Kurt R. Denninghoff

Effect of Transport Interval on Out-of-Hospital Cardiac Arrest Survival in the OPALS Study: Implications for Triaging Patients to Specialized Cardiac Arrest Centers

STUDY OBJECTIVE To identify any association between out-of-hospital transport interval and survival to hospital discharge in victims of out-of-hospital cardiac arrest. METHODS Data from the Ontario Prehospital Advanced Life Support Study (January 1, 1991, to December 31, 2002), an Utstein-compliant registry of out-of-hospital cardiac arrest patients from 21 communities, were analyzed. Logistic regression identified factors that were independently associated with survival in consecutive adult, nontraumatic, out-of-hospital cardiac arrest patients and in the subgroup with return of spontaneous circulation. RESULTS A total of 18,987 patients met criteria and 15,559 (81.9%) had complete data for analysis (study group). Return of spontaneous circulation was achieved in 2,299 patients (14.8%), and 689 (4.4%) survived to hospital discharge. Median transport interval was 4.0 minutes (25th quartile 3.0 minutes; 75th quartile 6.2 minutes) for survivors and 4.2 minutes (25th quartile 3.0, 75th quartile 6.2) for nonsurvivors. Logistic regression revealed multiple factors that were independently associated with survival: witnessed arrest (odds ratio 2.61; 95% confidence interval [CI] 2.05 to 3.34), bystander cardiopulmonary resuscitation (odds ratio 2.22; 95% CI 1.82 to 2.70), initial rhythm of ventricular fibrillation/tachycardia (odds ratio 2.22; 95% CI 1.97 to 2.50), and shorter emergency medical services (EMS) response interval (odds ratio 1.26; 95% CI 1.20 to 1.33). There was no association between transport interval and survival in either the study group (odds ratio 1.01; 95% CI 0.99 to 1.05) or the return of spontaneous circulation subgroup (odds ratio 1.04; 95% CI 0.99, 1.08). CONCLUSION In a large out-of-hospital cardiac arrest study from demographically diverse EMS systems, longer transport interval was not associated with decreased survival. Given the growing evidence showing major influence from specialized postarrest care, these findings support conducting clinical trials that assess the effectiveness and safety of bypassing local hospitals to take patients to regional cardiac arrest centers.

Increasing hospital volume is not associated with improved survival in out of hospital cardiac arrest of cardiac etiology

BACKGROUND Resuscitation centers may improve patient outcomes by achieving sufficient experience in post-resuscitation care. We analyzed the relationship between survival and hospital volume among patients suffering out-of-hospital cardiac arrest (OHCA). METHODS This prospective cohort investigation collected data from the Cardiac Arrest Registry to Enhance Survival database from 10/1/05 to 12/31/09. Primary outcome was survival to discharge. Hospital characteristics were obtained via 2005 American Hospital Association Survey. A hospitals use of hypothermia was obtained via direct survey. To adjust for hospital- and patient-level variation, multilevel, hierarchical logistic regression was performed. Hospital volume was modeled as a categorical (OHCA/year≤10, 11-39, ≥40) variable. A stratified analysis evaluating those with ventricular fibrillation or pulseless ventricular tachycardia (VF/VT) was also performed. RESULTS The cohort included 4125 patients transported by EMS to 155 hospitals in 16 states. Overall survival to hospital discharge was 35% among those admitted to the hospital. Individual hospital rates of survival varied widely (0-100%). Unadjusted survival did not differ between the 3 hospital groups (36% for ≤10 OHCA/year, 35% for 11-39, and 36% for ≥40; p=0.75). After multilevel adjustment, differences in survival across the groups were not statistically significant. Compared to patients at hospitals with ≤10 OHCA/year, adjusted OR for survival was 1.04 (CI(95) 0.83-1.28) among 11-39 annual volume and 0.97 (CI(95) 0.73-1.30) among the ≥40 volume hospitals. Among patients presenting with VF/VT, no difference in survival was identified between the hospital groups. CONCLUSION Survival varied substantially across hospitals. However, hospital OHCA volume was not associated with likelihood of survival. Additional efforts are required to determine what hospital characteristics might account for the variability observed in OHCA hospital outcomes.

The Effectiveness of Ultrabrief and Brief Educational Videos for Training Lay Responders in Hands-Only Cardiopulmonary Resuscitation Implications for the Future of Citizen Cardiopulmonary Resuscitation Training

Background— Bystander cardiopulmonary resuscitation (CPR) improves survival from out-of-hospital cardiac arrest (OHCA) but often is not performed. We hypothesized that subjects viewing very short Hands-Only CPR videos will (1) be more likely to attempt CPR in a simulated OHCA scenario and (2) demonstrate better CPR skills than untrained individuals. Methods and Results— This study is a prospective trial of 336 adults without recent CPR training randomized into 4 groups: (1) control (no training) (n=51); (2) 60-second video training (n=95); (3) 5-minute video training (n=99); and (4) 8-minute video training, including manikin practice (n=91). All subjects were tested for their ability to perform CPR during an adult OHCA scenario using a CPR-sensing manikin and Laerdal PC SkillReporting software. One half of the trained subjects were randomly assigned to testing immediately and the other half after a 2-month delay. Twelve (23.5%) controls did not even attempt CPR, which was true of only 2 subjects (0.7%; P=0.01) from any of the experimental groups. All experimental groups had significantly higher average compression rates (closer to the recommended 100/min) than the control group (P<0.001), and all experimental groups had significantly greater average compression depth (>38 mm) than the control group (P<0.0001). Conclusions— Laypersons exposed to very short Hands-Only CPR videos are more likely to attempt CPR and show superior CPR skills than untrained laypersons. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01191736.

Epidemiology of organophosphate pesticide poisoning in Taiwan.

Introduction. The nationwide epidemiology of organophosphate pesticide (OP) poisoning has never been reported in detail for Taiwan. Methods. This study retrospectively reviewed all human OP exposures reported to Taiwans Poison Control Centers (PCCs) from July 1985 through December 2006. Results. There were 4799 OP exposures. Most OP exposures were acute (98.37%) ingestions (74.50%) of a single OP (80.37%) to attempt suicide (64.72%) in adults (93.25%). Males were the most common gender (64.95%). Most patients (61.97%) received atropine and/or pralidoxime. The mortality rate for all 4799 OP exposures was 12.71%. Exposures to single OPs without co-intoxicants caused 524 deaths; of these, 63.36% were due to dimethyl OPs. Conclusion. Dimethyl OPs cause the majority of deaths in Taiwan.

Effect of multiple light paths on retinal vessel oximetry

Techniques for noninvasively measuring the oxygen saturation of blood in retinal arteries and veins are reported in the literature, but none have been sufficiently accurate and reliable for clinical use. Addressing the need for increased accuracy, we present a series of oximetric equations that explicitly consider the effects of backscattering by red blood cells and lateral diffusion of light in the ocular fundus. The equations are derived for the specific geometry of a scanning-beam retinal vessel oximeter; however, the results should also be applicable to photographic oximeters. We present in vitro and in vivo data that suggest the validity of these equations.

Sepsis Bundles and Compliance With Clinical Guidelines

Realizing the vast medical benefits of validated protocols, recommendations and practice guidelines requires acceptance and implementation by frontline care providers. Knowledge translation is the science of accelerating the transfer of knowledge to practice by understanding and creatively addressing the barriers that prevent adoption of new professional standards. In an attempt to improve patient care and reduce mortality, the Surviving Sepsis Campaign and The Institute for Healthcare Improvement created the resuscitation and management bundles for patients with severe sepsis and septic shock. These bundles have been accepted as best practice by many clinicians since multiple clinical trials have produced similar positive results when they were implemented. However, transferring these research outcomes-based guidelines to the clinical practice arena has been associated with poor compliance due to important barriers to implementation. Delays in the adoption of sepsis bundles are not surprising since the time from validation to implementation of a new clinical practice is typically 17 years. Using sepsis bundles as a model, this article explores why guidelines are important, examines physician adherence to protocols, and reviews the literature on strategies to improve clinical compliance and enhance knowledge translation.

OXYGEN SATURATION MEASUREMENTS OF BLOOD IN RETINAL VESSELS DURING BLOOD LOSS

We describe a noninvasive technique and instrumentation for measuring the oxygen saturation of blood in retinal arteries and veins. The measurements are made by shining low-power lasers into the eye, and scanning the beams across a retinal blood vessel. The light reflected and scattered back out of the eye is collected and measured. The oxygen saturation of blood within the vessel is determined by analyzing the vessel absorption profiles at two wavelengths. A complete saturation measurement can be made in less than 1 s, allowing real-time measurement during physiologic changes. The sensitivity of this measurement technique to changes in retinal saturation has been demonstrated through a series of pilot studies in anesthetized swine. We present data indicating that retinal venous oxygen saturation decreases during ongoing blood loss, demonstrating a potential application of an eye oximeter to noninvasively monitor blood loss.

Retinal large vessel oxygen saturations correlate with early blood loss and hypoxia in anesthetized swine

BACKGROUND Noninvasive monitoring would likely improve trauma care. Using laser technology, we monitored the oxygen saturation in retinal vessels during exsanguination and hypoxia. METHODS Seven anesthetized swine were bled at 0.4 mL/kg/min for 40 minutes. During exsanguination, retinal venous saturation (SrvO2) was measured using an eye oximeter, and central venous saturation (SvO2) was measured using a fiber-optic catheter. After the shed blood was reinfused, the FiO2 was progressively decreased from 0.97 to 0.07. Femoral artery oxygen saturation (SaO2) and retinal artery oxygen saturation (SraO2) were measured at each increment. RESULTS During exsanguination, SrvO2 correlated with blood loss (r = -0.93) and SvO2 (r = 0.94). SraO2 correlated with SaO2 during incremental hypoxia (R2 = 0.93 +/- 0.15). CONCLUSIONS In this model of exsanguination, retinal venous oxygen saturation correlates with blood volume and with central venous oxygen saturation. The SraO2 correlates with SaO2 during graded hypoxia. Use of an eye oximeter to noninvasively monitor trauma patients appears promising and warrants further study.

Retinal Imaging Techniques in Diabetes

Diabetic retinopathy is progressive, and detection early is essential for the prevention of blindness. Doppler flowmetry, retinal photography, scanning laser ophthalmoscopy, and retinal oximetry measurements may identify proliferative disease early. Drawbacks of these methods include lack of compliance, failure to refer, and failure to identify disease early. As a result, diabetic retinopathy is a leading cause of blindness. Our retinal oximeter measures the blood oxygen saturation in the large vessels of the retina near the optic disc. Retinal vessel oxygen saturations measured with our instrument are sensitive indicators of blood loss and hypoxia in swine. We are generating scientific data that suggests that retinal vessel oxygen saturations may be used to identify retinal hypoxia prior to changes in retinal vessel architecture. We expect to study humans within the next two years, and a clinically useful eye oximeter should be available in the near future.

The Effect of Combined Out-of-Hospital Hypotension and Hypoxia on Mortality in Major Traumatic Brain Injury

Study objective: Survival is significantly reduced by either hypotension or hypoxia during the out‐of‐hospital management of major traumatic brain injury. However, only a handful of small studies have investigated the influence of the combination of both hypotension and hypoxia occurring together. In patients with major traumatic brain injury, we evaluate the associations between mortality and out‐of‐hospital hypotension and hypoxia separately and in combination. Methods: All moderate or severe traumatic brain injury cases in the preimplementation cohort of the Excellence in Prehospital Injury Care study (a statewide, before/after, controlled study of the effect of implementing the out‐of‐hospital traumatic brain injury treatment guidelines) from January 1, 2007, to March 31, 2014, were evaluated (exclusions: <10 years, out‐of‐hospital oxygen saturation ≤10%, and out‐of‐hospital systolic blood pressure <40 or >200 mm Hg). The relationship between mortality and hypotension (systolic blood pressure <90 mm Hg) or hypoxia (saturation <90%) was assessed with multivariable logistic regression, controlling for Injury Severity Score, head region severity, injury type (blunt versus penetrating), age, sex, race, ethnicity, payer, interhospital transfer, and trauma center. Results: Among the 13,151 patients who met inclusion criteria (median age 45 years; 68.6% men), 11,545 (87.8%) had neither hypotension nor hypoxia, 604 (4.6%) had hypotension only, 790 (6.0%) had hypoxia only, and 212 (1.6%) had both hypotension and hypoxia. Mortality for the 4 study cohorts was 5.6%, 20.7%, 28.1%, and 43.9%, respectively. The crude and adjusted odds ratios for death within the cohorts, using the patients with neither hypotension nor hypoxia as the reference, were 4.4 and 2.5, 6.6 and 3.0, and 13.2 and 6.1, respectively. Evaluation for an interaction between hypotension and hypoxia revealed that the effects were additive on the log odds of death. Conclusion: In this statewide analysis of major traumatic brain injury, combined out‐of‐hospital hypotension and hypoxia were associated with significantly increased mortality. This effect on survival persisted even after controlling for multiple potential confounders. In fact, the adjusted odds of death for patients with both hypotension and hypoxia were more than 2 times greater than for those with either hypotension or hypoxia alone. These findings seem supportive of the emphasis on aggressive prevention and treatment of hypotension and hypoxia reflected in the current emergency medical services traumatic brain injury treatment guidelines but clearly reveal the need for further study to determine their influence on outcome.