Evaluation of Emergency Medical Dispatch in Out-Of-Hospital Cardiac Arrest in Taipei

Resuscitation (2007) 73, 236—245

Introduction

Emergency medical dispatchers are the entry points to the emergency medical services (EMS).

The implementation of dispatching system has brought substantial gains in EMS performance with improved patient outcomes, including increased survival rate, reduced response time, and increased efficiency of the EMS system.

By using medically approved and written pre-arrival instruction (PAI), the dispatcher can instruct the caller or layperson to start treatment immediately, especially in the cases of OHCA.

Introduction

Telephone-assisted CPR (T-CPR) by dispatcher has found to be associated with a 50% improvement in the odds of survival to hospital discharge compared with those who received no CPR before the arrival of EMS.

Most people who witness a person in cardiac arrest may not have been trained in CPR or lack the knowledge to provide this life-saving intervention even when facing the victim as a close relative.

The instruction to start T-CPR is included in the protocol of emergency dispatch manual. When cardiac arrest is suspected, the dispatcher will ask caller four key questions:

1)What's the patient's skin color?

2) Is there any symptom of airway obstruction?

3) Is there anyone who can perform CPR at the

scene?

4)How long has the patient remained comatose?

Once OHCA is presumed, the dispatcher will instruct the caller to perform compression–ventilation CPR via telephone according to the ERC guidelines and dispatch an EMS response at the same time.

It is the dispatcher's responsibility to ensure that they adhere to the instruction protocols, and their performances are evaluated periodically by their supervisors.

Emotional Content and Cooperation Score (ECCS)

1. Normal conversational speech

2. Anxious but cooperative

3. Moderately upset but cooperative

4. Uncooperative, not listening, yelling

5. Uncontrollable, hysterical

Emotional Content and Cooperation Score (ECCS)

The average ECCS was remarkably low at 1.42 in Mandarin speaking population.

Most of the callers’ emotion is manageable and they were cooperative with the dispatcher interrogations.

Female callers were slightly more emotional with a higher ECCS compared to male callers.

Length of The Interview and Time Spent on Inquiring Address

The median length of the calls was 32.5 s (interquartile range: 22.0–58.5) and 90% of the calls were under 102.4 s.

The median time for enquiring address was 7.0 s (interquartile range: 4.0–10.0) and 90% of the calls were under 17.2 s.

Dispatcher Ability in Identifying Cases of OHCA

Among 193 OHCAs identified by the dispatcher, 189 cases were confirmed by the field provider (false positive patient, n = 4).

6 patients initially determined as not requiring OHCA by the dispatcher were later found to be in arrest (false negative, n = 6).

The sensitivity and positive predictive value (PPV) for predicting OHCA by dispatchers was 96.9% and 97.9%, respectively.

Dispatcher Ability in Identifying Cases of OHCA

Agonal breathing is commonly seen in the initial phase of OHCA patients. This breathing is an abnormal, gasping, jerking respiration that produces movement of the thoracic, neck and mouth, commonly described by the caller as “occasional or breathing, barely breathing, weak breathing, heavy, labored or noisy breathing”.

Failure to recognise agonal respiration could result in failure to identify OHCA correctly.

Determination of The Level of Consciousness and Breathing Status in The Interview

For OHCA cases, the questions of “level of consciousness” and “breathing status” are two of the most important questions to be asked to identify possible OHCA.

The Percentage of “Level of Consciousness” Determined

In 62 cases (31% = 62/199), information on the level of consciousness was provided directly from the interview, without it being asked for.

Of the remaining 137 patients, the dispatcher asked about unconsciousness in 62 cases (45% = 62/137) and did not ask about it in 75 cases (55% = 75/137).

Of the 62 cases in which the level if consciousness was sought, the actual consciousness level was determined in 57 cases and in 5 cases was unclear.

The Percentage of “Breathing Status Determined

In 24 cases (12% = 24/199), the breathing status was provided directly from the interview, without it being asked for.

Of the remaining 175 patients, the dispatcher raised the question of the patients breathing status in 119 cases (68% = 119/175) and did not raise the question in 56 cases (32% = 56/175).

Of the 119 cases, actual breathing status was determined in 91 cases and 28 cases it was unclear.

Provision of T-CPR

Only 6.5% of patients received bystander CPR prior to any T-CPR from dispatchers. Approximately 1/3 of victims received T-CPR provided by the dispatcher (or duty nurse in dispatching center) and the rest of the patients received no CPR before arrival of the paramedics.

T-CPR by dispatcher is associated with a 50% improvement in the odds of survival to hospital discharge compared with those who received no CPR before the arrival of EMS.

Provision of T-CPR

When instructions were offered by the dispatcher, most bystanders agreed to attempt CPR and actually initiated CPR.

But occasionally bystanders refused to perform CPR even when they are provided with instructions.

The most common reasons is the fear of contracting a communicable disease like hepatitis, TB or AIDS through performing mouth-to-mouth resuscitation.

There is an increasing evidence to suggest that chest compression only CPR may be as efficacious as compression–ventilation CPR.

Conclusion

Most callers were emotionally stable and cooperative when calling for help, even when facing cardiac arrest patients.

The dispatchers have shown satisfactory interview skills in approaching emergency calls, and the dispatcher's ability to identify OHCA was high in this study.

The compliance of dispatchers in posing priority questions such as the level of consciousness and the breathing status is unsatisfactory. This could possibly be related to the low rate of T-CPR offered to the callers in the interviews.