Weekly Review #9

ScanCrit reviewed a case report of double sequential defibrillation (DSD) published in the journal of Prehospital Emergency Care. DSD is a process of hooking a patient up to two defibrillators and providing sequential shocks. In this particular case the patient had refractory V-Fib and had received 7 unsuccessful shocks with lead placement changes. The team performed DSD using the standard anterior/apex as well as anterior/posterior placements, with the deliver shock button pressed as close to simultaneously as possible. DSD converted the patient to sinus rhythm, who went on to survive to discharge. The exact mechanism of why DSD works when standard defibrillation has failed is not known, there haven't been any good quality trials performed to date; until that happens this care report is unlikely to significantly change current practice. DSD is an exciting concept: it's a novel approach, and one that can easily be deployed without expensive new equipment. This may not be a game changer in the management of refractory arrest, but it's at least one more tool.

http://www.scancrit.com/2015/07/07/one-two-punch/#more-8222




On July 8 & 9th I participated in the inaugural Eastern Association for the Surgery of Trauma (EAST) journal club discussion. It was on an study published the Journal of Trauma and Acute Care Surgery on the use of hemostatic foam in recently deceased cadavers. The study by Mesar et al., was attempting to determine what a safe dose of foam would be. Essentially the team wanted to extend their animal models to humans to determine how much intra-abdominal pressure, and internal organ contact would be made with differing volumes of injectable foam.




The study used recently deceased cadavers (146 minutes, ± 34min), added IV fluids to the abdominal cavity to mimic blood volume, and injected foam into the cavity. Intra-abdominal pressures (IAP) where monitored and the abdomen measured every minute for 15 minutes; after 15 minutes the foam was removed to evaluate the amount of contact with internal organs.

Of the 409 patients screened 21 were recruited, 18 met inclusion criteria, 3 of the patients were excluded from the final results due to errors in administering the foam. 4 cadavers received either 45, 55, or 65mls of intra-abdominal foam using one of two purpose built delivery systems. The foam quickly reached peak volume, the resulting increase in IAP fell below the maximum threshold of 65mmHg; while the cadaveers given larger doses exceeded the IAP cutoff.

After 15 minutes the Cadavers all successfully had the foam block removed, in one piece, by laprotomy. The contact with underlying organs was noted in each case, and the average contact areas was determined. Best coverage, unsurprisingly, occurred with larger doses, and the foam didn't absorb extra fluid.

The goal of this study was to determine what a "safe" dose of intra-abdominal foam would be, and it appears that doses of 65ml will generally fall below their IAP cutoff of 65mmHg. There are some limitations to this study: the sample size is quite small, and IAP results appear to vary significantly between cadavers receiving similar doses, making predictions on average IAP by dose would be difficult. The delivery system could also use improvement, of 18 attempts there were 3 (16%) errors, one of which resulted in accidental bowel perforation. From a clinical perspective I think that this technology still needs a fair bit of refining: there is no clearly articulated target population (injury mechanism). The intent is clearly hemorrhage control, but the foam is too superficial to access major vessels (which is fine, REBOA can do that), but it also has poor contact with solid organs at doses below the IAP cutoff.

From a nursing perspective I think that this technology is exciting, abdominal bleeds account for a large number of battlefield deaths, and any tools that can increase survival for these injuries is worth investigating. I'm looking forward to additional research on this technology, and would love to see if can be used in human trials.

The moderators at the EAST journal club did an excellent job. Responses to questions were generally rapid, and they were able to offer some additional information not explicitly stated in the research article. I look forward to the next journal club discussion, this and future reviews are on twitter at #EASTjc.

http://journals.lww.com/jtrauma/Fulltext/2015/07000/Human_dose_confirmation_for_self_expanding.6.aspx







Ryan Radecki from emlitofnote had a post reviewing the specificity and sensitivity of urinalysis for UTI in febrile pediatric patients. This is a 15 year 276 patient multicenter review of infants less than three months of age with fevers, bacteremia and UTI. The goal of the study was to determine how effective urinalysis as in predicting urinary tract infection. The results are surprisingly positive, as a predictive tool urinalysis is impressively accurate: 

• Trace or greater leukocyte esterase: 97.6% (94.5-99.2) sensitive and 93.9% (87.9-97.5) specific.
• Pyuria, >3 WBC/HPF: 96% (92.5-98.1) sensitive and 91.3% (84.6-95.6) specific.
• Pyuria or any LE: 99.5% (98.5-100) sensitive and 87.8% (80.4-93.2) specific.

These results are interesting because as a screening tool UA alone is generally not effective in adult or geriatric populations. All three of these are worth a review, as the differing conclusions offer an excellent case study in Bayesian statistics and determining likelihood ratios. From a nursing perspective having a non-invasive tool with high diagnostic power is great news, taking blood from an infant is traumatic for the care team, the parents, and most importantly the patient.  

http://www.emlitofnote.com/2015/07/the-utility-of-urinalysis-in-young.html

A new study published in Critical Care by Acheampong and Vincent examined the relationship between fluid balance and mortality in ICU patients admitted with sepsis. This study was a prospective observational study of 173 patients admitted to a single Belgian ICU for sepsis in 2012. Inclusion criteria were: patients >15 years of age, admitted to ICU >48hrs for sepsis. These patients were treated using the "surviving sepsis" guidelines. Total enteral/parenteral volumes were recorded against total sensible fluid loss to determine net fluid balance; there were 225 patients enrolled, 173 met inclusion criteria. Patients with a net positive fluid balance, or in septic shock were more likely to have poor outcomes. Overall ICU mortality rate was 34%, and the results suggest that positive fluid balance was associated with an increase in mortality (HR 1.014/ml/kg: 1.008-1.027, P<0.001). Non-surviving patients however tended to be sicker (SOFA score 9.0±3.3 vs 7.7±3.3), to be in septic shock (97 vs. 68%), and to have an infection of pulmonary origin (53 vs. 30%). There were significant differences between groups; unfortunately vital sign parameters, and rates of vasopressor use were not discussed, making it impossible to determine if the relationship between fluid balance and mortality is one of cause or effect. This was a small single center study with no control arm, we know the patients who didn't survive tended to be sicker, and to be in septic shock: they likely needed more fluids to maintain BP and likely had higher rates of vascular leakage and therefore fluid retention. This study does establish that positive fluid balance is prognostic of mortality, but we knew that, from a nursing perspective this study adds little to our understanding of sepsis, or fluid resuscitation.

http://www.ccforum.com/content/19/1/251




TamingtheSRU had a discussion posted on their site by Dr. Brian Burns from Sydney HEMS. Where he was discussed the concepts of marginal gains, or aggregation of gains, and how they can be used to improve pre-hospital patient care. The talk wasn't about medical or technical skills; rather it focused on different human factor aspects of self mastery. There were several methods reviewed, but the discussion focused primarily on tools such as cognitive offloading, cognitive buildups, and cognitive rally points. Dr. Burns emphasized the usefulness of simulation, not only for difficult skills that are seldom performed, but also for common skills that need constant practice, and how to perform common skills in uncommon scenarios. This is an excellent video for all clinicians, as a nurse it's great to see some of the best clinicians around discussing simple strategies such as visualization and checklists, strategies that everyone can use to improve their everyday performance, as well as their performance in critical moments.


http://www.tamingthesru.com/blog/prehospital-medicine/when-that-1-makes-all-the-difference