Thoracic electrical bioimpedance (TEB) was used in ED patients presenting with dyspnoea to differentiate between cardiac and non-cardiac causes.
The fundamental principle behind TEB is based on Ohm’s law. If a constant electrical current is applied to the thorax, changes in impedance (ΔZ) to flow are equal to changes in voltage drop across the circuit. As a current will always seek the path of lowest resistivity, which in the human body is blood, ΔZ of the thorax will primarily reflect the dynamic changes of blood volume in the thoracic aorta. Changes in thoracic electrical impedance are continuously recorded and processed using a computer algorithm to calculate a number of cardiohaemodynamic parameters such as stroke volume, CO, CI, SVR and systemic vascular resistance index (SVRi).
A cardiac index cut-off of 3.2 l/m/m2 had a 86.7% sensitive (95% CI 59.5% to 98.0%) and 88.9% specific (95% CI 73.9% to 96.8%) for cardiac dyspnoea in the 52 patients studies, of which 15 had cardiac-related dyspnoea.
The study has several limitations including small numbers and using the gold standard of discharge diagnosis.
Thoracic electrical bioimpedance: a tool to determine cardiac versus non-cardiac causes of acute dyspnoea in the emergency department
Emerg Med J. 2010 May;27(5):359-63
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Traumatic Aortic Injury
Two recent papers expand our knowledge of blunt traumatic aortic injury.
UK crash data identified risk factors for low impact blunt traumatic aortic rupture, or ‘LIBTAR’ (crashes at relatively low speed): age >60, lateral impacts and being seated on the side that is struck are predictive of LIBTAR. This study should raise our index of suspicion of aortic injury in low-impact scenarios since low-impact collisions account for two thirds of fatal aortic injuries.
Low-impact scenarios may account for two-thirds of blunt traumatic aortic rupture
Emerg Med J. 2010 May;27(5):341-4
Data from the Victorian State Trauma Registry showed pre-hospital mortality from traumatic thoracic aortic transection was approximately 88.0%, whereas patients who survive to reach hospital have a much lower hospital mortality (33.3%, and once patients who arrived in extremis were removed hospital mortality was reduced to 5.9%). Repair was performed in 46 patients, with 22 receiving initial endovascular repair and 24 receiving initial open repair. Mortality rates following surgery were 9.1% and 16.7%, respectively.
The majority of patients arriving at hospital (57.1%) had an ISS of over 40 highlighting that these patients are unlikely to have only one serious injury and are likely to be more seriously injured than the normal trauma population. An ISS greater than 40 was a main predictor of mortality before repair.
Aortic transection: demographics, treatment and outcomes in Victoria, Australia
Emerg Med J. 2010 May;27(5):368-71
Junior pre-hospital doctors spend a bit longer on scene
More junior pre-hospital doctors took longer on scene than their senior colleagues according to a German study, although patient clinical factors were the main determinant of scene time. The majority of cases were non-trauma presentations
Duration of mission time in prehospital emergency medicine: effects of emergency severity and physicians level of education
Emerg Med J 2010;27:398-403
Terlipressin for refractory cardiac arrest in kids
Okay so it’s a small case series – but the results warrant further investigation: 10-20 mcg/kg terlipressin was given to five infants and children who arrested in the paediatric intensive care unit and who had not responded to several doses of adrenaline (epinephrine)1. Sustained return of spontaneous circulation (ROSC) was achieved in four, and two survived to be discharged home without sequelae and with good neurologic status at 6 and 12 month follow up. Interestingly, the four patients who had ROSC all had septic shock as the cause of their arrest. The two survivors had severe bradycardia and severe bradycarda-asystole as the arrest rhythms, and both received 20 mcg/kg terlipressin.
Terlipressin is a synthetic arginine vasopressin analog with a significantly longer duration of effect, which previously showed positive effects when administered to a small group of children unresponsive to prolonged resuscitative efforts2.
1. Pediatric cardiac arrest refractory to advanced life support: Is there a role for terlipressin?
Pediatr Crit Care Med. 2010 Jan;11(1):139-41
2. Beneficial effects of terlipressin in prolonged pediatric cardiopulmonary resuscitation: A case series.
Crit Care Med. 2007 Apr;35(4):1161-4
Guideline improved pre-hospital RSI in kids
French physicians provide pre-hospital critical care in medical teams of regional SAMU (service d’aide me ́dicale urgente). A national guideline was introduced in France to guide the management of traumatic brain injury (TBI), which included airway management. A study was conducted which examined the practice of paediatric pre-hospital intubation in TBI in comatose children both before and after the introduction of the guideline.
After the guideline there were more pre-hospital intubations, with more standardised approach to rapid sequence induction(RSI). There were fewer complications and a 100% intubation success rate. Despite an increase in portable capnography use, PaCO2 was measured outside the recommended range of 35– 40 mmHg (3.5-4.5 kPa) in 70% of the cases upon arrival.
Emergency tracheal intubation of severely head-injured children: Changing daily practice after implementation of national guidelines
Pediatr Crit Care Med. 2010 May 13. [Epub ahead of print]
Paediatric Retrieval – what's the rush?
The Children’s Acute Transport Service (CATS) in the UK performed 2106 interfacility transports between April 2006 and March 2008. The stabilisation time averaged just over 2 hrs. Stabilisation time was prolonged by the number of major interventions required to stabilise the patient before transfer and differed significantly between various diagnostic groups. The length of time spent by the retrieval team outside the intensive care environment had no independent effect on subsequent patient mortality.
They have shown that stabilisation time can be influenced by a number of patient- and transport team-related factors, and that time spent undertaking intensive care interventions early in the course of patient illness at the referring hospital does not increase patient mortality. In the authors’ words: ‘the “scoop and run” model can be safely abandoned in favor of early goal-directed management during interhospital transport for intensive care.‘
There’s NO rush guys!
Effect of patient- and team-related factors on stabilization time during pediatric intensive care transport
Pediatr Crit Care Med. 2010 May 6
Control oxygenation after resuscitation
How much oxygen should we give patients after successful cardiac arrest resuscitation? Too little oxygen may potentiate anoxic injury. Too much oxygen may increase oxygen free radical production, possibly triggering cellular injury and apoptosis. A multicentre ICU database of over 6300 post-arrest patients was analysed and demonstrated an association between ‘hyperoxia’ and in-hospital mortality.
Adult patients who sustained nontraumatic cardiac arrest and were admitted to the ICU at a participating center between 2001 and 2005 were included. Specifically, inclusion criteria were age older than 17 years, nontraumatic cardiac arrest, cardiopulmonary resuscitation within 24 hours prior to ICU arrival, and arterial blood gas analysis performed within 24 hours following ICU arrival.
The cohort was divided into 3 exposure groups defined a priori based on PaO2 on the first arterial blood gas values obtained in the ICU. Hyperoxia was defined as PaO2 of 300 mm Hg (39.5 kPa) or greater; hypoxia, PaO2 of less than 60 mm Hg (7.9 kPa) (or ratio of PaO2 to fraction of inspired oxygen [FIO2] <300); and normoxia, cases not classified as hyperoxia or hypoxia.
Exposure to hyperoxia was found to be a significant predictor of in-hospital death (OR, 1.8 [95% CI, 1.5-2.2]; this was an independent effect that persisted after adjusting for all other significant risk factors
The authors acknowledge that association does not necessarily imply causation, but add that these data support the hypothesis that high oxygen delivery in the postcardiac arrest setting may have adverse effects.
Association Between Arterial Hyperoxia Following Resuscitation From Cardiac Arrest and In-Hospital Mortality
JAMA. 2010;303(21):2165-2171
Post cardiac arrest guideline
A patient is resuscitated from an out-of-hospital cardiac arrest and is in your emergency department, comatose, with a pulse.
You know that therapeutic hypothermia is indicated and are happy with the protocol for that. You clinically assess for the underlying cause with history, examination, ECG, and other investigations as indicated.
Someone asks you if you want to give some magnesium “as per the guidelines”. As you are wondering what that’s for someone else asks you how long myocardial stunning lasts for and whether that’s the likely cause of hypotension now.
Luckily you avoid getting annoyed with all these reasonable questions by suddenly remembering that there are international recommendations for the management of ‘Post–Cardiac Arrest Syndrome’. You excuse yourself from the room on the pretext of going to the lavatory and quickly find a quiet area where you scan the following article for help:
Post–Cardiac Arrest Syndrome Epidemiology, Pathophysiology, Treatment, and Prognostication
A Consensus Statement From the International Liaison Committee on Resuscitation (American Heart Association, Australian and New Zealand Council on Resuscitation, European Resuscitation Council, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Council of Asia, and the Resuscitation Council of Southern Africa); the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; and the Stroke Council
Circulation 2008;118;2452-2483 Full Text Article
Ultrasoundpaedia
A useful site containing ultrasound images is Ultrasoundpaedia at 
Pre-hospital intubation experience and outcomes
Hospitals and medical personnel performing high volumes of procedures demonstrate better patient outcomes and fewer adverse events. The relationship between rescuer experience and patient survival for out-of-hospital endotracheal intubation is unknown.
An American study analysing 3 statewide databases with 26,000 records aimed to determine the association between endotracheal intubation experience and patient survival.
In-the-field intubators were EMS paramedics, nurses, and physicians, although paramedics performed more than 94% of out-of-hospital tracheal intubations. Although all air medical rescuers may use neuromuscular- blockade-assisted (rapid sequence) tracheal intubation, select ground EMS units are allowed to use tracheal intubation facilitated by sedatives only; the rest are done ‘cold’.
Patients in cardiac arrest and medical nonarrest experienced increased odds of survival when intubated by rescuers with high procedural experience. In trauma patients, survival was not associated with rescuer experience.
The odds of survival for air medical trauma patients were almost twice that of other patients, which may be related to the use of neuromuscular- blocking agents by air medical crews, or due to more specialised critical care training. The authors suggest that rescuers should perform at least 4 to 12 annual tracheal intubations.
Out-of-Hospital Endotracheal Intubation Experience and Patient Outcomes
Ann Emerg Med. 2010 Jun;55(6):527-537