Sonography in Hypotension and Cardiac Arrest in the Emergency Department.

STRUCTURED RESEARCH ABSTRACT

Introduction

Patients who present to the ED (emergency department) with undifferentiated, non-trauma associated hypotension are often affected by conditions with a prognosis largely dependent on the time taken from presentation to correct diagnosis and intervention. The ACES protocol (Abdominal and Cardiothoracic Evaluation with Sonography in Shock) provides a rapid focused ultrasound protocol for making or refining diagnoses in patients who present to the ED with this type of hypotension. This will be the first study to compare the clinical outcomes of patients who are assessed with the ACES protocol as part of their initial workup to those of patients who are assessed without any intervention by ultrasound. The goal of this study is to determine if ACES enhances the patient's clinical outcomes, as measured by: 1) Time to restoration (or improvement) of CVS (cardiovascular system) parameters, 2) Rate of normalization of acid-base balance, as well as venous lactate 3) Significant change in diagnosis or recommended intervention 4) Frequency of unexpected diagnosis, and 5) Patient 7 and 30-day, and discharge mortality rate.

Methods

SHoC-ED 1 is a stratified randomized control trial that will run in multiple centers across Canada and internationally. The data will be stratified in that each center involved will recruit equal amounts of control and intervention patients. While different centers will recruit different numbers of participants, each individual center will recruit near-equal amounts for each arm of the study.

ED nurses will identify potential candidates for the SHoC-ED 1 study, and flag their charts to notify the attending physician. ED Physicians trained on the ACES protocol will then proceed to review the exclusion criteria (part of patient inclusion sheet/patient flag) and where appropriate, obtain consent. After these are completed, the physician will retrieve an envelope that contains the already randomized forms appropriate for whichever arm the patient has been randomized to. This randomization will place patients in either the ACES group (to be referred to as Group 1), or the control group (to be referred to as Group 2). Physicians following the group 1 protocol will perform their normal initial assessment and then do ACES, recording their data after each step. Physicians in group 2 will simply record their data after the initial assessment. Both groups of physicians will then record their impressions at 60 minutes as this will enable this project to determine how changes in diagnoses are affected by non-ultrasound factors in the first hour a patient is in the ED. These diagnoses will then be compared against the "final" diagnoses made during the patient's admission. Exclusion criteria for this study include the following: A) necessity of CPR or other advanced life support interventions before enrollment, B) History of significant trauma in past 24 hours, C) A 12 lead ECG diagnostic of STEMI, D) Mechanism of shock is clear (i.e. not undifferentiated shock), E) previously known diagnosis from other hospital, F) previously confirmed pregnancy, G) vagal episode H) Low blood pressure is not actually pathologic hypotension, but instead a normal variant or some other phenomenon.

To ensure that scans are being performed properly and consistently at all sites included in this study local principal investigators will be responsible for ensuring appropriate training and monitoring of standards for the physicians at their center performing ACES.

The data collected from both Group 1 and Group 2 will then be compared against each other, and follow-up will be conducted to ascertain if the early intervention with ACES had any implications on long-term outcomes.

Results

Given that much of the data interpreted will be comparing numerical values from different strata (Example: Time taken to operating theatre compared between Group 1 and 2), ANOVA testing will be used. The results of the ANOVA test will be used to determine if there is a significant difference in outcome, as measured by 1) Time to restoration (or improvement) of CVS parameters, and 2) Rate of normalization of acid-base balance (using either venous or arterial blood gas), and blood lactate.

For categorical data (Example: Mortality rate between groups), chi-square analyses will be performed to determine statistically significant increase in clinical outcome. This will be done for:

• Significant changes in diagnosis/recommendations in intervention change, and
• Frequency of unexpected diagnosis.

Conclusion

This SRCT (stratified randomized control trial) will determine whether the ACES protocol leads to improved clinical outcomes in patients who present to the ED with undifferentiated, non-trauma associated shock. It will compare intervention with the ACES protocol to intervention with no ultrasound at all.