The impact of peri-shock pause on survival from out-of-hospital shockable cardiac arrest during the Resuscitation Outcomes Consortium PRIMED trial

© Gary Wilson/ Pre-hospital Research Forum

Resuscitation. Available online 25 October 2013

Previous research has demonstrated significant relationships between peri-shock pause and survival to discharge from out-of-hospital shockable cardiac arrest (OHCA).

Objective
To determine the impact of peri-shock pause on survival from OHCA during the ROC PRIMED randomized controlled trial.

Methods
The authors included patients in the ROC PRIMED trial who suffered OHCA between June 2007 and November 2009, presented with a shockable rhythm and had CPR process data for at least one shock. We used multivariable logistic regression to determine the association between peri-shock pause duration and survival to hospital discharge.

Results
Among 2006 patients studied, the median (IQR) shock pause duration was: pre-shock pause 15 s (8, 22); post-shock pause 6 s (4, 9); and peri-shock pause 22.0 s (14, 31). After adjusting for Utstein predictors of survival as well as CPR quality measures, the odds of survival to hospital discharge were significantly higher for patients with pre-shock pause <10 s (OR: 1.52, 95% CI: 1.09, 2.11) and peri-shock pause <20 s when compared to patients with pre-shock pause ≥20 s and peri-shock pause ≥40 s. Post-shock pause was not significantly associated with survival to hospital discharge. Results for neurologically intact survival (Modified Rankin Score ≤ 3) were similar to our primary outcome.

Conclusions
In patients with cardiac arrest presenting in a shockable rhythm during the ROC PRIMED trial, shorter pre- and peri-shock pauses were significantly associated with higher odds of survival. Future cardiopulmonary education and technology should focus on minimizing all peri-shock pauses.

http://www.sciencedirect.com/science/article/pii/S0300957213008149

Vented Chest Seals for Prevention of Tension Pneumothorax in a Communicating Pneumothorax

The Journal of Emergency Medicine. Volume 45, Issue 5, Pages 686-694, November 2013

Tension pneumothorax accounts for 3%–4% of combat casualties and 10% of civilian chest trauma. Air entering a wound via a communicating pneumothorax rather than by the trachea can result in respiratory arrest and death. In such cases, the Committee on Tactical Combat Casualty Care advocates the use of unvented chest seals to prevent respiratory compromise.

Objective
A comparison of three commercially available vented chest seals was undertaken to evaluate the efficacy of tension pneumothorax prevention after seal application.

Methods
A surgical thoracostomy was created and sealed by placing a shortened 10-mL syringe barrel (with plunger in place) into the wound. Tension pneumothorax was achieved via air introduction through a Cordis to a maximum volume of 50 mL/kg. A 20% drop in mean arterial pressure or a 20% increase in heart rate confirmed hemodynamic compromise. After evacuation, one of three vented chest seals (HyFin®, n = 8; Sentinel®, n = 8, SAM®, n = 8) was applied. Air was injected to a maximum of 50 mL/kg twice, followed by a 10% autologous blood infusion, and finally, a third 50 mL/kg air bolus. Survivors completed all three interventions, and a 15-min recovery period.

Results
The introduction of 29.0 (±11.5) mL/kg of air resulted in tension physiology. All three seals effectively evacuated air and blood. Hemodynamic compromise failed to develop with a chest seal in place.

Conclusions
HyFin®, SAM®, and Sentinel® vented chest seals are equally effective in evacuating blood and air in a communicating pneumothorax model. All three prevented tension pneumothorax formation after penetrating thoracic trauma.

http://www.jem-journal.com/article/S0736-4679(13)00507-6/abstract?elsca1=etoc&elsca2=email&elsca3=0736-4679_201311_45_5&elsca4=emergency_medicine

Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes

© Gary Wilson/ Pre-hospital Research Forum

This Cochrane Review examines the effects of different policies for clamping the umbilical cord after birth for babies born at term. It compares early cord clamping, which usually takes place within 60 seconds of birth, versus later clamping that usually involves clamping the cord more than one minute after birth or when cord pulsation has ceased.

In the past, the umbilical cord has usually been clamped shortly following the birth of the baby, as part of the active management of the third stage of labour. This strategy might also involve the infant being placed on the mother’s abdomen, put to the breast or more closely examined on a warmed cot if resuscitation was required. However, more recent guidelines for management of the third stage of labour no longer recommend immediate cord clamping, and later clamping of the umbilical cord might take place when cord pulsation has ceased or beyond the first minute following the birth of the baby. However, there is ongoing uncertainty about the relative benefits, or harms, of the two approaches. There have been concerns that late cord clamping might increase the mother’s risk of a postpartum haemorrhage, that could outweigh potential benefits to the baby of delaying clamping which might arise from the extra time for a transfer of the fetal blood in the placenta to the infant at the time of birth. This placental transfusion can provide the infant with an additional 30% more blood volume and up to 60% more red blood cells.

Policies for timing of cord clamping vary, with early cord clamping generally carried out in the first 60 seconds after birth, whereas later cord clamping usually involves clamping the umbilical cord more than one minute after the birth or when cord pulsation has ceased. The benefits and potential harms of each policy are debated.

No studies in this review reported on maternal death or on severe maternal morbidity. There were no significant differences between early versus late cord clamping groups for the primary outcome of severe postpartum haemorrhage or for postpartum haemorrhage of 500 mL or more. There were no significant differences between subgroups depending on the use of uterotonic drugs. Mean blood loss was reported in only two trials with data for 1345 women, with no significant differences seen between groups; or for maternal haemoglobin values at 24 to 72 hours after the birth in three trials.

Neonatal outcomes: There were no significant differences between early and late clamping for the primary outcome of neonatal mortality, or for most other neonatal morbidity outcomes, such as Apgar score less than seven at five minutes or admission to the special care nursery or neonatal intensive care unit. Mean birthweight was significantly higher in the late, compared with early, cord clamping. Fewer infants in the early cord clamping group required phototherapy for jaundice than in the late cord clamping group.

Haemoglobin concentration in infants at 24 to 48 hours was significantly lower in the early cord clamping group. This difference in haemoglobin concentration was not seen at subsequent assessments. However, improvement in iron stores appeared to persist, with infants in the early cord clamping over twice as likely to be iron deficient at three to six months compared with infants whose cord clamping was delayed . In the only trial to report longer-term neurodevelopmental outcomes so far, no overall differences between early and late clamping were seen for Ages and Stages Questionnaire scores.

Authors’ conclusions
A more liberal approach to delaying clamping of the umbilical cord in healthy term infants appears to be warranted, particularly in light of growing evidence that delayed cord clamping increases early haemoglobin concentrations and iron stores in infants. Delayed cord clamping is likely to be beneficial as long as access to treatment for jaundice requiring phototherapy is available.

http://www.cochranejournalclub.com/umbilical-cord-clamping-timing-clinical/pdf/CD004074.pdf (full text)

Waveform Analysis–Guided Treatment Versus a Standard Shock-First Protocol for the Treatment of Out-of-Hospital Cardiac Arrest Presenting in Ventricular Fibrillation

© Gary Wilson/ Pre-hospital Research Forum

Circulation. 2013; 128: 995-1002

Ventricular fibrillation (VF) waveform properties have been shown to predict defibrillation success and outcomes among patients treated with immediate defibrillation. We postulated that a waveform analysis algorithm could be used to identify VF unlikely to respond to immediate defibrillation, allowing selective initial treatment with cardiopulmonary resuscitation in an effort to improve overall survival.

Methods and Results In a multicenter, double-blind, randomized study, out-of-hospital cardiac arrest patients in 2 urban emergency medical services systems were treated with automated external defibrillators using either a VF waveform analysis algorithm or the standard shock-first protocol. The VF waveform analysis used a predefined threshold value below which return of spontaneous circulation (ROSC) was unlikely with immediate defibrillation, allowing selective treatment with a 2-minute interval of cardiopulmonary resuscitation before initial defibrillation. The primary end point was survival to hospital discharge. Secondary end points included ROSC, sustained ROSC, and survival to hospital admission. Of 6738 patients enrolled, 987 patients with VF of primary cardiac origin were included in the primary analysis. No immediate or long-term survival benefit was noted for either treatment algorithm (ROSC, 42.5% versus 41.2%, P=0.70; sustained ROSC, 32.4% versus 33.4%, P=0.79; survival to admission, 34.1% versus 36.4%, P=0.46; survival to hospital discharge, 15.6% versus 17.2%, P=0.55, respectively).

Conclusions Use of a waveform analysis algorithm to guide the initial treatment of out-of-hospital cardiac arrest patients presenting in VF did not improve overall survival compared with a standard shock-first protocol. Further study is recommended to examine the role of waveform analysis for the guided management of VF.

http://circ.ahajournals.org/content/128/9/995.abstract.html?etoc

Death in the Field: Teaching Paramedics to Deliver Effective Death Notifications Using the Educational Intervention “GRIEV_ING”

© Gary Wilson/ Pre-hospital Research Forum

Prehospital Emergency Care. October-December 2013, Vol. 17, No. 4 , Pages 501-510

Emergency medical services (EMS) personnel are rarely trained in death notification despite frequently terminating resuscitation in the field. As research continues to validate guidelines for the termination of resuscitation (TOR) and reputable organizations such as NAEMSP lend support to such protocols, death notification in the field will continue to increase. The authors sought to test the hypothesis that a learning module, GRIEV_ING, which teaches a structured method for death notification, will improve the confidence, competency, and communication skills of EMS personnel in death notification.

Methods. The GRIEV_ING didactic session consisted of a 90-minute education session composed of a didactic lecture, small group breakout session, and role-plays. This was both preceded and followed by a 15-minute case role-play using trained standardized survivors. To assess performance we used a pre–post design with 3 quantitative measures: confidence, competency, and, communication. Paramedics from the local EMS agency participated in the education as a part of continuing education. Pre–post differences were measured using a paired t-test and McNemar’s test.

Results. Thirty EMS personnel consented and participated. Confidence and competency demonstrated statistically significant improvements: confidence (percent change in scores = 11.4%, p < 0.0001) and competency (percent change in scores = 13.9%, p = 0.0001). Communication skill scores were relatively unchanged in pre–post test analysis (percent change in scores = 0.4, p = 0.9).

Conclusion. This study demonstrated that educating paramedics to use a structured communication model based on the GRIEV_ING mnemonic improved confidence and competence of EMS personnel delivering death notification.

http://informahealthcare.com/doi/abs/10.3109/10903127.2013.804135

Wilderness Medical Society Practice Guidelines for Treatment of Exercise-Associated Hyponatremia

© Gary Wilson/ Pre-hospital Research Forum

Wilderness & Environmental Medicine. Volume 24, Issue 3 , Pages 228-240, September 2013

Exercise-associated hyponatremia (EAH) typically occurs during or up to 24 hours after prolonged physical activity, and is defined by a serum or plasma sodium concentration below the normal reference range of 135 mEq/L. It is also reported to occur in individual physical activities or during organized endurance events conducted in austere environments in which medical care is limited or often not available, and patient evacuation to definitive care is often greatly delayed. Rapid recognition and appropriate treatment are essential in the severe form to ensure a positive outcome. Failure in this regard is a recognized cause of event-related fatality.

In an effort to produce best practice guidelines for EAH in the austere environment, the Wilderness Medical Society convened an expert panel. The panel was charged with the development of evidence-based guidelines for management of EAH. Recommendations are made regarding the situations when sodium concentration can be assessed in the field and when these values are not known. These recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks/burdens for each parameter according to the methodology stipulated by the American College of Chest Physicians.

http://www.wemjournal.org/article/S1080-6032(13)00063-X/fulltext (full text)

Wilderness Medical Society Practice Guidelines for Spine Immobilisation in the Austere Environment

© Gary Wilson/ Pre-hospital Research Forum

Wilderness & Environmental Medicine. Volume 24, Issue 3 , Pages 241-252, September 2013

In an effort to produce best-practice guidelines for spine immobilization in the austere environment, the Wilderness Medical Society convened an expert panel charged with the development of evidence-based guidelines for management of the injured or potentially injured spine in an austere (dangerous or compromised) environment. Recommendations are made regarding several factors related to spinal immobilisation. These recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks or burdens for each factor according to the methodology stipulated by the American College of Chest Physicians. A treatment algorithm based on the guidelines is presented.

http://www.wemjournal.org/article/S1080-6032(13)00071-9/fulltext (full text)

A Prospective Evaluation of the Utility of the Prehospital 12-lead Electrocardiogram to change patient management in the Emergency Department

© Gary Wilson/ Pre-hospital Research Forum

Prehospital Emergency Care. Posted online on September 12, 2013. 

Retrospective research has shown that 19% of 12-lead prehospital electrocardiograms (prehospital ECGs) had clinically significant abnormalities that were not captured on the initial emergency department (ED) ECG and had the potential to change medical management. The purpose of this study was to prospectively determine how many prehospital ECGs had clinically significant abnormalities not present on the initial ED ECG and determine how many prehospital ECGs changed physician management.

Methods. We conducted a 3-month, prospective cohort study of patients who had a 12-lead prehospital ECG completed by EMS prior to arriving at one of two tertiary care EDs. STEMI bypass patients were excluded. Physicians reviewed the prehospital ECG to determine whether there were any clinically significant abnormalities present on the prehospital ECG not captured on the initial ED ECG. Physicians recorded if and how the prehospital ECG changed their management.

Results. A total of 281 patients were enrolled. Thirty-five (12.5%; 95% CI: 9.1%, 16.8%) prehospital ECGs showed changes that were not captured on the initial ED ECG (11 ST depression, 5 T-wave inversion [TWI], 2 ST depression and TWI, 12 arrhythmia, 2 arrhythmia with ST depression, 2 ST elevation, 1 unknown). Fifty-two (18.5%; 95% CI: 14.4%, 23.5%) prehospital ECGs influenced physician management. There were 30 (10.7%) instances where physicians were willing to refer the patient to an inpatient service based on information captured on the prehospital ECG, regardless if the initial ED ECG was normal.

Conclusions. Prehospital ECGs show clinically significant abnormalities that are not always captured on the initial ED ECG. Prehospital ECGs have the potential to change the management of patients in the ED.

http://informahealthcare.com/doi/abs/10.3109/10903127.2013.825350

Beta-Adrenergic Antagonists Improve Oxygen Saturation in Acute Pulmonary Oedema: A Case Series in the Prehospital Setting

Prehospital Emergency Care. July-September 2013, Vol. 17, No. 3 , Pages 421-423 

© Gary Wilson/ Pre-hospital Research Forum

The use of beta-adrenergic antagonists in acute heart failure is controversial. In this case series, the authors report the use of intravenous atenolol, a short-acting cardioselective beta-adrenergic antagonist, to treat acute pulmonary oedema in the prehospital setting. Four patients with a documented history of cardiac disease and one patient with unknown cardiac issues experienced severe respiratory distress and presented with pulmonary oedema; the local emergency medical service was utilized.

In all of the patients, the saturation of peripheral oxygen (SpO2) was severely low, and the patients were rapidly treated with oxygen, diuretics, morphine, and nitrates. However, only a small increase in oxygen saturation was observed. Intravenous atenolol was administered and led to a dramatic increase in SpO2. In the case series, the authors observed the positive effect of early treatment with short-acting beta-adrenergic antagonists on the recovery of rapid oxygen delivery in severely hypoxemic patients.

http://informahealthcare.com/doi/abs/10.3109/10903127.2013.785621

Prehospital Use of Tranexamic Acid for Haemorrhagic Shock in Primary and Secondary Air Medical Evacuation

Air Medical Journal. Volume 32, Issue 5 , Pages 289-292, September 2013

© Gary Wilson/ Pre-hospital Research Forum

Major haemorrhage remains a leading cause of death in both military and civilian trauma. The authors report the use of tranexamic acid (TXA) as part of a trauma exanguination/massive transfusion protocol in the management of haemorrhagic shock in a civilian primary and secondary air medical evacuation (AME) helicopter EMS program.

Methods
TXA was introduced into the CCP flight paramedic program in June 2011. Indications for use include age > 16 years, major trauma (defined a priori based on mechanism of injury or findings on primary survey), and heart rate (HR) > 110 beats per minute (bpm) or systolic blood pressure (SBP) < 90 mmHg. The protocol, which includes 24-hour online medical oversight, emphasizes rapid initiation of transport, permissive hypotension in select patients, early use of blood products (secondary AME only), and infusion of TXA while en route to a major trauma centre.

Results

Over a 4-month period, the CCP flight crews used TXA a total of 13 times. Patients had an average HR of 111 bpm [95% CI 90.71–131.90], SBP of 91 mmHg [95% CI 64.48–118.60], and Glascow Coma Score of 7 [95% CI 4.65–9.96]. For primary AME, average response time was 33 minutes [95% CI 19.03–47.72], scene time 22 minutes [95% CI 20.23–24.27], and time to TXA administration 32 minutes [95% CI 25.76–38.99] from first patient contact. There were no reported complications with the administration of TXA in any patient.

Conclusion
The authors report the successful integration of TXA into a primary and secondary AME program in the setting of major trauma with confirmed or suspected hemorrhagic shock. Further studies are needed to assess the effect of such a protocol in this patient population.

http://www.airmedicaljournal.com/article/S1067-991X(13)00113-2/abstract?elsca1=etoc&elsca2=email&elsca3=1067-991X_201309_32_5&elsca4=emergency_medicine