Therapeutic Hypothermia, Treatment of Hypoxic Ischemic Encephalopathy, Part 2, by Denise
Casey.
We'll now begin to discuss pre-hospital management for patients with hypoxic ischemic encephalopathy.
Pre-Hospital Management.
We advise our outside referring hospitals to passively cool infants with suspected HIE.
For passive cooling, we ask that they remove all external heat sources, turn the radiant
warmer off, and upon transport team's arrival, they will shut the isolette off.
And we have found that infants achieve a target temperature quicker with passive cooling when
initiated at our referring institutions.
There was a small study completed at our institution of 27 infants who were passively cooled.
Their temperatures upon arrival were 33.8 plus or minus 1.3 degrees.
The majority of patients were within our targeted range, and we were then able to jump right
into the maintenance phase of the protocol, achieving our goal of getting these patients
cooled by six hours.
Currently, we are looking into a process for active cooling on transport to ensure tighter
control of temperatures as well as achieving goal temperatures quicker.
While awaiting the transport team arrival, the referring team should be monitoring for
evolving neurologic symptoms, such as pupils, level of consciousness, which will help determine
their degree of encephalopathy, respiratory insufficiency, apnea or bradycardia, increased
intracranial pressure, seizures, and their tone.
And if possible, attempting central access would be key, as this is difficult to obtain
once the infants are cooled.
Initiating Cooling at Tertiary Care Center.
As a patient arrives from the referring hospital, we need to confirm that the infant meets criteria
for therapeutic hypothermia.
They need to meet the inclusion criteria we discussed previously.
They have to have an abnormal cerebral function monitor or full 20-lead EEG read by neurology,
a neurologic exam, and neurology needs to confirm the need for therapeutic hypothermia.
And then we place an esophageal probe.
And this is positioned 2 to 4 centimeters above the diaphragm.
This probe can be placed immediately upon arrival if the team is highly suspicious that
the infant will meet criteria.
By placing the probe earlier, there's tighter control of the patient's temperature.
There are several equipment choices on the market for providing therapeutic hypothermia.
Some examples are the Olympic Cool-Cap, which is for selective head cooling, the CritiCool
with CureWrap, which is a body wrap, and the Cincinnati Sub-Zero with Gelli-Roll blanket
for total body cooling.
Here at our institution, we utilize the Cincinnati Sub-Zero Blanketrol III with Gelli-Roll blanket.
Once you identify the patient meets inclusion criteria, we begin by initiating our cooling
checklist.
Our cooling checklist is very detailed.
It includes how to set up the equipment, how to initiate cooling treatment, how to jump
to maintenance phase of treatment if your patient arrives at goal temperature, as well
as what to do when your therapy is interrupted, such as going to MRI.
All setup and changes are performed by two RNs.
Our overall goal is to get patients to goal temperature within six hours.
The target temperature we aim for is 32.5 degrees to 34.5 degrees with the goal of 33.5.
Now that we've reviewed the cooling checklist, we'll move on to the nursing assessment aspects
of caring for a patient with HIE.
Nursing Assessment.
We monitor temperature very closely.
The esophageal temperature is monitored continuously every 15 minutes until a goal temperature
is achieved and hourly thereafter.
We monitor the patient's physical appearance.
These patients are typically sedate, pale, hypotonic with low tone and little to no spontaneous
activity.
They can have seizures.
They can be ventilated.
And their peripheral perfusion is poor.
From a neurologic perspective, we're monitoring for evolving neurologic injury.
We're monitoring their pupils, their level of consciousness, respiratory insufficiency,
seizures, apnea and bradycardia, as well as increased intracranial pressure.
The cerebral function monitor or a full 20-lead EEG is monitored during the cooling therapy.
There is a button that we can activate during the monitoring if a patient is having a seizure,
so the neurology service can look back at the specific event when reviewing the recording
and give us recommendations on anticonvulsants if necessary.
A full 20-lead EEG and MRI are ordered at the discretion of the neurology service.
Typically, we have an early MRI, which is done within the first 24 to 48 hours, and
a late MRI, which is done at day 10 to 14.
We request MRI-compatible leads, so these do not have to be removed prior to the patient
going to MRI during cooling therapy.
And you have to remove the esophageal probe, as this is not compatible with MRI.
For transporting a patient to MRI, we leave our patient on the Gelli-Roll blanket and
disconnect the cords that go to the machine.
And this keeps our patients cool and within a goal temperature during that transition.
From a sedation standpoint, we follow the state behavioral scale with a goal of a negative
1 to a negative 2 during treatment.
Patients within this range are responsive to noxious stimuli and responsive to a gentle
touch or voice.
Typically, we maintain our infants on pharmacologic sedation.
They are typically on a low-dose opioid infusion.
And currently, we are using a low-dose morphine drip.
This helps to maintain their comfort as well as optimizing the efficacy of the treatment.
We believe that inadequate sedation can lead to an increased metabolic rate, the infant
attempting to rewarm, and decreasing the effectiveness of the therapy.
From a respiratory standpoint, the majority of these patients are intubated.
There is a small subset that are extubated.
And we are seeing a trend towards more patients on non-invasive ventilation or CPAP.
We monitor arterial blood gases at baseline as well as at frequent intervals during treatment.
From a cardiovascular point, we monitor their color, their perfusion.
We're monitoring for hypotension and titrating vasoactive infusions as needed to maintain
their goal mean arterial pressures.
We're also monitoring for bradycardia.
The heart rate typically is in the mid to high 70s, low 80s during maintenance phase
of treatment.
And we're also monitoring for arrhythmias.
Hematology, we are monitoring PT/PTT, INR, fibrinogen, and a platelet count.
They'll be measured daily while cooled and then as clinically indicated.
Coagulopathy should be treated per routine with the exception of a platelet count, which
will be kept over 100,000 to compensate for decreased platelet function.
A hematology consult may be requested for assistance.
Patients may require transfusions of FFP, cryo, and platelets.
From an electrolyte fluid balance standpoint, these patients are NPO when passive cooling
starts until they're rewarmed to normal temperature.
They are fluid restricted at 60 to 80 mLs per kilo per day.
What this does is to assist in maintaining the serum sodium level above 140.
Maintaining the serum sodium level in the upper limit of normal is important, because
these patients are at risk for cerebral edema.
Magnesium we tend to keep in the upper limits of normal as well due to its neuroprotective
effects.
We are monitoring fluid balance closely on an hourly basis as well as monitoring glucose,
serum lytes, with calcium, BUN/creatinine, and liver function tests at frequent intervals
during the treatment.
From an ID perspective, blood cultures are drawn at the birth hospital.
And because of the relative immune dysfunction related to cooling, we continue antibiotics
for 72 hours.
From a skin perspective, we do a skin assessment every four hours.
We're monitoring for color, perfusion, skin breakdown, as well as subcutaneous fat necrosis.
Subcutaneous fat necrosis is characterized by induration, erythematous nodules and plaques
over bony prominences, such as the back, arms, buttocks, thighs, and cheeks of full-term
newborns.
To avoid this, we do reposition frequently, every two hours.
Our patient has now completed their 72 hours of cooling therapy.
And we'll now begin with the rewarming phase of treatment.
Rewarming.
The rewarming phase begins after the completion of 72 hours of cooling.
We then pull out our rewarming checklist.
All changes are completed by two licensed clinicians.
We increase the set temp every two hours by 0.5 degrees Celsius until you reach 36.5 degrees.
The temperature will continue to be monitored hourly until rewarming is complete.
This whole process takes about 10 hours to complete.
Family Support.
Family support begins in the delivery room and continues throughout the hospitalization.
Therapeutic hypothermia is now considered standard of care and consent is obtained only
in extenuating circumstances.
A family information sheet is given to families to review what HIE is as well as the treatment
and what to expect during their stay.
We provide honest, open, and transparent communication with families.
We allow 24-hour visitation, family meetings, especially when we have any results of the
EEGs that have been done, MRIs, and any other information that the parents have requested.
We also have extra support from social work, chaplaincy, and the Pediatric Advanced Care
Team if necessary for these families.
That concludes this video on therapeutic hypothermia.
Thank you very much for watching.
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