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This week's featured articles


Heat Tolerance Testing and the Return to Duty Decision: A Two-Year Case Cohort Analysis


Kester R, Abraham PA, Leggit JC, Harp JB, Kazman JB, Deuster PA, O'Connor FG. 24(1). 48 - 52. (Journal Article)


Background: Among individuals with prior exertional heat illness (EHI), heat tolerance testing (HTT) may inform risk and return to duty/activity. However, little is known about HTT's predictive validity, particularly for EHI recurrence. Our project sought to demonstrate the predictive validity of HTT in EHI recurrence and HTT's utility as a diagnostic tool in exertional heat stroke (EHS). Methods: Participants with prior EHS were recruited for the study by a physician's referral and were classified as heat tolerant or intolerant after completing demographics and an HTT. Participants were further categorized as single/simple (SS) EHI or recurrent/complex (RC) EHI by conducting a retrospective record review of the following two years. We calculated the positive (PPV) and negative predictive values (NPV) of HTT. Results: The retrospective review of HTT records was used to categorize 44% of Servicemembers as RC, with 77% classified as heat tolerant, 14% as heat intolerant, and 9% as borderline. When borderline cases were classified as heat intolerant, HTT had a high NPV, indicating a high probability that heat-tolerant individuals did not have recurrent EHI. When borderline cases were classified as heat tolerant, NPV and sensitivity decreased while specificity increased. Conclusion: We demonstrated that the HTT had a 100% NPV for future EHI over two years of follow-up for Servicemembers with a history of recurrent heat injury and negative HTT results. An HTT can provide critical data points to inform return to duty decisions and timelines by predicting the risk of EHI recurrence.

Keywords: exertional heat stroke; heat stroke; heat tolerance testing; return to duty; heat tolerance; exertional heat illness; recurrent heat injury

PMID: 38360027


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When Minutes Matter: A Comparison of Whole Blood Collection Techniques


Wier R, Walther S, Woodard C, Jordan CS, Matthews KJ, Deaton TG, Drew B, Byrne T, Zarow GJ. 24(1). 53 - 59. (Journal Article)


Background: Fast and reliable blood collection is critical to emergency walking blood banks (WBB) because mortality significantly declines when blood is quickly administered to a warfighter with hemorrhagic shock. Phlebotomy for WBB is accomplished via either the "straight stick" (SS) or "ruggedized lock" (RL) method. SS comprises a 16-gauge phlebotomy needle connected to a blood collection bag via tubing. The RL device collects blood through the same apparatus, but has a capped, intravenous (IV) catheter between the needle and the donor's arm. This is the first study to compare these two methods in battlefield-relevant metrics. Methods: Military first responders and licensed medical providers (N=86) were trained in SS and RL as part of fresh whole blood training exercises. Outcomes included venipuncture success rates, time to IV access, blood collection times, total time, and user preferences, using a within-subjects crossover design. Data were analyzed using ANOVA and nonparametric statistics at p<0.05. Results: SS outperformed RL in first venipuncture success rates (76% vs. 64%, p=0.07), IV access times (448 [standard error of the mean; SE 23] vs. 558 [SE 31] s, p<0.01), and blood collection bag fill times (573 [SE 48] vs. 703 [SE 44] s, p<0.05), resulting in an approximate 3.5-minute faster time overall. Survey data were mixed, with users perceiving SS as simpler and faster, but RL as more reliable and secure. Conclusion: SS is optimal when timely collection is imperative, while RL may be preferable when device stability or replacing the collection bag is a consideration.

Keywords: phlebotomy; intravenous access; hemorrhagic shock; blood donation; walking blood bank; emergency donor panel; buddy transfusion; Tactical Combat Casualty Care

PMID: 38446068


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