Nitrate in shallow groundwater associated with residential land use in central Florida.

The primary objective of this study was to quantify the effects of residential fertilizer use on groundwater quality, which have not been well defined by field-scale investigations. Concentrations of constituents associated with fertilizer use were monitored in shallow groundwater in residential areas in Orange and Seminole Counties of Central Florida. The study area is within the Wekiva River basin, a river that is primarily spring fed. Sampling locations were selected to represent land in residential use for more than 5 yr and to avoid septic systems and areas recently used for citrus production. Twenty-six wells were installed in the surficial aquifer, screened within approximately 3 m of the water table, which was encountered between 0.3 and 11.5 m below land surface. Of these wells, 24 were in residential areas, scattered over an area of about 2600 ha, and two were in nearby undeveloped areas. Samples were collected four times between October 2008 and July 2009. Concentrations of nitrate plus nitrite nitrogen (NO-N) averaged 2.0 ± 0.2 mg L in the residential areas and were significantly higher ( < 0.01) than observed in undeveloped areas (0.3 ± 0.1 mg L). Groundwater was also analyzed for stable isotopes of nitrogen and oxygen and has been analyzed for bacteria (by others), which corroborated that these wells were not affected by human or animal waste. Levels of NO-N in the residential areas are primarily attributed to residential fertilizer use, considering the control for and exclusion of other plausible sources.

NICU medication errors: identifying a risk profile for medication errors in the neonatal intensive care unit.

OBJECTIVE: To identify a risk profile for harmful medication errors in the neonatal intensive care unit (NICU). STUDY DESIGN: A retrospective cross-sectional study on NICU medication error reports submitted to MEDMARX between 1 January 1999, and 31 December 2005. The Rao-Scott modified chi(2) test was used for analysis. RESULT: 6749 NICU medication error reports were submitted by 163 health-care facilities. Administering errors accounted for approximately one half of errors, and human factors were the most frequently cited cause of error. Patient age was not associated with an increased likelihood of an error being harmful (P=0.11). Error reports involving Institute for Safe Medication Practices (ISMP) High-Alert Medications, occurring in the prescribing phase of medication processing, or involving equipment/delivery device failures were more likely to be harmful (P< or =0.05). CONCLUSION: Risk factors for harmful medication error reports include use of ISMP High-Alert Medications, the prescribing phase of the medication use process, and failure of equipment/delivery devices.

Reliability of a handgrip test for evaluating heart rate and pressor responses in multiple sclerosis.

PURPOSE: The purpose of this study was to determine the test-retest reliability of an isometric handgrip exercise protocol designed to evaluate heart rate and arterial pressure responses in individuals with multiple sclerosis (MS). METHODS Three males and eleven females, aged 24 through 51, performed isometric handgrip contractions at 30% of maximal voluntary contraction (MVC) to the point of fatigue (defined as inability to maintain the target force for three consecutive seconds). During this exercise, rate of perceived exertion (RPE) was recorded every 30 s. Heart rate and beat-to-beat systolic, diastolic, and mean arterial pressures were recorded continuously throughout the duration of exercise. Surface EMG was monitored continuously via loudspeaker to provide feedback on extraneous muscular activity. Each subject performed three trials. A repeated measures ANOVA was used to calculate interclass reliability estimates for each dependent variable. RESULTS: Reliability estimates for MVC and time to fatigue were 0.98 and 0.84, respectively. Reliability estimates for the following dependent variables at the point of fatigue were: RPE, 0.90; delta HR, 0.97; delta systolic pressure, 0.92; delta diastolic pressure, 0.87; and delta MAP, 0.88. CONCLUSIONS: We conclude that this isometric handgrip protocol is a reliable method for evaluating heart rate and blood pressure responses in MS patient.

Pressor response to isometric exercise in patients with multiple sclerosis.

The purpose of this study was to determine whether patients with multiple sclerosis (MS) would show attenuated heart rate and/or pressor responses to isometric handgrip exercise. Patients with MS (30 males, 74 females, aged 23-61 yr) and control subjects (9 males, 16 females, aged 25-47 yr) performed isometric handgrip exercise at 30% of maximal voluntary contraction (MVC) to fatigue. Systolic, diastolic, and mean arterial pressure (MAP) increased linearly in both groups, but were significantly lower (P < 0.05) in patients with MS at 20%, 40%, 60%, 80%, and 100% of exercise duration. Mean change in MAP at fatigue was +47.9 mm Hg for controls and +28.2 mm Hg for patients with MS, with 18 patients with MS between -6 mm Hg and +15 mm Hg. Heart rate increased normally in patients with MS. To predict change in MAP at fatigue in patients with MS, stepwise regression analysis using six variables yielded an R2 of 0.26. These data suggest that in some patients MS lesions exist in areas of autonomic cardiovascular control that result in attenuated pressor responses to exercise. In 17% of patients tested, attenuation was profound. Data also suggest an abnormal dissociation between the heart rate and pressor response to static work in patients with MS.

Impact of aerobic training on fitness and quality of life in multiple sclerosis.

Fifty-four multiple sclerosis (MS) patients were randomly assigned to exercise (EX) or nonexercise (NEX) groups. Before and after 15 weeks of aerobic training, aspects of fitness including maximal aerobic capacity (VO2max), isometric strength, body composition, and blood lipids were measured. Daily activities, mood, fatigue, and disease status were measured by the Profile of Mood States (POMS), Sickness Impact Profile (SIP), Fatigue Severity Scale (FSS), and neurological examination. Training consisted of 3 x 40-minute sessions per week of combined arm and leg ergometry. Expanded Disability Status Scale (EDSS) scores were unchanged, except for improved bowel and bladder function in the EX group. Compared with baseline, the EX group demonstrated significant increases in VO2max, upper and lower extremity strength, and significant decreases in skinfolds, triglyceride, and very-low-density lipoprotein (VLDL). For the EX group, POMS depression and anger scores were significantly reduced at weeks 5 and 10, and fatigue was reduced at week 10. The EX group improved significantly on all components of the physical dimension of the SIP and showed significant improvements for social interaction, emotional behavior, home management, total SIP score, and recreation and past times. No changes were observed for EX or NEX groups on the FSS. Exercise training resulted in improved fitness and had a positive impact on factors related to quality of life.

Efficacy of bupivacaine delivered by wound catheter for post-Caesarean section analgesia.

A prospective, randomized, double-blind trial was conducted to assess contribution to postoperative analgesia of intermittent instillation of 0.25% bupivacaine beneath the rectus sheath in 70 women delivered by lower uterine segment Caesarean section. The operations were performed via a Pfannenstiel incision under spinal anaesthesia. Background intravenous narcotic analgesia was provided with a patient controlled analgesia system (PCAS) using a standard morphine regimen. Overall (44 hr) mean morphine consumption was significantly greater in the placebo (saline) group compared to the treatment group (84.2 mg versus 63.3 mg. Two tailed t test p < 0.001). The most significant intergroup differences in narcotic use were found in the first 4 hours and between 24 and 36 hours after commencing PCAS (Two tailed t test p = 0.014 and 0.003 respectively). Subjective pain scores were assessed with a 10 cm visual analogue scale (VAS). The mean peak VAS score was greater in controls (5.37) than the treatment group (4.25) between 18 and 24 hours postoperatively (Mann-Whitney U = 424, p = 0.027). There were no intergroup differences in pain scores for any other time period. The overall incidence of nausea was lower in the treatment group compared to the control group (Chi squared with Yates' correction p = 0.046) and a lower degree of sedation was seen in those receiving bupivacaine between 4 and 8 hours after commencing PCAS (Mann-Whitney U = 427, p = 0.028). No differences in other narcotic related side-effects (vomiting and pruritus) were shown between groups. Regular instillation of 0.25% bupivacaine beneath the rectus sheath of women delivered by Caesarean section reduces their morphine requirements by 25% in the 44 hours after operation, with an associated reduction in both nausea and early sedation.

Noninvasive assessment of hemodynamic responses to exercise in pulmonary regurgitation after operations to correct pulmonary outflow obstruction.

The influence of pulmonary regurgitation (PR) on exercise capacity is unknown. The hemodynamic responses to exercise in postoperative patients with PR was determined using Doppler-measured regurgitant fraction to indicate PR severity. Maximal heart rate, oxygen consumption and workload capacity were measured during upright cycle ergometry. Cardiac output was measured at rest and during submaximal supine cycle ergometry by pulsed Doppler echocardiography. Oxygen consumption was simultaneously measured and exercise factor was calculated as the change in cardiac output per change in oxygen consumption. Twenty-seven patients were compared with 17 age-, size- and sex-matched control subjects. Patients with PR had larger right ventricles (p less than or equal to 0.001), lower heart rate response (p less than or equal to 0.05), lower maximal oxygen consumption (p less than or equal to 0.005) and lower workloads (p less than or equal to 0.005) when compared with normal control subjects during maximal exercise testing. Exercise factor was the same for both groups. Patients with PR were then separated into mild, moderate and severe groups. Patients with mild PR had a normal response to exercise. However, patients with moderate and severe PR had lower maximal oxygen consumptions and maximal workloads than control subjects. Control, mild and moderate PR groups had similar exercise factors. Patients with severe PR had markedly low cardiac output responses. PR is associated with reduced exercise capability, which is related to the severity of the PR.

Measurement of cardiac output and exercise factor by pulsed Doppler echocardiography during supine bicycle ergometry in normal young adolescent boys.

The purposes of this study were to determine the ability of pulsed Doppler echocardiography to consistently and accurately measure cardiac output during exercise, and to measure the exercise factor by Doppler methodology when oxygen consumption was simultaneously measured. Thirty-four healthy young adolescent male volunteers (mean age 13 years) were recruited. Submaximal exercise was performed by supine bicycle ergometry. Cardiac output was calculated as mean velocity X cross-sectional area. Successful rest and exercise determinations of cardiac output were obtained in 81% (n = 52) of the studies. Mean cardiac output increased from 4.6 to 8.9 liters/min (p less than 0.001) during exercise and mean oxygen consumption increased from 212 to 899 ml/min (p less than 0.001). Doppler-estimated rest and exercise cardiac outputs correlated well with simultaneously measured oxygen consumption (r = 0.89, SEE = 1.2 liters/min; y = 0.006 X 3.2 liters/min). Mean exercise factor was 6.4 (1.2 SD). Twenty-six pairs of rest and exercise cardiac output determinations by Doppler technique and indirect Fick method were simultaneously compared in a subset population (r = 0.86, SEE = 1.4 liters/min; slope = 0.93, y intercept = 1.4 liters/min). Results of this study demonstrate that cardiac output and exercise factor can be estimated by pulsed Doppler echocardiography during exercise.

Beta-blockade reduces tidal volume during heavy exercise in trained and untrained men.

The effects of beta-blockade on tidal volume (VT), breath cycle timing, and respiratory drive were evaluated in 14 endurance-trained [maximum O2 uptake (VO2max) approximately 65 ml X kg-1 X min-1] and 14 untrained (VO2max approximately 50 ml X kg-1 X min-1) male subjects at 45, 60, and 75% of unblocked VO2max and at VO2max. Propranolol (PROP, 80 mg twice daily), atenolol (ATEN, 100 mg once a day) and placebo (PLAC) were administered in a randomized double-blind design. In both subject groups both drugs attenuated the increases in VT associated with increasing work rate. CO2 production (VCO2) was not changed by either drug during submaximal exercise but was reduced in both subject groups by both drugs during maximal exercise. The relationship between minute ventilation (VE) and VCO2 was unaltered by either drug in both subject groups due to increases in breathing frequency. In trained subjects VT was reduced during maximal exercise from 2.58 l/breath on PLAC to 2.21 l/breath on PROP and to 2.44 l/breath on ATEN. In untrained subjects VT at maximal exercise was reduced from 2.30 l/breath on PLAC to 1.99 on PROP and 2.12 on ATEN. These observations indicate that 1) since VE vs. VCO2 was not altered by beta-adrenergic blockade, the changes in VT and f did not result from a general blunting of the ventilatory response to exercise during beta-adrenergic blockade; and 2) blockade of beta 1- and beta 2-receptors with PROP caused larger reductions in VT compared with blockade of beta 1-receptors only (ATEN), suggesting that beta 2-mediated bronchodilation plays a role in the VT response to heavy exercise.