Nursing Care for Shivering Causes and Management

Causes and Management of Shivering

Whats is Shivering,Results of Shivering,Shivering in Healthy Persons,Body Cover During Shivering,Historical Cases of Shivering in Healthcare,Neuroregulatory and Immunological Evidence About Shivering.

Whats is Shivering

     Shivering is defined as involuntary shaking of the body and is the adult human's primary defense against the cold. Characterized by a protracted generalized course of involuntary contractions of skeletal muscles that are usually under voluntary control, thermo-regulatory shivering differs from transient tremors or “shivers” associated with fear, delight, or other forms of sympathetic arousal. 

    Shivering occurs when heat loss stimulates specific heat loss sensors in the skin, spinal cord, and brain. Sensory impulses are received and integrated at the pre-optic area of the hypothalamus. Shivering is stimulated when integrated thermos sensory information indicates body temperature is falling below optimal “set point” range (see Thermal Balance). 

    The shivering center in the posterior hypothalamus is stimulated, sending impulses via anterior spinal routes of the gamma efferent system. Heat is generated by oscillation and friction of the fibrous muscle spindles of the fuse motor system. Shivering occurs in fever despite rising temperatures because the set point level is raised to higher levels by circulating cytokines and other pyrogens.

Results of Shivering 

    The consequences of shivering for seriously ill or vulnerable patients are sometimes overlooked because they seem to be harmlessly compensatory warming responses. However, the aerobic activity generated by vigorous shivering activity raises oxygen consumption 3-5-fold, approximately that of shoveling snow or riding a bicycle. 

    The resulting oxidative phosphorylation of glucose and fatty acids raises metabolic demands, but it is only about 11% efficient in raising body temperature. The energy expenditure of shivering may be tolerated by healthy persons who shiver for short periods, but it puts specific patient groups at risk for cardio-respiratory, metabolic, and thermal instability. 

    Uncontrollable shivering is distressing to patients, yet it occurs frequently in situations where ambient temperatures are cool, patients are exposed, or therapies induce fever. Shivering is often recalled by patients as a negative aspect of postoperative recovery, childbirth, antifungal drug administration, blood transfusions, or other hospital experience. 

    Nursing research has documented correlates and sequelae of shivering in an effort to determine adverse consequences in postoperative care, febrile illness, and during induced hypothermia.     

    Intervention studies have tested efficacy of nursing measures to prevent shivering during surface cooling and febrile chills. Important to these studies has been the effort to standardize the measurement of shivering by use of a shivering severity scale, originated by Abbey and colleagues (1973).

Shivering in Healthy Persons

    Although shivering had been studied extensively by physiologists in healthy humans and animals, little clinical interest was evident until the 1970s. Abbey and Close (1979) used wraps of ordinary terry cloth towels as insulation to protect thermosensitive regions of the skin during use of cooling blankets. 

    Shivering during surface cooling was a significant problem treated at that time with chlorpromazine, a drug with undesirable side effects. The wrapping intervention was based on existing physiological research demonstrating dominance of the heat loss sensors on hands and feet in stimulating shivering. 

    This land mark pilot study demonstrated that insulation of extremities controls shivering and improves comfort without drugs, even when surface cooling induces hypothermic temperatures.

Body Cover During Shivering 

    Major studies by nurse investigators (Abbey & Close, 1979; Holtzclaw, 1998) using more extensive temperature and electromyographic measurements further supported the usefulness of “wrapping” extremities, with theoretical perspective based on Abbey's original work. 

    Stated briefly, insulation blunts the neurosensory stimulus of heat loss from dominant sensors, while larger but less thermosensitive regions of the trunk allow heat exchange without inducing shivering.

Historical Cases of Shivering in Healthcare

    Historically, interest in postoperative shivering grew in the mid-1980s with the rise in hypothermic cardiac surgery. Research findings show the hazardous increase in oxygen consumption, carbon dioxide production, and cardiovascular exertion during postoperative rewarming from hypothermic cardiac bypass (Holtzclaw & Geer, 1986; Phillips, 1997). 

    Clinical predictors of shivering became of interest as early prevention was indicated. The mandibular hum was detected by palpation of referred masseter vibrations over the ridge of the jaw (Holtzclaw & Geer, 1994). Widening of skin to core temperature gradients was found to predict shivering in this population, presumed to reflect the discrepancy between hypothalamic set point and peripheral temperatures that initiates shivering. 

    Sund-Levander and Wahren (2000) found that tympanic totoe temperature gradients predicted shivering in neurologically injured patients during hypothermic surface cooling and that patients were more likely to shiver if cooled too quickly. This study supported Abbey's (1973) earlier contention that shivering during surface cooling could be reduced by modifying the rate of body heat loss. 

    Studies confirm that little difference is found between pharmacologic suppressants, warmed blankets, or reflective wraps in preventing shivering during perioperative rewarming (Hershey, Valenciano, & Bookbinder, 1997); however, newer forced-air warming units (eg, Bair Hugger) and radiant lamps have been found in medical studies to maintain normothermia more effectively. 

    Extremity wraps were found to effectively reduce febrile shivering severity and duration (See Fever/Febrile Response) in immunosuppressed cancer patients and persons with HIV/AIDS (Holtzclaw, 1990, 1998).

Neuroregulatory and Immunological Evidence About Shivering 

    As scientific evidence grows about neuroregulatory and immunological factors influencing shivering, new avenues of study emerge. Little is known about how shivering can be controlled in emergency situations during rescue and evacuation. Few studies have examined outcomes of shivering among children. 

    Surgery, trauma, circulatory bypass, and hypothermia have all been linked in preliminary studies to acute phase reactions that stimulate febrile shivering (Phillips, RA, 1999). While shivering is common during the last stage of labor, little attention has been paid to its origin and management. 

    Future directions in the study of shivering by nursing will likely address the biobehavioral interface of environmental stimuli, biochemical and neurotransmitter activity, energy expenditure, physics of heat exchange, and thermal comfort.