Health & Medical intensive care

Intravascular Cooling Device in Neurologic Intensive Care

Intravascular Cooling Device in Neurologic Intensive Care
A total of 51 consecutive patients with an acute severe intracranial disease requiring admission to the NICU were prospectively enrolled. The study was approved by the Institutional Review Board, and, according to Austrian law, informed consent was obtained before enrollment from those patients who were competent at the time of enrollment. From those patients who were incompetent at the time point of admission, the informed consent was obtained by the next of kin or by the patient him- or herself after regaining legal competence.

The main inclusion criteria were a severe intracranial disease-with the main diagnoses being subarachnoid hemorrhage, intracerebral hemorrhage, traumatic brain injury, supratentorial brain infarction, basilar artery thrombosis, and hypoxic encephalopathy-requiring admission to the NICU and placement of a central venous catheter due to the primary disease. Exclusion criteria were age under 19 yrs, active cardiac arrhythmia, active sepsis syndrome, bleeding diathesis, and infection or bleeding at the site of the intended catheter insertion.

The baseline examination consisted of documentation of the initial body temperature, demographic data, and body weight. The location of the primary and the backup temperature probes and the insertion site of the intravascular cooling device (Cool Line catheter) were documented. The temperature probe was located in the bladder (by a Foley catheter). Body temperature was determined hourly, and the back-up probe (located in the esophagus) was used to ensure continuous hourly registration of the temperature even in case of malfunction of the bladder temperature probe. All adverse events were recorded and reviewed to determine whether they were complications arising from the use of the Cool Line catheter and Cool Gard system. The device performance was evaluated with respect to the ease of insertion, the performance as a two-lumen central venous catheter and with respect to its ergonomic properties. A scale 1 to 5 (1 = easy/excellent, 5 = difficult/below average) was used for this evaluation. All antipyretic drugs and their dosages were recorded as well as the administration of all other cooling devices (e.g., blankets).

The intravascular cooling device, the Cool Line catheter, was connected to an external cooling system, the Cool Gard system, which is similar to those used for cooling blankets. The Cool Gard system circulates temperature-controlled sterile saline through two small balloons mounted on the distal end of the catheter. The patient's blood is gently cooled as it passes over the balloons. Similar to cooling blanket equipment, the Cool Gard system responds to temperature probes measuring the patient's rising temperature and adjusts the temperature of the sterile saline flowing within the Cool Line catheter. The Cool Gard system was set with a target temperature of 36.5°C. Both the Cool Line catheter and the Cool Gard system have been developed by ALSIUS Corporation (Irvine, CA). Four Cool Gard systems with the sufficient number of Cool Line catheters were provided by ALSIUS Corporation for this study.

The primary efficacy endpoint of this study was to evaluate the cooling capacity of Cool Gard system and Cool Line catheter. The efficacy is expressed by the calculation formula of fever burden. Fever burden (FB) is defined as the fever time product (°C hours) under the fever curve, which constitutes the time interval when the bladder temperature is higher than 37.9°C. The FB is calculated by the three fever burden formulas given in Table 1 : the fever ramp up (FBa), the fever dwell (FBb), and the fever ramp down (FBc). The total fever burden is the summation of these three fever burden areas. Moreover, we converted the total fever burden to average fever burden per hour (by dividing total FB by the total hours the patient was in study), and likewise we calculated the average fever burden per day (= FB per hour




24).


Safety endpoints were defined to be the following: death; bacteremia and sepsis; major hemorrhage related to catheter insertion; pneumothorax, resulting from subclavian catheterization; malposition and malfunction of the Cool Line catheter and the Cool Gard system; and pulmonary embolism potentially resulting from thromboemboli released from the catheter. Every Cool Line catheter was subjected to microbiological examination after removal. White blood cell count and C-reactive protein were measured daily to allow earliest possible detection of inflammation and/or infection.

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