Axillary and tympanic membrane temperature recording in the preterm neonate: a comparative study

STUDY AIMS

The aim of this study is to compare axillary temperature recordings with those of the tympanic membrane, in healthy preterm neonates, to ascertain whether there is any significant difference between the two recordings, in particular in relation to postnatal age, and if so to evaluate the clinical implications.

RATIONALE

Immature thermoregulatory mechanisms, and small body size, mean preterm neonates are prone to temperature maintenance problems, and thermal stress is associated with increased morbidity and mortality. In order to ensure minimal handling, the ideal method of temperature recording would be rapid, painless and reproducible, and accurately reflect core temperature, whilst considering safety, comfort, ease of procedure and cost effectiveness. Recording of the tympanic membrane temperature is rapid and noninvasive, however, the accuracy of this method in preterm neonates has not been established.

STUDY DESIGN

A comparative descriptive design was used, to describe differences in the recorded temperature in healthy preterm neonates, of gestational age of 27-37 weeks, related to temperature recording.

METHOD

A second comparison was undertaken to establish difference in mean temperature recordings dependant on postnatal age of the baby in days. The sample included all babies fitting the selection criteria, admitted to the Neonatal Unit during the study period. Following approval by the local research ethics committee tympanic membrane and axillary temperatures were recorded consecutively for 7 days (n=154), using the Genius Model 3000A tympanic thermometer and a glass and mercury thermometer.

RESULTS

A t-test demonstrated a statistically significant difference between the recordings (P < 0.05), tympanic membrane recordings being higher. However, analysis of variance indicated that this difference was not associated with postnatal age, and thus the presence of vernix in the auditory canal (P > 0.05). The findings were not, however, deemed clinically significant in that no change in care or treatment resulted from differences in temperature recordings.

CONCLUSIONS

Whilst the findings cannot be applied to sick preterm neonate, it was concluded that tympanic membrane temperature recordings in healthy preterm neonates are safe, accurate, easy, and comfortable for the baby, and appropriate with this client group provided staff are trained in the technique.

Treatment of trauma-associated hypothermia in children: evidence-based practice

BACKGROUND

Hypothermia is a serious immediate consequence of traumatic injury in children. Although numerous studies have addressed the treatment of hypothermia in adults after trauma or surgery, few have examined this issue in injured children.

OBJECTIVES

To evaluate the research literature on when and how to treat hypothermia during emergency care of children with trauma and to apply these findings to clinical nursing practice.

METHODS

Electronic literature searches conducted periodically for 3 years yielded more than 50 publications on hypothermia and its treatment in trauma and surgical patients. Publications were grouped by cause of hypothermia and by warming methods. Single case reports and publications related to submersion injuries were excluded.

RESULTS

Three clinical trials of patients with head injuries included adolescents aged 15 years and older. One study compared peripheral and core warming methods used during operative management of infants and young children. Only one study evaluated core warming in children with trauma.

DISCUSSION

The treatments examined in the few research-based studies on the treatment of hypothermia during emergency care of children with trauma were given low recommendations. Although the warming methods were successful in selected surgical and adult patients, the methods cannot be recommended for treating children with trauma because of the lack of evidence-based findings.

CONCLUSIONS

Caution should be used when extrapolating published data on the treatment of hypothermia in injured adults to injured children. Ongoing clinical trials should evaluate in children with trauma those warming methods that have been used successfully in surgical patients.

Post-anaesthetic shaking. A review of the literature

This paper describes the phenomenon of post-anaesthetic shaking (PAS) as it is discussed in the literature. Literature was obtained via computerised searches of the Cochrane Library, Medline, and Cumulative Index of Nursing and Allied Health Literature (CINAHL) databases. This review considers PAS in adults, who have had either a general or regional anaesthetic. It focuses on the controversy regarding the cause of the condition, the role of anaesthetics in hypothermia, pharmacological interventions, and non-pharmacological interventions. The key conclusion to emerge is that nurses must take patients' shaking seriously and initiate treatment for it. If PAS is associated with hypothermia then the patient needs to be rewarmed, and if it is associated with pain, analgesia needs to be administered.

A patient temperature audit within a theatre recovery unit

Hypothermia in the postoperative recovery phase can be a source of potential danger for patients emerging from anaesthesia. In spite of the vast amount of literature dealing with principles of care in the recovery room, information regarding the incidence of hypothermia appear very limited. This article presents a patient temperature audit to assess whether patients were being discharged from a theatre recovery unit hypothermic. In addition, patient temperatures were recorded both pre- and postoperatively, as well as on discharge from recovery, to monitor the incidence of hypothermia throughout the theatre suite. The results show that patients were being discharged with core body temperatures ranging from 34.8 to 38 degrees C with no incidence of hypothermia recorded when the operating room temperature was above 23 degrees C. In general, the coldest theatres were orthopaedic, with this group of patients showing the most incidence of hypothermia. This article aims to demonstrate the use of clinical audit to investigate and evaluate current practice.

Responding to winter emergencies

Nurses need to know how to provide emergency care to victims of wintertime injuries and illnesses--and how to survive such circumstances themselves. In this article, the author, a ski patrol member, describes cold-weather strategies and how to respond to hypothermia, frostbite, winter sports injuries, and avalanches.

Inadvertent hypothermia: is it just a perioperative problem?

Patients undergoing surgery run the added risk of inadvertent hypothermia. This article suggests that simple measures undertaken in the ward can prevent this serious perioperative problem.

Inadvertent hypothermia in the OR

Hypothermia is one of the most common problems that patients experience in the perioperative environment. Hypothermia causes more problems for the patient than the mere unpleasant experience of feeling cold. Additional nursing interventions are required for a patient suffering from inadvertent hypothermia, which often delays the patient's discharge from the perioperative setting. Many of the nursing interventions that are successful in preventing hypothermia and restoring body heat to surgical patients, such as applying a warmed blanket to a patient's body, seem straightforward. Understanding the cause and effects of inadvertent hypothermia, however, is essential in recognizing it and implementing the most effective nursing interventions.

The trauma triad of death: hypothermia, acidosis, and coagulopathy

With the organization of trauma systems, the development of trauma centers, the application of standardized methods of resuscitation, and improvements in modern blood banking techniques, the ability to aggressively resuscitate patients in extremis has evolved. The concept of the "golden hour" has translated into unprecedented speed and efficiency of trauma resuscitation with the ultimate goal of short injury-to-incision times. As the shift in care of patients in extremis has continued to move from the street to the emergency department and beyond, the focus of trauma resuscitation has shifted to the operating room and ultimately to the intensive care unit. The "new" golden hour may well be the time in the operating room before the patient reaches the physiologic limit, defined as the onset of the triad: hypothermia, acidosis and coagulopathy. Critical care nurses must understand this triad, because it forms the basis and underlying logic on which the damage control philosophy has been built. This article explores the pathogenesis and treatment of acidosis, hypothermia, and coagulopathy as it applies to the exsanguinating trauma patient.

Temperature management in trauma patients across the continuum of care: the TEMP Group. Temperature Evaluation and Management Project

Hypothermia is a potentially preventable consequence of injury in the trauma patient. The physiologic aftermath of hypothermia is such that it is regarded as one of the three components in the trauma triad of death. A multidisciplinary group at a Level I trauma center was formed to originate an innovative team approach to managing temperature in trauma patients. This article describes this unique project to combat a preventable cause of significant morbidity and mortality.

Inadvertent hypothermia prevention: the anaesthetic nurses' role

Up to 90% of patients experience hypothermia perioperatively. Inadvertent hypothermia can have a profound physiological effect on the body, varying from mild vasoconstriction and feeling cold to cardiac arrest and death. Anaesthesia, general or regional, increases the risk as the normal protective reflexes such as shivering are absent, particularly when muscle relaxants are used. The very young and the elderly are particularly vulnerable. Preoperative assessment is essential. The greatest reduction in temperature occurs in the first hour of surgery, as a result of patient exposure, skin disinfection with cold fluids, inhalation of cold volatile gases and the administration of cold intravenous fluids, as well as exposure to cool theatre temperatures. If the theatre temperature drops below 21 degrees C, all patients will develop hypothermia. Patients lose heat through radiation, convention and conduction, with conduction having the greatest effect. Forced air warmers such as the Bair Hugger are the most effective means of preventing and treating heat loss. They should be used routinely although their contribution to infection also needs to be considered. Nurses should be aware of the risks of hypothermia so that modes of prevention can be employed to minimize the risks of inadvertent hypothermia.

Constant temperature monitoring: a study of temperature patterns in the postanesthesia care unit

Patients admitted to the PACU from the operating room exhibit fluctuations in core body temperature during the course of their stay in the PACU. Some patients present with normothermia and experience temperature decreases later in their stay. PACU policy does not dictate that temperatures be measured at a predetermined frequency in the absence of hypothermia; thus, it is possible that hypothermia may not be detected at its onset. The major purpose of this study was to describe the core body temperature patterns of postsurgical patients during the PACU stay. Secondary objectives were to (1) identify at which point in time patients become hypothermic and (2) describe length of stay in patients who develop hypothermia. Hypothermia was defined as a core tympanic temperature of less than 35.5 degrees C. A descriptive design was used using a convenience sample of 150 elective surgical patients over the age of 1 month who were normothermic on admission to the PACU. Data were analyzed using descriptive statistics. Concurrent tympanic and continuous axillary temperatures were monitored for comparison and trend monitoring. Temperatures showed clinically significant decreases into the hypothermic range (< 35.5 degrees C). Fifty-seven percent of the sample (n = 86) had temperatures that dropped after PACU admission and another 13% fell below 35.5 degrees C. Hypothermia occurred within the first 15 minutes of the PACU stay. The average length of stay for those that developed hypothermia was 1.83 hours. Monitoring temperatures more frequently will result in detecting hypothermia at its onset. Nurses may use the axillary device as a trend for continuous monitoring. Length of stay may be shortened if temperature management is embraced by the PACU nurse.

Adherence to standards of care and implications of body temperature measurement in trauma patients

PURPOSE

To identify adherence to the standard that trauma patients have body temperature (T) recorded, range-of-temperature measurements, and the incidence of hypothermia recorded; and to examine the relationship between (T) and Injury Severity Score (ISS).

METHODS

A retrospective review of the records of 60 trauma patients was conducted.

FINDINGS

Forty percent of the patient records had temperatures recorded with values that ranged from (T) 87-100.6 degrees F; 33% of the patients had hypothermia as defined by a temperature of 96.6 degrees F or less. There appeared to be a significant inverse relationship between (T) and ISS.

CONCLUSIONS

Based on the data, temperature was recorded in only 40% of the cases sampled. Adherence to the standard of measuring and recording a value was only intermittently followed. Nursing personnel should be educated to appreciate the potential for unsuspected hypothermia and to respond by following the standards of care.

Prevalence of inadvertent hypothermia during the perioperative period: a quality assurance and performance improvement study

The inadvertent hypothermia that is often seen after anesthesia in a cool environment has been associated with delays in recovery from anesthesia and longer stays in the PACU. This quality assurance/performance improvement study was undertaken to determine the following: (1) the effectiveness of current interventions for preventing intraoperative hypothermia, (2) whether there were any apparent differences in effectiveness among the current methods for preventing intraoperative hypothermia, and (3) was intraoperative hypothermia associated with delays in discharge from the PACU. Data were completed on 502 patients. Despite longer surgical procedures, those patients treated intraoperatively with the Bair Hugger (Augustine Medical Inc, Eden Prairie, MN) were less likely to arrive in the PACU hypothermic than those who did not receive this treatment. Patients who arrived in the PACU hypothermic had longer PACU stays than patients who arrived normothermic. As a result of these findings, changes in nursing practice in the PACU and in the availability of the Bair Hugger in the operating rooms were made.

Chronic subclinical hypothermia: home care alert

Chronic subclinical hypothermia poses a serious challenge to home health nurses because the condition may negatively impact the plan of care for very old and frail clients. This article provides a review of age-associated changes in thermoregulation, discusses the ways in which these changes may affect an elderly client's response to care, and offers home care interventions for individuals with chronic subclinical hypothermia.

Hypothermia

Hypothermia in the hospitalized adult may be a primary process, as in exposure, or a result of a multitude of disease processes or iatrogenic factors. The condition affects virtually every metabolic process in the body. A thorough understanding of the pathophysiology of hypothermia enables the clinician to differentiate between the hypothermic syndrome and underlying illness and can assist in the detection and management of clinical sequelae. A reliable patient history is the most helpful diagnostic tool, but careful physical examination and laboratory studies are also important for detection of primary or secondary illness.

Comparison of three rewarming methods in a postanesthesia care unit

Postoperative hypothermia is problematic because patients in postanesthesia care units (PACUs) often feel very cold, and unrecognized or prolonged postoperative hypothermia can aggravate patients' underlying cardiovascular disorders. The researchers compared three methods of rewarming PACU patients who had undergone laparotomy procedures. Patients were assigned randomly to three groups. Each patient in group one received the standard PACU rewarming intervention (ie, two warmed thermal blankets and a hospital bedspread). Each patient in group two received the standard PACU rewarming intervention plus a reflective blanket. Each patient in group three received the standard PACU rewarming intervention plus a reflective blanket and a reflective head covering. Nurses measured patients' vital signs on admission to the PACU and every 15 minutes thereafter until patients' sublingual temperatures reached 36 degrees C (96.8 degrees F). No significant temperature differences occurred among patients in the three groups, but an inverse relationship existed between patients' PACU admission temperatures and the time they required to reach normothermia.

Rewarming cardiac surgical patients: warm water vs warm air

BACKGROUND

Hypothermia is experienced by 60% to 90% of adult patients after surgery. The detrimental physiological consequences of prolonged hypothermia are a significant risk for cardiac surgical patients.

OBJECTIVE

To compare the effect of a warmed convective-air blanket with that of a warmed circulating-water blanket on the rates of increase in skin and core temperatures and on total rewarming time in patients with hypothermia after cardiac surgery.

METHODS

A quasi-experimental, repeated-measures design was used to study rewarming in 76 adult patients who were hypothermic after cardiac surgery. Subjects were randomized to two groups: 40 were warmed with a convective-air blanket; 36, with a circulating-water blanket. Skin and core temperatures were recorded every 15 minutes until the subject's pulmonary artery temperature reached 37 degrees C. Total time required for rewarming was the period between time of placement of the blanket and time of removal. The effects of 13 other variables on the time required for rewarming were also determined.

RESULTS

Both skin and core temperatures increased more rapidly in patients treated with the warm circulating-water blanket than in those treated with the convective-air blanket. The mean time required for rewarming was 45 minutes shorter in the group treated with the circulating-water blanket. The patient's age, volume of i.v. fluids received, length of anesthesia, starting core temperature, and treatment method had significant effects on the time required for rewarming.

CONCLUSIONS

The data suggest that rewarming with a circulating-water blanket produces normothermia more rapidly than rewarming with a warm convective-air blanket in adult patients who are hypothermic after cardiac surgery.

Perioperative problems: threats to thermal balance in the elderly

The perioperative period is a time of thermal instability for older surgical patients. Beyond the elder persons vulnerability to intraoperative heat loss and hypothermia, the surgical procedure initiates host responses that affect body temperature. Technology and drug therapies often deliberately or inadvertently alter thermal balance. Alterations range from mild hypothermia to shaking febrile chills. A reasoned approach to preventing or caring for each of these alterations is based on an understanding of the dynamics of heat loss or heat gain. Early recognition of problems and appropriate action by perioperative nurses may forestall more serious consequences.

Care of the older hypothermic patient using a self-care model

This paper focuses on the problem of hypothermia and provides an overview of its causes, signs and symptoms. A case study of a patient who was admitted to an acute assessment of the elderly ward with hypothermia is described and the use of Orem's self-care model of nursing is explained.

Methods of rewarming the hypothermic patient in the accident and emergency department

Hypothermia, occurring when the core body temperature falls below 35 degrees C, gives rise to life threatening physiological changes, and may present in the Accident and Emergency (A & E) department with varying aetiology and implications for nursing management. Rewarming the hypothermic patient is a priority of nursing care, and several different ways of achieving this are practised. This review of relevant literature aims to evaluate current methods of rewarming hypothermic patients commonly employed, their associated difficulties, and considers their potential implementation in the A & E setting.

Rewarming hypothermic postanesthesia patients: a comparison between a water coil warming blanket and a forced-air warming blanket

The warming effects of a Blanketrol water coil-heated hypothermia blanket and a Bair Hugger forced-warm air warming blanket were compared. Thirty-two patients admitted to the PACU with temperatures 34.4 degrees C (94 degrees F) or lower were assigned to treatment with the Blanketrol (Cincinnati Sub-Zero Products, Cincinnati, OH) or the Bair Hugger (Augustine Medical, Eden Prairie, MN) in alternating fashion, and treatment continued until the patients' temperatures reached 36.1 degrees C (97 degrees F). Every half hour each patient's temperature was measured using a tympanic temperature device and recorded on the data collection sheet. Analysis of the findings showed that the forced-air warming blanket warmed patients to 36.1 degrees C (97 degrees F) or higher significantly faster than the water coil-heated blanket (P < .001).

Thermal regulation of patients during the perioperative period

Surgery patients often become hypothermic during surgical procedures. The body's thermostat, the hypothalamus, strives to maintain a normal temperature; however, when a patient's temperature drops too low, the thermoregulatory processes are suppressed, and hypothermia occurs. Cardiopulmonary bypass procedures use induced hypothermia; however, inadvertent hypothermia may occur in many other surgical procedures during which the body temperature is not systematically monitored and regulated. Hypothermia may cause complications such as protein catabolism, hypokalemia, and changes in glucose metabolism and glomerular filtration. Nursing interventions used intraoperatively to maintain a normothermic state include applying warm and temperature regulating blankets, decreasing the amount of skin exposure, and warming operating rooms.

Forced-air warming versus routine thermal care and core temperature measurement sites

Hypothermia occurs commonly during the perioperative period and is preventable with proper warming measures and body temperature monitoring. Using a prospective, randomized study design, we compared forced-air warming (Warm Touch, Mallinckrodt Medical, Inc, St Louis, MO) (n = 15) with routine thermal care (n = 14) during the intraoperative and early postoperative periods. The results show that compared with routine thermal care, forced-air warming resulted in higher core temperatures both intraoperatively and postoperatively. The incidence of shivering was lower and thermal comfort scores were higher in the warming group. A secondary focus in this study was to assess the correlation between body temperatures measured at the urinary bladder, oral cavity, rectum, and tympanic membrane. The results indicated that the sites most highly correlated with tympanic temperature (listed in order of most to least correlated) were the bladder, rectum, and oral cavity. Assuming tympanic temperature is most representative of "core" temperature, oral measurements were likely to underestimate core temperature, whereas bladder and rectal temperatures overestimated core temperature. The relationship between body temperatures measured at commonly used monitoring sites must be recognized by nurses to account for the tendency to overestimate or underestimate core temperature. This knowledge can be applied in the management of patients in the operating room or PACU and specifically in the evaluation of PACU patients before discharge.

Hypothermia in trauma: the nurse's role in recognition, prevention, and management

Trauma patients are at risk for a number of complications that can jeopardize their ability to withstand the effects of injury. A serious and common problem is hypothermia, which can be caused or exacerbated by interventions used in resuscitation, surgery, and postoperative care. The trauma nurse has a primary responsibility in recognizing and beginning therapy to correct this potentially lethal condition. Many nursing measures can be modified to help the patient retain body heat or provide an exogenous source of warmth.

The effect of head covering on rewarming and shivering in cardiac surgical patients

In hypothermic postoperative cardiac surgical patients, heat loss from the head may interfere with rewarming and cause shivering. This study investigated the effect of head covering on rewarming rate and shivering during post-operative rewarming. The sample included 19 experimental and 21 control subjects. The heads of experimental subjects were wrapped with two terry cloth towels until urinary bladder temperature (UBT) reached 37 degrees C. Admission UBTs were mildly hypothermic (34.6 degrees C to 36.70 C). Four experimental and six control subjects shivered. There were no significant differences (P < .05) in the incidence of shivering (Yates' chi 2 = 0.33; P = 0.855). After controlling significant differences between groups in height and body surface area with analysis of covariance, there were no significant differences in rewarming rate (F = 3.270; P = .079). Shiverers were slightly colder (mean, 36.13 degrees C; t = 1.768; P = .085) on admission to the cardiac surgical intensive care unit and had significantly greater heat gain (t = -2.091, P = .043) than nonshiverers. Conclusions about the effect of head covering on shivering could not be made because of small sample size. Failure to demonstrate a significant difference in rewarming rate is due to the effects of mildly hypothermic admission UBTs on the mathematical calculation of rewarming rate and on the small sample size.

Shivering following cardiac surgery: predictive factors, consequences, and characteristics

BACKGROUND

Shivering is common after cardiac surgery and may evoke harmful hemodynamic changes. Neither those changes nor factors increasing probability of shivering are well defined.

OBJECTIVES

(1) To identify factors linked with risk of shivering by comparing age, weight, body surface area, gender, intraoperative details, anesthetics, postoperative temperatures, hemodynamics, and therapeutics in shivering vs nonshivering patients. (2) To describe temperatures, hemodynamics, therapeutics, myocardial oxygen consumption correlates (rate-pressure product, heart rate, systemic vascular resistance) in shivering and nonshivering groups, and shivering and nonshivering periods. (3) To characterize the electromyogram to determine whether the tremor is cold-induced.

METHODS

A descriptive design with a time series component was used to study a convenience sample of 10 shivering and 10 nonshivering adults for 4 hours during early recovery from cardiac surgery. Pulmonary artery and skin (facial, calf, trunk) temperature were measured every 60 seconds; heart rate and arterial pressure, every 15 minutes; cardiac output, 3 times. Electromyogram was recorded intermittently. Medications and treatments were noted.

RESULTS

Lower skin temperature was significantly related to shivering risk. Heart rate was significantly higher initially in shiverers and remained higher by 13.6 beats per minute. Significantly more nitroprusside was used to control arterial pressure before than after shivering. No significant differences were noted between groups in core temperature, age, weight, body surface area, anesthesia type, intraoperative temperature; or surgery, circulatory bypass, or cardiac cross-clamp duration. The electromyogram pattern during shivering was typical of that produced by cold.

CONCLUSIONS

These results suggest that true shivering occurs after cardiac surgery. Skin, but not core, temperature and elevated heart rate predict shivering. Shivering may be more likely in hemodynamically unstable patients.