Given that thromboembolism is the leading cause of maternal death in the UK according to the latest UK CEMACE report, it would be nice to have reliable non-ionising tests in the ED to rapidly rule out this disease in pregnant women. Unfortunately, the alveolar-arterial oxygen gradient does not do the job.
A recent study compared the A-a gradient with CTPA as the gold standard. Of 102 patients who were pregnant or up to 6 weeks post-partum, there were 13 PEs (2 antepartum and 11 postpartum). The best sensitivity, specificity, and negative and positive predictive values for A-a gradients were 76.9%, 20.2%, 80.0%, and 11.5%, respectively.
Assessment of the alveolar-arterial oxygen gradient as a screening test for pulmonary embolism in pregnancy
Am J Obstet Gynecol. 2010 Oct;203(4):373.e1-4
Etomidate vs midazolam in sepsis
Given that single-dose etomidate can cause measurable adrenal suppression, its use in patients with sepsis is controversial. A prospective, double-blind, randomised study of patients with suspected sepsis who were intubated in the ED randomised patients to receive either etomidate or midazolam before intubation. The primary outcome measure was hospital length of stay, and no difference was demonstrated. The study was not powered to detect a mortality difference.
This study is interesting as a provider of fuel for the ‘etomidate debate’, but still irrelevant to those of us who have abandoned etomidate in favour of ketamine as an induction agent for haemodynamically unstable patients. Personally I remain unconvinced of the existence of patients who can’t be safely intubated using the limited choice of thiopentone or ketamine.
A Comparison of the Effects of Etomidate and Midazolam on Hospital Length of Stay in Patients With Suspected Sepsis: A Prospective, Randomized Study
Annals Emergency Medicine 2010;56(5):481-9
CVCs placed in the ED
Central lines in the ED are more likely to get infected because they’re inserted under less scrupulously aseptic conditions than in ICU, done more urgently, and are more likely to be placed in the mucky old femoral site by clumsy emergency physicians who don’t wash their hands after scratching their arses. Anyway, the intensivists will usually replace them with a ‘more ideal’ line after ICU admission. Right? Well, that’s what’s often taught and assumed to be the case, but a new study from a single centre suggests otherwise. ED-placed central venous catheters (19% of which were femoral) were typically left in for 4 to 5 days. The infection rate was 1.9 per 1,000 catheter-days, similar to that reported for central lines in other ICU case series.
Infection and Natural History of Emergency Department–Placed Central Venous Catheters
Annals of Emergency Medicine 2010;56(5):492-7
GPIIb/IIIa inhibitors
A systematic review on use of GPIIb/IIIa inhibitors in NSTEACS has been updated as part of the Annals of Emergency Medicine‘s Evidence Based Emergency Medicine series. The bottom line:
In patients with non-ST-segment elevation acute coronary syndromes who do not undergo early percutaneous coronary intervention, administration of platelet glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitors, given in addition to aspirin and unfractionated heparin, does not reduce 30-day or 6-month mortality. For the composite endpoint of myocardial infarction or death, there was modest benefit at 30 days and 6 months; however, there was an increased risk of major hemorrhage among those receiving GPIIb/IIIa inhibitors.
Update: Use of Platelet Glycoprotein IIb/IIIa Inhibitors in Patients With Unstable Angina and Non-ST-Segment Elevation Myocardial Infarction
Annals of Emergency Medicine Volume 56, Issue 5 , Pages e1-e2, November 2010
Compare this with the recommendations of the European Resuscitation Council who provide the following summary regarding this class of drug:
Gp IIB/IIIA receptor inhibition is the common final link of platelet aggregation. Eptifibatide and tirofiban lead to reversible inhibition, while abciximab leads to irreversible inhibition of the Gp IIB/IIIA receptor. Older studies from the pre-stent era mostly support the use of this class of drugs. Newer studies mostly document neutral or worsened outcomes. Finally in most supporting, as well as neutral or opposing studies, bleeding occurred in more patients treated with Gp IIB/IIIA receptor blockers. There are insufficient data to support routine pre-treatment with Gp IIB/IIIA inhibitors in patients with STEMI or non-STEMI-ACS. For high-risk patients with non-STEMI-ACS, in-hospital upstream treatment with eptifibatide or tirofiban may be acceptable whereas abciximab may be given only in the context of PCI. Newer alternatives for antiplatelet treatment should be considered because of the increased bleeding risk with Gp IIB/IIIA inhibitors when used with heparins.
European Resuscitation Council Guidelines for Resuscitation 2010 Section 5. Initial management of acute coronary syndromes
Resuscitation 81 (2010) 1353–1363 – full text downloadable
High flow O2 and mortality in COPD
An Australian randomised controlled trial of pre-hospital oxygen therapy in COPD patients compared titrated oxygen therapy with high flow oxygen. The primary outcome was prehospital and in-hospital mortality.
Titrated oxygen treatment was delivered by nasal prongs to achieve arterial oxygen saturations between 88% and 92%, with concurrent bronchodilator treatment administered by a nebuliser driven by compressed air. High flow oxygen was 8-10 l/min administered by a non-rebreather face mask, with bronchodilators delivered by nebulisation with oxygen at flows of 6-8 l/min.
Titrated oxygen treatment significantly reduced mortality, hypercapnia, and respiratory acidosis compared with high flow oxygen in acute exacerbations of chronic obstructive pulmonary disease. The authors claim: ‘For high flow oxygen treatment in patients with confirmed chronic obstructive pulmonary disease in the prehospital setting, the number needed to harm was 14; that is, for every 14 patients who are given high flow oxygen, one will die.‘
The authors did not report data on the in-hospital management of the patients.
Effect of high flow oxygen on mortality in chronic obstructive pulmonary disease patients in prehospital setting: randomised controlled trial
BMJ. 2010 Oct 18;341:c5462
Titrated oxygen treatment significantly reduced mortality, hypercapnia, and respiratory acidosis compared with high flow oxygen in acute exacerbations of chronic obstructive pulmonary disease. The authors claim: ‘For high flow oxygen treatment in patients with confirmed chronic obstructive pulmonary disease in the prehospital setting, the number needed to harm was 14; that is, for every 14 patients who are given high flow oxygen, one will die.‘
The authors did not report data on the in-hospital management of the patients.
Effect of high flow oxygen on mortality in chronic obstructive pulmonary disease patients in prehospital setting: randomised controlled trial
BMJ. 2010 Oct 18;341:c5462
Rocuronium reusable after sugammadex
Sugammadex currently has no role in my own emergency / critical care practice. However a helpful paper informs us that patients whose rocuronium-induced neuromuscular blockade had been reversed by sugammadex may be effectively re-paralysed by a second high dose (1.2 mg/kg) of rocuronium. Onset was slower and duration shorter if the second dose of rocuronium was given within 25 minutes of the sugammadex.
The study was done with sixteen volunteers and the initial dose of roc was only 0.6 mg/kg – less than that used for rapid sequence intubation by many emergency & critical care docs.
When repeat dose roc was given five minutes after sugammadex (n=6), mean (SD) onset time maximal block was 3.06 (0.97) min; range, 1.92–4.72 min. For repeat dose time points ≥25 min after sugammadex (n=5), mean onset was faster (1.73 min) than for repeat doses <25 min (3.09 min) after sugammadex. The duration of block ranged from 17.7 min (rocuronium 5 min after sugammadex) to 46 min (repeat dose at 45 min) with mean durations of 24.8 min for repeat dosing <25 min vs 38.2 min for repeat doses ≥25 min.
Repeat dosing of rocuronium 1.2 mg kg−1 after reversal of neuromuscular block by sugammadex 4.0 mg kg−1 in anaesthetized healthy volunteers: a modelling-based pilot study
Br J Anaesth. 2010 Oct;105(4):487-92
Novel subclavian cannulation method
Ultrasound-guided subclavian vein cannulation has reduced complications, but there is still a high incidence of failure to cannulate the vein and of accidental arterial cannulation. Vassallo & Bennett noticed that a fast running intravenous infusion in the ipsilateral arm of a patient produced variable echogenicity (lighter echos) in the subclavian vein. They describe deliberately using this appearance to both identify the subclavian vein and differentiate it from the subclavian artery.
With the intravenous infusion running with frequent drips in the drip chamber, the ultrasound beam is placed in long axis to the subclavian vessels in the subclavicular position. The angle of the ultrasound beam is adjusted to reveal both the subclavian vein and artery. The variable echogenicity, together with compression, can then be used to identify the vein. The presence of variable echogenicity in the vessel gives continuous feedback that the ultrasound beam has not drifted onto the artery. In cases where the ultrasound beam has included both artery and vein in the same image, this method has clearly identified the intended target vessel.
Subclavian cannulation with ultrasound: a novel method
Anaesthesia, 2010;65:1041
Scene times for rural retrieval in Scotland
The Emergency Medical Retrieval Service (EMRS) provides an aeromedical retrieval service to remote and rural communities in Scotland. They examined 300 retrievals over a five year period and showed a correlation between amount of critical care interventions required and total time on scene (defined as the total length of time between the aircraft landing and taking off from the scene, this includes access to patient, transfer to the helicopter and packaging for flight departure). Median scene time for both medical and trauma patients was 60 minutes.
The authors remind us that critical care secondary retrieval from rural healthcare facilities has many similarities to prehospital care (primary retrieval), and therefore consideration of scene times is of interest.
On-scene times and critical care interventions for an aeromedical retrieval service
Emerg Med J. 2010 Aug 19. [Epub ahead of print]
Paediatric arrest outcomes
A study of out-of-hospital paediatric arrests in Melbourne gives some useful outcome data: overall, paediatric victims of out-of-hospital cardiac arrest survived to leave hospital in 7.7% of cases, which is similar to adult survival in the same emergency system (8%). Survival was very rare (<1%) unless there was return of spontaneous circulation prior to hospital arrival. Sixteen of the 193 cases studied had trauma, but the survival in this subgroup was not specifically documented.
Epidemiology of paediatric out-of-hospital cardiac arrest in Melbourne, Australia
Resuscitation. 2010 Sep;81(9):1095-100
Ketamine for HEMS intubation in Canada
Ketamine was used by clinical staff from the The Shock Trauma Air Rescue Society (STARS) in Alberta to facilitate intubation in both the pre-hospital & in-hospital setting (with a neuromuscular blocker in only three quarters of cases). Changes in vital signs were small despite the severity of illness in the study population.
A prospective review of the use of ketamine to facilitate endotracheal intubation in the helicopter emergency medical services (HEMS) setting
Emerg Med J. 2010 Oct 6. [Epub ahead of print]