Effect of clenbuterol on tracheal mucociliary transport in horses undergoing simulated long-distance transportation.

BACKGROUND: Pneumonia is observed in horses after long-distance transportation in association with confinement of head position leading to reduction in tracheal mucociliary clearance rate (TMCR). HYPOTHESIS/OBJECTIVES: Clenbuterol, a beta-2 agonist shown to increase TMCR in the horse, will ameliorate the effects of a fixed elevated head position on large airway contamination and inflammation in a model of long-distance transportation model. ANIMALS: Six adult horses. METHODS: A cross-over designed prospective study. Horses were maintained with a fixed elevated head position for 48 hours to simulate long-distance transport, and treated with clenbuterol (0.8 µg/kg PO q12h) or a placebo starting 12 hours before simulated transportation. TMCR was measured using a charcoal clearance technique. Data were collected at baseline and 48 hours, and included TMCR, tracheal wash cytology and quantitative culture, rectal temperature, CBC, fibrinogen, and serum TNFα, IL-10, and IL-2 levels. There was a 18-21 day washout between study arms, and data were analyzed using regression analysis and Wilcoxon rank-sum tests. RESULTS: Tracheal mucociliary clearance rate was significantly decreased after transportation in both treatment (P = .002) and placebo (P = .03) groups. There was a significant effect of treatment on TMCR, with the treatment group showing half the reduction in TMCR compared with the placebo group (P = .002). Other significant differences between before- and after-transportation samples occurred for serum fibrinogen, peripheral eosinophil count, quantitative culture, tracheal bacteria, and degenerate neutrophils, though no treatment effect was found. CONCLUSIONS AND CLINICAL IMPORTANCE: Treatment with clenbuterol modestly attenuates the deleterious effects of this long-distance transportation model on tracheal mucociliary clearance.

Repeatability, reproducibility, and effect of head position on central venous pressure measurement in standing adult horses.

BACKGROUND: Central venous pressure (CVP) is a used as an estimation of intravascular volume status in various species. Techniques for measuring CVP in horses have been described, but the repeatability of these readings at a single time point or over time has not been established. HYPOTHESIS: That CVP measurements in healthy adult horses would be repeatable at each time point, that these readings would be reproducible over time, and that alteration in head position relative to the heart would alter CVP. ANIMALS: Ten healthy adult research horses. METHODS: In an experimental study, horses were instrumented with a central venous catheter. Readings were taken in triplicate q6h for 2 days by water manometry, and twice daily with the head in neutral, elevated, and lowered positions by electronic manometry. RESULTS: Variation in the "neutral" measurements obtained at each time point was <0.1 ± 1.0 cmH(2)O (P = .718). There was a significant decrease in CVP over time (P = .015), which was eliminated when results were controlled for acute decrease in body weight of -1.35% (presumed hypohydration because of lack of acclimatization and decreased water intake). Head height had a significant and directional effect on CVP in that the elevated head position decreased CVP -2.0 ± 6.5 cmH(2)O (P < .001) while the lowered head position increased CVP by 3.7 ± 5.5 cmH(2)O (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: CVP values obtained by water manometry were repeatable in adult horses, but were reproducible only when controlled for changes in hydration. Care should be taken to maintain consistency in head position to prevent erroneous readings.

Comparison of water manometry to 2 commercial electronic pressure monitors for central venous pressure measurement in horses.

BACKGROUND: Central venous pressure (CVP) customarily has been measured in veterinary patients with water manometry. However, many institutions are now using stallside electronic monitors in both anesthesia and intensive care units for many aspects of patient monitoring. HYPOTHESIS: Electronic stall side monitoring devices will agree with water manometry for measurement of CVP in horses. ANIMALS: Ten healthy adult horses from the university research herd. METHODS: Central venous catheters were placed routinely, and measurements were obtained in triplicate with each of the 3 methods every 12 hours for 3 days. Data were analyzed by a Lin concordance correlation coefficient and modified Bland-Altman limits of agreement, with all devices compared pairwise. RESULTS: Compared with water manometry, agreement (bias) of the Passport was -1.94 cmH2O (95% limits of agreement, -8.54 to 4.66 cmH2O) and of the Medtronic was -1.83 cmH2O (95% limits of agreement, -8.60 to 4.94 cmH2O). When compared with the Passport, agreement of the data obtained with the Medtronic was 0.27 cmH2O (95% limits of agreement, -4.39 to 4.93 cmH2O). CONCLUSIONS AND CLINICAL IMPORTANCE: These data show that both electronic monitors systematically provide measurements that are approximately 2 cmH2O lower than water manometry, but differences between the 2 electronic devices are small enough (< 0.5 cmH2O) to be considered clinically unimportant. This discrepancy should be taken into account when interpreting data obtained with these monitoring devices.

The effects of hypohydration on central venous pressure and splenic volume in adult horses.

BACKGROUND: Central venous pressure (CVP) is used in many species to monitor right-sided intravascular volume status, especially in critical care medicine. HYPOTHESIS: That hypohydration in adult horses is associated with a proportional reduction in CVP. ANIMALS: Ten healthy adult horses from the university teaching herd. METHODS: In this experimental study, horses underwent central venous catheter placement and CVP readings were obtained by water manometry. The horses were then deprived of water and administered furosemide (1 mg/kg IV q6h) for up to 36 hours. Weight, CVP, vital signs, PCV, total protein (TP), and serum lactate were monitored at baseline and every 6 hours until a target of 5% decrease in body weight loss was achieved. The spleen volume was estimated sonographically at baseline and peak volume depletion. Linear regression analysis was used to assess the association of CVP and other clinical parameters with degree of body weight loss over time. RESULTS: There was a significant association between CVP and decline in body weight (P < .001), with a decrease in CVP of 2.2 cmH(2)O for every percentage point decrease in body weight. Other significant associations between volume depletion and parameters measured included increased TP (P = .007), increased serum lactate concentration (P = .048), and decreased splenic volume (P = .046). There was no significant association between CVP and vital signs or PCV. CONCLUSIONS AND CLINICAL IMPORTANCE: These findings suggest that CVP monitoring might be a useful addition to the clinical evaluation of hydration status in adult horses.

Echocardiographic changes in heart size in hypohydrated horses.

BACKGROUND: Hypohydration causes transient echocardiographic changes in pigs, dogs, humans, and cats. These changes mask the diagnosis of some cardiac diseases (valvular regurgitation, dilated cardiomyopathy) and promote the diagnosis of others (hypertropic cardiomyopathy and infiltrative disease), thus inhibiting accurate echocardiographic evaluation. OBJECTIVES: To describe the echocardiographic changes associated with hypohydration in normal horses. ANIMALS: Ten adult horses without detectable cardiac disease. METHODS: Experimental study. Echocardiographic examinations were performed on horses in the euhydrated and hypohydrated states. Horses were hypohydrated by combined water deprivation and furosemide administration until a 4-7% reduction in bodyweight was achieved. Statistical analyses were performed by paired t-tests. RESULTS: Hypohydration decreased left ventricular internal diameter in systole (0.8 ± 0.6 cm) and diastole (1.7 ± 0.9 cm), left atrial diameter (1.5 ± 0.4 cm) and left ventricular volume (490 ± 251 mL) (P-values < .01), and increased septal wall thickness in diastole (0.6 ± 0.3 cm), free wall thickness in diastole (0.5 ± 0.3 cm), mean wall thickness (0.5 ± 0.2 cm) and relative wall thickness (0.2 ± 0.1 cm) (P-values < .01). CONCLUSIONS AND CLINICAL IMPORTANCE: Hypohydration produces changes in left ventricular and atrial size that could mask or promote the severity of cardiac disease. The thickened, "pseudohypertrophied" appearance of the left ventricle in hypohydrated horses could affect interpretation of echocardiographic variables that are applied to the prediction of athletic performance. Echocardiography may prove a noninvasive method of monitoring volume status and response to fluid therapy in hypovolemic horses.

The impact of an ambulatory CPOE system on medication errors.

Few studies have evaluated the impact of an ambulatory computerized physician order entry (CPOE) system on medication errors. We conducted a retrospective analysis of 10,172 prescriptions to evaluate the impact of a basic CPOE system on prescribing-related medication errors, and found a significant decrease in the occurrence of errors.

Prostaglandin-H synthase-1 (PGHS-1) gene is expressed in specific neurons of the brain of the late gestation ovine fetus.

Prostaglandin (PG) E2 acts on the brain stem to modulate breathing activity in the ovine fetus. The source of this PGE2 is unknown and we hypothesized that it is produced locally in the developing brain and functions in a paracrine and/or autocrine manner. The purpose of the present study was to establish whether prostaglandin-H synthase-1 (PGHS-1), a crucial enzyme in de novo prostaglandin synthesis, is present and its gene expressed in the ovine fetal brain. Immunohistochemical and molecular hybridization techniques were used to identify sites of PGHS-1 immunoreactivity and PGHS-1 mRNA expression respectively in the brain of the ovine fetus in late gestation (approximately 126 days gestation, term 145 days). PGHS-1 immunoreactivity was localized to specific regions of the fetal brain, including the cortex, hypothalamus, hippocampal formation, superior colliculus of the midbrain, parabrachial nucleus of the pons, and the reticular formation, raphe, nucleus of the solitary tract, and gracile and cuneate nuclei of the medulla. The relative abundance of PGHS-1 mRNA in selected brain regions, as determined by Northern blot analysis, correlated qualitatively with the number of PGHS-1 immunoreactive neurons identified in each region. In situ hybridization demonstrated PGHS-1 mRNA to be localized in the same neurons or nuclei as PGHS-1 immunoreactivity. These results indicate that PGHS-1 synthesized de novo in many brain regions including two that are important in respiratory control: the pneumotaxic center (parabrachial nucleus) and the dorsal respiratory group (nucleus tractus solitarius) suggesting that prostaglandins that modulate fetal respiratory activity are synthesized endogenously.

Establishing an outpatient anticoagulation clinic in a community hospital.

The establishment of a pharmacist-managed out-patient anticoagulation clinic in a private community hospital is described. Discussions by pharmacy with office-based physicians at a 187-bed, private, nonprofit community medical center indicated that the traditional system of anticoagulation management was not ideal for the physicians or their patients. Development of a pharmacist-managed anticoagulation clinic began in fall 1993; operations began in spring 1994. Planning included analyzing existing practices, reviewing the relevant literature, obtaining physician input, visiting an established anticoagulation clinic, formulating a business plan, and developing clinical protocols. Collaborative relationships were established with the hospital laboratory, business office, and risk management, information services, and medical records departments. Two pharmacists were trained to work in the clinic and provide coverage 24 hours a day. Services include patient assessment, monitoring of anticoagulation, warfarin dosage adjustment, medication management, patient education, follow-up care, and providing feedback to referring and attending physicians. The clinic has met with physician and patient satisfaction, has reduced the number of admissions to treat warfarin-related bleeding, and has been able to cover its direct costs. A pharmacist-managed anti-coagulation clinic was successfully established in a private community hospital.

Cobalt-60: the heart of gamma-radiation sterilization.

Currently, more than three million cubic metres of single-use medical devices are sterilized by gamma radiation each year. The wide use of this method of sterilization is a result of the lethal effects of ionizing radiation on microbial populations and the penetrative powers of cobalt-60. This article describes how cobalt-60 is produced and used in gamma-radiation sterilization, and how it is disposed of once it has reached the end of its useful life. Cobalt-60 sources typically have a life of 20 years, at which point they are returned to the suppliers for re-encapsulation, reprocessing, recycling, or disposal.

Prostaglandin E2 in cerebrospinal fluid of fetal and newborn sheep: central versus peripheral source.

During the perinatal period, prostaglandin (PG) E2 levels show parallel changes in cerebrospinal fluid (CSF) and blood which may be important for the adaptation of the fetus to extrauterine life. It is not known, however, whether PGE2 in the CSF originates from a local or a peripheral source. Experiments were carried out in term fetal and newborn sheep chronically instrumented with a cannula inside the third ventricle and vascular lines. Indomethacin was given intracerebroventricularly (i.c.v.) (50 or 100 micrograms at hourly intervals), alone or in combination with intravenous (i.v.) PGE2 (1 or 1.5 micrograms/kg/min). In the fetus, i.c.v. indomethacin reduced PGE2 levels in both CSF and plasma. Conversely, no significant change was noted at either site when indomethacin was given i.c.v. to the newborn. At both ages, PGE2 increased in the CSF during i.v. infusion of the compound, but this elevation was proportionately smaller than in plasma. We conclude that, in the perinatal period, brain and peripheral circulation function as separate compartments with respect to PGE2, though there is passage of the compound across the blood-brain barrier. Results provide indirect evidence that perinatal brain produces PGE2 in measurable amounts.