Combitube (7.9s; 95% CI 6.9-9.0s), EasyTube (8.8s; CI 7.3-10.3s), LMA (10.2s; CI 8.6-11.7s), and I-Gel (11.9s; CI 10.2-13.7s) compared to endotracheal intubation (39.4s; CI 34.0-44.9s). Hands-off time was within the recommended limit of 10s for Combitube, EasyTube and Laryngeal tube after 1 month and for all supraglottic devices after 3 months without any training, but far beyond recommended limits in all three evaluations for endotracheal intubation.ConclusionUsing supraglottic airway devices, EMTs achieved a hands-off time within the recommended time limit of 10s, even after three months without any training or practice. Supraglottic airway devices are recommended tools for EMTs with lack of experience in advanced airway management.

Admission blood pressure and 1-year mortality in acute myocardial infarction

Arterial hypertension is a well‐established factor for increased risk of cardiovascular diseases, but low admission blood pressure has also been suggested as predictor for increased mortality. We hypothesised that in patients with acute myocardial infarction admission blood pressure at the Emergency Department predicts long‐term mortality.

Safety and Feasibility of the Laryngeal Tube When Used by EMTs During Out-of-Hospital Cardiac Arrest

BACKGROUND Ventilation is still one key element of advanced life support. Emergency medical technicians (EMTs) without training in advanced airway management usually use bag valve mask ventilation (BVM). Bag valve mask ventilation requires proper training and yet may be difficult and ineffective. Supraglottic airway devices, such as the laryngeal tube (LT), have been proposed as alternatives. Safety and feasibility are unclear if used by EMTs with limited training only. We compared efficacy of the LT to BVM for out-of-hospital cardiac arrest in a primarily volunteer-based emergency medical services. METHODS This is a prospective multicenter observational cohort study. We compared safety (injuries and regurgitation) and feasibility (successful ventilation) in patients who received BVM, LT, or fallback to BVM after LT and controlled for potential confounders using logistic regression. RESULTS A total of 517 cases were documented, 395 (76.7%) with LT, 74 (14.4%) with BVM, and 48 (9.3%) where EMTs fell back from LT to BVM. There was no difference between groups regarding demographics (71 ± 17 years; 37% female) and initial rhythm (44% shockable). Placement of LT at first attempt was possible in 300 cases (76%), and at second attempt, in 91 cases (23%). Compared to BVM (22 cases [30%]), ventilation was more frequently successful with LT in 367 cases (93%; adjusted risk ratio, 3.1 [95% confidence interval, 1.3-7.1]; P < .01) and less successful with LT to BVM in 7 cases (15%; 0.3 [0.1-0.7]; P = .01). Five injuries (1.3%) were documented. Regurgitation was observed 8 (11%), 22 (6%; P < .01), and 8 times (17%; P < .01), respectively. CONCLUSIONS Use of the LT during out-of-hospital cardiac arrest by EMTs with only basic training appears safe and feasible. Compared to BVM, success rates were higher. Injuries were relatively rare.

Different Mortality Time Points in Critical Care Trials: Current Practice and Influence on Effect Estimates in Meta-Analyses.

Objective:Mortality is frequently used as an outcome in critical care trials, being a patient-orientated variable and robust against information/selection bias. Mortality frequency, however, should be measured at a defined time point of follow-up. Practice of meta-analysis shows that follow-up times of trials in critical care medicine differ substantially. This may have substantial implications on potential pooling of effect estimates. We aimed to describe the current practice of mortality follow-up time definitions in a representative sample of published critical care randomized controlled trials and to analyze the influence of different follow-up times on subsequently pooled effect estimates. Data Sources:Cochrane CENTRAL, EMBASE, MEDLINE, PASCAL Biomed, and PsycINFO. Study Selection:Databases were searched for critical care randomized controlled trials published after 2000. A random sample of 50% was drawn for further review. Data Extraction:Study characteristics were extracted, as well as the number and time points of mortality ascertainment. Additional data were extracted from Kaplan-Meier plots, as available. Data Synthesis:Meta-regression and multilevel mixed-effects linear regression were used to analyze the influence of follow-up time (independent variable) on deviation of pooled risk ratios from study baseline (dependent variable). From 9,246 retrieved references, we included 106 studies representing 63,713 participants. Among these, 45 studies (43%) reported more than one time point, with 24 different time points at all, only three (28, 30, and 90 d) being reported in more than 10% of studies. Limiting meta-analyses to only one predefined time point would reduce the number of eligible studies by at least 60%. No influence of time points on meta-analytic summary effect estimates was found. Conclusions:In a large sample of critical care randomized controlled trials, numerous different mortality time points are reported. Mortality time points did not influence pooled point estimates of the effects. Consequently, it seems possible to pool effect estimates, which in turn will increase the precision of these effect estimates.

Prevalence of carbon monoxide poisoning in patients presenting to a large emergency department.

Carbon monoxide (CO) can cause lethal intoxication, but the burden of occult CO poisoning is still unclear. We aimed at prospectively assessing the number of patients with occult CO poisoning presenting to an emergency department within one year.

UNRECOGNIZED CARBON MONOXIDE POISONING LEADS TO A MULTIPLE-CASUALTY INCIDENT

BACKGROUND Carbon monoxide (CO) is regarded as a leading cause of morbidity and mortality. It endangers not only patients, but also health care professionals, especially emergency medical services (EMS) personnel because CO exposure is often unknown at the time EMS is called. OBJECTIVE Our objective was to report a case of unrecognized CO exposure during the treatment of a patient that finally led to the hospitalization of 11 EMS personnel. CASE REPORT A 71-year-old man was found unconscious in the basement of his house. EMS was called and, due to ST-segment elevations on electrocardiogram, the patient was treated for acute coronary syndrome. Unknown to EMS personnel, ongoing CO exposure was the cause of the patients symptoms. EMS staff finally had to be evacuated by firefighters, and a total of 12 persons, including the initial patient, had to be hospitalized. CONCLUSIONS In the prehospital setting, hazardous environments always have to be considered as potential causes of a patients altered status. Together with the correct use of modern equipment, such as permanently switched-on CO detectors, this can help avoid harm to both patients and staff.

Victim of carbon monoxide poisoning identified by carbon monoxide oximetry.

BACKGROUND Carbon monoxide (CO) is known as a leading cause of unintentional poisoning death in many countries. Diagnosis is usually made by measuring carboxyhemoglobin (COHb), but due to the non-specific symptoms, the crucial step is considering CO poisoning. A possible solution might be screening emergency department (ED) patients. A cutaneous sensor that measures oxygen and CO saturation simultaneously could accomplish that. OBJECTIVES We report a case in which CO-oximetry screening helped to identify CO poisoning in a patient with otherwise non-specific complaints presenting to a busy university hospital ED. CASE REPORT A 53-year-old woman presented to our ED, reporting non-specific but common symptoms including emesis and diarrhea, one-sided headache, paresthesia, and palpitations. Whereas conventional pulse oximetry showed normal results, a COHb level of 28% was measured using a CO-oximeter. This allowed a diagnosis of CO poisoning to be made at admission. The patient was treated with 100% oxygen continuous positive airway pressure ventilation, and CO washout was monitored continuously and non-invasively. In the meantime, the local fire department was alerted and found a malfunctioning water heater as the source of CO in the patients residence. As COHb fell to normal levels and the patient reported feeling well, she was discharged the next day. CONCLUSION CO-oximetry served as a powerful tool in both identifying and monitoring a CO-poisoned patient in a busy ED. Future studies should address possible sources of error using this method on a long-term basis and its level of acceptance by ED staff.

Laryngeal Tube Practice in a Metropolitan Ambulance Service: A Five-year Retrospective Observational Study (2009–2013)

Abstract Background: The endotracheal tube (ETT) is considered the gold standard in emergency airway management, although supraglottic airway devices, especially the laryngeal tube (LT), have recently gained in importance. Although regarded as an emergency device in case of failure of endotracheal intubation in most systems, we investigated the dynamics of the use of the LT in a metropolitan ambulance service without any regulations on the choice of airway device. Methods: A retrospective, observational study on all patients from the Municipal Ambulance Service, Vienna in need of advanced airway management over a 5-year period. Differences between years were compared; influencing factors for the use of the LT were analyzed using multivariable logistic regression. Results: In total 5,175 patients (mean age 62 ± 20 years, 36.6% female) underwent advanced airway management. Of these, 15.6% received the LT. LT use increased from 20 out of 1,001 (2.0%) in 2009 to 292 of 1,085 (26.9%) in 2013 (p < 0.001). The increase between each consecutive year was also significant. Paramedics more frequently inserted the LT than physicians (RR 1.80 (95%CI 1.48–2.16); p < 0.001). Female patients received a LT less frequently (RR 0.84 (95%CI 0.72–0.97), p = 0.013). There was no difference regarding airway device due to underlying causes requiring airway management and no relationship to the NACA-score. Conclusion: In a European EMS system of physician and paramedic response, the proportion of airway managed by LT over ETT rose considerably over five years. Although the ET is still the gold standard, the LT is gaining in importance for EMS physicians and paramedics.

Exposure to carbon monoxide for patients and providers in an urban emergency medical service.

Abstract Background. Carbon monoxide (CO) poisoning poses danger to both patients and emergency medical services (EMS) personnel, as its symptoms are nonspecific and EMS is currently not equipped to detect CO in ambient air. Objective. We aimed to assess the degree of non–fire-related CO exposure at the high-volume EMS system of a city with 2 million inhabitants. Methods. The EMS system was equipped with handheld CO detectors (Dräger Pac 3500), which were added to EMS standard backpacks and had to be carried to the patient at all times. During a period of one year, all alarms by those devices were recorded, sources of CO were confirmed by the fire department, and hospital follow-up was conducted for both patients and exposed EMS staff. Results. During the study period, there were 40 alarms, including two false alarms. Alarms occurred during the whole year, with a peak during the winter months. The median ambient CO concentration was 167 parts per million; gas heating systems were the main source of CO. One hundred ten patients and 108 EMS personnel were exposed. One hundred fifteen persons, including 22 EMS staff, had to be hospitalized, which represents one out of 1,000 total EMS patients. Conclusions. Carbon monoxide poisoning was found to be a significant matter for a high-volume EMS system. Handheld CO detectors helped in identifying those cases. Key words: carbon monoxide; emergency care, prehospital; equipment and supplies; poisoning