The sternal rub is a technique medical professionals use, particularly in emergency settings, to test a patient’s neurological responsiveness. This procedure involves applying a painful stimulus to the breastbone, or sternum, of a person who is unresponsive to voice or touch. It functions as a rapid, physical assessment tool to gauge the level of consciousness when a patient cannot communicate verbally. The technique is considered a central painful stimulus, and its primary purpose is to provoke a reaction that indicates the patient’s brain function.
The Purpose of the Sternal Rub
The medical reason for performing a sternal rub is to assess a patient’s response to noxious stimuli, which helps determine their neurological status. This assessment is a component of standardized scoring systems used across healthcare, such as the Glasgow Coma Scale (GCS) and the simpler AVPU scale (Alert, Voice, Pain, Unresponsive). If a patient does not respond to being Alert or to a verbal stimulus (Voice), the next step is to apply a Pain stimulus.
The goal is to elicit any observable reaction from a patient who is in a stupor or coma-like state, as this reaction is a measure of brain function. A response might include movement, a grimace, an attempt to push the stimulus away, or a vocalization like a moan or groan. Observing the specific quality of the motor response—whether the patient localizes the pain or simply withdraws—helps medical personnel assign a score on the GCS.
The presence or absence of a response provides information about the patient’s condition, especially in cases of head injury or overdose. The procedure helps differentiate between deep sleep, a stuporous state, and a true coma, guiding immediate medical decisions of first responders. It is only performed after less invasive methods of attempting to wake the patient have failed.
Step-by-Step Technique
The healthcare provider first needs to ensure the patient’s sternum is accessible and free of any pre-existing injuries or recent surgical scars, as these would contraindicate the procedure. Once the patient is positioned flat, the provider makes a tight fist with one hand. The knuckles of the second and third fingers are typically used for the application of pressure.
The provider then places the knuckles firmly against the center of the patient’s sternum. The proper technique involves applying firm, downward pressure while simultaneously rubbing the knuckles up and down or in a circular motion on the bone. The pressure must be controlled and firm enough to create significant discomfort, but not so excessive as to cause immediate bruising or injury.
The duration of the stimulus application is an important factor in achieving an accurate assessment. Although often performed quickly in emergency settings, a brief application can lead to a misinterpretation of unresponsiveness. For a definitive assessment, the firm rubbing should be maintained for a recommended period, often between 5 and 10 seconds, though some clinicians may apply the stimulus for up to 30 seconds.
While applying the pressure, the medical professional must watch the patient’s body for any reaction, such as a slight movement of the limbs, eye opening, or a verbal sound. A purposeful movement, like the patient reaching up to stop the rubbing, indicates a better level of brain function than a simple, non-purposeful withdrawal. If no response is observed after the appropriate duration, the patient is considered unresponsive to pain.
Clinical Context and Alternatives
The sternal rub is frequently associated with pre-hospital and emergency medical services due to its quick and direct nature for assessing consciousness. Because the technique is intentionally painful and carries a risk of physical harm, it is viewed as a last resort for pain stimuli in clinical environments. The significant discomfort it causes, combined with the potential for bruising or abrasions, especially in patients with fragile skin, has led to it being discouraged in some settings.
There is a risk of causing physical injury, including severe bruising or abrasions to the skin over the sternum, or even a fracture in patients with underlying bone fragility, such as osteoporosis. For this reason, the sternal rub should only be performed by trained medical personnel who understand the contraindications, such as suspected spinal injury or existing chest trauma. The chest area should be checked for damage before each assessment.
Alternative methods of applying a central painful stimulus are preferred in hospital settings, as they can be less invasive and have a lower risk of causing injury. These alternatives include the trapezius squeeze, which involves pinching and twisting the muscle between the neck and shoulder, or supraorbital pressure, which applies pressure to the bony ridge above the eye. Peripheral stimuli, such as applying pressure to the nail bed, are another option, though central stimuli are considered more reliable for neurological assessment.