Correspondence
Accidental Hypothermia
N Engl J Med 1995; 332:1033-1035April 13, 1995
- Article
To the Editor:
Danzl and Pozos discuss active core rewarming for accidental hypothermia (Dec. 29 issue).1 We are located in an alpine region and frequently encounter profound hypothermia caused by submersion in cold water,2 snow-avalanche accidents, or prolonged exposure to the cold.
All our patients with asystole or ventricular fibrillation from severe hypothermia receive the same treatment: standard femorofemoral cardiopulmonary bypass, which provides continuous rewarming after rapid introduction of cannulas into the femoral artery and vein (by percutaneous insertion or an open surgical technique). A long venous cannula is inserted and gently advanced through the inferior vena cava to the right atrium. With such a cannula, venous drainage is excellent; the arterial cannula is inserted similarly into the vessel but is advanced only about 5 cm. Oxygenation and rewarming are achieved by means of a hollow-fiber oxygenator with an efficient heat exchanger, and the warmed perfusate is delivered through the arterial line. This retrograde body perfusion restores adequate cerebral blood flow early.
Despite the extracorporeal circulation, intermittent chest compression is continued to reduce the risk of left ventricular distention in a fibrillating heart and subsequent pulmonary edema. Chest compression is carried out until rhythmic contractions resume (or decompression is established by left ventricular cannulation after sternotomy). To evaluate ventricular load, valve function, and possible distention of a severely damaged heart, we use transesophageal echocardiography during these procedures.3
Since heparin-coated bypass systems are now available, patients can be rewarmed without major bleeding complications. We provide this treatment for all patients with hypothermia except those who have severe brain injuries.
We believe that there are prognostic markers4 that can identify patients in whom death preceded the cooling, which is important when several patients with hypothermia are admitted at the same time and the cardiopulmonary-bypass resources are limited. Bypass should be performed in the patients with the greatest probability of a successful outcome. We therefore use cardiopulmonary bypass for rewarming of patients with profound hypothermia if there are no severe brain injuries and if, at the time of admission, the pH is above 6.5, the serum potassium level is less than 10 mmol per liter, and the rectal or core temperature is above 12°C.
The long-time survival of a handful of patients with complete neurologic recovery after profound hypothermia (between 16.4°C and 24°C with cardiocirculatory arrest) provides confirmation of the effectiveness of our therapeutic strategy.
4 ReferencesHerwig Antretter, M.D.
Johannes Bonatti, M.D.
Otto E. Dapunt, M.D.
University of Innsbruck School of Medicine, 6020 Innsbruck, Austria1
Danzl DF ,Pozos RS . Accidental hypothermia. N Engl J Med 1994;331:1756-1760
Full Text | Web of Science | Medline2
Antretter H ,Dapunt OE ,Mueller LC . Survival after prolonged hypothermia. N Engl J Med 1994;330:219-219
Full Text | Web of Science | Medline3
Mair P ,Furtwaengler W ,Baubin M . Aortic-valve function during cardiopulmonary resuscitation. N Engl J Med 1993;329:1965-1966
Full Text | Web of Science | Medline4
Mair P ,Kornberger E ,Furtwaengler W ,Balogh D ,Antretter H . Prognostic markers in patients with severe accidental hypothermia and cardiocirculatory arrest. Resuscitation 1994;27:47-54
CrossRef | Web of Science | Medline
To the Editor:
Danzl and Pozos comment only briefly on the role of hemodialysis in the treatment of accidental hypothermia. They say that with this method, exchange-cycle volumes of 200 to 250 ml per minute can be achieved and that the anticoagulation required with extracorporeal rewarming is “problematic, particularly in traumatized patients.” We disagree.
In our experience,1 hemodialysis by means of two separate one-lumen catheters placed in the femoral vein allows a continuous blood flow of 450 to 500 ml per minute in patients with accidental hypothermia. Moreover, heparin-free hemodialysis is now available with modern dialysis membranes and high blood-flow rates.2 Hemodialysis in patients with accidental hypothermia also offers other important advantages: correction of electrolyte and acid–base disturbances and removal of drugs or toxins in patients with associated drug overdose or poisoning.
Although cardiopulmonary bypass is the most rapid method of rewarming, it is available only in a few specialized centers. Hemodialysis, however, is now performed routinely in many hospitals. Consequently, we think that hemodialysis should be considered a first-line therapeutic option for patients with severe accidental hypothermia.
2 ReferencesEduardo Hernández, M.D.
Manuel Praga, M.D.
Jose Maria Alcázar, M.D.
Hospital 12 de Octubre, 28041 Madrid, Spain1
Hernandez E ,Praga M ,Alcazar JM , et al. Hemodialysis for treatment of accidental hypothermia. Nephron 1993;63:214-216
Medline2
Schwab SJ ,Onorato JJ ,Sharar LR ,Dennis PA . Hemodialysis without anticoagulation: one-year prospective trial in hospitalized patients at risk for bleeding. Am J Med 1987;83:405-410
CrossRef | Web of Science | Medline
To the Editor:
Danzl and Pozos make clear recommendations for rewarming strategies. It is our view that the use of standard hemodialysis for active core rewarming of patients with moderate-to-severe hypothermia deserves further consideration.
We recently reported successful rewarming by hemodialysis in two such patients,1 one with an initial core temperature of 29°C and the other with a core temperature of 32.5°C. (The latter patient had had no response to surface, airway, or intravenous methods of rewarming.) Heat gains of 699.3 and 400.7 kJ per hour (167.3 and 95.86 kcal per hour) were calculated on the basis of rewarming rates of 3.6°C and 1.16°C per hour, respectively. In each case, percutaneous femoral-vein dual-lumen access resulted in a blood-flow rate of 300 ml per minute; the dialysis fluid had a flow rate of 500 ml per minute and a temperature of 37.5°C. No anticoagulant was administered. Previous reports2,3 (one in which hemodialysis was successful) have described patients intoxicated with potentially dialyzable substances that contribute to hypothermia. In both cases heparin was used for anticoagulation during the dialysis.
Hemodialysis provides greater heat delivery4 than peritoneal lavage, without the risk of perforating a viscus (and ileus is common). Hemodialysis also avoids the arrhythmias that can be precipitated by pleural or gastric lavage. There is no need for the arterial puncture, anticoagulation, and less widely available equipment and personnel required for the use of cardiopulmonary bypass or countercurrent fluid warmers. (Indeed, one of our patients was rewarmed with hemodialysis in the emergency room, and the other in the intensive care unit.) More efficient drug detoxification is possible with hemodialysis than with peritoneal dialysis. There is the potential for hemolysis if the dialysis fluid is heated to a temperature above 42°C, and efficiency declines because of recirculation at blood-flow rates above 300 ml per minute. Aggressive intravascular administration of warmed fluids is needed to avoid the development of “rewarming shock.”
We recommend the use of standard hemodialysis as a safe, widely available, portable, efficient method of active core rewarming of patients with moderate-to-severe hypothermia, especially if accompanied by renal failure or intoxication with a dialyzable substance.
4 ReferencesPatrick T. Murray, M.D.
Susan K. Fellner, M.D.
University of Chicago Hospitals, Chicago, IL 606371
Murray PT ,Fellner SK . Efficacy of hemodialysis in rewarming accidental hypothermia victims. J Am Soc Nephrol 1994;5:422A-422A
Web of Science2
Hernandez E ,Praga M ,Alcazar JM , et al. Hemodialysis for treatment of accidental hypothermia. Nephron 1993;63:214-216
Medline3
Carr ME Jr ,Wolfert AI . Rewarming by hemodialysis for hypothermia: failure of heparin to prevent DIC. J Emerg Med 1988;6:277-280
CrossRef | Medline4
Myers RA ,Britten JS ,Cowley RA . Hypothermia: quantitative aspects of therapy. JACEP 1979;8:523-527
Medline
To the Editor:
Danzl and Pozos discuss what to do in an intensive care unit if a patient has accidental hypothermia. Unfortunately, most of my work in this area is done under more humble conditions. What can I do on a sailboat, at a diving station on a remote island, or in the mountains of Nepal before the patient makes it to the hospital — if ever? The world outside the intensive care unit needs some answers too.
Norbert Mülleneisen, M.D.
Schleiderweg 42, 40789 Monheim, GermanyAuthor/Editor Response
The authors reply:
To the Editor: All techniques of extracorporeal blood rewarming are valuable adjuncts to treatment. The principal advantage of cardiopulmonary bypass is the provision of fully oxygenated circulatory support if a persistent nonperfusing cardiac rhythm develops during rewarming.1 The role of hemodialysis as compared with arteriovenous or other types of venovenous rewarming continues to evolve.
We certainly agree with Hernández et al. that hemodialysis can offer advantages. There is no need for a pump or a perfusionist with any of the nonbypass techniques. Clinical experience is still limited, and stratifying the risk of death while comparing therapies is desirable. In the patient described by Hernández et al., hemodialysis was performed after the administration of fresh-frozen plasma “with tight heparinization.”2 Recent insights into hypothermic coagulation will expand the applicability of all forms of extracorporeal rewarming.
Ideal flow rates with these techniques minimize complications. There is no evidence that a rapid acceleration of the rate of rewarming alone will improve survival rates among patients with spontaneously perfusing cardiac rhythms.
Murray and Fellner's points are also well advised. Many factors influence the clinical decision to apply simultaneous or sequential invasive methods of active core rewarming. Our suggested treatment algorithm accommodates these factors.
In response to Mülleneisen, treatment under humble conditions is indeed the art of the possible.3 Gentle handling, insulation, and thermal stabilization are often the only practical options. Oxygenation and resuscitation with crystalloids are usually the priorities.
Antretter et al. provide a valuable update on their experience with bypass. Twenty of the 22 patients they previously described also received anticoagulation therapy.4 Predicting the outcome is another kettle of fish. There is a great need for a valid marker of death for the purpose of triage. In their heterogeneous series, the plasma potassium level, central venous pH, and activated clotting time were only of limited prognostic value in patients with hypothermia due to submersion in cold water or prolonged exposure but were useful in avalanche victims, in whom death probably preceded cooling.
The suggested threshold of 12°C for initiating bypass may prove useful, if tempered by clinical judgment. There is a report of a patient resuscitated from a temperature of 9°C.5 Considering the clinical experience with bypass in patients with temperatures below 12°C, perhaps the range between 5°C and 12°C will ultimately emerge as the consensus guideline.
5 ReferencesDaniel F. Danzl, M.D
University of Louisville, Louisville, KY 40292Robert S. Pozos, Ph.D.
Naval Health Research Center, San Diego, CA 921861
Bolgiano E ,Sykes L ,Barish RA ,Zickler R ,Eastridge B . Accidental hypothermia with cardiac arrest: recovery following rewarming by cardiopulmonary bypass. J Emerg Med 1992;10:427-433
CrossRef | Medline2
Hernandez E ,Praga M ,Alcazar JM , et al. Hemodialysis for treatment of accidental hypothermia. Nephron 1993;63:214-216
Medline3
Steinman AM . Cardiopulmonary resuscitation and hypothermia. Circulation 1986;74:Suppl IV:IV-294
Mair P ,Kornberger E ,Furtwaengler W ,Balogh D ,Antretter H . Prognostic markers in patients with severe accidental hypothermia and cardiocirculatory arrest. Resuscitation 1994;27:47-54
CrossRef | Web of Science | Medline5
Niazi SA ,Lewis FJ . Profound hypothermia in man: report of a case. Ann Surg 1958;147:264-266
CrossRef | Web of Science | Medline
