Intra-arrest transnasal evaporative cooling: a randomized, prehospital, multicenter study (PRINCE: Pre-ROSC IntraNasal Cooling Effectiveness)

Transnasal cooling: a Pandora's box of transnasal patho-physiology

The innovative concept of transnasal evaporative cooling for therapeutic hypothermia in cardio-pulmonary-cerebro-resuscitation has therapeutic implications with evidence of rapid and selective brain cooling; however, this author wants to elicit that this concept may hold answers for many physiological phenomena which have not been explored or completely understood up till now. To affirm the physiological role of transnasal cooling, the innovative non-invasive brain temperature monitoring can help the investigators to explore and understand the following transnasal pathophysiological phenomena: (1) understanding correlation of brain temperature and sinus headache secondary to nasal blockade, (2) exploring the therapeutic role of nasal oxygen for prevention of delirium in intubated patients, (3) realizing the impact of controlled enclosed environments on the mood and affect of the inhabitants, (4) understanding the etio-pathogenesis of claustrophobia after excluding the confounding factors of morbid obesity, severe cardiopulmonary disease and incapacitating musculoskeletal diseases, (5) exploring the anthropological role of male pattern of moustache, beard and hair loss, and (6) possible development of a coolant moustache as proposed by the author. In summary, transnasal pathophysiology offers many promising lines of fruitful research to explore the non-olfactory physiological functions of nose in human beings.

Early selective trans-nasal cooling during CPR improves success of resuscitation in a porcine model of prolonged pulseless electrical activity cardiac arrest

AIM OF STUDY

In the present study, we investigated trans-nasal cooling in settings of pulseless electrical activity (PEA). We hypothesized that early trans-nasal cooling during CPR improves outcomes when cardiac arrest is associated with PEA.

METHODS

Ventricular fibrillation (VF) was electrically induced in 16 domestic male pigs weighing 40±3 kg. After 14 min of untreated VF, PEA was induced following delivery of one or more electrical shocks. One min after onset of PEA, CPR was started, including chest compression and ventilation. Each animal received 5 min of CPR prior to defibrillation attempt. CPR and resuscitation efforts were discontinued at 15 min unless return to spontaneous circulation was achieved. In 8 animals, selective trans-nasal cooling was begun coincident with start of CPR and 8 randomized controls were identically treated except for trans-nasal cooling. Mean aortic pressure was continuously measured together with aortic and right atrial pressure and nasal, body and right jugular vein temperatures. Coronary perfusion pressure (CPP) was computed from measured data.

RESULTS

Six of eight animals were resuscitated after early trans-nasal cooling, while only one untreated control was resuscitated (p=0.012). Nasal, body and jugular vein temperatures decreased after cooling. At PC (precordial compression) 5 min, the cooled group recorded a higher CPP (25±5 mmHg) than the non-cooled group (15±4 mmHg, p=0.001).

CONCLUSION

When selective trans-nasal cooling was initiated during CPR in the animal model of prolonged cardiac arrest with PEA, CPP was higher and the likelihood of return of spontaneous circulation was improved.

Out-of-hospital CPR: better outcome for our patients

Out-of-hospital cardiac arrest is a leading cause of death in developed countries and early resuscitation attempts are crucial to improve survival rates and neurological outcome. Gräsner and colleagues performed an intriguing analysis on the combined approach of mild therapeutic hypothermia (MTH) and immediate percutaneous coronary intervention (PCI) for post-resuscitation care of 584 patients with out-of-hospital cardiac arrest from the German Resuscitation Registry. PCI was independently associated with good neurological outcome at hospital discharge after successful resuscitation, and MTH was associated as an independent factor with increased chance of 24-hour survival. Moreover, a binary logistic regression analysis did not show statistical significance for MTH, in addition to PCI, as an independent predictor for good neurological outcome. The present study supports the evidence that post-resuscitation care based on standardized protocols is beneficial after successful resuscitation. Further prospective and randomized studies are warranted to elucidate criteria for a better selection of candidates for those strategies and to evaluate the potential, in terms of neurological outcome at hospital discharge, of a prehospital cooling strategy in patients who cannot be referred to immediate PCI.

The role of hypothermia in post-cardiac arrest patients with return of spontaneous circulation: a systematic review

OBJECTIVES

To update a comprehensive systematic review of the use of therapeutic hypothermia after cardiac arrest that was undertaken initially as part of the 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science. The specific question addressed was: 'in post-cardiac arrest patients with a return of spontaneous circulation, does the induction of mild hypothermia improve morbidity or mortality when compared with usual care?'

METHODS

Pubmed was searched using ("heart arrest" or "cardiopulmonary resuscitation") AND "hypothermia, induced" using 'Clinical Queries' search strategy; EmBASE was searched using (heart arrest) OR (cardiopulmonary resuscitation) AND hypothermia; The Cochrane database of systematic reviews; ECC EndNote Library for "hypothermia" in abstract OR title. Excluded were animal studies, reviews and editorials, surveys of implementation, analytical models, reports of single cases, pre-arrest or during arrest cooling and group where the intervention was not hypothermia alone.

RESULTS

77 studies met the criteria for further review. Of these, four were meta-analyses (LOE 1); seven were randomised controlled trials (LOE 1), although six of these were from the same set of patients; nine were non-randomised, concurrent controls (LOE 2); 15 were trials with retrospective controls (LOE 3); 40 had no controls (LOE 4); and one was extrapolated from a non-cardiac arrest group (LOE 5).

CONCLUSION

There is evidence supporting the use of mild therapeutic hypothermia to improve neurological outcome in patients who remain comatose following the return of spontaneous circulation after a cardiac arrest; however, much of the evidence is from low-level, observational studies. Of seven randomised controlled trials, six use data from the same patients.

Therapy of human rabies

Preventive therapy for rabies, including wound cleansing and active and passive immunization after a recognized exposure, is highly efficacious. Unfortunately, there is no established therapy that is effective for patients who develop rabies encephalomyelitis. There have been several survivors from rabies and all but one received rabies vaccine prior to the onset of clinical illness. Aggressive approaches to therapy of human rabies may be appropriate in certain situations. There is no scientific rationale for the use of therapeutic coma, and there are many reports of failures using this approach. Therapeutic coma should be abandoned for the therapy of rabies. New approaches such as therapeutic hypothermia should be evaluated, in combination with other therapeutic agents. More basic research is needed on the mechanisms involved in rabies pathogenesis, which will hopefully facilitate the development of new therapeutic approaches in the future for this ancient disease.

State of the art in therapeutic hypothermia

Historically, hypothermia was induced prior to surgery to enable procedures with prolonged ischemia, such as open heart surgery and organ transplant. Within the past decade, the efficacy of hypothermia to treat emergency cases of ongoing ischemia such as stroke, myocardial infarction, and cardiac arrest has been studied. Although the exact role of ischemia/reperfusion is unclear clinically, hypothermia holds significant promise for improving outcomes for patients suffering from reperfusion after ischemia. Research has elucidated two distinct windows of opportunity for clinical use of hypothermia. In the early intra-ischemia window, hypothermia modulates abnormal cellular free radical production, poor calcium management, and poor pH management. In the more delayed post-reperfusion window, hypothermia modulates the downstream necrotic, apoptotic, and inflammatory pathways that cause delayed cell death. Improved cooling and monitoring technologies are required to realize the full potential of this therapy. Herein we discuss the current state of clinical practice, clinical trials, recommendations for cooling, and ongoing research on therapeutic hypothermia.

Pre-hospital cooling of patients following cardiac arrest is effective using even low volumes of cold saline

Introduction

Pre-hospital induction of therapeutic mild hypothermia (TH) may reduce post-cardiac arrest brain injury in patients resuscitated from out-of-hospital cardiac arrest. Most often, it is induced by a rapid intravenous administration of as much as 30 ml/kg of cold crystalloids. We decided to assess the pre-hospital cooling effectivity of this approach by using a target dose of 15-20 ml/kg of 4°C cold normal saline in the setting of the physician-staffed Emergency Medical Service. The safety and impact on the clinical outcome have also been analyzed.

Methods

We performed a prospective observational study with a retrospective control group. A total of 40 patients were cooled by an intravenous administration of 15-20 ml/kg of 4°C cold normal saline during transport to the hospital (TH group). The pre-hospital decrease of tympanic temperature (TT) was analyzed as the primary endpoint. Patients in the control group did not undergo any pre-hospital cooling.

Results

In the TH group, administration of 12.6 ± 6.4 ml/kg of 4°C cold normal saline was followed by a pre-hospital decrease of TT of 1.4 ± 0.8°C in 42.8 ± 19.6 min (p < 0.001). The most effective cooling was associated with a transport time duration of 38-60 min and with an infusion of 17 ml/kg of cold saline. In the TH group, a trend toward a reduced need for catecholamines during transport was detected (35.0 vs. 52.5%, p = 0.115). There were no differences in demographic variables, comorbidities, parameters of the cardiopulmonary resuscitation and in other post-resuscitation characteristics. The coupling of pre-hospital cooling with subsequent in-hospital TH predicted a favorable neurological outcome at hospital discharge (OR 4.1, CI95% 1.1-18.2, p = 0.046).

Conclusions

Pre-hospital induction of TH by the rapid intravenous administration of cold normal saline has been shown to be efficient even with a lower dose of coolant than reported in previous studies. This dose can be associated with a favorable impact on circulatory stability early after the return of spontaneous circulation and, when coupled with in-hospital continuation of cooling, can potentially improve the prognosis of patients.

Trial Registration

ClinicalTrials (NCT): NCT00915421