Case 1

A 27 y/o BM with history of bipolar disorder on lithium therapy was found face down outside his house in mid-December. The patient had been binge drinking the day prior along with illicit drug use. Upon admission to the Emergency Department, the patient's mean arterial pressure (MAP) was 55, rectal temperature of 27.7oC. Electrocardiogram revealed sinus bradycardia without Osboune waves. An endotrachial tube was placed for airway protection. The patient received volume expansion and dopamine for BP support. A dual lumen dialysis catheter was inserted into the femoral vein.

The patient was placed on a Prisma® (Gambro; Littleton, CO) CRRT machine with the return line placed through a Hotline® (Level 1; Rockland, Maine) set at 40 degrees centigrade. The blood pump was set to circulate 125ml/min through the system. Warmed Normosol® (Abbott Labs; North Chicago, Ill) was used as a replacement solution set at 1000ml/hour.

The graph below describes the patient's clinical course and rate of re-warming. The patient maintained hemodynamic and cardiac stability throughout this re-warming process.

Figure 1

Figure 1: Graph showing the temperature (in degrees centigrade) over the first 9 hours of hospitalization.

After 4 hours of veno-venous re-warming the patient's mental status improved and the dopamine was discontinued. Once the patient's rectal temperature researched 37oC, the veno-venous system was discontinued. The patient was able to maintain normal temperature and was extubated one hour later. The patient was completely alert and oriented. After 10 hours in the ICU, the patient was transferred to a regular floor.

Case 2

An 82 y/o female was found unresponsive in her apartment. She had not been seen for several days and her neighbors called the police and EMS. Upon their arrival, the patient was cold to touch, hypotensive with a systolic BP of 82 mmHg and a heart rate of 54. The patient was transferred to LSUHSC.

At time of admission to the ER, the patient remained unresponsive. The patient had an endotrachial tube placed in transit by EMS. The patient's rectal temperature was 28 oC rectally. She was noted to be in slow atrial fibrillation with “classic” Osbourne waves. The patient received fluid resuscitation with improvement in her MAP.

A double lumen dialysis catheter was inserted into her right femoral vein. The veno-venous system was initiated as described above and at identical settings. Below is a graph demonstrating the patient's temperature after starting veno-venous re-warming.

Figure 2

Figure 2: Graph illustrating the initial re-warming process.

The patient had steady and consistent re-warming. The patient converted to sinus rhythm when her temperature rose to above 33 degrees. However, the patient's mental status never improved and was found to have a pontine CVA. The patient was hemodynamically and cardiovascularly stable and able to maintain physiologic temperature. However, she later succumbed to her neurologic process.

Discussion

As illustrated by these two cases, there were excellent results using this system. The patients had a re-warming rate of 1.7 C/hr without adverse cardiovascular or hemodynamic complications. Similar experiences have been reported using this system of active re-warming [⁷,⁸].

With the increased availability of CRRT machines and circuits, applying this technology to extra corporal re-warming appears both effective and safer than other invasive methods if re-warming. Most concerns with this system are the risk of anticoagulation. Neither of these patients received neither systemic nor regional anticoagulation. It has been our experience that filter life and patency of the access catheter can be maintained without anticoagulation in patients at high risk of bleeding complications. In patients with underlining coagulopathy, such that is induced by hypothermia, we maintain the filter and catheter by adjustments in blood flow rate and reduction in hemofiltration rates.

Conclusion

These two cases show that veno-venous re-warming is an effective method of core re-warming in patients suffering accidental hypothermia. This method can be performed with the use of anticoagulation in patients with high risk of bleeding complications.