Internal cardiac massage and mediastinal irrigation in hypothermic cardiac arrest

Rewarming With Closed Thoracic Lavage Following 3-h CPR at 27°C Failed to Reestablish a Perfusing Rhythm

Introduction: Previously, we showed that the cardiopulmonary resuscitation (CPR) for hypothermic cardiac arrest (HCA) maintained cardiac output (CO) and mean arterial pressure (MAP) to the same reduced level during normothermia (38°C) vs. hypothermia (27°C). In addition, at 27°C, the CPR for 3-h provided global O₂ delivery (DO₂) to support aerobic metabolism. The present study investigated if rewarming with closed thoracic lavage induces a perfusing rhythm after 3-h continuous CPR at 27°C.

Materials and Methods: Eight male pigs were anesthetized, and immersion-cooled. At 27°C, HCA was electrically induced, CPR was started and continued for a 3-h period. Thereafter, the animals were rewarmed by combining closed thoracic lavage and continued CPR. Organ blood flow was measured using microspheres.

Results: After cooling with spontaneous circulation to 27°C, MAP and CO were initially reduced by 37 and 58% from baseline, respectively. By 15 min after the onset of CPR, MAP, and CO were further reduced by 58 and 77% from baseline, respectively, which remained unchanged throughout the rest of the 3-h period of CPR. During CPR at 27°C, DO₂ and O₂ extraction rate (VO₂) fell to critically low levels, but the simultaneous small increase in lactate and a modest reduction in pH, indicated the presence of maintained aerobic metabolism. During rewarming with closed thoracic lavage, all animals displayed ventricular fibrillation, but only one animal could be electro-converted to restore a short-lived perfusing rhythm. Rewarming ended in circulatory collapse in all the animals at 38°C.

Conclusion: The CPR for 3-h at 27°C managed to sustain lower levels of CO and MAP sufficient to support global DO₂. Rewarming accidental hypothermia patients following prolonged CPR for HCA with closed thoracic lavage is not an alternative to rewarming by extra-corporeal life support as these patients are often in need of massive cardio-pulmonary support during as well as after rewarming.

Endovascular rewarming in the emergency department for moderate to severe accidental hypothermia

BACKGROUND

Endovascular temperature control catheters can be utilized for emergent rewarming in accidental hypothermia. The purpose of this study was to compare patients with moderate to severe hypothermia rewarmed with an endovascular temperature control catheter versus usual care at our institution.

METHODS

We conducted a retrospective, observational cohort study of patients with moderate to severe accidental hypothermia (core body temperature less than 32°C) in the Emergency Department of an urban, tertiary care medical center. We identified the rewarming techniques utilized for each patient, including those who had an endovascular temperature control catheter placed (Quattro© or Icy© catheter, CoolGuard© 3000 regulation system, Zoll Medical). Rewarming rates and outcomes were compared for patients with and without the endovascular temperature control catheter. We systematically screened for procedural complications.

RESULTS

There were 106 patients identified with an initial core temperature less than or equal to 32°C; 52 (49%) patients rewarmed with an endovascular temperature control catheter. Other methods of rewarming included external forced-air rewarming (85, 80%), bladder lavage (17, 16%), gastric lavage (10, 9%), closed pleural lavage (6, 6%), and peritoneal lavage (3, 3%). Rate of rewarming did not differ between the groups with and without catheter-based rewarming (1.3°C/h versus 1.0°C/h, difference 0.3°C, 95% confidence interval [CI] of the difference 0-0.6°C) and neither did survival (70% versus 71%, difference 1%, 95% CI -17 to 20%). We did not identify any significant vascular injuries resulting from endovascular catheter use.

CONCLUSION

The endovascular temperature control system was not associated with an increased rate of rewarming in this cohort with moderate to severe hypothermia; however, this technique appears to be safe and feasible.

[Management of accidental hypothermia]

Patients with hypothermia are frequently encountered in emergency medicine. Particularly trauma patients, but also other predisposed persons, can be expected to suffer from hypothermia at any time of the year. Therapy focuses not only on symptom-oriented intensive care to stabilize and secure vital functions, but also on rewarming. Even in cases of severe hypothermia with circulatory arrest, therapy can produce excellent results. This paper first gives a brief overview of the typical clinical symptoms of hypothermia, before giving a detailed description of the preclinical and in-hospital management of the hypothermia patient. The various rewarming strategies are the subject of special attention and critical evaluation.

Thoracic lavage in accidental hypothermia with cardiac arrest — report of a case and review of the literature

BACKGROUND

Accidental hypothermia resulting in cardiac arrest poses numerous therapeutic challenges. Cardiopulmonary bypass (CPB) should be used if feasible since it optimally provides both central rewarming and circulatory support. However, this modality may not be available or is contraindicated in certain cases. Thoracic lavage (TL) provides satisfactory heat transfer and may be performed by a variety of physicians. This paper presents the physiological rationale, technique, and role for TL in accidental hypothermia with cardiac arrest.

METHODS

A patient with hypothermic cardiac arrest, treated by the author using TL, serves as the basis for this report. A search of the English language literature using PubMed (National Library of Medicine, Bethesda, Maryland) was conducted from 1966 to 2003 and 13 additional patients were identified. Demographic information, lavage method, rewarming rate, complications, and neurological outcome were analysed.

RESULTS

There were numerous causes for hypothermia, with drug and alcohol intoxication being the most common (n = 4; 28.6%). Patient age ranged from 8 to 72 years (median = 36 years). Mean core temperature was 24.5+/-0.60 degrees C. Most patients were without blood pressure or pulse upon presentation to the Emergency Department and the predominant cardiac rhythm was ventricular fibrillation (VF) (n = 9; 64.3%). Thoracic lavage was accomplished by thoracotomy in seven patients and tube thoracotomy in the remaining seven. Median rewarming rate was 2.95 degrees C/h. Median time until sinus rhythm was restored was 120 min. Median length of hospital stay was 2 weeks. Four (28.6%) patients died. Complications were seen in 12 (85.7%) patients. Among survivors, neurological outcome was normal in 8 (80%) while two were left with residual impairments.

CONCLUSIONS

Patients presenting in cardiac arrest from accidental hypothermia may be rewarmed effectively using TL. Among survivors, normal neurological recovery is seen. Thoracic lavage should be strongly considered for these patients if CPB is not available or contraindicated.

Cardiopulmonary resuscitation following profound immersion hypothermia

A case is presented in which prolonged resuscitation and rewarming was performed following post-rescue cardiopulmonary arrest in severe immersion hypothermia. The rescue and resuscitation techniques necessary to optimise outcome in such cases are described.