2014 - May R3 Journal Review
Peterson MA et al. Ultrasound for Routine Lumbar Puncture. Acad Emerg Med. 2014; 21:130–6.This single center, prospective, randomized controlled trial assessed the ability of ultrasound, when wielded by emergency physicians, to improve the performance of lumbar puncture. Following a brief ultrasound training session for emergency residents and attendings, a convenience sample of 100 ED patients with planned lumbar punctures were randomized into two groups: 50 patients received ultrasound localized(not guided) lumbar punctures, while the other 50 received standard spinal landmark lumbar punctures. The patient characteristics of both groups were similar. Both of the primary outcome measures, the number of needle insertion attempts required for procedural success and success of the LP procedure, showed no significant difference between the two groups. The secondary outcomes, such as procedural time, patient pain, patient satisfaction, and traumatic taps showed no significant differences between the groups. An additional unplanned subgroup analysis of difficult to palpate or not palpable patients also showed no significant differences.
This study concluded that there may not be an advantage to using ultrasound for routine lumbar punctures, although the authors suggest difficult to palpate and obese patients may still benefit from ultrasound localization. There were several main limitations, including an admitted lack of power, as their initial calculations did not account for the wide variability in number of needle insertions, skewing their statistics. They also noted their brief training sessions as a potential limitation, as other studies that demonstrated an advantage to using ultrasound included a majority of advanced sonographers. Finally, they did wait ~10 years following enrollment completion to publish their results, and improvements in ultrasound technology over the past decade could potentially result in a different outcome should a similar study be repeated today. While this study does not support the use of ultrasound for routine lumbar punctures by the average emergency physician, additional studies are likely indicated, as a highly trained sonographer, when presented with a challenging lumbar puncture, may have an advantage.
Somjot SB et al. Haemodynamic-guided fluid administration for the prevention of contrast-induced acute kidney injury: the POSEIDON randomised controlled trial. Lancet 2014; 383: 1814-23. This single-center, randomized, single-blind (patients) trial looked at the “efficacy of a new fluid protocol based on left ventricular end-diastolic pressure for the prevention of contrast-induced acute kidney injury in patients undergoing cardiac catheterization.” Of 396 patients undergoing cardiac catheterization with GFR < 60, aged 18 or older, and 1 or more risk factors predisposing to contrast-induced AKI, 196 were given fluid per left ventricular end-diastolic pressure-guided volume expansion and 200 received fluids per standard therapy. The new protocol had decreased occurrence (12/178 [6.7%]) compared to the control group (28/172 [16.3%]) of the primary outcome measure of contrast-induced kidney injury (determined by > 25% or 0.5 mg/dL increase in serum creatinine). Cumulative adverse events at 30 days (2/196 [1.0%] v 8/200 [4.0%]) and 6 months (6/196 [3.1%] v 19/200 [9.5%]) were also less for the new protocol group. The study concluded that contrast-induced acute kidney injury occurred less often with the new protocol than in the control group. Though acutely in the ED, the use of left ventricular end-diastolic pressure as a guide during fluid administration for patients at risk for contrast-induced kidney injury is doubtful, the study did identify that fluid rates of up to 3-5 ml/kg for 5 hours in patients without severe CHF were feasible, with pulmonary edema in only 3 patients from each group. Perhaps, our patients destined for cardiac catheterization during their admission, should have their volume expansion begun at once in the ED to prevent contrast-induced AKI.
Beck V et al. Timing of Vasopressor Initiation and Mortality in Septic Shock: A Cohort Study. Crit Care. 2014,18:R97.
There is little evidence of the timing of vasopressor initiation has an impact on mortality for patients with septic shock. Using the Cooperative Antimicrobial Therapy in Septic Shock (CATSS) Database, the authors examined 6,514 patients (age >18) with the diagnosis of septic shock from 28 medical institutions in Canada, the U.S., and Saudi Arabia between 1996 and 2008.
Hypotension in this study was defined as MAP <65 mmHg, SBP <90mmHg, or a decrease in SBP >40mmHg from patient’s baseline. Onset of hypotension was defined as that which did not resolve despite at least 2L crystalloid or which improved but then recurred within one hour of fluid administration.
Mean age was 62 years with 57% male predominance. The most common vasopressor used was norepinephrine (66%) followed by dopamine. The authors adjusted for independent correlates for mortality in septic shock (AIDS, HTN, liver failure, neutropenia, malignancy, metastatic disease, APACHE II score, delay in antibiotics) and found a mildly increased risk of mortality only in the group with vasopressor delay of > 14 hours (OR 1.34, 95% CI 1.03-1.76, p=0.048). There was a stronger association with organ dysfunction, also driven by the 14-hour delay group, including increased risk of renal, respiratory, hematologic, CNS, coagulation, and metabolic complications. There was no impact on total in-hospital or ICU LOS.
This study has the usual limitation of a retrospective cohort study with multiple sub-group analyses. It is unknown why some patients had a vasopressor delay of > 14 hours despite meeting the criteria for persistent hypotension. Until more rigorous and prospective studies can be undertaken, it is probably prudent to treat each patient on an individual basis and start vasopressors as soon after recognition of persistent hypotension as possible.
Hansen GW et al. The Neglected Lead on Electrocardiogram: T Wave Inversion in Lead aVL, Nonspecific Finding or a Sign for Left Anterior Descending Artery Lesion? JEM. 2014;48:165- 170
This study was a retrospective chart review of 431 patients that underwent PCI for various reasons from 2009 - 2011. Twenty-nine percent of patients were found to have a mid LAD lesion, and 85% of those had the occlusion >50%. Eighty-five percent of these patients had T wave inversion (TWI) on lead aVL. When patients with LVH or BBB pattern were excluded, the presence of TWI in aVL and at least one addition lead had a sensitivity of a mid LAD lesions of >50% of 90%, and a specificity of 62%. The conclusion from the study is that T wave inversion in lead aVL is a possible predictor for mid LAD lesions and patients with concerning symptoms and risk factors should be referred for further cardiac workup as they are high risk for future occlusive events. Limitations include the small size of the study and the retrospective nature.