The Evidence Base for Nursing Care and Monitoring of Patients During Therapeutic Temperature Management

Abstract

Therapeutic temperature management (TTM) is fast becoming a primary management strategy for a variety of medical conditions treated in critical care settings throughout the world. Nurses who provide direct care and who are tasked with developing multidisciplinary protocols and pathways are struggling to collate evidence from which to support specific nursing interventions. The aim of this project was to create the first comprehensive set of evidence-based guidelines specific to nursing care of the patient for whom TTM is medically necessary. Evidence-based nursing practice summaries are provided for nine nursing content areas: interventions to manage temperature, monitoring temperature, neurologic, cardiac, pulmonary, skin care, gastrointestinal/endocrine, laboratory findings, and general considerations for nursing care.

Background

The first portion of the new millennia has seen a resurgent effort toward controlling the temperature of patients who have, or are at risk for, secondary brain injury. In 2005, the American Hospital Association (AHA) and the International Liaison Committee on Resuscitation (ILCOR) both issued guidelines that support aggressive use of therapeutic hypothermia (AHA, 2006; ICLOR, 2006). Several authors have provided articles that summarize medical and nursing treatment of patients who are treated with hypothermia (Holden and Makic, 2006; Bernard, 2009; Polderman and Herold, 2009; Seder and Van der Kloot, 2009). However, the literature supporting specific nursing monitoring and management considerations has not been summarized.

Patient assessment and monitoring is a hallmark of nursing practice. Until 2005, there were no international guidelines that supported the use of induced hypothermia outside the bounds of a randomized clinical trial. Currently, therapeutic temperature management (TTM) is clinically indicated for hypothermia after cardiac arrest, therapeutic rewarming for accidental hypothermia, postsurgical hypothermia, induced normothermia after traumatic brain injury, and for secondary brain injury prevention (Grossman et al., 2002; Hypothermia After Cardiac Arrest Study Group, 2002). Hypothermia may provide benefit for ischemic and hemorrhagic stroke, but further research is needed (Linares and Mayer, 2009).

Nurses are often tasked with protocol development, which includes assessment and monitoring of the TTM patient. However, concise summary of the evidence to support TTM assessment and monitoring within the domain of nursing care is lacking in the literature. The purpose of this manuscript is to provide a foundation for the development of evidence-based practice protocols specifically addressing the role of the nurse in providing care to patients receiving TTM.

This is a review article to summarize areas of nursing practice for TTM; this is not a systematic review of TTM. The impact of temperature manipulation on major physiologic systems is explored and guidelines for assessment and management are discussed as they relate to the delivery of nursing care within the current body of evidence. Because a compilation of this evidence does not currently exist, it is anticipated that this article will offer a point of departure for future manuscripts that seek to develop and clarify the nurse's role in assessment and planning to care for patients during TTM.

Methods

This literature search was completed using Medline (PubMed) and limited to the years 2000–2010. Additional studies from years prior to 2000 were included if they were cited as primary source articles in manuscripts published after 2000, and they were considered by the authors to provide key evidence. The initial search was performed using the following MeSH term combinations: hypothermia + nursing, normothermia + nursing, temperature + nursing.

After removing duplicate references, references prior to the year 2000, and non-human studies, we reviewed 941 articles for title and abstract (Table 1). There were 165 articles considered for full-read inclusion that met the following criteria: included an abstract; adult population of inpatient; included a cardiac, traumatic brain injury, or stroke diagnosis; or the setting was described as critical care. Articles were then excluded for the following reasons: not ICU population (27), not adult population ( 23), not about therapeutic hypothermia or temperature manipulation (26), opinion/editorial articles not designed as literature reviews (26), article not available in English (16), not human subjects (2), and 15 articles that were not available online nor in the Duke University Medical Center Library. These exclusions resulted in 30 full-text articles (Henker, 2000; Sund-Levander and Wahren, 2000; Cohen et al., 2002; Grossman et al., 2002; Price et al., 2003; Holtzclaw, 2004; Farnell et al., 2005; Loke et al., 2005; Hooper and Andrews, 2006; Woodrow et al., 2006; Ferguson, 2007; Henker and Carlson, 2007; Kiekkas et al., 2007; Thompson et al., 2007; Badjatia et al., 2008; Bassin et al., 2008; Christian et al., 2008; Hay et al., 2008; Hoyt et al., 2008; Kiekkas et al., 2008; Morita et al., 2008; Olson et al., 2008; Wolfrum et al., 2008; Kheirbek et al., 2009; Melhuish, 2009; Sagalyn et al., 2009; Bigham et al., 2010; Claridge et al., 2010; McNett and Gianakis, 2010; Skulec et al., 2010). There were four additional articles included because they were found through the list of references and passed title, abstract, and full-read inclusion criteria (Gupta et al., 2002; Badjatia et al., 2007; Polderman and Herold, 2009; Choi et al., 2011). One final article, which was published after the initial peer-review of this manuscript, was also selected for inclusion (Clifton et al., 2011).

Table 1.

Number of Articles Retrieved for Each Combination of MeSH Terms

		MeSH term
		Nursing	Patient care management	Nursing assessment
MeSH term	Hypothermia	274	354	107
	Normotheria	8	17	3
	Temperature	739	1003	279

An evidence table was developed to summarize the 35 articles (Table 2). Each article was explored for the following content areas: method of cooling; temperature monitoring; neurologic, cardiac, pulmonary, skin/integumentary, gastrointestinal, or endocrine; and laboratory data. Additionally, a general considerations category was added for articles with a significant finding relating to nursing care outside of the aforementioned categories.

Table 2.

Nursing Content Areas Discussed in Each Article

First author	Year	Cooling method	Monitoring	Neurologic	Cardiac	Pulmonary	Integumentary	GI/Endocrine	Laboratory	Other
Badjatia	2007			X
Badjatia	2008			X				X	X
Bassin	2008	X
Bigham	2010	X
Choi	2011						X			X
Christian	2008
Claridge	2010					X
Clifton	2011		X		X			X
Cohen	2002									X
Farnell	2005		X
Ferguson	2007	X	X
Grossman	2002	X		X	X					X
Grupta	2002		X	X
Hay	2008	X								X
Henker	2000		X				X		X
Henker	2007	X	X	X
Holtzclaw	2004		X							X
Hooper	2006		X
Hoyt	2008	X							X
Kheirbek	2009				X	X		X	X
Kiekkas	2008		X	X						X
Kiekkas	2007				X
Loke	2005	X	X
McNett	2010			X
Melhuish	2009							X
Morita	2008	X
Olson	2008	X		X						X
Poldeman	2009				X	X		X	X
Price	2003	X
Sagalyn	2009	X	X
Skulec	2010	X			X			X		X
Sund-Levander	2000			X
Thompson	2007	X
Wolfrom	2008			X	X	X			X	X
Woodrow	2006		X

X=The article addressed this content area.

Each section concludes with a table of recommendations with class and level of evidence (Table 3). The level of evidence is based on standard classification where class is based on the size of the treatment effect and level is an estimate of the certainty of the treatment effect (Gibbons et al., 2003).

Table 3.

Levels of Evidence

	Class I Should be performed	Class IIa Reasonable to perform	Class IIb Not unreasonable	Class III Not helpful – possibly harmful
Level A	Multiple populations and RCTs	Multiple populations and RCTs; conflicting evidence	Multiple populations and RCTs; greater conflicting evidence	Multiple populations and RCTs
Level B	One RCT and/or non-randomized trials	One RCT and/or non-randomized trials; conflicting evidence	One RCT and/or non-randomized trials; greater conflicting evidence	One RCT and/or non-randomized trials
Level C	Consensus, case studies, opinion	Case studies, opinion; no consensus	Case studies, opinion; divergent opinion	Consensus, case studies, opinion

Adapted from Gibbons et al. (2003).

Content Areas

Interventions to manage temperature

We identified 15 articles that provide evidence for nurses regarding methodologies for managing temperature in critically ill patients (Grossman et al., 2002; Price et al., 2003; Loke et al., 2005; Ferguson, 2007; Henker and Carlson, 2007; Thompson et al., 2007; Bassin et al., 2008; Christian et al., 2008; Hay et al., 2008; Hoyt et al., 2008; Morita et al., 2008; Olson et al., 2008; Sagalyn et al., 2009; Bigham et al., 2010; Skulec et al., 2010). The different methods evaluated are categorized into external with device, simple external, intravascular, and other. External TTM with a device is simple and effective (Grossman et al., 2002; Loke, 2005; Christian et al., 2008; Hay et al., 2008). External devices utilizing airflow are more effective than fluid-circulating devices, resulting in patients achieving goal temperature faster and more frequently (Grossman et al., 2002; Loke et al., 2005). Simple external methods (including, but not limited to, ice packs, fans, tepid baths, and infusion of cold or warm intravenous fluid) are commonly used (Thompson et al., 2007; Hoyt et al., 2008; Olson et al., 2008; Bigham et al., 2010; Skulec et al., 2010). Price found fans were not effective in reducing temperature and inconclusive evidence to support other simple external methods. However, intravascular TTM is an accurate method of regulating temperature (Bassin et al., 2008). Portable percutaneous cardiopulmonary bypass has also been reported as an effective and quick method of managing temperature (Morita et al., 2008). Regardless of method, the use of a temperature management clinical pathway or protocol increases the practice of TTM, increases the number of patients meeting temperature goals, and is convenient (Grossman et al., 2002; Hay et al., 2008).

Device-based methods of TTM are reliable and less time-consuming for nurses, though combinations of simple external methods are more commonly used in intensive care units and emergency departments (Bassin et al., 2008; Bigham et al., 2010; Skulec et al., 2010). Multiple simple external methods are independently initiated by nurses to manage temperature (Grossman et al., 2002; Thompson et al., 2007; Olson et al., 2008). Though a variety of simple external methods are utilized, Olson et al. (2008) found no correlation between the priority given to a nursing intervention to manage temperature and the length of time necessary to complete the intervention

Recommendation	Category	Evidence
Nurses should develop protocols that employ a variety of TTM interventions including surface and intravascular interventions	Class IIa	Level B

Monitoring and Assessing Temperature

We identified 10 articles that provide evidence for nurses regarding the site and method of monitoring and assessing temperature (Gupta et al., 2002; Farnell et al., 2005; Loke et al., 2005; Hooper and Andrews, 2006; Woodrow et al., 2006; Ferguson, 2007; Henker and Carlson, 2007; Kiekkas et al., 2008; Sagalyn et al., 2009; Clifton et al., 2011). There is broad disagreement as to the best or most accurate site from which to determine temperature (Hooper and Andrews, 2006; Henker and Carlson, 2007; Sagalyn et al., 2009). The different sites evaluated in this set of manuscripts include: axillary (Farnell et al., 2005; Loke et al., 2005; Ferguson, 2007; Kiekkas et al., 2008); bladder (Ferguson, 2007; Henker and Carlson, 2007; Clifton et al., 2011); brain (Gupta et al., 2002); esophageal (Hooper and Andrews, 2006); oral (Farnell et al., 2005; Hooper and Andrews, 2006); pulmonary artery (Gupta et al., 2002; Farnell et al., 2005; Hooper and Andrews, 2006; Ferguson, 2007); and tympanic (Farnell et al., 2005; Hooper and Andrews, 2006; Ferguson, 2007; Kiekkas et al., 2008).

Pulmonary artery temperature monitoring was most often the referenced source against which other methods were assessed. This requires insertion of an invasive line, but remains the best validated method of continuous temperature monitoring (Gupta et al., 2002; Farnell et al., 2005; Hooper and Andrews, 2006; Ferguson, 2007). Axillary is primarily used because it is easy, but generally provides a lower value than other sites (Farnell et al., 2005; Loke et al., 2005; Ferguson, 2007). Monitoring bladder temperatures is emerging as a convenient method and compares well with oral thermometry (Ferguson, 2007; Henker and Carlson, 2007). Gupta et al. (2002) found that while brain and (pulmonary) arterial temperatures were highly correlated, there is still an unpredictable variability between these two sites that leads the authors to recommend discrete monitoring of the target organ. An esophageal site approximates the pulmonary artery temperature and provides a mechanism of continuous measurement (Hooper and Andrews, 2006).

Monitoring of oral temperatures, while falling out of favor, remains a validate method, but suffers from observer variability if not properly performed (Farnell et al., 2005; Hooper and Andrews, 2006). Tympanic temperatures correlate well with pulmonary artery thermistors, but are dependent on the end user's skill. Additionally, such measurements have not been adequately studied in the setting of TTM and do not provide a mechanism for continuous temperature monitoring (Farnell et al., 2005; Hooper and Andrews, 2006; Ferguson, 2007; Henker and Carlson, 2007). Prior clinical practice guidelines indicate that the rectal route should probably be avoided due to the relative risk of trauma in general, patients at risk for coagulopathy, or those who require neutropenic precautions (O'Grady et al., 1998).

At present, there is insufficient evidence to support any single site. There was limited examination of the need to monitor more than one site at any given time (Kiekkas et al., 2008). There is also a growing trend to monitor temperature continuously rather than obtain intermittent measurements (Gupta et al., 2002; Kiekkas et al., 2008).

Recommendation	Category	Evidence
Nurses should use instruments that provide for continuous temperature monitoring	Class I	Level C
The site of temperature monitoring should include bladder, brain, or esophageal monitoring^*	Class IIa	Level C

Additional evidence exists, but does not include patients undergoing TTM.

Neurologic Considerations

Induced hypothermia is frequently employed in critically ill neurology and neurosurgical patients as an intracranial pressure (ICP) management tool and as a neuroprotection strategy for comatose postcardiac arrest patients (Bernard, 2009; Josephson, 2004). For traumatic brain injury and postoperative neurosurgical patients, induced normothermia is used to treat hypo- or hyperthermia. We identified 12 articles that provide evidence for nurses regarding temperature management strategies and neurologic monitoring and assessment (Sund-Levander and Wahren, 2000; Grossman et al., 2002; Gupta et al., 2002; Holtzclaw, 2004; Badjatia et al., 2007; Henker and Carlson, 2007; Badjatia et al., 2008; Kiekkas et al., 2008; Olson et al., 2008; Wolfrum et al., 2008; McNett and Gianakis, 2010; Choi et al., 2011). The effect on nursing workload during the implementation of temperature management strategies was addressed in five articles (Grossman et al., 2002; Kiekkas et al., 2008; McNett and Gianakis, 2010; Olson et al., 2008; Wolfrum et al., 2008). There were two articles that specifically addressed temperature control therapies and their effect on physiologic parameters that nurses will monitor, and five that addressed recognition, prevention, or treatment of shivering in brain injured patients (Sund-Levander and Wahren, 2000; Gupta et al., 2002; Badjatia et al., 2007; Henker and Carlson, 2007; Badjatia et al., 2008).

TTM implementation and monitoring in neurologic ICU (NICU) patients is similar to other ICU populations with a few exceptions. For nurses taking care of traumatic brain injury patients, up to half will be responsible for managing intracranial device parameters, such as ICP or brain temperature (McNett and Gianakis, 2010). In those with intracranial temperature probes, it should be expected that brain temperature will be 0.5–2.0°C higher than systemic measurements. If the nurse is also monitoring brain tissue oxygen levels (P_btO₂), changing temperature may have variable effects. One study has found that the P_btO₂ will increase when temperature is lowered to 35°C but may decrease if temperature is lowered further (Gupta et al., 2002). As a result of TTM in NICU patients, nursing workload should be expected to increase, and therefore nursing assignments should be planned accordingly (Kiekkas et al., 2008; Olson et al., 2008; McNett and Gianakis, 2010). TTM undertaken by nursing can involve numerous interventions, some of which may require an average of 20 min per maneuver to complete. Nursing may also be required to assist in cooling a patient during cardiac catheterization (Wolfrum et al., 2008). However, the individual effectiveness of many of these therapies is unknown in many cases. These interventions are applied during induction, maintenance, and rewarming of patients undergoing TTM, a therapy that is often utilized for several days.

During all stages of TTM, patients often require sedation and analgesia to facilitate the process of care and reduce the fear and anxiety associated with mechanical ventilation (Jacobi et al., 2002). The ICU sedation literature generally suggests the use of validated observational scales in conjunction with neurofunction monitors and daily wakeup protocols (Dotson, 2010). However, TTM may negate the feasibility of daily wakeups, and the reliability of observational and physiologic tools is not yet established in this population. Neurofunction monitors such as bispectral index have been reported to be used during TTM (Seder and Van der Kloot, 2009). Schmidlin et al. (2001), found that while BIS values were lower associated with lower body temperature, the difference was clinically insignificant. The literature supporting nursing monitoring of sedation during TTM is limited.

In critically ill neurologic patients, the common occurrence of shivering is of particular concern (Holtzclaw, 2004). Prior work suggests that shivering results in increased metabolic demand on the body and the brain (Badjatia et al., 2008). However, recent evidence has begun to question the overall metabolic demand of the shivering patient (Haman et al., 2010). From a recent study testing the bedside shivering assessment scale (BSAS), clinically evident shivering significantly increased metabolism (Badjatia et al., 2007). In brain injured patients, shivering can negate the desired cerebral metabolic suppression that hypothermia induces.

Currently, the BSAS is the only validated scale for assessing shivering at the bedside. However, investigators are beginning to explore the use of physiologic monitors such as derived electromyography to provide additional measures of shivering (Badjatia et al., 2008; May et al., 2011). Additionally, awareness and correction of certain laboratory abnormalities, like hyponatremia and hypomagnesemia, may help reduce shivering (Badjatia et al., 2008). Maneuvers to limit or eliminate shivering should focus on decreasing the temperature gradient between core and peripheral temperatures (Sund-Levander and Wahren, 2000; Henker and Carlson, 2007; Choi et al., 2011). This can be accomplished by a combination of pharmaceutical and nursing interventions, such as covering the patient with blankets or using surface counter-warming devices (Holtzclaw, 2004; Choi et al., 2011).

Recommendation	Category	Evidence
Nurses should monitor for shivering during TTM	Class IIa	Level B
Nurses should monitor sedation using validated observational scales and physiologic monitors	Class IIb	Level C
Nurses should develop and adhere to shivering reduction protocols.	Class IIb	Level C

Cardiac Considerations

We identified seven articles that provide evidence for nurses regarding the assessment and monitoring of the cardiac system (Grossman et al., 2002; Kiekkas et al., 2007; Wolfrum et al., 2008; Kheirbek et al., 2009; Polderman and Herold, 2009; Skulec et al., 2010; Clifton et al., 2011). Standard parameters monitored in the ICU that are reflective of cardiovascular function include heart rate, electrocardiogram (ECG), and arterial blood pressure (Kiekkas et al., 2007). TTM has been reported to affect all three of these parameters. Though heart rate varies in response to changes in temperature, induced hypothermia first produces tachycardia followed by bradycardia as temperature decreases (Kiekkas et al., 2007; Kheirbek et al., 2009; Polderman and Herold, 2009). Multiple ECG changes are noted with TTM, including various dysrhythmias, repolarization abnormalities, and conduction delays. Examples include prolonged PR and QT intervals, J waves, and first degree heart block. However, electrical disturbances are often asymptomatic and may be related to the rate of temperature change (Grossman et al., 2002; Kheirbek et al., 2009; Polderman and Herold, 2009). If intervention is required to increase heart rate, using chronotropic drugs or transvenous pacing may decrease myocardial contractility (Polderman and Herold, 2009). TTM also causes an increase in systemic vascular resistance (SVR) and central venous pressure (CVP). Hypovolemia secondary to diuresis may occur during TTM (Polderman and Herold, 2009). However, there is no clear recommendation for adjusting the frequency of intake and output documentation routines. Skulec et al. (2010) found that 62.2% of ICUs routinely utilized goal-directed therapy early in the application of TTM, including a combination CVP and mean arterial pressure (MAP) monitoring.

Although a variety of hemodynamic changes are cited as being associated with TTM, Wolfrum et al. (2008) found no difference in left ventricular function and use of catecholamines between patients treated with TTM and those not treated with TTM. Similarly, Clifton et al. (2011) report no significant difference in cardiac complications for patients during TTM. All six articles mention cardiac changes associated with TTM, though only one defines standard parameters of monitoring in the ICU. All six articles fail to define the standard for frequency of monitoring in patients undergoing TTM. None of the articles mentions if noninvasive cardiac output monitoring is as effective as a pulmonary artery catheter for measuring hemodynamics during TTM.

Recommendation	Category	Evidence
Nurses should monitor for cardiac arrhythmias	Class IIa	Level C
Nurses should monitor blood pressure from an intra-arterial line	Class IIa	Level C
Nurses should include measure of circulatory volume such as CVP and SVR during TTM	Class IIb	Level C

Pulmonary System Considerations

We identified four articles that provide evidence for nurses regarding the assessment and monitoring of the pulmonary system (Wolfrum et al., 2008; Kheirbek et al., 2009; Polderman and Herold, 2009; Claridge et al., 2010). Wolfrum et al. (2008) found that, though neuromuscular blockade was not consistently used, patients treated with mild therapeutic hypothermia stayed on mechanical ventilation considerably longer. Prolonged mechanical ventilation, combined with relative immune suppression including decreased cytokine production and neutrophil migration, may predispose patients to respiratory infection. However, findings from a recent study fail to find an association between positive respiratory cultures and a specific range of temperatures (Claridge et al., 2010). However, prevention of pneumonia is of great concern to nurses, particularly during the maintenance phase of TTM. Strategies focusing on preventing pneumonia should be emphasized (Polderman and Herold, 2009). However, guidelines only exist for preventing ventilator-associated pneumonia in those not undergoing TTM (Grap et al., 2004; Munro et al., 2009). Adjusting ventilator settings during induction due to changes in oxygen consumption and carbon dioxide production has been recommended (Polderman and Herold, 2009). Frequent arterial blood gases are also recommended, especially during induction; however, the frequency of monitoring is not specified (Polderman and Herold, 2009).

Recommendation	Category	Evidence
Nurses should include and employ pneumonia prevention strategies for patients during TTM^*	Class IIa	Level B
Nurses should coordinate care with physicians and respiratory care therapists to change ventilator settings during the induction phase of TTM^*	Class IIa	Level C
Nurses should include frequent arterial blood gas monitoring in TTM protocols	Class IIb	Level C

Additional evidence exists, but does not include patients undergoing TTM.

Skin Care

We identified two articles that specifically address considerations for skin care and assessment (Henker, 2000; Choi et al., 2011). One additional article, which provides a comprehensive overview of the literature for temperature management, was included (Polderman and Herold, 2009). There is evidence that the skin surface is sensitive to changes in temperature, and counterwarming may provide a strategy for reducing shivering during TTM (Henker, 2000; Polderman and Herold, 2009; Choi et al., 2011. There is evidence to support that blood flow to the skin is decreased (Henker, 2000; Polderman and Herold, 2009). Polderman and Herold (2009) advocate that nurses should provide additional skin care when patients are being cooled because the increased risk of infection combined with decreased microcirculation increases the risk for decubitis ulcer manifestation and exacerbation. Although frequent turning has been linked to pressure ulcer prevention, we found no studies which provided direct evidence to guide the frequency of reposition for patients during TTM (Hagisawa et al., 2008).

Recommendation	Category	Evidence
Nurses should reposition patients at least once every 2 h during TTM^*	Class IIa	Level C
Nurses should monitor for skin breakdown associated with TTM^*	Class IIa	Level B
Consider counterwarming measures to reduce shivering associated with TTM	Class IIa	Level C

Additional evidence exists, but does not include patients undergoing TTM.

GI and Endocrine Considerations

We identified five articles that provide evidence for guidance for nurses assessing the gastrointestinal and endocrine systems (Badjatia et al., 2008; Kheirbek et al., 2009; Melhuish, 2009; Polderman and Herold, 2009; Skulec et al., 2010). TTM is associated with decreased bowel function and gastric emptying, but there is minimal evidence to support a preferred formulation of feeding or an optimal time for initiation of enteral nutrition (Badjatia et al., 2008; Polderman and Herold, 2009; Skulec et al., 2010). Skulec et al. (2010) found the largest percentage of ICUs began feeding the patient after rewarming, while others began during TTM or on the third day after admission. Seventy percent of ICUs used enteral feeding combined with parenteral feeding. A consistently reported side effect of TTM is insulin resistance, with hyperglycemia reported typically during induction (Kheirbek et al., 2009; Melhuish, 2009; Polderman and Herold, 2009). Melhoiush (2009) recommends intravenous insulin therapy during TTM guided by a software-based glucose management system rather than paper-based insulin protocols. While hyperglycemia is seen during induction, hypoglycemia may occur during rewarming due to decreasing insulin requirements (Polderman and Herold, 2009). Three articles discuss tight control of glucose with frequent assessments though none of the articles specify how often to obtain measurements (Kheirbek et al., 2009; Melhuish, 2009; Polderman and Herold, 2009). One article reports an increase in liver enzymes and serum amylase during TTM, though there are no recommendations regarding the frequency of monitoring (Polderman and Herold, 2009).

Recommendation	Category	Evidence
Nurses should frequently monitor blood glucose during TTM^*	Class IIa	Level C
Nurses should treat abnormal blood glucose using established intravenous insulin therapy protocols^*	Class IIb	Level C
Nurses should initiate, maintain nutritional support, and monitor the nutritional status of patients during TTM	Class IIa	Level C
Nurses should develop protocols that include monitoring of liver enzymes and amylase	Class IIa	Level C

Additional evidence exists, but does not include patients undergoing TTM.

Considerations for Laboratory Findings

For the patient undergoing TTM, laboratory parameters may be altered by changes in body temperature. We identified seven articles that provide guidance for nurses regarding laboratory findings (Henker, 2000; Badjatia et al., 2008; Hoyt et al., 2008; Wolfrum et al., 2008; Kheirbek et al., 2009; Polderman and Herold, 2009; Clifton et al., 2011). This is true for therapeutic hypothermia and induced normothermia where changes in coagulation and electrolyte homeostasis should be expected in many circumstances. Coagulopathy is a common occurrence in the patient who is hypothermic and is directly related to the temperature of the patient. Due to temperature-related effects on the function of coagulation factors and platelets, moderate to deep hypothermia (<28–33°C) typically results in a higher risk of bleeding (Kheirbek et al., 2009). This is especially true for the patient with multisystem trauma who is suffering from hemorrhagic shock. In these circumstances, coagulopathy is multifactorial and is the result of massive blood loss, shock, as well as hypothermia. For such patients, most physicians recommend checking clotting parameters including PT/PTT and platelets early in the admission in addition to monitoring pH and blood loss (Hoyt et al., 2008; Clifton et al., 2011). If the patient requires massive red blood cell transfusion, plasma and coagulation factors are transfused as well. For a patient undergoing mild to moderate therapeutic hypothermia, increased bleeding may occur and checking coagulation parameters is advised in order to prevent bleeding (Wolfrum et al., 2008). Coagulopathy as a result of hypothermia may also occur in the operative setting where core temperature is significantly decreased either intentionally (i.e., cardiothoracic procedures) or incidentally (i.e., long, open abdominal procedures; Polderman and Herold, 2009).

Electrolyte abnormalities should be expected during TTM in many cases. For the patient undergoing therapeutic hypothermia, colder temperatures can produce diuresis and intracellular shift of potassium and magnesium. “Cold diuresis” may also lead to hypovolemia if intake and output are not carefully monitored; some evidence supports that more rapid cooling moderates the fluid and electrolyte shifts associated with hypothermia (Polderman and Herold, 2009). Clifton et al. (2011) report significantly lower potassium levels during hypothermia. For patients with brain injury, fluid balance disorders like cerebral salt wasting or the administration of diuretics such as mannitol or furosemide will have an additive effect on volume and electrolyte loss. A reduction in the serum concentrations of magnesium and potassium can predispose a patient to dangerous arrhythmias. Low serum magnesium is of concern in the setting of brain injury and increased ICP because low magnesium is associated with a higher incidence of shivering (Badjatia et al., 2008). Supplementation of these electrolytes is often necessary but must be done with caution. During rewarming, potassium will shift out of the cell; if potassium has been aggressively replaced during cooling, this shift may result in hyperkalemia. One final concern relates to infection surveillance in the critically ill undergoing TTM. Hypothermia or induced normothermia may mask a febrile response to bacteremia. Therefore, the decision to obtain blood cultures may need to be made based primarily on laboratory and radiologic data (Badjatia et al., 2008).

Recommendation	Category	Evidence
Nurses should employ strategies to monitor laboratory values that signal increased risk of bleeding^*	Class IIb	Level C
Nurses should employ strategies to monitor laboratory values associated with electrolyte changes^*	Class IIa	Level C

Additional evidence exists, but does not include patients undergoing TTM.

General Considerations

A fair number of authors provided evidence for interventions and considerations not described above (Cohen et al., 2002; Grossman et al., 2002; Hay et al., 2008; Kiekkas et al., 2008; Olson et al., 2008; Wolfrum et al., 2008; Skulec et al., 2010). The impact of hypothermia on nursing work or nursing workload was explored in three studies with conflicting results (Hay et al., 2008; Kiekkas et al., 2008; Olson et al., 2008). Two articles found an increase in nursing workload associated with various nursing interventions required during TTM (Kiekkas et al., 2008; Olson et al., 2008). There is additional work associated with TTM requiring nurses to frequently monitor for hypovolemia and bleeding (Grossman et al., 2002; Wolfrum et al., 2008). However, Hay et al found that the implementation of TTM did not result in a net increase in resource utilization or nursing burden (Hay et al., 2008).

There is minimal evidence guiding nursing decisions regarding sedation and analgesia during TTM. Skulec et al. (2010) reports on the use of midazolam and sufentanyl in combination with neuromuscular blockade agents. Choi et al. (2011) report that nurses could implement and maintain sedation during TTM using a sedation algorithm.

Recommendation	Category	Evidence
Work assignments should be adjusted for patients undergoing TTM	Class IIb	Level C
Nurses should use sedation assessment and treatment algorithms during TTM^*	Class IIb	Level C

Additional evidence exists, but does not include patients undergoing TTM.

Discussion

This article extends the work of several prior publications which have provided excellent reviews of TTM for patients at risk for secondary brain injury. Bernard (2009) recently summarized TTM within the scope of hypothermia after cardiac arrest. Two recent articles provide a summary for understanding the mechanics of implementing TTM (Polderman and Herold, 2009; Seder and Van der Kloot, 2009). Holden and Makic (2006) provide an excellent summary of literature supporting induced hypothermia with recommendations for specific nursing care considerations.

The primary limitation of this article derives from the depth and scope of literature on which to base specific recommendations. As the purpose of this article was to provide information to support evidence-based nursing practice, the literature was deliberately confined to address nursing care concerns specific to TTM. There is a wide variety of literature available on hypothermia and TTM that does not address the role of the nurse; this literature in not included in this review. Equally, there is a wide variety of literature that addresses nursing care, which is not included in this review because the studies do not address TTM. Although the literature search described above was designed to be both broad and inclusive as possible, it is possible that there are articles not included in this review that may provide additional understanding for nursing care of patients during TTM.

The majority of the nursing care recommendations made in this article are based on only a few articles (level C). Much of the current evidence is based on case studies, opinion, or a single randomized trial. Another large portion of the evidence cited comes from nursing care interventions that were tested in non-TTM populations. This review focuses specifically on nursing care during TTM and therefore provides a platform for discovery and research. The article highlights the need for additional research specifically targeted at determining the role and contribution of nurses who provide care for patients during TTM.

Conclusion

There is a growing body of literature to support evidence-based practice recommendations for nursing care of patients during TTM. We found 33 articles that provided data for 22 recommendations across 10 nursing care content areas. Most recommendations have limited evidence specific to nursing care of TTM. Future nursing research should include randomized trials, which provide specific evidence to define the role and contributions of nursing care during TTM more precisely.

Footnotes

Disclosure Statement

The authors received a $3,000 unrestricted educational grant from Zoll Medical.

References

2005 American Heart Association (AHA) guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) of pediatric and neonatal patients: pediatric basic life support. Pediatrics, 2006; 117:e989–1004.

Badjatia

, Kowalski

, Schmidt

et al. Predictors and clinical implications of shivering during therapeutic normothermia. Neurocrit Care, 2007; 6:186–191.

Badjatia

, Strongilis

, Gordon

et al. Metabolic Impact of shivering during therapeutic temperature modulation. The bedside shivering assessment scale. Stroke, 2008; 39:3242–3247.

Bassin

, Bleck

, Nathan

. Intravascular temperature control system to maintain normothermia in organ donors. Neurocrit Care, 2008; 8:31–35.

Bernard

. Hypothermia after cardiac arrest: expanding the therapeutic scope. Crit Care Med, 2009; 37:S227–233.

Bigham

, Dainty

, Scales

, Morrison

, Brooks

. Predictors of adopting therapeutic hypothermia for post-cardiac arrest patients among Canadian emergency and critical care physicians. Resuscitation, 2010; 81:20–24.

Choi

, Ko

, Presciutti

et al. Prevention of shivering during therapeutic temperature modulation: the Columbia anti-shivering protocol. Neurocrit Care, 2011; 14:389–394.

Christian

, Zada

, Sung

, Giannotta

. A review of selective hypothermia in the management of traumatic brain injury. Neurosurg Focus, 2008; 25:E9.

Claridge

, Golob

Jr. , Leukhardt

et al. The “fever workup” and respiratory culture practice in critically ill trauma patients. J Crit Care, 2010; 25:493–500.

10.

Clifton

, Valadka

, Zygun

et al. Very early hypothermia induction in patients with severe brain injury (the National Acute Brain Injury Study: Hypothermia II): a randomised trial. Lancet Neurol., 2011; 10:131–139.

11.

Cohen

, Hayes

, Tordella

, Puente

. Thermal efficiency of prewarmed cotton, reflective, and forced-warm-air inflatable blankets in trauma patients. Int J Trauma Nurs, 2002; 8:4–8.

12.

Dotson

. Daily interruption of sedation in patients treated with mechanical ventilation. Am J Health Syst Pharm, 2010; 67:1002–1006.

13.

Farnell

, Maxwell

, Tan

, Rhodes

, Philips

. Temperature measurement: comparison of non-invasive methods used in adult critical care. J Clin Nurs, 2005; 14:632–639.

14.

Ferguson

. Evaluation and treatment of fever in intensive care unit patients. Crit Care Nurs Q, 2007; 30:347–363.

15.

Gibbons

, Smith

Jr. , Antman

. American College of Cardiology/American Heart Association clinical practice guidelines: Part II: evolutionary changes in a continuous quality improvement project. Circulation, 2003; 107:3101–3107.

16.

Grap

, Munro

. Preventing ventilator-associated pneumonia: evidence-based care. Crit Care Nurs Clin North Am, 2004; 16:349–358.

17.

Grossman

, Bautista

, Sullivan

. Using evidence-based practice to develop a protocol for postoperative surgical intensive care unit patients. Dimens Crit Care Nurs, 2002; 21:206–214.

18.

Gupta

, Al-Rawi

, Hutchinson

, Kirkpatrick

. Effect of hypothermia on brain tissue oxygenation in patients with severe head injury. Br J Anaesth, 2002; 88:188–192.

19.

Hagisawa

, Ferguson-Pell

. Evidence supporting the use of two-hourly turning for pressure ulcer prevention. J Tissue Viability, 2008; 17:76–81.

20.

Haman

, Blondin

, Imbeault

, Maneshi

. Metabolic requirements of shivering humans. Front Biosci (Schol Ed), 2010; 2:1155–1168.

21.

Hay

, Swann

, Bell

, Walsh

, Cook

. Therapeutic hypothermia in comatose patients after out-of-hospital cardiac arrest. Anaesthesia, 2008; 63:15–19.

22.

Henker

. Use of blood cultures in critically ill patients. Crit Care Nurse, 2000; 20:45–50.

23.

Henker

, Carlson

. Fever: applying research to bedside practice. AACN Adv Crit Care, 2007; 18:76–87.

24.

Holden

, Makic

. Clinically induced hypothermia: why chill your patient? AACN Adv Crit Care, 2006; 17:125–132.

25.

Holtzclaw

. Shivering in acutely ill vulnerable populations. AACN Clin Issues, 2004; 15:267–279.

26.

Hooper

, Andrews

. Accuracy of noninvasive core temperature measurement in acutely ill adults: the state of the science. Biol Res Nurs, 2006; 8:24–34.

27.

Hoyt

, Dutton

, Hauser

et al. Management of coagulopathy in the patients with multiple injuries: results from an international survey of clinical practice. J Trauma, 2008; 65:755–764; discussion 764–755.

28.

Jacobi

, Fraser

, Coursin

et al. Clinical practice guidelines for the sustained use of sedatives and analgesics in the critically ill adult. Crit Care Med, 2002; 30:119–141.

29.

Josephson

. Management of increased intracranial pressure: a primer for the non-neuro critical care nurse. Dimens Crit Care Nurs, 2004; 23:194–207.

30.

Kheirbek

, Kochanek

, Alam

. Hypothermia in bleeding trauma: a friend or a foe? Scand J Trauma Resusc Emerg Med, 2009; 17:65.

31.

Kiekkas

, Brokalaki

, Manolis

, Askotiri

, Karga

, Baltopoulos

. Fever and standard monitoring parameters of ICU patients: a descriptive study. Intensive Crit Care Nurs, 2007; 23:281–288.

32.

Kiekkas

, Sakellaropoulos

, Brokalaki

et al. Nursing workload associated with fever in the general intensive care unit. Am J Crit Care, 2008; 17:522–531.

33.

Linares

, Mayer

. Hypothermia for the treatment of ischemic and hemorrhagic stroke. Crit Care Med Jul, 2009; 37:S243–249.

34.

Loke

, Chan

. Comparing the effectiveness of two types of cooling blankets for febrile patients. Nurs Crit Care, 2005; 10:247–254.

35.

May

, Seder

, Fraser

et al. Association of the Bedside Shivering Assessment Scale and derived EMG power during therapeutic hypothermia in survivors of cardiac arrest. Resuscitation, 2011; 82:1100–1103.

36.

McNett

, Gianakis

. Nursing interventions for critically ill traumatic brain injury patients. J Neurosci Nurs, 2010; 42:71–77; quiz 78–79.

37.

Melhuish

. Linking hypothermia and hyperglycemia. Nurs Manage, 2009; 40:42–45.

38.

Morita

, Inokuchi

, Inoue

et al. The efficacy of rewarming with a portable and percutaneous cardiopulmonary bypass system in accidental deep hypothermia patients with hemodynamic instability. J Trauma, 2008; 65:1391–1395.

39.

Munro

, Grap

, Jones

, McClish

, Sessler

. Chlorhexidine, toothbrushing, and preventing ventilator-associated pneumonia in critically ill adults. Am J Crit Care, 2009; 18:428–437; quiz 438.

40.

O'Grady

, Barie

, Bartlett

et al. Practice guidelines for evaluating new fever in critically ill adult patients. Task Force of the Society of Critical Care Medicine and the Infectious Diseases Society of America. Clin Infect Dis, 1998; 26:1042–1059.

41.

Olson

, Kelly

, Washam

, Thoyre

. Critical care nurses' workload estimates for managing patients during induced hypothermia. Nurs Crit Care, 2008; 13:305–309.

42.

Polderman

, Herold

. Therapeutic hypothermia and controlled normothermia in the intensive care unit: practical considerations, side effects, and cooling methods. Crit Care Med, 2009; 37:1101–1120.

43.

Price

, McGloin

, Izzard

, Gilchrist

. Cooling strategies for patients with severe cerebral insult in ICU (Part 2) Nurs Crit Care, 2003; 8:37–45.

44.

Sagalyn

, Band

, Gaieski

, Abella

. Therapeutic hypothermia after cardiac arrest in clinical practice: review and compilation of recent experiences. Crit Care Med., 2009; 37:S223–226.

45.

Schmidlin

, Hager

, Schmid

. Monitoring level of sedation with bispectral EEG analysis: comparison between hypothermic and normothermic cardiopulmonary bypass. BR J Anaesth, 2001; 86:769–776.

46.

Seder

, Van der Kloot

. Methods of cooling: practical aspects of therapeutic temperature management. Crit Care Med, 2009; 37:S211–222.

47.

Skulec

, Truhlar

, Knor

, Seblova

, Cerny

. The practice of therapeutic mild hypothermia in cardiac arrest survivors in the Czech republic. Minerva Anestesiol, 2010; 76:617–623.

48.

Sund-Levander

, Wahren

. Assessment and prevention of shivering in patients with severe cerebral injury. A pilot study. J Clin Nurs, 2000; 9:55–61.

49.

The Hypothermia After Cardiac Arrest Study Group. Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest. N Engl J Med, 2002; 346:549–556.

50.

The International Liaison Committee on Resuscitation (ILCOR) consensus on science with treatment recommendations for pediatric and neonatal patients: pediatric basic and advanced life support. Pediatrics, 2006; 117:e955–977.

51.

Thompson

, Kirkness

, Mitchell

, Webb

. Fever management practices of neuroscience nurses: national and regional perspectives. J Neurosci Nurs, 2007; 39:151–162.

52.

Wolfrum

, Pierau

, Radke

, Schunkert

, Kurowski

. Mild therapeutic hypothermia in patients after out-of-hospital cardiac arrest due to acute ST-segment elevation myocardial infarction undergoing immediate percutaneous coronary intervention. Crit Care Med, 2008; 36:1780–1786.

53.

Woodrow

, May

, Buras-Rees

et al. Comparing no-touch and tympanic thermometer temperature recordings. Br J Nurs, 2006; 15:1012–1016.