Category: H

  • Hectogram

    One hundred grams, or 3.527 avoirdupois ounces.  

  • Heavy chain disease

    Any one of several abnormalities of immunoglobulins in which excessive quantities of alpha, gamma, delta, epsilon, or mu chains are produced. The immunoglobulins formed are incomplete, causing, in some cases, distinct clinical signs and symptoms including weakness, recurrent fever, susceptibility to bacterial infections, lymphadenopathy, hepatosplenomegaly, nephrotic syndrome and renal failure, anemia, leukopenia, thrombocytopenia, and eosinophilia.…

  • Heat unit

    The amount of heat created at the anode during the production of x-ray photons. It is the product of the milliamperage times the seconds of exposure times the kilovoltage peak.  

  • Heat gun

    A device used in splint fabrication that produces heated air to render thermoplastic splinting materials malleable for fitting.  

  • Heat escape lessening position

    A body posture that decreases the rate of heat loss when a person is immersed in water. It is an important component of aquatic safety. The HELP position safeguards the head, neck, chest, and groin from rapid heat loss, delaying the onset of hypothermia. The position is assumed by floating on the back with the…

  • Heated in aqueous solution

    The technically accurate synonym for pasteurization.  

  • Heat and moisture exchanger

    A filter that retains some warmth and moisture from expired air and returns it to the intubated or laryngectomized patient during the following inspiration. The device prevents the patient from inhaling excessively cool, dry air that may damage the lower airways.  

  • Heart of evaporation

    The heat absorbed per unit of mass when a substance is converted from a liquid to a gas, such as the change of water to steam when it is heated sufficiently. For water, the amount of heat required to transform water into steam is 540 cal/g of water.  

  • Heart size

    The dimensions of the cardiac image as seen on radiographs, echocardiographs, computed tomography, angiography, or magnetic resonance imaging of the thorax.  

  • Heart rate recovery

    The decrease in heart rate that occurs one minute after maximal exercise. Normal people decrease their heart rates by at least 12 beats per minute (bpm) a minute after stopping maximal exercise. People whose heart rate does not decrease by 12 bpm have an increased risk of cardiac death.