Monthly Archives: February 2010

Ultrasound

Fetal ultrasound safe

From the UK’s Health Protection Agency website:
The independent Advisory Group on Non-Ionising Radiation (AGNIR), which reports to the Health Protection Agency, has reviewed the latest scientific evidence on the health effects of ultrasound (frequencies above 20 kilohertz) and infrasound (below 20 Hz).
The report finds that the available evidence does not suggest that diagnostic ultrasound affects mortality of babies during pregnancy or soon after birth. The evidence also does not suggest any effect on childhood cancer risk. There have, however, been some unconfirmed reports suggesting possible effects on the developing nervous system – for instance, on handedness of the child.
AGNIR concluded that there is no established evidence that diagnostic levels of ultrasound are hazardous. However, further research is needed to determine whether there are any long-term adverse health effects, especially following exposure of the unborn child.

All Updates, ICU, Resus

ScvO2 in sepsis: high is bad too

ScvO2 values are obtained by measuring the oxygen saturation in venous blood returning to the heart, and reflect the balance between oxygen delivery and oxygen consumption.
Low (<70%) ScvO2 values were targeted by Rivers in his Early Goal Directed Therapy study: by improving the macrocirculation with fluids, vasoactive drugs, and packed red cells the aim is to improve oxygen delivery to tissues, and therefore a higher oxygen saturation is found in the venous blood returning to the heart in adequately resuscitated patients. The story is more complex, however, as mechanisms of oxygen supply (macrocirculatory flow), distribution (microcirculatory flow), and processing (mitochondrial function) must all function at an adequate level to maintain normal physiology.
Although low ScvO2 values may be a marker for macrocirculatory failure, high ScvO2 values may reflect microcirculatory or mitochondrial failure.
A multicentre study demonstrated a higher mortality on patients whose ScvO2 in the ED was high (90-100%) compared with those with a normal ScvO2.
Mortality associated with three groups according to their highest recorded ScvO2 in the ED was:
Hypoxia group (ScvO2 <70%) – 40% mortality (95% CI 29-53)
Normoxia group (ScvO2 71-89%) – 21% mortality (95% CI 17-25)
Hyperoxia group (ScvO2 90-100%) – 34% mortality (95% CI 25-44)
The study design could not control for many potential confounders, but this opens the door for further study, and reminds us that the unthinking pursuit of a single physiological target may miss the bigger clinical picture.
Multicenter Study of Central Venous Oxygen Saturation (ScvO2) as a Predictor of Mortality in Patients With Sepsis
Annals of Emergency Medicine 2010;55(1):40-46

Acute Med, All Updates

80 lead ECG increases AMI detection – so what?

The 80-lead ECG is more sensitive than a 12 lead ECG for detecting infarcts in the posterior, right, inferior, and high lateral areas of the heart.
80-lead ECG body surface mapping was applied to 1830 patients in the emergency department with moderate to high risk chest pain. 12 lead ECG detected STEMI in 91 patients and an additional 25 patients had 80-lead-only STEMI.

The authors and an editorialist point out some interesting issues and unanswered questions regarding the application of this technology:

  • Since almost all of the 80-lead-only STEMI patients had an elevated troponin, is this just another way of diagnosing NSTEMI?
  • Since there are no convincing data demonstrating a benefit from immediate therapy of NSTEMI, would the earlier detection improve outcome?
  • Angiographic findings in the 80-lead-only STEMI group showed similar lesions to 12-lead STEMI patients, with more frequent involvement of posterior (left circumflex) and right ventricular (right coronary artery) regions
  • Is the increase in sensitivity offered by the 80-lead ECG accompanied by a decrease in specificity?

More research is needed – preferably in a randomised controlled trial – before this interesting technology is rolled out in emergency departments
Acute detection of ST-elevation myocardial infarction missed on standard 12-Lead ECG with a novel 80-lead real-time digital body surface map: primary results from the multicenter OCCULT MI trial.
Ann Emerg Med. 2009 Dec;54(6):779-788
The 80-lead ECG: more expensive NSTEMI or Occult STEMI
Ann Emerg Med. 2009 Dec;54(6):789-90

Acute Med, All Updates, Resus

Levosimendan in beta blocker overdose

Not a human study, but toxicology RCTS rarely are…
Levosimendan – a calcium sensitiser with inotropic properties, was superior to dobutamine and to saline placebo in the end points of survival, cardiac output, and mean arterial pressure in anaesthetised pigs with propranolol overdose.
Levosimendan as a Rescue Drug in Experimental Propranolol- Induced Myocardial Depression: A Randomized Study
Ann Emerg Med. 2009 Dec;54(6):811-817

Acute Med, All Updates

ABCD2 evaluated

Investigators evaluated in admitted patients with transient ischemic attack, the accuracy of the ABCD2 (age [A], blood pressure [B], clinical features [weakness/speech disturbance] [C], transient ischemic attack duration [D], and diabetes history [D]) score in predicting ischemic stroke within 7 days.
Of 1667 patients admitted with TIA, 23% developed an ischaemic stroke within 7 days. ABCD2 scores were available in 1054 patients, in whom a low score (0-3) had a negative likelihood ratio for disabling ischaemic stroke with 7 days of 0.16 ((5% CI 0.04-0.64) and sensitivity of 92.2% (83.4-96.5)
The authors suggest the best application of the ABCD2 score may be to identify patients at low risk for an early disabling ischemic stroke.
A multicenter evaluation of the ABCD2 score’s accuracy for predicting early ischemic stroke in admitted patients with transient ischemic attack.
Ann Emerg Med. 2010 Feb;55(2):201-210
ABCD2 Score Calculator

All Updates, PHARM, Resus

External jugular vein a tricky one

Emergency medicine residents and paramedics cannulated patients who were anaesthetised. The external jugular vein (EJV) took longer to cannulate and had a higher failure rate than an antecubital vein. More than a quarter of the paramedics and a third of the doctors failed to cannulate the EJV.
Is external jugular vein cannulation feasible in emergency care? A randomised study in open heart surgery patients
Resuscitation. 2009 Dec;80(12):1361-4