Previous case reports and animal studies have suggested a possible role for naloxone in cardiac arrest even in the absence of opioid overdose.
Possible mechanisms include reducing the myocardial depressant effect of endogenous opioids, stimulating catecholamine release, and providing antiarryhthmic effects through an effect on cardiomyocyte ion channels.
A retrospective review of 32,544 out of hospital cardiac arrests over 5 years revealed 36 to have received pre-hospital naloxone. Of these, only one survived to hospital discharge, who tested positive for opiates in a urine toxicology screen in the emergency department.
No need to change the guidelines yet then.
Naloxone in cardiac arrest with suspected opioid overdoses
Resuscitation. 2010 Jan;81(1):42-6
Ionised hypocalcaemia has been observed post-cardiac arrest in previous studies. Investigators in Utah induced VF in a swine model and resuscitated them back to spontaneous circulation1. Ionised hypocalcaemia was associated with hypotension and impaired LV function, and its treatment with a calcium infusion resulted in improved mean arterial pressure and left ventricular stroke work.
Although iv calcium is not recommended as a blind treatment in cardiac arrest, in part due to concerns about exacerbating cellular injury, this study reminds us that the treatment of ionised hypocalcaemia is important, and may be necessary after ROSC.
1. Hypocalcemia following resuscitation from cardiac arrest revisited
Resuscitation 2010 Jan;81:117–122
Thirty-eight post-cardiac arrest patients were effectively cooled to the target temperature range of 32-34 celsius using intravenous cold saline and ice packs to groin, axillae, and neck. The ice packs were frozen 250 ml saline bags wrapped in pillow cases. If shivering occurred muscle relaxation with rocuronium was used until the target temperature was reached. Interestingly, rebound hyperthermia occurred in 8/34 patients.
Although a small study, these data reassure those of us who induce therapeutic hypothermia without the use of dedicated cooling equipment.
Cold saline infusion and ice packs alone are effective in inducing and
maintaining therapeutic hypothermia after cardiac arrest
37 patients with blunt traumatic cardiac arrest underwent attempted resuscitation by a HEMS crew over a four year period. Chest decompression was performed in 18 cases (17 thoracostomy, one needle decompression). The procedure revealed evidence of chest injury in 10 cases (pneumothorax, haemothorax, massive air leak) and resulted in return of circulation and survival to hospital in four cases. All four cases died of associated major head injury, although one became a heart beating organ donor. Only half of the cases found to have pneumothorax demonstrated clinical signs of one prior to chest decompression.
The authors state: ‘Relying on clinical signs of the thorax alone will not identify all patients with these injuries, and our data support extending the practice into all patients with a suitable mechanism of injury together with external evidence of chest injury.’
Chest decompression during the resuscitation of patients in prehospital traumatic cardiac arrest
Emerg Med J. 2009 Oct;26(10):738-40
A Norwegian randomised controlled trial over five years compared out-of-hospital nontraumatic cardiac arrest outcomes between ACLS protocols with and without access to intravenous drugs (epinephrine/adrenaline, atropine, amiodarone).
Patients randomised to the drug group had a higher rate of hospital admission with return of spontaneous circulation, but there was no significant difference in survival to discharge, survival with favourable neurological outcome, or one year survival.
Intravenous Drug Administration During Out-of-Hospital Cardiac Arrest
JAMA. 2009 Nov 25;302(20):2222-9
Large volume cold fluid resuscitation after return of spontaneous circulation can contribute to effective cooling but does it impair cardiac or respiratory function? A retrospective review of 52 resuscitated cardiac arrest patients suggests that the infusion of large volumes of cold fluid does not cause a further significant reduction in respiratory function beyond that normally seen after cardiac arrest despite significantly reduced LV function.
Effects of large volume, ice-cold intravenous fluid infusion on respiratory function in cardiac arrest survivors
Resuscitation. 2009 Nov;80(11):1223-8
In the same issue of Resuscitation, a prospective study of cardiac arrest survivors in positive fluid balance from cold fluid cooling showed frequent evidence of hypovolaemia as determined by serial ultrasound assessment.
An accompanying editorial suggests this may be due to the systemic inflammatory response syndrome that follows successful cardiac arrest resuscitation; large volumes are tolerated well and myocardial dysfunction should not lead to restriction of fluids after cardiac arrest.
Assessment of intravascular volume by transthoracic echocardiography during therapeutic hypothermia and rewarming in cardiac arrest survivors
Resuscitation. 2009 Nov;80(11):1234-9
Smaller self-inflating bags produce greater guideline consistent ventilation in simulated cardiopulmonary resuscitation
A comparison between two sizes of self-inflating resuscitation bags revealed improved adherence to resuscitation guidelines with the smaller bag. Student paramedics were more likely to produce suboptimal tidal volumes and ventilation rates with a 1500ml bag than a 1000ml bag during simulated ventilation of an artificial lung model.
BMC Emerg Med. 2009 Feb 20;9:4
Full text at http://www.biomedcentral.com/1471-227X/9/4
No rescuer or bystander has ever been seriously harmed by receiving an inadvertent shock while in direct or indirect contact with a patient during deﬁbrillation. New evidence suggests that it might even be electrically safe for the rescuer to continue chest compressions during deﬁbrillation if self-adhesive deﬁbrillation electrodes are used and examination gloves are worn. This paper reviews the existing evidence, but warns more deﬁnite data are needed to make absolutely sure that there is no risk before deﬁbrillation safety recommendations are changed.
Is external defibrillation an electric threat for bystanders?
Resuscitation. 2009 Apr;80(4):395-401