7.1 Adult Telephone CPR (T-CPR): Compressions-First Protocol & Cadence

7.1 Adult Telephone CPR (T-CPR): Compressions-First Protocol & Cadence

Quick Answer: For adult non-traumatic cardiac arrest, the International Academies of Emergency Dispatch (IAED), American Heart Association (AHA), and International Liaison Committee on Resuscitation (ILCOR) mandate continuous chest compressions (Compressions-First T-CPR) without mouth-to-mouth rescue breaths. Compressions must be delivered at a rate of 100 to 120 beats per minute, to a depth of at least 2 inches (5 cm) but no more than 2.4 inches (6 cm), with complete chest wall recoil between strokes. Compressions performed on a bed lose up to 40%–50% of depth to mattress deflection, making immediate bed-to-floor extrication mandatory. The EMD acts as an auditory metronome, counting rhythmically aloud in sets of 10 to sustain vital myocardial and cerebral perfusion.

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Physiological Foundations: The Hemodynamic Imperative of Continuous Compressions

To understand why modern Emergency Medical Dispatch protocols mandate continuous chest compressions without rescue breaths for adult cardiac arrest, telecommunicators must grasp the underlying cardiovascular hemodynamics of sudden arrest.

+=============================================================================+
|                  CORONARY PERFUSION PRESSURE (CPP) DYNAMICS                 |
|                                                                             |
|   CPP (mmHg)                                                                |
|     30 |                           Peak Perfusion (~15-20 mmHg)             |
|     25 |                                 /-----------------                 |
|     20 |                                /                   |               |
|     15 |      Threshold for ROSC ------>:                   :               |
|     10 |                               /                     |              |
|      5 |       Ramp-Up (10-15 pumps)  /                       | Interrupt!  |
|      0 +----------------------------/-------------------------+-------      |
|        0s                          15s                       30s   35s      |
|        [ Compressions Initiated ]       [ Continuous Flow ]  [ Paused ]     |
+=============================================================================+

1. The Coronary Perfusion Pressure (CPP) Curve

Myocardial viability and the likelihood of achieving Return of Spontaneous Circulation (ROSC) depend almost entirely on Coronary Perfusion Pressure (CPP)—the pressure gradient driving oxygenated blood through the coronary arteries into the ischemic myocardium during the decompression phase of CPR.

• It requires 10 to 15 continuous, uninterrupted chest compressions to build sufficient intravascular pressure to reach the minimum CPP threshold (~15 mmHg) necessary for myocardial capillary perfusion.
• If compressions stop for even 3 to 5 seconds (e.g., while an untrained caller attempts mouth-to-mouth breaths, checks for a pulse, or readjusts their position), intravascular pressure drops instantly to zero.
• Once compressions resume, another 10 to 15 compressions are required just to rebuild that lost pressure. Pauses in compressions produce extended periods of total myocardial ischemia.

2. The Oxygen Reservoir in Adult Dysrhythmic Arrest

Approximately 70% to 80% of non-traumatic adult sudden cardiac arrests are caused by primary cardiac dysrhythmias—most commonly ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). At the moment of electrical collapse, the patient's arterial blood, lungs, and tissues are fully saturated with oxygen.

The physiological bottleneck is not oxygen depletion, but circulatory stagnation. What the patient lacks is a mechanical pump to circulate that reservoir of oxygen to the brainstem and myocardium. Continuous chest compressions maintain a continuous forward flow of blood, preserving vital organs until defibrillation can restore an organized cardiac rhythm.

3. Elimination of Bystander Hesitation

Decades of dispatch research revealed that requiring lay callers to perform mouth-to-mouth ventilations introduced catastrophic delays:

• Callers expressed severe aversion, disgust, or fear of infectious disease when instructed to perform mouth-to-mouth on strangers or regurgitating victims.
• Untrained callers spent an average of 45 to 90 seconds fumbling to seal the nose and deliver breaths, prolonging the "no-flow" period.
• Bystander ventilations frequently resulted in severe gastric insufflation, triggering vomiting, massive pulmonary aspiration, and complete airway obstruction.

Compressions-Only T-CPR eliminates these hurdles, slashing the time from call receipt to the first compression and significantly boosting bystander CPR participation rates worldwide.

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Biomechanical Standards of High-Quality T-CPR

Delivering compressions over the telephone requires the EMD to translate complex physical biomechanics into concise, actionable auditory commands:

+-----------------------------------------------------------------------------+
|                      BIOMECHANICAL TARGETS FOR ADULT T-CPR                  |
|                                                                             |
|   Compression Rate:   100 - 120 beats per minute (bpm)                      |
|   Compression Depth:  At least 2 inches (5 cm) | Maximum 2.4 inches (6 cm)  |
|   Chest Wall Recoil:  100% full recoil | Zero residual leaning              |
|   Hand Landmark:      Center of chest | Lower half of breastbone            |
|   Duty Cycle:         50% compression stroke / 50% relaxation phase         |
+-----------------------------------------------------------------------------+

1. Target Rate: 100 to 120 Compressions Per Minute

Resuscitation science identifies 100–120 bpm as the narrow therapeutic window for adult resuscitation:

• Rates below 100 bpm: Generate inadequate cardiac output and fail to achieve sufficient coronary perfusion pressure.
• Rates above 120 bpm: Severely compromise ventricular filling time (diastole) and cause rescuer fatigue to escalate rapidly, resulting in shallow, ineffective compressions.

2. Target Depth: At Least 2 Inches (5 cm)

In an adult victim, compressions must achieve a vertical displacement of at least 2 inches (5 cm) to physically compress the ventricles between the sternum and the thoracic vertebrae and generate positive intrathoracic pressure. Compressions exceeding 2.4 inches (6 cm) increase the risk of serious skeletal and visceral injuries (e.g., sternal separation, pulmonary contusion, hepatic laceration).

3. Full Chest Wall Recoil (Zero Leaning)

Equally vital to the downward stroke is the upward relaxation phase. During recoil, negative intrathoracic pressure is generated, drawing venous blood from the vena cava back into the right atrium and ventricles while coronary perfusion takes place.

If the rescuer fails to release all downward pressure—a common error known as "leaning"—the heart cannot refill with blood. Incomplete recoil reduces cardiac output by up to 50%, rendering subsequent compressions completely ineffective even if the downward rate and depth appear correct.

4. Hand Placement Landmark

The EMD instructs the caller:

"Place the heel of your hand on the center of his chest, right between the nipples. Put your other hand on top of that hand and interlock your fingers. Keep your elbows locked straight."

Locking the elbows forces the rescuer to use their upper body weight and hips rather than their arm muscles, dramatically delaying the onset of physical fatigue.

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Patient Positioning & The Bed-to-Floor Extraction Protocol

A critical pre-arrival instruction in the MPDS is verifying that the victim is positioned flat on a hard, firm surface—almost universally the floor.

The Physics of Mattress Deflection

Performing CPR on an adult who remains in a bed, on a sofa, or on a soft mattress is clinically futile. Up to 40% to 50% of the rescuer's downward force is absorbed by mattress spring and foam deflection. When a bystander pushes down 2 inches on a bed, the patient's entire torso sinks 1 to 1.5 inches into the mattress, delivering a net compression depth of only 0.5 to 1 inch into the thoracic cage. This fails to generate cardiac output.

   COMPRESSION ON MATTRESS                    COMPRESSION ON FLOOR
   =======================                    ====================
        [ Rescuer Push ]                           [ Rescuer Push ]
               |                                          |
               v                                          v
       [ Sternal Depth: 0.8" ]                    [ Sternal Depth: 2.2" ]
               |                                          |
               v                                          v
   [ Mattress Deflection: 1.4" ]                  [ Rigid Concrete / Wood ]
   (Hemodynamically Ineffective)                  (Therapeutic Perfusion Generated)

Scripted Bed-to-Floor Extraction Mechanics

When a caller reports the victim is in bed, the EMD must never permit compressions to begin on the mattress. The dispatcher immediately delivers scripted extrication instructions:

1. Clear Obstacles: "Clear away any pillows or heavy blankets around him."
2. Grasp Securely: "Grab him by his clothes at the shoulders or by his ankles."
3. Controlled Slide: "Pull him down toward you onto the floor. It is okay if he slides off the bed—getting him flat on the floor is the only way to save his life."

If the caller expresses doubt about their physical ability, the EMD uses firm reassurance: "Do not worry about hurting him. Just grab him and pull him down to the floor right now. I will help you." Once on the floor, the patient must be rolled onto their back with arms positioned alongside the body.

[!IMPORTANT] The Absolute Exception: If the patient is exceptionally massive (morbidly obese) and the caller is an elderly or frail individual who physically cannot budge the victim after repeated attempts, the EMD must not waste minutes in a futile struggle. The dispatcher instructs: "If you cannot move him, leave him on the bed and push as hard and fast as you possibly can!" Sub-optimal CPR on a bed is superior to zero CPR.

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Instructional Delivery, Cadence Coaching & The Dispatcher's Voice

The EMD's vocal delivery directly dictates bystander compression quality. The telecommunicator must project steady, relentless, and calm authority.

Scripted Pre-Arrival Instructions (PAIs)

In MPDS Protocol 9, once the patient is positioned flat on the floor, the EMD works from the Protocol C: Airway/Arrest/Choking (Unconscious) DLS Link and delivers the scripted instructions verbatim:

"Kneel by his side. Put the heel of your hand on the center of his chest, right between his nipples. Put your other hand on top of that hand. Lock your elbows straight. Lean directly over his chest and push down hard and fast, at least 2 inches deep. Let the chest come all the way back up between pumps."

Active Cadence Coaching

Simply telling a caller to "pump at 110 beats per minute" is clinically useless; lay callers in acute panic have severe tachycardia and severe time distortion. The EMD must establish and enforce the cadence verbally:

• The dispatcher counts aloud with the caller: "1, 2, 3, 4, 5, 6, 7, 8, 9, 10! 1, 2, 3, 4, 5, 6, 7, 8, 9, 10!"
• The EMD times their counting to match 100–120 bpm (approximately two compressions per second).
• ProQA integrates an electronic metronome tone. The dispatcher activates the metronome and instructs: "Match your pumps to this clicking sound: Push, push, push, push!"
• The EMD commands: "Count out loud with me so I know you are doing it!" Hearing the caller count aloud verifies that compressions are actively occurring and prevents the caller from freezing.

Managing Sternal Cracking and Caller Hesitation

Within the first 30 to 60 compressions on an adult or elderly victim, the rescuer will frequently feel or hear cracking sounds as the costochondral cartilage separates from the sternum. Callers routinely stop in horror, screaming: "I just broke his ribs! I'm hurting him!"

The EMD must anticipate this reaction and counter it instantly without hesitation:

"Keep pumping! Cracking sounds are completely normal—it is just cartilage flexing. You are not hurting him, he is dead without this. Push hard and fast, do not stop!"

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Rescuer Fatigue, Swapping & Responder Handover

Rescuer Fatigue Decay Curve

Scientific studies show that even fit, trained healthcare providers experience significant degradation in compression depth after just 90 to 120 seconds of continuous CPR. Crucially, the rescuer is usually unaware of their fatigue, believing they are still pushing at full depth when actual sternal displacement has decayed by 30% to 50%.

To combat this decay:

• The EMD provides constant verbal reinforcement: "Push harder! Push deeper! Let the chest come all the way up!"
• Two Rescuers Present: If a second bystander is available, the EMD coordinates a swap every two minutes (or roughly every 200–240 compressions): "Without stopping, get the other person ready to take over. On three, switch hands immediately: 1, 2, 3, switch! Keep pumping!" The transition must take less than 5 seconds.

Managing the Arrival Phase

When sirens are heard outside or a doorbell rings, callers instinctively stop compressions to run to the door. This creates a lethal 60- to 120-second perfusion gap just as advanced care is arriving.

The EMD strictly instructs:

"Do not stop pumping to open the door! The responders know how to get in. Keep your hands on his chest and keep pumping until the paramedics walk into the room and physically tap you on the shoulder!"

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Comparative Matrix: High-Quality vs Sub-Optimal T-CPR

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Realistic Dispatch Simulation: Adult T-CPR Execution

EMD:        "9-1-1 Emergency, what is the address of the emergency?"
CALLER:     "412 Oak Lane! My husband collapsed on the bed! He's blue!"
EMD:        "What is your phone number?"
CALLER:     "555-0182."
EMD:        "Tell me exactly what happened."
CALLER:     "He was lying down taking a nap. I came in and he won't wake up! 
            He isn't moving!"
EMD:        "Is he awake?"
CALLER:     "No!"
EMD:        "Is he breathing normally?"
CALLER:     "No, he isn't breathing at all!"
            [EMD TRIGGERS 9-E-1 ECHO DISPATCH INSTANTLY]
EMD:        "I'm sending the paramedics to help you right now. Stay on the line. 
            We need to move him to the floor immediately. CPR will not work on a bed."
CALLER:     "He's too heavy! I can't move him!"
EMD:        "You can do this. Grab his shirt at the shoulders and pull him straight 
            down toward you onto the floor. Let him slide. It's the only way to save him."
CALLER:     "(grunting, thud) Okay! He's on the floor!"
EMD:        "Roll him flat on his back. Listen carefully. Kneel next to his chest."
CALLER:     "I'm kneeling next to him."
EMD:        "Put the heel of your hand on the center of his chest, right between 
            his nipples. Put your other hand on top of that hand. Lock your elbows 
            straight. Push down hard and fast, at least 2 inches deep. Count out 
            loud with me! 1, 2, 3, 4! 1, 2, 3, 4!"
CALLER:     "1... 2... (crack) Oh God! Something cracked! I'm breaking his ribs!"
EMD:        "Do not stop! Cracking sounds are completely normal, it is just cartilage. 
            You must keep pumping! Push hard and fast! 1, 2, 3, 4, 5, 6, 7, 8, 9, 10!"
CALLER:     "1, 2, 3, 4, 5, 6, 7, 8, 9, 10!"
EMD:        "Good! Keep that exact speed! Let the chest come all the way up between 
            pumps! Do not stop until the paramedics walk into the room!"