Neonatal Hypothermia

A Method to Provide Neuroprotection After Hypoxic Ischemic Encephalopathy

Katherine M. Newnam, MS, RN, CPNP, NNP-BC; Donna L. DeLoach, MS, RN, CPNP, NNP-BC

Disclosures

NAINR. 2011;11(3):113-124. 

In This Article

Nursing Care of the Patient Receiving Hypothermia

The bedside nurse is responsible for providing cardiorespiratory monitoring and pulse oximetry. The nurse must be aware that hypothermia will induce changes in the baseline parameters of vital signs, and therefore, assessment parameters are adjusted accordingly. The most common change seen with hypothermia is a reduction of the infant's heart rate. The heart rate can be expected to fall by 14 beats per degree centigrade between the temperature ranges of 37 to 33 in infants.[30]

Preparing the infant in a timely manner for placement of central vascular access on arrival to the NICU is a key component to care. An umbilical arterial catheter is commonly required for arterial blood sampling and continuous monitoring of blood pressure. An umbilical venous catheter or central venous line is also necessary for venous access to deliver fluids, nutritional support, medications, and blood products that will be urgently needed. In hypoxic or "shock states," peripheral intravenous access is often challenging to obtain and maintain.[29]

Placement of an indwelling urinary catheter will be necessary to monitor urinary output. Low urinary output may be secondary to hypovolemia and should be treated accordingly with volume administration. The output may also be affected by decreased myocardial contractility.[30] Using serum electrolyte measurements and monitoring urinary output are essential to recognizing avascular tubular necrosis or syndrome of inappropriate antidiuretic hormone secretion, which are conditions resulting from the initial hypoxic event.[33]

The infant may require resuscitative efforts for cardiopulmonary failure and will need intubation and ventilator support, including nitric oxide. Continuous pulse oximetry provides an accurate measurement of the oxygen saturation status, and the bedside nurse should be in tuned to needed adjustments in oxygen regardless of delivery method for this critical patient. Blood gases analysis will be affected by the temperature of the patient and should be interpreted accordingly. It is the nurse's responsibility to record the patient's temperature so that the blood gas analyzer can be programmed properly to ensure accurate blood gas analysis. At lower temperatures, more CO2 is absorbed into the gas. Thoresen and Whitelaw[30] explain that the partial pressure of CO2 is reduced approximately 4% for each degree centigrade that the core temperature is reduced. In addition, the reduced metabolism of the hypothermic infant reduces carbon dioxide production, resulting in hypocapnia. The goal is to keep CO2 within a reference range because the seizure threshold may be lower with alkalosis secondary to hypocapnia.[30] Small effects are also noted on the Pao2 and pH as a result of hypothermia; however, they are considered insignificant and adjustment is not indicated. The infant would benefit from more frequent turning with close monitoring of suctioning need because the secretions are thicker during hypothermia.[30] Saline instillation may be necessary to maintain endotracheal tube patency.

The infant is also at risk for infection secondary to central line placement, and a baseline complete blood count and surveillance blood culture are indicated. It is the nurse's responsibility to observe strict aseptic technique with all handling of central lines, when managing intravenous therapy, medication administration, and blood sampling.

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