Infusion warm during selective hypothermia in acute ischemic stroke

Abstract

INTRODUCTION:Mechanical thrombectomy (MT) has dramatically improved the prognosis for acute ischemic stroke (AIS) patients. Despite high recanalization rates, up to half of the patients will not present a good neurological outcome after MT. Therapeutic hypothermia is perhaps the most robust neuroprotectant studied preclinically. MATERIALS AND METHODS:We explored various warming effects that can reduce the effectiveness or potency of selective hypothermia during AIS under conditions similar to actual clinical care. Four different selective hypothermia layouts were chosen. Layouts 1 and 2 used a single catheter without and with an insulated IV bag. Layouts 3 and 4 used two catheters arrange coaxially, without and with an insulated IV bag. Independent variables measured were IV bag exit temperature, catheter inlet temperature, and catheter outlet temperature at four different flow rates ranging from 8 to 25 ml/min over an infusion duration of 20 min.RESULTS: Dominant warming occurs along the catheter pathway compared to warming along the infusion line pathway, ranging from 66% to 72%. Coaxial configurations provided an approximate 4°C cooler temperature benefit on delivered infusate over a single catheter. Brain tissue temperature predictions show that the maximum cooling layout, Layout 4 at maximum flow provides a 1°C within 5 min. CONCLUSION:Significant rewarming effects occur along the infusate flow path from IV bag to site of injury in the brain. Previous selective hypothermia clinical work, using flow rates and equipment at conditions similar to our study, likely produced rapid but not deep tissue cooling in the brain (~ 1°C).

Dual-sized hollow particle incorporated fibroin thermal insulating coatings on catheter for cerebral therapeutic hypothermia

“…This shortcoming inevitably causes the warming of the cold perfusate within the catheter as shown in Fig. 1 b [ 12 ] and reduces the potency of the hypothermia treatment for AIS [ 13 ]. For example, an in vitro phantom experiment indicated that the temperature of the 33 mL/min cold saline within the 5F interventional catheter increased from 5.4 ± 0.41 °C (at the initial femoral inflow site) to 25.21 ± 0.49 °C (at the distal tip of catheter in carotid artery) [ 14 ].…”

“…For example, an in vitro phantom experiment indicated that the temperature of the 33 mL/min cold saline within the 5F interventional catheter increased from 5.4 ± 0.41 °C (at the initial femoral inflow site) to 25.21 ± 0.49 °C (at the distal tip of catheter in carotid artery) [ 14 ]. Current studies focus on making catheters with novel designs to improve their cooling performance by minimizing the heat exchange of the cold infusion fluid within catheter with the outside warm blood and tissues, such as balloon-wrapping [ 15 ], balloon-coaxial (TwinFlo @ ) [ 16 ] and coaxial configurations [ 13 ]. However, these cooling catheters are complicated to be manufactured and expensive, lack flexibility, and cannot be inserted into some target vessels due to their increased diameters.…”

A Systematic Review and Meta-Analysis of Animal Studies Testing Intra-Arterial Chilled Infusates After Ischemic Stroke

“…Indeed, a phantom model constructed by Choi et al ( 69 ) showed that saline infused by a femoral catheter, running to the “internal carotid artery,” warmed to ~25°C at the catheter tip. Such warming is less likely to occur in animal studies of IA-SCI ( 69 , 71 ). These results are important for investigators to consider given the current methodology of ischemic stroke treatment and limitations with current medical equipment and experimental modeling.…”

Therapeutic hypothermia in stroke: Quo Vadis?

“…Open-loop, intra-arterial infusion of chilled saline can be easily incorporated into the workflow of endovascular thrombectomy procedures. However, the article by Merrill et al [17] shows that significant warming occurs when chilled saline passes through the tubes and then via uninsulated catheters into the carotid artery when it warms further as it mixes with the blood. The infusate volume required to produce brain cooling and the resulting hemodilution are also factors to be considered when employing this approach.…”