Intraoperative blood transfusions in burn patients.

BACKGROUND: Donated blood is a valuable and limited resource. Excision of burn wounds often leads to significant blood loss requiring transfusion. Accurately estimating blood loss is difficult, so examining the amount of blood products given intraoperatively is a clinically relevant way to measure utilization of this valuable resource. In this study, we examined the factors that influenced the amount of blood given intraoperatively during burn wound excisions. STUDY DESIGN AND METHODS: A retrospective analysis of patients admitted to a single burn center over 5 years who underwent excision of their burn wounds and received intraoperative blood products was performed. Patient and burn characteristics as well as pertinent surgical data and laboratory values on the day of surgery and postoperatively were gathered. A linear regression analysis examined factors influencing the number of units of products given and a predictive model was generated. RESULTS: A total of 563 operations performed on 166 patients were included. The amount of burn excised was the most influential variable on the amount of blood products given. Hemoglobin level, international normalized ratio, and platelet count on the day of surgery were associated with transfusion of different blood products. A predictive model was generated to aid in preoperative ordering of blood products. CONCLUSION: The amount of burn excised and common hematology and coagulation lab values were associated with the amount of different blood products administered during burn surgery. The predictive model generated needs to be validated prospectively to aid in preoperative planning for burn excisions.

Oxygen uptake and energy expenditure for children during rock climbing activity.

The purpose of this study was to measure oxygen uptake and energy expenditure in children during rock climbing activity. 29 children (age = 10.9 ± 1.7 yr) participated in the study. A commercially available rock climbing structure with ample features for submaximal effort climbing provided continuous terrain. Participants were instructed to climb at a comfortable pace. Following an initial 5-min rest, each child climbed one sustained 5-min bout followed by 5-min sitting recovery for a total of 10 min (SUS). This was immediately followed by five 1-min climbing + 1-min recovery intervals for a second total of 10 min (INT). Expired air was analyzed continuously. Energy expenditure (EE) was determined via the Weir method for 10-s intervals throughout the full protocol. The total energy expenditure in kilocalories during the 10-min SUS period was 34.3 ± 11.3 kcal. Energy expenditure during the 10-min INT period averaged 39.3 ± 13.1 kcal and was significantly higher than during SUS (p < .05). The mean total EE for SUS + INT was 73.7 ± 24.2 kcal. EE was correlated with body mass; r = .86. The rock climbing tasks employed in this study produced EE levels similar to what have been reported in children for stair climbing, sports/games activities, and easy jogging.

Physiological responses in rock climbing with repeated ascents over a 10-week period.

The purpose was to analyze the physiological responses and energy expenditure during repeated ascents of the same climbing route over a 10-week period. Nine climbers completed nine ascents of a specific route spaced 1 week apart. Expired air was analyzed continuously during each ascent, and time of ascent was recorded to the nearest second. Energy expenditure during climbing (EE(CLM)), and during climbing +10 min recovery (EE(TOT)) was calculated by the Weir and Zuntz equations. Differences among ascents 1, 4, 6 and 9 were analyzed by repeated measures ANOVA. Climbing time was longer for ascent 1 compared with ascents 4, 6 and 9 (P < 0.001). Differences were found for EE(CLM) (kcal; P < 0.001), between ascent 1 versus 6 and 9 and ascent 4 versus 9, using both Zuntz and Weir equations. Also, differences were observed in EE for recovery (P < 0.05) and EE(TOT) (P < 0.05) using both equations. Repeated ascents of a climbing route decreased the climbing time and absolute energy expenditure during climbing. Initially, the decrease in climbing energy expenditure is accompanied by an increase in energy expenditure during recovery; however, by the ninth ascent, the total energy expenditure of the task is lower than for ascent 1.

Change in geometric entropy with repeated ascents in rock climbing.

Lower geometric entropy (GE) could represent more economical movement in rock climbing. Repetition of a climbing route decreases energy expenditure (EE), however, association with changes in GE has not been studied. The purpose of this study was to observe changes in GE with repetition of a climbing route relative to changes in EE. Nine climbers completed nine ascents each, one week apart, on an indoor climbing structure. Digital video was recorded at 30 Hz and a marker point was digitised as an estimate of a climber's centre of mass position (CME). The displacement of CME was expressed as the length of the line of motion (LM). GE was calculated as ln((2 x LM)/CH)) where CH is the value of the convex hull about the LM. Indirect energy expenditure (EECLM) was calculated from expired air by the Weir method. Data were analysed for ascents 1 (A1), 3 (A3), 6 (A6) and 9 (A9) and compared via repeated measures ANOVA. GE was significantly different for A1 vs A6 and A9 (p < 0.05) and not different for other comparisons. GE was correlated with EECLM; r = 0.67 (p < 0.01). Climbers reduce geometric entropy with route familiarity and the lower entropy may be associated with lower energy expenditure.