Treatment Implementation and Monitoring
Once it has been determined that the infant will receive TH and informed consent has been obtained, many steps must occur to implement treatment during the therapeutic window. Preparation includes setting up the cooling device, assisting with placement of central or peripheral access lines, obtaining blood samples for baseline laboratory tests, and initiating passive cooling if possible. Before cooling begins, a rectal or esophageal temperature probe will be placed to monitor core temperatures. Esophageal placement will be verified by chest x-ray. Additionally, an axillary temperature probe attached to the warmer bed may be used though the heating element should be off.
After preparation is complete, initiate cooling and begin monitoring of temperatures, vital signs, laboratory results, and aEEG if applicable. Monitoring schedule will vary by institution but often starts with core, axillary, and water temperature every 15 minutes for 2–4 hours and then spaces out to every 30–60 minutes. Blood pressure, heart rate, respiratory rate, and pre-ductal and post-ductal oxygen saturations are often documented on the same schedule as temperatures. Expect for the cooled infant's heart rate to be lower than usual, often below 100 beats per minute. Lower heart rates are tolerated as long as there is sinus heart rhythm and perfusion and blood pressure remain adequate. Additionally, serial monitoring of serum electrolytes, BUN and creatinine, blood glucose, blood gases, prothrombin time (PT), partial prothrombin time (PPT), and international normalized ration (INR) may be done.
Because infants with NE are at risk for developing seizures, monitoring for seizure activity is imperative to prompt treatment. Stiffening, rhythmic movements of one or more extremity, and repetitive sucking or extension of the tongue are signs of seizure activity. Amplitude-integrated EEG (aEEG) is a newer, continuous brain monitoring technique that is useful for detecting seizures, especially in sedated infants. Since aEEG is a bedside device that may be more widely available than continuous full channel array video EEG, it allows nurses to play a critical role in brain monitoring. Routine use in asphyxiated and cooled infants has become more common because training is simple and users are able to easily detect abnormal activity. Subsequent early detection and notification of the provider allow for early treatment of seizures, which can lead to improved outcomes.
Continuous assessment of skin and monitoring for pain are also important during TH. Skin complications such as subcutaneous fat necrosis and cold panniculitis may occur. Each present with painful, reddened or bluish-purple indurated areas over the skin that was in contact with the cooling device. Periodic mobilization and turning, if tolerated by the infant, can prevent these complications. Additional treatment may be required if skin complications occur.
The infant's level of stress and agitation is greatly affected by his or her comfort level. Additionally, excess agitation or activity due to pain can lead to increased temperatures and difficulty reaching the target temperature. Pain scores should be performed routinely so that appropriate interventions can be implemented. However, infants undergoing TH are frequently treated with anti-epileptics, which are sedating, or are otherwise sedated and ventilated, so pain scoring may not be a reliable measure. In this case, monitoring vital signs closely for increases in heart rate and blood pressure can help in assessment of pain. Neither the NICHD Whole Body Hypothermia trial, nor the TOBY, ICE, or CoolCap trials included sedation or pain control as part of the study intervention. There is no standard or recommended clinical approach to use of sedatives or pain control for infants with NE undergoing cooling.
Rewarming
Rewarming begins after 72 hours of cooling. The automatic mode of the cooling device will be changed to allow a gradual increase in temperature of 0.5 °C per hour until a core temperature of 36.5 °C is reached. The device will then be used to hold the infant's temperature at 36.5 °C for 24 hours. Serial monitoring of core temperature during this time is imperative to prevent overheating. Hyperthermia is associated with poorer outcomes in infants that experience NE.
Parental Support
Throughout the cooling process, nurses also have the responsibility of supporting parents through a scary and unpredictable situation. Parents may have feelings of helplessness, fear, and uncertainty when their newborn is critically ill. They also feel a loss of control since the care of the infant is transferred to the nurses and healthcare providers. Nursing staff can support parents by offering education, opportunities to participate in care, and limiting separation when possible.