Workshift Changes in Hydration Status During Wildfire Suppression.

OBJECTIVE: Document wildland firefighters (WLFFs) hydration status during a singular workshift (13.7 ±â€Š1.4 hours). METHODS: WLFF researchers documented real-time WLFF (n = 71) urine metrics and fluid consumption. Body weight and blood samples (n = 25) were also collected. Two-tailed dependent t tests determined statistical significance (P < 0.05). RESULTS: Body weight significantly decreased (-0.3 ±â€Š1.1%, P > 0.05). Fluid consumption totaled 6.2 ±â€Š2.3 L including food and 5.0 ±â€Š2.1 L without food. Morning versus afternoon urine frequency (2.6 ±â€Š1.3, 3.1 ±â€Š1.9 voids), urine volume (1.2 ±â€Š0.7, 1.3 ±â€Š0.8 L), urine volume per void (440 ±â€Š157, 397 ±â€Š142 mL), and urine specific gravity (1.010 ±â€Š0.007, 1.010 ±â€Š0.007) were not significantly different (P > 0.05). Pre- to post-workshift serum chloride (103.2 ±â€Š1.9, 101.4 ±â€Š1.7 mM) and blood glucose (5.2 ±â€Š0.4, 4.5 ±â€Š0.7 mM) significantly decreased (P < 0.05), while serum sodium (141.5 ±â€Š2.4, 140.8 ±â€Š2.0 mM) and serum potassium (4.3 ±â€Š0.3, 4.2 ±â€Š0.3 mM) remained stable (P > 0.05). CONCLUSIONS: WLFFs can ingest fluid and food amounts that maintain workshift euhydration and electrolyte status.

Influence of Fluid Delivery Schedule and Composition on Fluid Balance, Physiologic Strain, and Substrate Use in the Heat.

INTRODUCTION: Wildfire suppression is characterized by high total energy expenditure and water turnover rates. Hydration position stands outline hourly fluid intake rates. However, dose interval remains ambiguous. We aimed to determine the effects of microdosing and bolus-dosing water and microdosing and bolus-dosing carbohydrate-electrolyte solutions on fluid balance, heat stress (physiologic strain index [PSI]), and carbohydrate oxidation during extended thermal exercise. METHODS: In a repeated-measures cross-over design, subjects completed four 120-min treadmill trials (1.3 m·s-1, 5% grade, 33°C, 30% relative humidity) wearing a US Forest Service wildland firefighter uniform and a 15-kg pack. Fluid delivery approximated losses calculated from a pre-experiment familiarization trial, providing 22 doses·h-1 or 1 dose·h-1 (46±11, 1005±245 mL·dose-1). Body weight (pre- and postexercise) and urine volume (pre-, during, and postexercise) were recorded. Heart rate, rectal temperature, skin temperature, and steady-state expired air samples were recorded throughout exercise. Statistical significance (P<0.05) was determined via repeated-measures analysis of variance. RESULTS: Total body weight loss (n=11, -0.6±0.3 kg, P>0.05) and cumulative urine output (n=11, 677±440 mL, P>0.05) were not different across trials. The micro-dosed carbohydrate-electrolyte trial sweat rate was lower than that of the bolus-dosed carbohydrate-electrolyte, bolus-dosed water, and microdosed water trials (n=11, 0.8±0.2, 0.9±0.2, 0.9±0.2, 0.9±0.2 L·h-1, respectively; P<0.05). PSI was lower at 60 than 120 min (n=12, 3.6±0.7 and 4.5±0.9, respectively; P<0.05), with no differences across trials. The carbohydrate-electrolyte trial's carbohydrate oxidation was higher than water trial's (n=12, 1.5±0.3 and 0.8±0.2 g·min-1, respectively; P<0.05), with no dosing style differences. CONCLUSIONS: Equal-volume diverse fluid delivery schedules did not affect fluid balance, PSI, or carbohydrate oxidation during extended thermal work.

Total Energy Intake and Self-Selected Macronutrient Distribution During Wildland Fire Suppression.

INTRODUCTION: Wildland firefighters (WLFF) work long hours in extreme environments, resulting in high daily total energy expenditure. Increasing work-shift eating episodes and/or providing rations that promote convenient eating has shown augmented self-selected work output, as has regular carbohydrate (CHO) consumption. It remains unclear how current WLFF feeding strategies compare to more frequent nutrient delivery. Our aim was to determine WLFFs' self-selected field total energy intake (TEI), composition, and feeding patterns during wildland fire suppression shifts. METHODS: WLFF were deployed to fire incidents across the United States throughout the 2018 fire season. Preshift food inventories collected at basecamp provided item-specific nutrient content (kilocalories, CHO, fat, protein). Work shift consumption (TEI, feeding frequency, episodic composition) was monitored in real time by field researchers on fireline via observational data capture using mobile tablets. Shift work output was also quantified via actigraph accelerometry. RESULTS: Eighty-six WLFF (27.5±6.4 y; 16 female, 70 male) worked 14.0±1.1 h shifts, with a TEI of 6.3±2.5 MJ (1494±592 kcal) (51±10, 37±9, 13±4% for CHO, fat, and protein, respectively). WLFF averaged 4.3±1.6 eating episodes (1.4±1.3 MJ [345±306 kcal] and 44±38 g CHO·episode-1). WLFF who consumed >20 kcal·kg-1 averaged less sedentary activity than those consuming <16 kcal·kg-1. Data are presented as mean±SD. CONCLUSIONS: Not including fire camp meals (breakfast, dinner), the present work-shift TEI approximates 33% of previously determined WLFF total energy expenditure and demonstrates that current WLFF consumption patterns may not deliver adequate nutrients for occupational demands.

Significance of lymph vessel invasion identified by the endothelial lymphatic marker D2-40 in node negative breast cancer.

Monoclonal antibody D2-40, a marker of lymphatic endothelium, identifies tumor emboli in lymph vessels. The aim of the study was to assess whether D2-40+ lymph vessel invasion (LVI) correlates with clinicopathologic factors including lymphovascular invasion (LVI) as assessed by haematoxylin and eosin-stained sections (H&E+ or H&E-) and to assess the prognostic significance in node-negative breast cancer. The study group consisted of 303 node-negative breast cancer patients that had a median follow-up of 7.6 years. Clinical and pathological data were retrieved from the Henrietta Banting database. Immunohistochemical staining was performed on formalin-fixed, paraffin-embedded tissue sections of the primary invasive carcinoma using D2-40. Immunostaining with CD31 was performed on the discordant cases that were H&E+/D2-40-. D2-40+ lymph vessel invasion was detected in 82/303 (27%) cases. The foci of lymphatic invasion occurred predominantly at the invasive front of the tumor. The absence of D2-40 and CD31 in 13/17 discordant cases was suggestive of retraction artefact. D2-40+ lymph vessel invasion correlated significantly with age (P=0.0003), tumor size (P=0.005), histological grade (P=0.0001), H&E+ (P=<0.0001) and estrogen receptor status (P=0.005) but not with histological type or progesterone receptor status. Multivariate analysis revealed that D2-40+ lymph vessel invasion was the only significant predictor of distant recurrence. There was no significant association between D2-40 status and local recurrence (P=0.752) or regional recurrence (P=0.13). Both D2-40+lymph vessel invasion (P=0.009) and H&E+LVI cases (P=0.02) were associated with overall shorter survival in univariate analysis. These data indicate that D2-40 identifies lymphatic invasion in breast tumors and is a significant predictor of outcome in breast cancer.