Effect of prehospital induction of mild hypothermia on 3-month neurological status and 1-year survival among adults with cardiac arrest: long-term follow-up of a randomized, clinical trial.

BACKGROUND: Randomized trials of prehospital cooling after cardiac arrest have shown that neither prehospital cooling nor targeted temperature management differentially affected short-term survival or neurological function. In this follow-up study, we assess the association of prehospital hypothermia with neurological function at least 3 months after cardiac arrest and survival 1 year after cardiac arrest. METHODS AND RESULTS: There were 508 individuals who were discharged alive from hospitals in King County, Washington; 373 (73%) were interviewed by telephone 123±43 days after the initial event. Overall, 59% of the treatment group and 58% of the control group had Cerebral Performance Category (CPC) 1 or 2 (P=0.70), and 50% of the treatment group and 49% of the control group had slight disability or better by the Modified Rankin Scale (MRS; (P=0.35). One-year survival was 87% in the treatment group and 84% in the control group (P=0.42). Of those with CPC 1 at hospital discharge, 68% had CPC 1 or 2 at follow-up, and 59% had MRS of slight disability or better. Of 41 patients with CPC 3 or 4 at discharge, only 12% had CPC 2 at follow-up, and just 5% had MRS of slight disability or better. One-year survival was 92% for CPC 1 at discharge, but only 40% for CPC 4. CONCLUSION: In addition to excellent survival, patients who had good neurological function at discharge continued to have good function at least 3 months after the event. CLINICAL TRIAL REGISTRATION: URL: Clinicaltrials.gov. Unique identifier: NCT00391469.

Pre-hospital aspiration is associated with increased pulmonary complications.

BACKGROUND: Rates of ventilator-associated pneumonia (VAP) are highest among patients intubated on an emergency basis following trauma. We reported previously a retrospective analysis demonstrating an association between subjective aspiration and VAP after pre-hospital intubation. We hypothesize that by directing paramedics to note features of aspiration at intubation, we will confirm prospectively the association between pre-hospital aspiration and subsequent pneumonia in trauma patients. METHODS: Paramedics collected data regarding aspiration at the time of intubation. All intubated patients admitted to a level 1 trauma center intensive care unit (ICU) were included. Data comprised a clinical impression of pre-hospital aspiration, as well as the presence and timing of blood and emesis in the airway. Injury severity, co-morbidities, and outcomes were collected from the trauma registry. Healthcare-associated pneumonia (HAP) was identified by medical record review of both bronchoalveolar lavage culture results and discharge diagnosis. Descriptive statistics and univariate analysis of outcomes by aspiration status, as well as covariable adjustment using propensity scores, were performed. RESULTS: Of the 228 patients, 89 (39%) were determined by paramedics to have aspirated. The majority of those who aspirated (84 [94%]) did so prior to intubation. Patients who aspirated had higher Injury Severity Scores than those who did not aspirate (25.0 ± 1.7 vs. 21.9 ± 1.5 points; p=0.04) and lower preintubation Glasgow Coma Scale scores (8.2 ± 0.50 vs. 9.6 ± 0.40; p=0.02). Of the 89 patients who aspirated around the time of intubation, 14 (16%) developed HAP vs. five (3.6%) of those who did not aspirate (p<0.01). We observed non-significant increases in mortality rate, ICU length of stay (LOS) and duration of mechanical ventilation after aspiration (deaths: 21 [23.6%] vs. 23 [16.6%]; p=0.19; ICU LOS: 5.3 ± 0.9 vs. 4.1 ± 0.5 days; p=0.13; duration of mechanical ventilation: 5.3 ± 1.2 vs. 3.2 ± 0.5 days; p=0.10). CONCLUSIONS: Aspiration prior to intubation was reported commonly by paramedics and was associated with a higher risk of HAP.

Effect of prehospital induction of mild hypothermia on survival and neurological status among adults with cardiac arrest: a randomized clinical trial.

IMPORTANCE: Hospital cooling improves outcome after cardiac arrest, but prehospital cooling immediately after return of spontaneous circulation may result in better outcomes. OBJECTIVE: To determine whether prehospital cooling improves outcomes after resuscitation from cardiac arrest in patients with ventricular fibrillation (VF) and without VF. DESIGN, SETTING, AND PARTICIPANTS: A randomized clinical trial that assigned adults with prehospital cardiac arrest to standard care with or without prehospital cooling, accomplished by infusing up to 2 L of 4°C normal saline as soon as possible following return of spontaneous circulation. Adults in King County, Washington, with prehospital cardiac arrest and resuscitated by paramedics were eligible and 1359 patients (583 with VF and 776 without VF) were randomized between December 15, 2007, and December 7, 2012. Patient follow-up was completed by May 1, 2013. Nearly all of the patients resuscitated from VF and admitted to the hospital received hospital cooling regardless of their randomization. MAIN OUTCOMES AND MEASURES: The primary outcomes were survival to hospital discharge and neurological status at discharge. RESULTS: The intervention decreased mean core temperature by 1.20°C (95% CI, -1.33°C to -1.07°C) in patients with VF and by 1.30°C (95% CI, -1.40°C to -1.20°C) in patients without VF by hospital arrival and reduced the time to achieve a temperature of less than 34°C by about 1 hour compared with the control group. However, survival to hospital discharge was similar among the intervention and control groups among patients with VF (62.7% [95% CI, 57.0%-68.0%] vs 64.3% [95% CI, 58.6%-69.5%], respectively; P = .69) and among patients without VF (19.2% [95% CI, 15.6%-23.4%] vs 16.3% [95% CI, 12.9%-20.4%], respectively; P = .30). The intervention was also not associated with improved neurological status of full recovery or mild impairment at discharge for either patients with VF (57.5% [95% CI, 51.8%-63.1%] of cases had full recovery or mild impairment vs 61.9% [95% CI, 56.2%-67.2%] of controls; P = .69) or those without VF (14.4% [95% CI, 11.3%-18.2%] of cases vs 13.4% [95% CI,10.4%-17.2%] of controls; P = .30). Overall, the intervention group experienced rearrest in the field more than the control group (26% [95% CI, 22%-29%] vs 21% [95% CI, 18%-24%], respectively; P = .008), as well as increased diuretic use and pulmonary edema on first chest x-ray, which resolved within 24 hours after admission. CONCLUSION AND RELEVANCE: Although use of prehospital cooling reduced core temperature by hospital arrival and reduced the time to reach a temperature of 34°C, it did not improve survival or neurological status among patients resuscitated from prehospital VF or those without VF. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00391469.

Long-term outcomes following pediatric out-of-hospital cardiac arrest*.

OBJECTIVES: Pediatric out-of-hospital cardiac arrest is an uncommon event with measurable short-term survival to hospital discharge. For those who survive to hospital discharge, little is known regarding duration of survival. We sought to evaluate the arrest circumstances and long-term survival of pediatric patients who experienced an out-of-hospital cardiac arrest and survived to hospital discharge. DESIGN: Retrospective cohort study SETTING: King County, WA Emergency Medical Service Catchment and Quaternary Care Children's Hospital PATIENTS: Persons less than 19 years old who had an out-of-hospital cardiac arrest and were discharged alive from the hospital between 1976 and 2007. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: During the study period, 1,683 persons less than 19 years old were treated for pediatric out-of-hospital cardiac arrest in the study community, with 91 patients surviving to hospital discharge. Of these 91 survivors, 20 (22%) subsequently died during 1449 person-years of follow-up. Survival following hospital discharge was 92% at 1 year, 86% at 5 years, and 77% at 20 years. Compared to those who subsequently died, long-term survivors were more likely at the time of discharge to be older (mean age, 8 vs 1 yr), had a witnessed arrest (83% vs 56%), presented with a shockable rhythm (40% vs 10%), and had a favorable Pediatric Cerebral Performance Category of 1 or 2 (67% vs 0%). CONCLUSIONS: In this population-based cohort study evaluating the long-term outcome of pediatric survivors of out-of-hospital cardiac arrest, we observed that long-term survival was generally favorable. Age, arrest characteristics, and functional status at hospital discharge were associated with prognosis. These findings support efforts to improve pediatric resuscitation, stabilization, and convalescent care.

Prehospital systolic blood pressure thresholds: a community-based outcomes study.

OBJECTIVES: Emergency medical services (EMS) personnel commonly use systolic blood pressure (sBP) to triage and treat acutely ill patients. The definition of prehospital hypotension and its associated outcomes are poorly defined. The authors sought to determine the discrimination of prehospital sBP thresholds for 30-day mortality and to compare patient classification by best-performing thresholds to traditional cutoffs. METHODS: In a community-based cohort of adult, nontrauma, noncardiac arrest patients transported by EMS between 2002 and 2006, entries to state hospital discharge data and death certificates were linked. Prehospital sBP thresholds between 40 and 140 mm Hg in derivation (n = 132,624) and validation (n = 22,020) cohorts and their discrimination for 30-day mortality, were examined. Cutoffs were evaluated using the 0/1 distance, Youden index, and adjusted Z-statistics from multivariable logistic regression models. RESULTS: In the derivation cohort, 1,594 (1.2%) died within 24 hours, 7,404 (6%) were critically ill during hospitalization, and 6,888 (5%) died within 30 days. The area under the receiver operating characteristic (ROC) curve for sBP was 0.60 (95% confidence interval [CI] = 0.59, 0.61) for 30-day mortality and 0.64 (95% CI = 0.62 0.66) for 24-hour mortality. The 0/1 distance, Youden index, and adjusted Z-statistics found best-performing sBP thresholds between 110 and 120 mm Hg. When compared to an sBP ≤ 90 mm Hg, a cutoff of 110 mm Hg would identify 17% (n = 137) more deaths at 30 days, while overtriaging four times as many survivors. CONCLUSIONS: Prehospital sBP is a modest discriminator of clinical outcomes, yet no threshold avoids substantial misclassification of 30-day mortality among noninjured patients.

Comparison of role of early (less than six hours) to later (more than six hours) or no cardiac catheterization after resuscitation from out-of-hospital cardiac arrest.

Despite reports of patients with resuscitated sudden cardiac arrest (rSCA) receiving acute cardiac catheterization, the efficacy of this strategy is largely unknown. We hypothesized that acute cardiac catheterization of patients with rSCA would improve survival to hospital discharge. A retrospective cohort of 240 patients with out-of-hospital rSCA caused by ventricular tachycardia or fibrillation was identified from 11 institutions in Seattle, Washington from 1999 through 2002. Patients were grouped into those receiving acute catheterization within 6 hours (≤6-hour group, n = 61) and those with deferred catheterization at >6 hours or no catheterization during the index hospitalization (>6-hour group, n = 179). Attention was directed to survival to hospital discharge, neurologic status, extent of coronary artery disease, presenting electrocardiographic findings, and symptoms before arrest. Propensity-score methods were used to adjust for the likelihood of receiving acute catheterization. Survival was greater in patients who underwent acute catheterization (72% in the ≤6-hour group vs 49% in the >6-hour group, p = 0.001). Percutaneous coronary intervention was performed in 38 of 61 patients (62%) in the ≤6-hour group and 13 of 170 patients (7%) in the >6-hour group (p <0.0001). Neurologic status was similar in the 2 groups. A significantly larger percentage of patients in the acute catheterization group had symptoms before cardiac arrest and had ST-segment elevation on electrocardiogram after resuscitation. Age, bystander cardiopulmonary resuscitation, daytime presentation, history of percutaneous coronary intervention or stroke, and acute ST-segment elevation were positively associated with receiving cardiac catheterization. In conclusion, in this series of patients who sustained out-of-hospital cardiac arrest, acute catheterization (<6 hours of presentation) was associated with improved survival.

Understanding of sepsis among emergency medical services: a survey study.

BACKGROUND: Emergency medical services (EMS) personnel commonly encounter sepsis, yet little is known about their understanding of sepsis. STUDY OBJECTIVES: To determine the awareness, knowledge, current practice, and attitudes about sepsis among EMS personnel. METHODS: We performed an anonymous, multi-agency, online survey of emergency medical technicians (EMTs), firefighter-emergency medical technicians (FF-EMTs), and paramedics in a metropolitan, 2-tier EMS system. We compared responses according to the level of EMS training and used multivariable logistic regression to determine the odds of correctly identifying the definition of sepsis, independent of demographic and professional factors. RESULTS: Overall response rate of study participants was 57% (786/1390), and was greatest among EMTs (79%; 276/350). A total of 761 respondents (97%) had heard of the term "sepsis." EMTs and FF-EMTs were at significantly reduced odds of correctly defining sepsis compared to paramedics, independent of age, sex, and years of experience (EMTs: odds ratio 0.44, 95% confidence interval 0.3-0.8; FF-EMTs: odds ratio 0.32, 95% confidence interval 0.2-0.6. Overall, knowledge of the clinical signs and symptoms and recommended treatments for sepsis was typically>75%, though better among paramedics than EMTs or FF-EMTs (p<0.01). The majority of respondents believed sepsis is not recognized by EMS "some" or "a lot" of the time (76%, 596/786). CONCLUSIONS: EMS personnel demonstrated an overall sound awareness of sepsis. Knowledge of sepsis was less among FF-EMTs and EMTs compared to paramedics. These results suggest that paramedics could be integrated into strategies of early identification and treatment of sepsis, and EMTs may benefit from focused education and training.

The association between obesity and difficult prehospital tracheal intubation.

BACKGROUND: Nonphysician advanced life support (ALS) providers often perform tracheal intubation (TI) for cardiac arrest or other life-threatening indications in the prehospital setting, where airway assessment and airway management tools are limited. However, the frequency of difficult TI in obese patients in this setting is unclear. In this study we determined factors associated with TI success, and determined TI difficulty as a function of body mass index (BMI) in a system of ALS providers experienced in TI, to guide future prehospital education efforts. METHODS: A retrospective review was performed of all patients ≥15 years of age who underwent prehospital TI by paramedics in the Seattle Medic One system over a 4-year period, and were transported to the regional level 1 trauma center (Harborview Medical Center). Data were abstracted from a prospectively collected prehospital airway management database and from the hospital medical records, including demographic information, number of TI attempts, TI success or failure, and body weight/height (BMI). Descriptive statistics and multivariable logistic regression were calculated, with the primary end point being difficult TI (defined as ≥4 TI attempts or the need to use an alternative airway management technique). RESULTS: Of 80,501 patient contacts in whom 4114 TIs were attempted during the 4-year study period, 823 met study entry criteria (including a calculable BMI). The overall TI success rate in the study population was 98.5% (811 out of 823), with 6.8% (56 out of 823) meeting the predetermined definition for difficult TI. There was no significant association between difficult TI and patient age, gender, use of succinylcholine, or medical diagnosis (trauma vs. nontrauma). In comparison with the lean patient subgroup (BMI <30 kg/m(2)), patients with class III obesity (BMI >40 kg/m(2)) had a significant association with difficult TI (odds ratio 3.68; confidence interval [CI] 1.27-10.59), whereas those with class I/II obesity (BMI ≥30 kg/m(2) and <40 kg/m(2)) did not (odds ratio 0.98; CI 0.46 -2.07). CONCLUSIONS: Among prehospital ALS providers with previously documented and published successful TI performance, increased difficulty with TI was observed in patients with extreme obesity, but not in patients with lesser degrees of obesity. Because extreme obesity is an easily identifiable patient characteristic, didactic and clinical (e.g., operating room) airway management education for such providers should emphasize airway management challenges and strategies associated with obesity, including specific equipment, patient positioning, and practice recommendations that may facilitate both TI and alternative airway management techniques in this population.

Endogenous red blood cell membrane fatty acids and sudden cardiac arrest.

Little is known of the associations of endogenous fatty acids with sudden cardiac arrest (SCA). We investigated the associations of SCA with red blood cell membrane fatty acids that are end products of de novo fatty acid synthesis: myristic acid (14:0), palmitic acid (16:0), palmitoleic acid (16:1 n7), vaccenic acid (18:1 n7), stearic acid (18:0), oleic acid (18:1 n9), and a related fatty acid, cis-7 hexadecenoic acid (16:1 n9). We used data from a population-based case-control study where cases, aged 25 to 74 years, were out-of-hospital SCA patients attended by paramedics in Seattle, WA (n = 265). Controls, matched to cases by age, sex, and calendar year, were randomly identified from the community (n = 415). All participants were free of prior clinically diagnosed heart disease. We observed associations of higher red blood cell membrane levels of 16:0, 16:1n-7, 18:1n-7, and 16:1n-9 with higher risk of SCA. In analyses adjusted for traditional SCA risk factors and trans- and n-3 fatty acids, a 1-SD-higher level of 16:0 was associated with 38% higher risk of SCA (odds ratio, 1.38; 95% confidence interval, 1.12-1.70) and a 1-SD-higher level of 16:1n-9 with 88% higher risk (odds ratio, 1.88; 95% confidence interval, 1.27-2.78). Several fatty acids that are end products of fatty acid synthesis are associated with SCA risk. Further work is needed to investigate if conditions that favor de novo fatty acid synthesis, such as high-carbohydrate/low-fat diets, might also increase the risk of SCA.

A population-based investigation of public access defibrillation: role of emergency medical services care.

BACKGROUND: Although strategic use of public access defibrillation (PAD) can improve cardiac arrest survival, little is known about temporal trends in PAD deployment and use or how PAD affects the role of emergency medical services (EMS). We sought to determine the frequency, circumstances, and time trends of PAD AED and determine implications of PAD use for EMS providers. METHODS: The investigation was a population-based cohort study of treated out-of-hospital cardiac arrest from a heterogeneous metropolitan setting between January 1, 1999 and December 31, 2006. The study focused on cases where a PAD AED was applied. RESULTS: During the 8-year period, a PAD AED was applied in 1.5% (157/10,332) of all arrests and 4.4% (122/2759) of ventricular fibrillation arrests. PAD application increased over time overall (0.6% in 1999 to 2.4% in 2006) and among ventricular fibrillation arrests (1.8% in 1999 to 8.2% in 2006) (p<0.001 test for trend). Upon EMS arrival, over 90% (143/157) of PAD cases were unconscious and 73% (114/157) required CPR. EMS defibrillation occurred in 47% (73/157). Advanced life support included intubation in 85% (134/157), epinephrine treatment in 57% (90/157), and antiarrhythmic treatment in 64% (100/157). By the end of EMS care, spontaneous pulses were present in 76% (120/157) overall and 84% (102/122) of ventricular fibrillation arrests, a 50% absolute increase when compared to status upon EMS arrival. CONCLUSION: PAD AED increased over time. Most PAD patients were pulseless upon EMS arrival and required basic and advanced resuscitation care by EMS; yet most subsequently achieved spontaneous circulation.

Paramedic training for proficient prehospital endotracheal intubation.

BACKGROUND: Emergency airway management is an important component of resuscitation of critically ill patients. Multiple studies demonstrate variable endotracheal intubation (ETI) success by prehospital providers. Data describing how many ETI training experiences are required to achieve high success rates are sparse. OBJECTIVES: To describe the relationship between the number of prehospital ETI experiences and the likelihood of success on subsequent ETI and to specifically look at uncomplicated first-pass ETI in a university-based training program with substantial resources. METHODS: We conducted a secondary analysis of a prospectively collected cohort of paramedic student prehospital intubation attempts. Data collected on prehospital ETIs included indication, induction agents, number of direct laryngoscopy attempts, and advanced airway procedures performed. We used multivariable generalized estimating equations (GEE) analysis to determine the effect of cumulative ETI experience on first-pass and overall ETI success rates. RESULTS: Over a period of three years, 56 paramedic students attempted 576 prehospital ETIs. The odds of overall ETI success were associated with cumulative ETI experience (odds ratio [OR] 1.097 per encounter, 95% confidence interval [CI] = 1.026-1.173, p = 0.006). The odds of first-pass ETI success were associated with cumulative ETI experience (OR 1.061 per encounter, 95% CI = 1.014-1.109, p = 0.009). CONCLUSION: In a training program with substantial clinical opportunities and resources, increased ETI success rates were associated with increasing clinical exposure. However, first-pass placement of the ETT with a high success rate requires high numbers of ETI training experiences that may exceed the number available in many training programs.

Sodium azide-associated laryngospasm after air bag deployment.

The advent and incorporation of the air bag into motor vehicles has resulted in the mitigation of many head and truncal injuries in motor vehicle collisions. However, air bag deployment is not risk free. We present a case of sodium azide-induced laryngospasm after air bag deployment. An unrestrained male driver was in a moderate-speed motor vehicle collision with air bag deployment. Medics found him awake, gasping for air with stridorous respirations and guarding his neck. The patient had no external signs of trauma and was presumed to have tracheal injury. The patient was greeted by the Anesthesiology service, which intubated him using glidescope-assisted laryngoscopy. The patient was admitted for overnight observation and treatment of alkaline ocular injury and laryngospasm. Although air bags represent an important advance in automobile safety, their use is not without risk. Bruising and tracheal rupture secondary to air bag deployment have been reported in out-of-position occupants. Additionally, alkaline by-products from the combustion of sodium azide in air bags have been implicated in ocular injury and facial burns. Laryngospasm after sodium azide exposure presents another diagnostic challenge for providers. Therefore, it is incumbent to maintain vigilance in the physical examination and diagnosis of occult injuries after air bag deployment.

Active surface cooling protocol to induce mild therapeutic hypothermia after out-of-hospital cardiac arrest: a retrospective before-and-after comparison in a single hospital.

OBJECTIVE: To evaluate whether implementation of a therapeutic hypothermia protocol on arrival in a community hospital improved survival and neurologic outcomes in patients initially found to have ventricular fibrillation, pulseless electrical activity, or asystole, and then successfully resuscitated from out-of-hospital cardiac arrest. DESIGN: A retrospective study of patients who presented after implementation of a therapeutic hypothermia protocol compared with those who presented before the protocol was implemented. SETTING: Harborview Medical Center, Seattle, WA. PATIENTS: A total of 491 consecutive adults with out-of-hospital, nontraumatic cardiac arrest who presented between January 1, 2000 and December 31, 2004. INTERVENTIONS: An active cooling therapeutic hypothermia protocol, using ice packs, cooling blankets, or cooling pads to achieve a temperature of 32 degrees C to 34 degrees C was initiated on November 18, 2002 for unconscious patients resuscitated from cardiac arrest. MEASUREMENTS AND MAIN RESULTS: Demographics and outcomes were obtained from medical records and an emergency medical database. The primary outcomes were survival and favorable neurologic outcome at discharge associated with the therapeutic hypothermia protocol. An adjusted analysis was performed, using a multivariate regression. During the therapeutic hypothermia period, 204 patients were brought to the emergency department; of these 204 patients, 132 (65%) ultimately achieved temperatures of <34 degrees C. Of the 72 patients who did not achieve goal temperatures: 40 (20%) died in the emergency department or shortly after being admitted to the hospital, 15 (7%) regained consciousness, four (2%) had contraindications, 13 (6%) had temperature increase or did not have documented use of the therapeutic hypothermia protocol. In the prior period, none of the 287 patients received active cooling. Patients admitted in the therapeutic hypothermia period had a mean esophageal temperature of 34.1 degrees C during the first 12 hrs compared with 35.2 degrees C in the pretherapeutic hypothermia period (p < .01). Survival to hospital discharge improved in the therapeutic hypothermia period in patients with an initial rhythm of ventricular fibrillation (odds ratio, 1.88, 95% confidence interval, 1.03-3.45), however not in patients with nonventricular fibrillation (odds ratio, 1.17, 95% confidence interval, 0.66-2.05). In adjusted analysis, ventricular fibrillation patients during the therapeutic hypothermia period trended toward improved survival (odds ratio, 1.71, 95% confidence interval, 0.85-3.46) and had favorable neurologic outcome (odds ratio, 2.62, 95% confidence interval, 1.1-6.27) compared with the earlier period. This benefit was not observed in patients whose initial rhythm was pulseless electrical activity or asystole. CONCLUSIONS: The therapeutic hypothermia period was associated with a significant improvement in neurologic outcomes in patients whose initial rhythm was ventricular fibrillation, but not in patients with other rhythms.

Red blood cell membrane alpha-linolenic acid and the risk of sudden cardiac arrest.

Higher levels of long-chain n-3 polyunsaturated fatty acids in red blood cell membranes are associated with lower risk of sudden cardiac arrest. Whether membrane levels of alpha-linolenic acid, a medium-chain n-3 polyunsaturated fatty acid, show a similar association is unclear. We investigated the association of red blood cell membrane alpha-linolenic acid with sudden cardiac arrest risk in a population-based case-control study. Cases, aged 25 to 74 years, were out-of-hospital sudden cardiac arrest patients attended by paramedics in Seattle, WA (n = 265). Controls, matched to cases by age, sex, and calendar year, were randomly identified from the community (n = 415). All participants were free of prior clinically diagnosed heart disease. Blood was obtained at the time of cardiac arrest (cases) or at the time of an interview (controls). Higher membrane alpha-linolenic acid was associated with a higher risk of sudden cardiac arrest: after adjustment for matching factors and smoking, diabetes, hypertension, education, physical activity, weight, height, and total fat intake, the odds ratios corresponding to increasing quartiles of alpha-linolenic acid were 1.7 (95% confidence interval [CI], 1.0-3.0), 1.9 (95% CI, 1.1-3.3), and 2.5 (95% CI, 1.3-4.8) compared with the lowest quartile. The association was independent of red blood cell levels of long-chain n-3 fatty acids, trans-fatty acids, and linoleic acid. Higher membrane levels of alpha-linolenic acid are associated with higher risk of sudden cardiac arrest.

The utility of early end-tidal capnography in monitoring ventilation status after severe injury.

BACKGROUND: An arterial CO2 (Paco2) of 30 mm Hg to 39 mm Hg has been shown to be the ideal target range for early ventilation in trauma patients; however, this requires serial arterial blood gases. The use of end-tidal capnography (EtCO2) has been recommended as a surrogate measure of ventilation in the prehospital arena. This is based on the observation of close EtCO2 Pa(CO2) correlation in healthy patients, yet trauma patients frequently suffer from impaired pulmonary ventilation/perfusion. Thus, we hypothesize that EtCO2 will demonstrate a poor reflection of actual ventilation status after severe injury. METHODS: Prospective observational study on consecutive intubated trauma patients treated in our emergency department (ED) during 9 months. Arterial blood gas values and concomitant EtCO2 levels were recorded. Regression was used to determine the strength of correlation among all trauma patients and subgroups based on injury severity (Abbreviated Injury Score and Injury Severity Score) and physiologic markers of perfusion status (lactate, shock index, and arterial base deficit). RESULTS: During 9 months, 180 patients were evaluated. The EtCO2 Paco2 correlation was poor at R2 = 0.277. Patients ventilated in the recommended EtCO2 (range, 35 to 40) were likely to be under ventilated (Pa(CO2) > 40 mm Hg) 80% of the time, and severely under ventilated (Pa(CO2) > 50 mm Hg) 30% of the time. Correlation was best for patients with isolated traumatic brain injury and worst for those with evidence of poor tissue perfusion. CONCLUSION: EtCO2 has low correlation with Pa(CO2), and therefore should not be used to guide ventilation in intubated trauma patients in the ED. Better strategies for guiding prehospital and ED ventilation are needed.

The use of pre-hospital mild hypothermia after resuscitation from out-of-hospital cardiac arrest.

Hypothermia has emerged as a potent neuroprotective modality following resuscitation from cardiac arrest. Although delayed hospital cooling has been demonstrated to improve outcome after cardiac arrest, in-field cooling begun immediately following the return of spontaneous circulation may be more beneficial. Cooling in the field following resuscitation, however, presents new challenges, in that the cooling method has to be portable, safe, and effective. Rapid infusion of intravenous fluid at 4 degrees C, the use of a cooling helmet, and cooling plates have all been proposed as methods for field cooling, and are all in various stages of clinical and animal testing. Whether field cooling will improve survival and neurologic outcome remains an important unanswered clinical question.

Prehospital management of the difficult airway: a prospective cohort study.

The role of prehospital endotracheal intubation (ETI) remains controversial, with significant national variability in practice. The purpose of this project was to evaluate ETI management in a system of advanced life support (ALS) providers experienced in ETI and other advanced airway techniques, and describe management and outcomes of patients with a "difficult airway." Data were collected prospectively for all ETIs performed by the fire department over a 4-year period (2001-2005), and included demographics, number of laryngoscopy attempts, airway procedures, complications, and outcomes. Of 80,501 ALS patient contacts, 4091 (5.1%) underwent attempted oral ETI, with a 96.8% success rate in four or fewer attempts. The difficult airway cohort included 130 patients (3.2%), whose airway management consisted of oral ETI after more than four attempts (46%), bag-valve-mask ventilation (33%), cricothyroidotomy (8%), retrograde ETI (5%), and digital ETI (1%). Procedural success rates ranged from 14% (digital ETI) to 91% (cricothyroidotomy). Nine patients (7%) had failed airway management, of whom 5 were found in cardiac arrest. The two most common reasons subjectively reported by ALS providers for airway difficulty were anterior trachea (39%) and small mouth (30%). Overall mortality for the difficult airway cohort was 44%. Prehospital ETI can be performed with a high success rate by experienced ALS providers, but may still require advanced airway techniques in a small subset of patients. Patient anatomy is a primary factor in failed ETI. Among the advanced procedures, cricothyroidotomy had the highest success rate and should not be delayed by other interventions.

Clinical trials in the out-of-hospital setting: rationale and strategies for successful implementation.

Cardiopulmonary arrest and trauma are two of the major epidemics of our time. In most cases, the final outcome is altered, for better or for worse, by how interventions are provided in the prehospital setting, making that venue critical for lifesaving community research efforts. In certain venues, out-of-hospital emergency medical services personnel are highly skilled at managing resuscitations and routinely operate under strict, highly scrutinized protocols, resulting in extraordinary study compliance. Larger patient enrollment derived from population-based investigations can lead to faster study completion, less selection bias, higher-powered data, and enhanced subgroup analysis. Most importantly, the concomitant training, expert protocol development, and rigid scrutiny all lead to improved patient outcomes, regardless of study intervention. For successful implementation, emergency medical services personnel should be involved in study design, and utilize routine, automated data collection. Technologies should be provided that simplify tasks and diminish confounding variables. Considering that exception to informed consent is a critical component, prospective education and involvement of the medical community, community leaders, employee groups and the media, long before protocol implementation, is essential. Such efforts should be led by respected, academically authoritative, grassroots emergency medical services medical directors and trauma chiefs, preferably those based at the main trauma centers or public receiving facilities.