Target Oxygen Saturation in Extreme Prems

1316 infants who were born between 24 weeks 0 days and 27 weeks 6 days of gestation were randomised to one of two different target ranges of oxygen saturation: 85 – 89% vs. 91 – 95%. The primary outcome was a composite of severe retinopathy of prematurity (defined as the presence of threshold retinopathy, the need for surgical ophthalmologic intervention, or the use of bevacizumab), death before discharge from the hospital, or both.

All infants were also randomly assigned to continuous positive airway pressure or intubation and surfactant in a 2-by-2 factorial design.

The rates of severe retinopathy or death did not differ significantly between the lower-oxygen-saturation group and the higher-oxygen-saturation group (28.3% and 32.1%, respectively; relative risk with lower oxygen saturation, 0.90; 95% confidence interval [CI], 0.76 to 1.06; P=0.21). Death before discharge occurred more frequently in the lower-oxygen-saturation group (in 19.9% of infants vs. 16.2%; relative risk, 1.27; 95% CI, 1.01 to 1.60; P=0.04), whereas severe retinopathy among survivors occurred less often in this group (8.6% vs. 17.9%; relative risk, 0.52; 95% CI, 0.37 to 0.73; P<0.001). There were no significant differences in the rates of other adverse events.

An editorial notes that the unmasked trial data showed that the distribution of oxygen saturation levels was within or above the target range in the higher-oxygen-saturation group, but in the lower-oxygen-saturation group, it was about 90 to 95% (i.e., above the target range). The difference in oxygen saturation levels between the groups was about 3 percentage points instead of the 6 percentage points that had been planned. Therefore, this study actually compared saturation levels of about 89 to 97% with saturation levels of 91 to 97%; the results should be ascribed to these higher ranges.

Targeting oxygen saturation levels is difficult, and a recommended oxygen saturation range that is effective yet safe remains elusive. A lower oxygen saturation level significantly reduces the incidence of severe retinopathy of prematurity but may increase the rate of death.

Target Ranges of Oxygen Saturation in Extremely Preterm Infants
N Engl J Med. 2010 May 16. [Epub ahead of print]

Early CPAP versus Surfactant in Extreme Prems

In a randomised, multicentre trial of 1316 infants born between 24 weeks 0 days and 27 weeks 6 days of gestation, infants were randomly assigned to intubation and surfactant treatment (within 1 hour after birth) or to CPAP treatment initiated in the delivery room, with subsequent use of a protocol-driven limited ventilation strategy. The primary outcome was death or bronchopulmonary dysplasia as defined by the requirement for supplemental oxygen at 36 weeks.

Infants who received CPAP treatment, as compared with infants who received surfactant treatment, less frequently required intubation or postnatal corticosteroids for bronchopulmonary dysplasia (P<0.001), required fewer days of mechanical ventilation (P=0.03), and were more likely to be alive and free from the need for mechanical ventilation by day 7 (P=0.01). However the rates of the primary outcome did not differ significantly between the CPAP group and the surfactant group (47.8% and 51.0%, respectively; relative risk with CPAP, 0.95; 95% confidence interval [CI], 0.85 to 1.05).

The infants randomised to CPAP could receive limited invasive ventilation if necessary; 83.1% of the infants in the CPAP group were intubated. They did not include infants who were born at a gestational age of less than 24 weeks, since the results of a pilot trial showed that 100% of such infants required intubation in the delivery room.

This study had a 2-by-2 factorial design in which infants were also randomly assigned to one of two target ranges of oxygen saturation.

Early CPAP versus Surfactant in Extremely Preterm Infants
N Engl J Med. 2010 May 16. [Epub ahead of print]

Carotid Artery Stenting versus Endarterectomy

The Carotid Revascularization Endarterectomy vs. Stenting Trial (CREST) compared the outcomes of carotid-artery stenting with those of carotid endarterectomy among over 2500 patients with symptomatic or asymptomatic extracranial carotid stenosis.
The authors offer the following conclusions:

  • Stroke was more likely after carotid artery stenting.
  • Myocardial infarction was more likely after carotid endarterectomy, but the effect on the quality of life was less than the effect of stroke.
  • Younger patients had slightly fewer events after carotid-artery stenting than after carotid endarterectomy; older patients had fewer events after carotid endarterectomy.
  • The low absolute risk of recurrent stroke suggests that both carotid-artery stenting and carotid endarterectomy are clinically durable and may also reflect advances in medical therapy.

Stenting versus Endarterectomy for Treatment of Carotid-Artery Stenosis
NEJM May 26 2010 Published Online

Guidelines for Clostridium Difficile

Guidelines for preventing, detecting, and treating Clostridium Difficile infection from the Infectious Diseases Society of America have been published.

Clinical Practice Guidelines for Clostridium difficile Infection in Adults: 2010 Update by the Society for Healthcare Epidemiology of America (SHEA) and the Infectious Diseases Society of America (IDSA)
Infect Control Hosp Epidemiol 2010;31:431–455 Full Text

Bloodtest Not Pertinent (BNP)

Despite a lack of evidence that it’s useful, many emergency departments have introduced BNP testing. Some smart Australians decided to properly evaluate its benefit the best way possible – with a randomised controlled trial on 612 patients with acute severe dyspnoea. Guess what? Clinician knowledge of BNP values in patients who presented with shortness of breath to the emergency department did not reduce the probability of hospital admission or alter management or length of hospital stay. The study findings do not support indiscriminate BNP testing in all dyspnoea patients, but do not rule out a possible role in patients with milder dyspnoea.

B-type natriuretic peptide testing, clinical outcomes, and health services use in emergency department patients with dyspnea: a randomized trial
Ann Intern Med. 2009 Mar 17;150(6):365-71

PCI and therapeutic hypothermia

Percutaneous coronary intervention did not increase the risk of dysrhythmia, infection, coagulopathy, or hypotension associated with therapeutic hypothermia after cardiac arrest. Intensivists and cardiologists should perhaps agree that this adds to existing evidence that the two therapies are not mutually exclusive.
Feasibility and safety of combined percutaneous coronary intervention and therapeutic hypothermia following cardiac arrest
Resuscitation. 2010 Apr;81(4):398-403

The myth of ketamine and head injury

A literature review addresses the myth that ketamine is contraindicated in head injured patients. They summarise articles from the 1970’s which identified an association between ketamine and increased ICP in patients with abnormal cerebrospinal fluid pathways (such as those caused by aqueductal stenosis, obstructive hydrocephalus and other mass effects). In more recent studies no statistically significant increase in ICP was observed following the administration of ketamine in patients with head injury; some of the studies showed a net increase in CPP following ketamine administration. They list ketamine’s stable haemodynamic profile and potential neuroprotective effects as further rationale for its use.

The authors boldly summarise:

Based on its pharmacological properties, ketamine appears to be the perfect agent for the induction of head-injured patients for intubation.’

Myth: ketamine should not be used as an induction agent for intubation in patients with head injury
CJEM. 2010 Mar;12(2):154-7

Rapid discharge in AF

The Ottawa Aggressive Protocol is used to treat recent onset (< 48 hours) atrial fibrillation or flutter with procainamide and/or cardioversion to allow discharge from the emergency department.
A cohort of 660 patient visits is described in a paper in the Canadian Journal of Emergency Medicine, 95.2% involving atrial fibrillation and 4.9% involving atrial flutter. The mean age of patients enrolled was 64.5 years. In total, 96.8% were discharged home and, of those, 93.3% were in sinus rhythm. All patients were initially administered intravenous procainamide, with a 58.3% conversion rate. A total of 243 patients underwent subsequent electrical cardioversion with a 91.7% success rate. Adverse events occurred in 7.6% of cases: hypotension 6.7%, bradycardia 0.3% and 7-day relapse 8.6%. There were no cases of torsades de pointes, stroke or death. The median lengths of stay in the ED were as follows: 4.9 hours overall, 3.9 hours for those undergoing conversion with procainamide and 6.5 hours for those requiring electrical conversion.

This proactive approach by emergency physicians seems excellent for patients who in some centres probably still get admitted for this presentation. I’m not sure why they continue to use a drug with a conversion percentage in the 50’s, which the authors have demonstrated before. Many of us routinely use flecainide for recent onset AF in patients likely to have structurally normal hearts, as it has been shown to be superior to procainamide in AF.

Association of the Ottawa Aggressive Protocol with rapid discharge of emergency department patients with recent-onset atrial fibrillation or flutter
Canadian Journal of Emergency Medicine 12.3 (May 2010): p181(11)

Vital signs of severely injured children

Systolic blood pressures of severely injured children are very often hypertensive compared with APLS ‘norms’. A lower pulse rate is associated with more severe brain injury

SBP (Mean+/- 95% confidence limits) in moderately injured children with and without TBI by age and Advanced Paediatric Life Support (APLS) range for normal systolic blood pressure (shaded region)

Comparing the systolic blood pressure (SBP) and pulse rate (PR) in injured children with and without traumatic brain injury
Resuscitation. 2010 Apr;81(4):418-21