Evidence for opioid variability, Part 1: A biological perspective.

The interplay of biological and pyschosocial factors explain the unique individual differences in opioid requirements that occur among postoperative patients. Nurses must be familiar with the physiologic mechanisms that influence opioid analgesia. Despite growing evidence that doses of opioid analgesics needed to achieve pain relief vary significantly from patient to patient, standardized dosing regimens continue to drive administration of medications for postoperative pain. In this article, evidence-based literature related to the biologic factors that contribute to differences in responses to opioid medication will be examined. Content will assist the Perioperative Nurse to recognize the pharmacology of opioid analgesics and the scientific basis for differences in the body's ability to metabolize and excrete opioids. These differences include age, gender, genetic predisposition, type of surgical procedure, preexisting pain, and prior or concurrent opioid use. Specific terms are introduced and defined to increase understanding of opioid variability.

Water running with and without a flotation vest in competitive and recreational runners.

The purpose of this study was to determine whether competitive and recreational runners would replicate land training intensity during water immersion (WI) running with (V) and without (NV) a flotation vest and during treadmill running (Tm). Seven female competitive runners (CR) and seven female noncompetitive runners (NR) were asked to replicate preferred land training intensity characteristic of a 45-min run under three conditions (Tm, V, and NV). When 20-min submaximal runs at the preferred land training intensity were performed for Tm, V, and NV conditions, CR were able to elicit a similar submaximal VO2 for all three conditions. In contrast, the NR group had a significantly (P < 0.05) lower VO2 (27%), HR (23%), VE (26%) and %VO2max (27%) during V versus Tm condition. During the NV condition, NR had a significantly lower VO2 (13%), %VO2max (13%), and a higher RPE compared with Tm running, and a significantly higher VO2 (16%), HR (15%), VE (24%), %VO2max (15%) and RPE compared with the V condition. Competitive runners were able to achieve training intensities similar to land training for WI running with or without a flotation vest. However, recreational runners failed to replicate land training pace, where intensity was significantly lower during WI running without a vest and lowest with a vest, despite efforts to maintain a similar level of exertion.

Recovery energy expenditure for steady state exercise in runners and nonexercisers.

This study examined the effects of intensity, mode of exercise, and aerobic fitness on the energy expended during recovery (recovery oxygen consumption, or rec VO2) following steady state exercise. Eight runners (4 males, 4 females; 22-32 yr) walked at 3.2 and 6.4 km X h-1 and ran at 8.1 and 11.3 km X h-1 (18, 33, 50, and 68% peak VO2). All subjects completed 3.2 km of walking or running each session. Eight sedentary adults (4 male, 4 female; 21-33 yr) completed the 6.4 km X h-1 test. For the runners, net rec VO2 for 3.2, 6.4, 8.1 and 11.3 km X h-1 exercise was (X +/- SE) 12.52 +/- 3.00, 29.53 +/- 5.41, 28.64 +/- 2.91, and 44.27 +/- 5.32 ml X kg-1, respectively, for the recovery period (18-48 min). Differences among group means were significant (P less than 0.05), except between 6.4 and 8.1 km X h-1 walking (29.53 +/- 5.41 and 35.09 +/- 9.39 ml X kg-1). Statements attributing substantial energy expenditure to the recovery period may be misleading to people exercising at levels similar to those described in this study, since the recovery energy expenditure only amounted to approximately 13-71 kJ (3-17 kcal).