Airway & Respiratory, Cardiac & Resuscitation, Columns, Patient Care, Trauma

Studies Show EMS Needs to Better Identify & Treat Pulmonary Edema

Issue 7 and Volume 38.

Underuse of CPAP
Spijker EE, de Bont M, Bax M, et al. Practical use, effects and complications of prehospital treatment of acute cardiogenic pulmonary edema using the Boussignac CPAP system. Int J Emerg Med. 2013;6(1):8.

This study comes to us from The Hague, Netherlands where ALS ambulances are staffed by a registered nurse and a driver. In 2008, the national EMS system implemented the use of prehospital continuous positive airway pressure (CPAP).

In a retrospective study, patients who were admitted to the hospital anytime from June 2009 to April 2010 with a diagnosis of acute pulmonary edema were tracked via medical records and prehospital care reports. Of all the patients presented to the emergency department with clinical signs of pulmonary edema, there were 76 who the authors felt would benefit from use of prehospital CPAP. Seventeen cases were excluded due to lack of data.

Of 59 patients, 16 (27%) received CPAP via Boussignac device. Furthermore, only seven of the 43 (16%) patients in the non-CPAP group had documented reason for not having CPAP placed, with the most common reason being agitation (two of seven patients, or 29%). Patients who were placed on CPAP had generally shorter hospital stays with a median stay of 4.6 days vs. a median stay of 5.1 days in the non-CPAP group. Although, given the size of the study, it is difficult to say if that can be attributed to the CPAP (although previous studies can attest to the merit of CPAP in that respect).

Discussion: CPAP is undoubtedly a phenomenal tool for the EMS setting. Although a very small clinical trial, this study teaches us two things. Firstly, it seems acute pulmonary edema is under-recognized in the prehospital setting and this therefore leads to an underuse of CPAP. As EMS providers, we need to work hard to differentiate our dyspnea patients and treat them aggressively; it’s time to be clinicians rather than technicians. This article also hammers home the need for thorough documentation.

We need to keep in mind that, although we document why we do something, we need to also document why we don’t do something. For patients who seem to have needed a treatment that was missed, a simple line stating why you were unable to provide that care should be routine.

A Challenge to Grow
Williams TA, Finn J, Celenza A, et al. Paramedic identification of acute pulmonary edema in a metropolitan ambulance service. Prehosp Emerg Care. 2013 March 13. [Epub ahead of print.]

Let’s take a shift from treatment to detection. Coming to us from Perth, Western Australia, this article is a multicenter study (retrospective review) of paramedic diagnosis vs. emergency department diagnosis of acute pulmonary edema. The authors’ goal was to assess the accuracy of diagnosis of APE by paramedics. It should be mentioned that paramedics at this particular ambulance service do not use CPAP but do give nitrates and inhaled beta-agonists.

In the results, 495 patients had acute pulmonary edema documented as their primary problem by paramedics. Of that number, 92% (455) of patients presented with shortness of breath, while 26% (131) presented with chest pain and 59% (292) had crackles or otherwise “wet” breath sounds. Only 3% (16) of patients presented with “frothy sputum.”

Overall, 38% (186) of patients identified as pulmonary edema patients by EMS were discharged from the emergency department with the same diagnosis, which yields a positive predictor (same as sensitivity) of 41%. A total of 631 patients were diagnosed by a physician with pulmonary edema, a sensitivity of 29%. The authors attribute such a low sensitivity and specificity to the lack of advanced diagnostic tools in the prehospital field; however, we should view this as a challenge to grow in our physical exam skills. Medicine existed for a very long time without X-rays or lab work, and providers were able to care for their patients nonetheless.
Bottom Line:
What we know: Acute pulmonary edema is a life-threatening condition that benefits from early, aggressive treatment.
What this study adds: As a profession, there is room for improvement in diagnosis.

Protecting Skills
Hasegawa K, Hiraide A, Chang Y, et al. Association of prehospital advanced airway management with neurologic outcome and survival in patients with out-of-hospital cardiac arrest. JAMA. 2013;309(3):257–266.

Great, you’re thinking to yourself, another article trying to take endotracheal (ET) tubes away from paramedics. Published in JAMA earlier this year, cardiac arrest data from the Japanese Utstein Registry was reviewed by the authors.

In all, 649,359 patients were entered into the Utstein database for out-of-hospital cardiac arrest from January 2005 to December 2010. Of those, 57% (370,135) received bag valve mask (BVM) ventilation, while 43% (279,224) had advanced airway management, with 6% (38,962) receiving ET intubation and the remainder receiving supraglottic airways. (The type of airway wasn’t listed.)

Reviewing the data shows that 92.2–92.8% of patients in cardiac arrest on EMS arrival were in a non-shockable rhythm. Unadjusted data shows the overall return of spontaneous circulation (ROSC) rate in patients who received ET intubation at 8.4%, compared to 7.0% of patients who received only BVM ventilation. Patients with a supraglottic airway placed had an overall ROSC rate at 5.3%. Unadjusted rates of favorable neurologic outcome were fairly similar across the board, with 2.9% of patients receiving BVM ventilations having a favorable neurological outcome vs. 1% of patients who had an airway placed.

The authors then performed stratified analysis of multivariable associations, which is essentially a fancy way of putting data into favorable groups such as witnessed arrest vs. unwitnessed arrest. With adjustments, the overall return of spontaneous circulation rate for BVM patients was 2.9% vs. 1.1% for advanced airway management. Further stratified analysis shows that patients who presented in a shockable rhythm were more than twice as likely to achieve ROSC with just BVM ventilations.

This JAMA article is receiving a lot of attention in the medical community, specifically the prehospital care community. What we need to keep in mind as readers is that stratified analysis is a way to make data fit into neat little groups. By manipulating these neat little groups, statisticians can make data fit a hypothesis.

This is well-done research. It contains a large sample size, complete and thorough data and was published in a peer-reviewed journal. As prehospital care providers, we need to work hard to protect the skills we’re trained to perform. The bigger picture to see in upcoming research is the push for minimizing stoppage in compressions, continuing CPR through intubation attempts and using end-tidal CO2 monitoring rather than just breath sounds to verify tubes. By using end-tidal CO2 monitoring, we can decrease the amount of “hands-off time” which is what’s really been proven to be detrimental to cardiac arrest patients.

Watch Box – Sleep Disruption
Kruse M, Cabanas J, Gardner T, et al. Off-duty sleep disruption negatively impacts behavioral health in paramedics. Prehosp Emerg Care. 2013;17(1):120.
Note: This is currently only available as an abstract, look for upcoming review of the full paper soon.

Presented at the National Association of EMS Physicians conference earlier this year, paramedics from Austin Fire Department and Austin-Travis County EMS in Texas were asked to anonymously fill out data regarding demographic and sleep-related information as well as questions meant for screening of depression, post-traumatic stress disorder (PTSD), occupational stress and others. Unsurprisingly, on-duty sleep disruption was identified as the No. 1 cause of occupational stress, and respondents who reported reduced off-duty stress had higher rates of PTSD, lower psychological resilience and poorer coping strategies.

Watch Box – Response Time
Weiss S, Fullerton L, Oglesbee S, et al. Does ambulance response time influence patient condition among patients with specific medical and trauma emergencies? South Med J. 2013;106(3):230–235.

Sent to us by a reader, these researchers from the University of Albuquerque and the Albuquerque Ambulance Service set out to correlate morbidity and mortality associated with response time, which is something we haven’t seen a lot of since we usually look at transport time.

The authors looked at 2,164 cases of motor vehicle crashes, penetrating trauma, difficulty breathing and chest pain. They found a response time of less than eight minutes vs. greater than eight minutes wasn’t associated with any change in morbidity, mortality or hospital admission days that was statistically significant.

This presents an interesting point for services that respond emergent to all calls regardless of problem type; however, this is probably not going to change response times overnight. Much praise to the authors in New Mexico for publishing research with medic safety in mind.