Effect on noradrenaline on tissue oxygen delivery

Some persist in thinking and teaching that the ‘vasopressor’ noradrenaline (norepinephrine) increases mean arterial pressure (MAP) simply by increasing systemic vascular resistance, leading to concerns that it may increase blood pressure at the expense of tissue perfusion. This assertion is contested by many, who now have further support from this study.

In 16 patients with septic shock, various measures of peripheral perfusion were recorded while the dose of noradrenaline was increased to achieve target MAPs. The use of noradrenaline to achieve incremental targets for MAP was associated with increases in global oxygen delivery, cutaneous microvascular flow, and tissue oxygenation in patients with established septic shock; there were no associated changes in the preexisting abnormalities of sublingual microvascular flow. The authors state that these findings suggest that in patients with septic shock, improvements in global hemodynamics and tissue oxygen delivery can be achieved with noradrenaline, without exacerbating microcirculatory flow abnormalities.

The effect of increasing doses of norepinephrine on tissue oxygenation and microvascular flow in patients with septic shock
Crit Care Med. 2009 Jun;37(6):1961-6

Cuffed tracheal tubes for children

In a prospective randomised controlled multi-centre trial, cuffed tracheal tubes were compared with uncuffed tubes in 2246 children aged from birth to five years undergoing general anaesthesia. There was no significant difference in post-extubation stridor but the need for tube exchange was 2.1% in the cuffed and 30.8% in the uncuffed groups (P<0.0001).

From the resuscitation point of view, there remain few if any arguments for using an uncuffed tube.

Prospective randomized controlled multi-centre trial of cuffed or uncuffed endotracheal tubes in small children

Br J Anaesth. 2009 Dec;103(6):867-73

First Aid for Burns

A review of burn first aid treatments highlights the paucity of evidence on which to make firm recommendations. The authors recommend using cold running tap water (between 2 and 15 degrees C) and to avoid ice or alternative therapies. The optimum duration of first aid application and the delay after the injury for which first aid can still be effective are two areas of research which need further exploration.

A review of first aid treatments for burn injuries
Burns. 2009 Sep;35(6):768-75

Physicians didn’t improve outcome from nontraumatic cardiac arrest

A Norwegian study retrospectively compared outcomes from non-traumatic cardiac arrest between ambulances staffed by physicians (PMA) and non-physician ambulances (non-PMA). There were no differences in any of the clinical outcome measures used in this study of 977 patients, in which 13% (PMA) and 11% (non-PMA) survived to hospital discharge.

Out-of hospital advanced life support with or without a physician: Effects on quality of CPR and outcome
Resuscitation. 2009 Nov;80(11):1248-52

Fluids for cooling post cardiac arrest

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

Pre-hospital intubation for head injury: ?no benefit

A systematic review of pre-hospital intubation for head injured patients failed to show evidence of benefit of tracheal intubation or invasive ventilation. The authors acknowledge the lack of methodological quality in the studies reviewed and the predominance of US paramedic-delivered intubations without the use of anaesthetic drugs.

Pre-hospital tracheal intubation in patients with traumatic brain injury: systematic review of current evidence
Br J Anaesth. 2009 Sep;103(3):371-86

Pre-hospital intubation ’success’ at a US centre

Of 203 patients attending a US Level 1 trauma centre who had pre-hospital airway management, 25 (12%) had unrecognised oesophageal intubations.

Patients were treated in the field by fire rescue personnel of various municipalities and with different experience levels. Patients transported by air were significantly more likely to be successfully intubated than those transported by ground, perhaps due to both increased experience and the use by air crews of succinylcholine. The authors in their discussion contrast these results with those of European studies which report higher success rates with pre-hospital systems that employ emergency physicians and anaesthetists.

Prehospital intubations and mortality: a level 1 trauma center perspective
Anesth Analg. 2009 Aug;109(2):489-93

Vehicle Rollover

Vehicle rollover as an indicator of mechanism of injury was investigated in a study examining accident databases and the medical literature. Only 2.4% of crashes involved rollovers but they accounted for one third of occupant deaths.

Some facts on vehicle rollover from the article:

• Rollover is defined as a vehicle overturned by at least one quarter turn (at least onto its side).
• Some rollovers involve many quarter turns and the final resting position may be on the vehicle’s side, roof, or back on its wheels.
• Factors that cause a vehicle to roll over include trajectory (i.e., turning vs. straight), vehicle type, and speed (precrash velocity may be the most predictive factor)

The importance of vehicle rollover as a field triage criterion
J Trauma. 2009 Aug;67(2):350-7