Time Spent Working in Custody Influences Work Sample Test Battery Performance of Deputy Sheriffs Compared to Recruits

This study determined the influence of years spent working in custody on fitness measured by a state-specific testing battery (Work Sample Test Battery; WSTB) in deputy sheriffs. Retrospective analysis was conducted on one patrol school class (51 males, 13 females) divided into three groups depending on time spent working in custody: DS24 (<24 months; n = 20); DS2547 (25–47 months; n = 23); and DS48+ (≥48 months; n = 21). These groups were compared to a recruit class (REC; 219 males, 34 females) in the WSTB, which comprised five tasks completed for time: 99-yard (90.53-m) obstacle course (99OC); 165-pound (75-kg) dummy drag; six-foot (1.83-m) chain link fence (CLF) and solid wall (SW) climb; and 500-yard (457.2-m) run (500R). A univariate analysis of covariance (ANCOVA) (controlling for sex and age) with Bonferroni post hoc determined significant between-group differences. DS48+ were slower in the 99OC compared to the REC (p = 0.007) and performed the CLF and SW slower than all groups (p ≤ 0.012). DS24, DS2547, and DS48+ were all slower than REC in the 500R (p ≤ 0.002). Physical training should be implemented to maintain fitness and job-specific task performance in deputy sheriffs working custody, especially considering the sedentary nature of this work

Anatomic Dead Space Cannot Be Predicted by Body Weight

Anatomic, airway, or tracheal, dead space is the part of the tidal volume that does not participate in gas exchange. Knowledge of the size of the dead space is important for proper mechanical ventilation, especially if small tidal volumes are used. Respiratory and medical textbooks state that anatomic dead space can be estimated from the patient’s body weight. Specifically, these references suggest dead space can be predicted using a relationship of one milliliter per pound of body weight. Using a volumetric capnography monitor that incorporates on-airway flow and CO2 monitoring (NICO2, Respironics, Wallingford CT), anatomic dead space can be automatically and directly measured using Fowler’s method in which dead space equals the exhaled volume up to the point when CO2 rises above a threshold [4]. We retrospectively analyzed data collected in 58 (43 male, 15 female) patients to assess the accuracy of weight-based estimation of anatomic dead space. It appears that the average anatomic dead space roughly corresponds to the average body weight for the overall population; however, the poor correlation between individual patient weight and dead space contradicts the suggestion that dead space can be estimated from body weight

Testing an Oxygen Demand Delivery Device

Anesthesia care providers routinely deliver supplemental O2 during monitored anesthesia care to prevent hemoglobin desaturation. The existing method of delivery, however, contributes to complications including respiratory depression and fire hazard. Patient variability also makes delivering O2 difficult. We have developed a demand oxygen delivery system that only gives oxygen during early inspiration. We designed a volunteer study to evaluate patient monitoring and to compare continuous flow to demand delivery. We hypothesized that ceasing oxygen delivery during expiration will facilitate reliable capnography in non-intubated patients. We also hypothesized that delivering oxygen on demand leads to higher alveolar oxygen concentrations and higher hemoglobin saturation. Methods: We recruited thirty healthy volunteers. We asked volunteers to lie down in a hospital bed and fitted them with a nasal cannula and a pulse oximeter. Our prototype system delivered both constant and demand oxygen delivery, one at a time, of flows between 0 and 10 L/min. Each flow rate and mode combination was delivered for two minutes. At the end of each two-minute period, oxygen flow was turned off and the expired oxygen and carbon dioxide was sampled for three breaths. Results: When using demand delivery, the observed etCO2 value was within ±0.57 mm Hg for all flow rates. When using constant mode, the error increased as the supplemental O2 flow rate increased. Statistical analysis showed no significant difference when monitoring etCO2 using demand delivery. A statistically significant (P \u3c 0.05) difference in etCO2 measurement was observed for all rates when monitoring etCO2 during constant flow. ETO2 values were significantly higher (P \u3c 0.05) during demand delivery than during continuous flow. Higher SpO2 values were also observed during demand delivery. For flow rates of 1-4 L/min, less than 40% percent of constant flow oxygen values were needed to obtain equivalent ETO2 concentrations when using demand oxygen delivery. Discussion: EtCO2 can be monitored accurately when supplemental O2 delivery is interrupted during expiration. Demand delivery is useful for delivering O2 while still ensuring accurate etCO2 readings on exhalation. Higher ETO2 concentrations and SpO2 values can be achieved using demand oxygen delivery. These findings are consistent with prior evaluation of demand oxygen delivery systems used for long-term oxygen therapy. This study has shown that our intelligent oxygen flowmeter can obtain ETO2 and SpO2 values equivalent to or higher than continuous flow oxygen delivery while providing the benefits of demand oxygen delivery including reduced operating room fire hazar

Administering Model-based Patient-specific Supplemental Oxygen Therapy

Purpose: The oxyhemoglobin dissociation curve describes the relationship between the partial pressure of oxygen and the percent of hemoglobin saturated with oxygen and varies with chemical and physical factors that differ for every patient. If variability could be determined, patient specific oxygen therapy could be administered. We have developed a procedure for characterizing variations in the oxygen dissociation curve. The purpose of this study was to validate this procedure in surgical patients. Methods: The procedure uses an automated system to alter oxygen therapy and Hill\u27s equation to fit measurements. Once measurements are gathered, the procedure uses an iterative least-squares method to determine best-fit parameters for the Hill equation. The procedure was performed on surgical patients after which model fit was assessed. Results: 39 patients participated in this study. Using patient-specific parameter values increases correlation when compared to standard values. The procedure improved the model fit of patient saturation values significantly in 19 patients. Conclusions: This paper has demonstrated a procedure for determining patient specific pulse oximeter response. This procedure determined best-fit parameters resulting in a significantly improved fit when compared to standard values. These best-fit parameters increased the coefficient of determination R2 in all cases

Rebreathing Used for Cardiac Output Monitoring Does Not Increase Heart Rate

The partial rebreathing method for cardiac output determination produces short periods of elevated arterial CO2 content. Because previous work had shown that elevated etCO2 levels increased cardiac output, mostly due to heart rate increases, a concern was raised that the rebreathing periods could be inducing an elevated heart rate. This could also raise the cardiac output (CO), since CO = (Heart Rate) X (Stroke Volume). We studied 93 patients in the OR and the ICU who had undergone a total of 5142 partial rebreathing measurements by the NICO2 monitor (Novametrix Medical Systems) to determine whether the heart rate was raised, even if transiently, during the monitored period. Our conclusion was that the rebreathing periods caused no detectable change in the heart rate