STEMI identification algorithm

An algorithm for identification of ST-elevation myocardial infarction patients by emergency medicine services

© Gary Wilson/ Pre-hospital Research Forum

© Gary Wilson/ Pre-hospital Research Forum

American Journal of Emergency Medicine. Volume 31, Issue 7 , Pages 1098-1102, July 2013

ST-elevation myocardial infarction (STEMI) identification by emergency medicine services (EMS) leading to pre-hospital catheterization laboratory (CL) activation shortens ischemic time and improves outcomes. The authors examined the incremental value of addition of a screening clinical tool (CT), containing clinical information and a Zoll electrocardiogram (ECG)-resident STEMI identification program (ZI) to ZI alone.

All EMS-performed and ZI-analyzed ECGs transmitted to a percutaneous coronary intervention hospital from October 2009 to January 2011 were reviewed for diagnostic accuracy. ZI performance was also compared to ECG interpretations by 2 experienced readers The CT was then retrospectively applied to determine the incremental benefit above the ZI alone. The CT required  the answer to be yes to all to the following questions for CL activation:

  • Computer interprets ECG as ***ACUTE MI***?
  • Ongoing chest pain or other symptoms suggestive of cardiac ischemia for > 15 min & < 12 h?
  • Paramedic confirmation of quality of ECG tracing and presence of ST-elevation ≥ 1 mm in at least 2 anatomically contiguous leads?
  • Patient alert and able to give a history?
  • Absence of active bleeding?
  • Absence of acute trauma?
  • Absence of signs of acute stroke?
  • Absence of treatment limiting comorbidity?

ST-elevation myocardial infarction was confirmed in 23 (7.5%) of 305 patients. ZI was positive in 37 (12.1%): sensitivity: 95.6% and specificity: 94.6%, positive predictive value (PPV), 59.5%, negative predictive value (NPV), 99.6%, and accuracy of 93.8%. Moderate agreement was observed among the readers and ZI. CT criteria for CL activation were met in 24 (7.8%): 20 (83.3%) were confirmed STEMIs: sensitivity: 86.9%, specificity: 98.5%, a PPV: 83.3%, and NPV: 98.6%, accuracy of 97.7%. CT + ZI increased PPV and specificity (P<0.003) by reducing false positive STEMI identifications from 15 (4.9%) to 4 (1.3%).

In an urban cohort of all EMS transmitted ECGs, ZI has high sensitivity and specificity for STEMI identification. Whereas the PPV was low, reflecting both low STEMI prevalence and presence of STEMI-mimics, the NPV was very high. These findings suggest that a simplified CT combined with computer STEMI interpretation can identify patients for pre-hospital CL activation.  These findings suggest that the addition of the CT to the ZI results in a modest increase in STEMI diagnostic accuracy and a significant reduction in the number of potential false CL activations. Confirmation of these results could improve the design of STEMI care systems.

London’s increases in cardiac arrest survival

Increases in survival from out-of-hospital cardiac arrest: A five year study

Resuscitation. Volume 84, Issue 8, August 2013, Pages 1089–1092

© Gary Wilson/ Pre-hospital Research Forum

© Gary Wilson/ Pre-hospital Research Forum

This study reports improvements in survival from out-of-hospital cardiac arrest in London over a five year period from 2007 to 2012 and explores the potential reasons for the very striking increases observed. The authors believe that it is evident that public education, an awareness of cardiac arrest, a co-ordinated fast EMS response along with robust guidelines and programme of EMS training are fundamental and may have contributed to the increases in Utstein comparator survival rates.

Data from the London Ambulance Service’s cardiac arrest registry from 2007 to 2012 were analysed retrospectively for all patients who met the Utstein comparator group criteria (an arrest of a presumed cardiac cause that was bystander witnessed with an initial rhythm of VF/VT).

It was observed an increase in survival from out-of-hospital cardiac arrest during the five year period, with incremental improvements each year from 12% to 32% for the Utstein comparator group of patients.

The authors’ suggest that a range of important changes made to pre-hospital cardiac care in London over the last five years have contributed to the observed increase in survival over the study period. In addition they advocate a range of further initiatives to continue improving survival from out-of-hospital cardiac arrest.

Drowning relating cardiac arrests

Drowning related out-of-hospital cardiac arrests: Characteristics and outcomes

Resuscitation. Volume 84, Issue 8, August 2013, Pages 1114–1118

© Gary Wilson/ Pre-hospital Research Forum

© Gary Wilson/ Pre-hospital Research Forum

There are few studies on drowning-related out-of-hospital cardiac arrest (OHCA) in which patients are followed from the scene through to hospital discharge. This study aims to describe this population and their outcomes in the state of Victoria (Australia).

The Victorian Ambulance Cardiac Arrest Registry was searched for all cases of OHCA with a precipitating event of drowning attended by emergency medical services (EMS) between October 1999 and December 2011.

EMS attended 336 drowning-related OHCA during the study period. Cases frequently occurred in summer (45%) and the majority of patients were male (70%) and adult (77%). EMS resuscitation was attempted on 154 (46%) patients. Of these patients, 41 (27%) survived to hospital arrival and 12 (8%) survived to hospital discharge (5 adults [6%] and 7 [12%] children). Few patients were found in a shockable rhythm (6%), with the majority presenting in asystole (79%) or pulse-less electrical activity (13%). An initial shockable rhythm was found to positively predict survival (AOR 48.70, 95% CI: 3.80–624.86) while increased EMS response time (AOR 0.73, 95% CI: 0.54–0.98) and salt water drowning (AOR 0.69, 95% CI: 0.01–0.84) were found to negatively predict survival.

Rates of survival in OHCA caused by drowning are comparable to other OHCA causes. Patients were more likely to survive if they did not drown in salt water, had a quick EMS response and they were found in a shockable rhythm. Prevention efforts and reducing EMS response time are likely to improve survival of drowning patients.

Improving cardiac resuscitation

AHA Consensus Statement: Cardiopulmonary Resuscitation Quality: Improving Cardiac Resuscitation Outcomes Both Inside and Outside the Hospital

Circulation. 2013; 128: 417-435

© Gary Wilson/ Pre-hospital Research Forum

© Gary Wilson/ Pre-hospital Research Forum

The “2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care” increased the focus on methods to ensure that high-quality cardiopulmonary resuscitation (CPR) is performed in all resuscitation attempts.

There are 5 critical components of high-quality CPR: minimize interruptions in chest compressions, provide compressions of adequate rate and depth, avoid leaning between compressions, and avoid excessive ventilation. Although it is clear that high-quality CPR is the primary component in influencing survival from cardiac arrest, there is considerable variation in monitoring, implementation, and quality improvement. As such, CPR quality varies widely between systems and locations. Victims often do not receive high-quality CPR because of provider ambiguity in prioritization of resuscitative efforts during an arrest. This ambiguity also impedes the development of optimal systems of care to increase survival from cardiac arrest.

This consensus statement addresses the following key areas of CPR quality for the trained rescuer: metrics of CPR performance; monitoring, feedback, and integration of the patient’s response to CPR; team-level logistics to ensure performance of high-quality CPR; and continuous quality improvement on provider, team, and systems levels. Clear definitions of metrics and methods to consistently deliver and improve the quality of CPR will narrow the gap between resuscitation science and the victims, both in and out of the hospital, and lay the foundation for further improvements in the future. (Full text link)

Association between quality of care and pain management

The Association between Patients’ Perception of Their Overall Quality of Care and Their Perception of Pain Management in the Prehospital Setting

Prehospital Emergency Care. July-September 2013, Vol. 17, No. 3 , Pages 386-391

© Gary Wilson/ Pre-hospital Research Forum

© Gary Wilson/ Pre-hospital Research Forum

The authors’ objective was to determine whether there is an association between a patient’s impression of his or her overall quality of care and his or her satisfaction with the pain management provided. It was hypothesised that satisfaction with pain management would show a significant positive association with a patient’s impression of overall quality of care.

Methods. This was a retrospective review of patient satisfaction data initially collected by a third-party company from January 1, 2007, to September 1, 2010. Participants were randomly selected from all transported patients, proportional to their paramedic-defined acuity level, with a goal of 100 interviews per month. The proportions of patients sampled from each acuity level were 25% priority 1 (high), 50% priority 2 (medium), and 25% priority 3 (low). Patients were excluded if there was no telephone number recorded in the prehospital patient record, no transportation was recorded, or the call was labelled as a psychiatric complaint. All satisfaction questions used a five-point Likert scale with ratings from excellent to poor, which were dichotomized for analysis. The outcome variable was the patient’s perception of his or her overall quality of care. The main independent variable was the patient’s rating of his or her pain management by emergency medical services (EMS) staff at the scene. Demographic variables were assessed for potential confounding.

Results. There were 2,741 patients with complete data for the outcome and main independent variables; 41.7% of the respondents were male and the average age was 54.1 years (standard deviation = 22.6). The overall quality of care was rated as excellent by 65.9% of the patients, whereas 59.2% rated their pain management as excellent. Of the patients who rated their pain management as excellent, 79.0% rated the overall quality of care as excellent, whereas only 21.0% of the patients rated the overall quality of care as excellent if pain management was not excellent. When the patients rated EMS staff as excellent for both helping to control or reduce pain and explaining the medications given, they were 2.7 (95% confidence interval 1.4–5.4) times more likely to rate their overall quality of care as excellent.

Conclusion. The model indicated that pain management was associated with increased perception of overall quality of care only when EMS providers explained the medications provided and their potential side effects.

Paramedic identification of APO

Paramedic Identification of Acute Pulmonary Oedema in a Metropolitan Ambulance Service

Prehospital Emergency Care. July-September 2013, Vol. 17, No. 3 , Pages 339-347

© Gary Wilson/ Pre-hospital Research Forum

© Gary Wilson/ Pre-hospital Research Forum

Acute pulmonary oedema (APO) is a common cause of acute dyspnea. In the prehospital setting, it is often difficult to differentiate APE from other causes of shortness of breath (SOB). Radiography and echocardiography aid in the identification of APO but are often not available. There is little information on how accurately ambulance paramedics identify patients with APO.

Objectives. This study aimed to 1) describe the prehospital clinical presentation and management of patients with a clinical diagnosis of APO and 2) compare the accuracy of coding of APO by paramedics against the emergency department (ED) medical discharge diagnosis.

Methods. This study included a retrospective cohort of all patients who had episodes identified as APO by ambulance paramedics and were transported to a metropolitan hospital ED in 2011. Two databases were used: an ambulance database and the Emergency Department Information System. The ED medical discharge diagnosis (using International Statistical Classification of Diseases and Related Problems, 10th Revision, Australian Modification [ICD-10-AM] codes) was used as the comparator with paramedic-assigned problem codes for APE. The outcomes for the study were the positive predictive value, i.e., the proportion of patients identified as having APE in the ambulance database who also had an ED discharge diagnosis of APO, and the sensitivity of paramedic identification of APO, i.e., the proportion of patients with an ED discharge diagnosis of APO that were correctly identified as APO by the ambulance paramedics.

Results. Four hundred ninety-five patients were transported to an ED with APO identified by the paramedics as the primary problem code. Shortness of breath, crepitations, high systolic blood pressure, and chest pain were the most common presenting signs and symptoms. Pink frothy sputum was rare (3% of patient episodes of APO). One hundred eighty-six patients received an ED discharge diagnosis of APO, i.e., a positive predictive value of 41%. Of 631 ED presentations with APO, paramedics identified 186, i.e., a sensitivity of 29%.

Conclusion. Acute pulmonary oedema is difficult to identify in the prehospital setting because of the variability in the signs and symptoms associated with this condition. Improved identification of OPE is essential in the initiation of appropriate and timely care. Ambulance paramedics need to be aware of such variability when considering patients who may be suffering from OPE.

Dispatch triage of low acuity calls

Implementation of Prehospital Dispatch Protocols That Triage Low-acuity Patients to Advice-line Nurses

Prehospital Emergency Care Posted online on July 18, 2013. 

Although EMS agencies have been designed to efficiently provide medical assistance to individuals, the overuse of 9-1-1 as an alternative to primary medical care has resulted in the need for new methods to respond to this increasing demand. The study analyses the efficacy of classifying specific low-acuity calls that can be transferred to an advice-line nurse for further medical instruction. The objectives of the study were to analyse the impact of implementing this protocol and resultant patient feedback regarding the transfer to an advice-line nurse.

Methods. The authors collected data for retrospective review from April 2011 to April 2012 from a single municipal EMS agency with an average annual call volume of approximately 90,000. Medical Priority Dispatch System response codes were assigned to calls based on patient acuity. Patients classified under Omega response codes were assessed for eligibility of transfer to nurse advice lines. Exclusion criteria included the following: if the call was placed by a third-party caller; if the patient refused to be transferred to the advice-line nurse; anytime the MPDS system was not used; if the patient was referred from a skilled nursing facility, school, or university nursing office, or physician’s office. Telephone surveys were conducted for those patients who spoke to an advice-line nurse and did not receive an ambulance response 24 hours after calling 9-1-1 to obtain patient feedback.

Results. The database included 1660 patients initially classified as Omega and eligible for transfer to an advice-line nurse. After applying the exclusion criteria, 329 (19.8%) patients were ultimately transferred to an advice-line nurse and 204 (12.3%) received no ambulance response. Of those patients who were not transported by ambulance 118 (57.8%), patients completed telephone follow-up, with 104 (88.1%) reporting the nontransport option met their health-care needs and 108 (91.5%) responding they would accept the transfer again for a similar complaint.

Conclusion. We identified an average of two patients per day as eligible for transfer to the nurse advice line, with less than one patient successfully completing the Omega protocol per day. While impact was limited, there was a decrease in ambulance response.

Newborn airway mangement

Oronasopharyngeal suction versus wiping of the mouth and nose at birth: a randomised equivalency trial

© Gary Wilson/ Pre-hospital Research Forum

© Gary Wilson/ Pre-hospital Research Forum

The Lancet, Volume 382, Issue 9889, Pages 326 – 330, 27 July 2013

Wiping of the mouth and nose at birth is an alternative method to oronasopharyngeal suction in delivery-room management of neonates, but whether these methods have equivalent effectiveness is unclear.

Methods For this randomised equivalency trial, neonates delivered at 35 weeks’ gestation or later at the University of Alabama at Birmingham Hospital, Birmingham, AL, USA, between October, 2010, and November, 2011, were eligible. Before birth, neonates were randomly assigned gentle wiping of the face, mouth (implemented by the paediatric or obstetric resident), and nose with a towel (wipe group) or suction with a bulb syringe of the mouth and nostrils (suction group). The primary outcome was the respiratory rate in the first 24 h after birth. We hypothesised that respiratory rates would differ by fewer than 4 breaths per min between groups. Analysis was by intention to treat.

Findings 506 neonates born at a median of 39 weeks’ gestation (IQR 38—40) were randomised. Three parents withdrew consent and 15 non-vigorous neonates with meconium-stained amniotic fluid were excluded. Among the 488 treated neonates, the mean respiratory rates in the first 24 h were 51 (SD 8) breaths per min in the wipe group and 50 (6) breaths per min in the suction group (difference of means 1 breath per min, 95%.

Interpretation Wiping the nose and mouth has equivalent efficacy to routine use of oronasopharyngeal suction in neonates born at or beyond 35 weeks’ gestation.

Mechanical CPR in EMS

Implementation of mechanical chest compression in out-of-hospital cardiac arrest in an emergency medical service system.

American Journal of Emergency Medicine. Volume 31, Issue 8 , Pages 1196-1200, August 2013

© Gary Wilson/ Pre-hospital Research Forum

© Gary Wilson/ Pre-hospital Research Forum

The aim of this study was to describe the outcome changes after out-of-hospital cardiac arrest (OHCA) in Gothenburg, Sweden, after introduction of mechanical chest compression (MCC).

Methods Following introduction of MCC, 1183 OHCA patients were treated from November 1, 2007, to December 31, 2011 (period 2). They were compared with 1218 OHCA patients before MCC was introduced from January 1, 1998, to May 30, 2003 (period 1). Patients in period 2 were evaluated for survival in relation to MCC use.

Results The percentage of patients admitted to hospital alive increased from 25.4% to 31.9% (P < .0001). Survival to 1 month increased from 7.1% to 10.7% from period 1 to period 2. The proportion of ventricular fibrillation/ventricular tachycardia decreased in period 2. However, bystander cardiopulmonary resuscitation, crew-witnessed cases, percutaneous coronary intervention, therapeutic hypothermia, and implantable cardioverter-defibrillator use increased, as did time from call to emergency medicine service arrival and to defibrillation.

In period 2, 60% of OHCA patients were treated with MCC. The percentages admitted alive to hospital (MCC vs no MCC) were 28.6% and 36.1%. Corresponding figures for survival to 1 month were 5.6% and 17.6%. In the MCC group, we found increase in the delay from collapse to defibrillation, greater use of adrenaline, and fewer crew-witnessed cases.

Conclusion Survival to 1 month after implementation of MCC was higher than before introduction. However, patients receiving MCC had low survival. Although case selection might play a role, results do not support a widespread use of MCC after OHCA.

Paediatric supra-glottic airways

A comparison of three supraglottic airway devices used by healthcare professionals during paediatric resuscitation simulation

Emerg Med J 2013;30:754-757

© Gary Wilson/ Pre-hospital Research Forum

© Gary Wilson/ Pre-hospital Research Forum

Objective The aim of this study was to determine the best airway device among the laryngeal mask, I-gel and the laryngeal tube used by healthcare professional groups with different levels of experience with paediatric airway management.

Method Three groups of healthcare professionals were separately provided with brief supervised training in using the three devices. Afterwards the participants were asked to place the airway device. For every participant, the positioning of each device was recorded. The success rate and timing of insertion were measured. Furthermore, each insertion was scored for the ease of insertion, clinical and fibreoptic verification of the position and successful ventilation.

Results A total of 66 healthcare providers (22 paramedics, 22 nurse anaesthetists and 22 anaesthesia residents) participated in the study. The median time of insertion of both the laryngeal mask and the tube was significantly longer than for the I-gel for all professional groups. The success rate with the I-gel was higher than that with the laryngeal mask or tube. Except for the laryngeal mask, there were no differences among the professional groups regarding the fibreoptic evaluation.

Conclusions In terms of both the time required for successful placement and the rate of successful placement, the I-gel is superior to the laryngeal mask and tube in paediatric resuscitation simulations by healthcare professional groups with different levels of experience with paediatric airway management.