1.3 Scene Safety, Cardiac Arrest & Heart Attack Recognition

1.3 Scene Safety, Cardiac Arrest & Heart Attack Recognition

The first seconds of a BLS response determine whether high-quality care begins promptly. The assessment is deliberately brief: make the scene safe enough to enter, determine responsiveness, summon help and an AED, then assess breathing and a pulse at the same time for no more than 10 seconds.

Scene safety and protective equipment

Pause before contact and scan for hazards such as traffic, fire, electricity, violence, unstable structures, water, chemicals, or infectious exposure. Use gloves and other personal protective equipment appropriate to the setting when available. Scene safety does not require a lengthy investigation, but a rescuer should not enter a situation likely to create another victim. Activate specialized help when a hazard requires fire, law-enforcement, hazardous-materials, or water-rescue resources.

Check responsiveness and call for help

For an adult or child, tap the shoulders and shout. For an infant, tap the foot and shout. Look for purposeful movement or a meaningful response. If the person is unresponsive:

1. Call for nearby help.
2. Activate the emergency response system according to the setting.
3. Send a specific person to retrieve an AED and emergency equipment.
4. If alone with a mobile phone, use speaker mode when practical so assessment and care can continue while speaking with dispatch.

In a facility, activation may mean a code or rapid-response system. Outside a facility, it usually means calling the local emergency number. Follow dispatcher instructions without delaying immediately needed care.

Assess breathing and pulse together

A healthcare provider checks breathing and a pulse simultaneously for at least 5 but no more than 10 seconds. Look for normal chest movement while palpating the age-appropriate central pulse site:

Do not spend extra time trying multiple sites. If no definite pulse is felt within 10 seconds, act as though the pulse is absent and start CPR.

Recognize abnormal breathing

Agonal gasps may be slow, irregular, snorting, or labored. They can occur early in cardiac arrest and are not normal breathing. An unresponsive person who is only gasping should not be placed in a recovery position while the rescuer waits for improvement.

The combined findings lead to three immediate pathways:

For an adult with a pulse but no normal breathing, give 1 breath every 6 seconds. For an infant or child with a pulse but inadequate breathing, give 1 breath every 2-3 seconds. Each breath is delivered over about 1 second and should produce visible chest rise.

Minimize delay to compressions

The 10-second limit is a ceiling, not a target to exceed. Do not repeatedly stop to check a pulse because the finding is uncertain. Begin compressions when the person is unresponsive, not breathing normally, and no definite pulse is identified within the assessment window. Once CPR begins, apply the AED as soon as it arrives and follow its prompts.

Special pediatric activation pattern

For an infant or child, the lone-rescuer sequence can depend on whether the collapse was witnessed and whether a phone is available. A witnessed sudden collapse favors immediate activation and AED retrieval because the cause may be cardiac. For an unwitnessed collapse when the rescuer has no phone and must leave the patient, provide about 2 minutes of CPR before leaving to activate the emergency response system and obtain an AED. If a phone is available, activate on speaker without leaving and begin care.

Recognize a possible heart attack

A heart attack is not the same as cardiac arrest. During a heart attack, blood flow to part of the heart muscle is reduced or blocked, but the person may remain awake and have a pulse. A heart attack can deteriorate into cardiac arrest, so early recognition and emergency activation matter.

Warning signs can include:

• Discomfort in the center of the chest that lasts more than a few minutes or goes away and returns; it may feel like pressure, squeezing, fullness, or pain.
• Pain or discomfort in one or both arms, the back, neck, jaw, shoulder, or stomach.
• Shortness of breath with or without chest discomfort.
• Cold sweat, nausea, lightheadedness, unusual fatigue, weakness, or a rapid or irregular heartbeat.

Symptoms are not identical for every person and may be mild. Do not require dramatic “crushing” pain, and do not dismiss shortness of breath, nausea, back or jaw discomfort, or unusual fatigue because chest pain is absent.

If a heart attack is possible, activate emergency medical services immediately—even when uncertain. Keep the person at rest in a position of comfort, monitor responsiveness and breathing, and follow dispatcher instructions. Do not have the person drive to the hospital and do not delay the emergency call while waiting to see whether symptoms improve. If the person becomes unresponsive and is not breathing normally, move immediately to the cardiac-arrest assessment, begin CPR when no definite pulse is felt within 10 seconds, and use an AED as soon as available.

Aspirin decisions must not postpone the emergency call. Follow dispatcher, local protocol, and the person's known medical guidance rather than improvising treatment when allergy, bleeding risk, or the cause of symptoms is uncertain.

Common errors

• Treating agonal gasps as normal breathing.
• Checking breathing and pulse one after the other instead of simultaneously.
• Extending a doubtful pulse check beyond 10 seconds.
• Calling vaguely for “someone” instead of assigning AED retrieval to a specific person.
• Entering an unsafe scene without the needed rescue resources.
• Delaying CPR while looking for a monitor or blood-pressure reading.
• Waiting for heart attack symptoms to become severe before activating emergency medical services.

The exam cue is the combination of responsiveness, breathing, and pulse. When the patient is unresponsive, not breathing normally, and has no definite pulse within 10 seconds, the answer is immediate CPR—not further diagnostic testing.