Evaluation of postsale endoscopy as a predictor of future racing performance in an Australian thoroughbred yearling population.

INTRODUCTION: Upper airway endoscopy of thoroughbred (TB) yearlings is commonly used in an attempt to predict laryngeal function (LF) and its impact on future race performance. The aim of this study was to determine if different grading systems and laryngeal grades were correlated with future performance. MATERIALS AND METHODS: Postsale endoscopic recordings were obtained from an Australian TB yearling sale during a four-year period from 2008 to 2011. Horses were included if they had a diagnostic postsale video endoscopic recording and raced within Australia. Recordings were graded using the Havemeyer system and subsequently recategorised according to the Lane scale and two condensed scales. Performance data were sourced from Racing Australia and comparisons were made between groups. RESULTS: A total of 1244 horses met the inclusion criteria. There were no significant differences in sex or sales price between groups. There were no significant differences in the number of starts or wins between groups for any grading system. For the condensed Havemeyer scale, horses with intermediate LF were separated into two groups. Significant differences in earnings were found between 'normal' and 'abnormal' (P = 0.02) and 'intermediate-low' and 'abnormal' grades (P = 0.03). There were no significant differences between horses with 'intermediate-high' and 'abnormal' grades (P = 0.40). No significant differences were found between the two intermediate grades (P = 0.60) or between horses with normal LF and either 'intermediate-low' or 'intermediate-high' grades (P = 0.99). DISCUSSION: Resting LF in Australian yearling TBs assessed using a condensed Havemeyer grading scale had some predictive value for future racing performance. This information should be considered when performing yearling endoscopic examinations.

Oxyhemoglobin desaturation and aberrant carbon dioxide homeostasis during electrically stimulated exercise in a ventilator-dependent tetraplegic patient.

This single-subject case examined oxyhemoglobin saturation and alveolar end-tidal carbon dioxide levels in a ventilator-dependent tetraplegic patient undergoing electrical stimulation cycle ergometry. When exercising with a closed tracheostomy cuff under resting ventilator settings (resting intermittent mandatory ventilation; frequency = 6breaths/min, tidal volume = 83.3mL, minute ventilation =5L/min), his oxyhemoglobin saturation decreased from 100% to 92%, while alveolar endtidal carbon dioxide increased linearly to 47mmHg. These undesirable changes were corrected under adjusted intermittent mandatory ventilation conditions (frequency = 12breaths/min, tidal volume = 83.3mL, minute ventilation = 10L/min), during which oxyhemoglobin saturation remained above 98% and the alveolar end-tidal carbon dioxide trend resembled that of ventilator-independent tetraplegic individuals undergoing the same exercise. Because the subject's heart rate was higher under adjusted ventilation conditions, these responses may have been caused by augmented venous return resulting from greater abdominothoracic pumping at the higher breathing frequency. These findings support the need to modify ventilator settings in ventilator-dependent tetraplegic persons while undergoing exercise to maintain oxyhemoglobin saturation and carbon dioxide homeostasis.

The effect of exercise training on pulmonary function in persons with quadriplegia.

The purpose of this study is to determine if measures of pulmonary function are different between endurance trained and nontrained groups of persons with quadriplegia. After minimum criteria were met, 57 subjects with spinal cord injuries ranging from C5-T1 were surveyed to determine type, duration and intensity of exercise training for the previous 6 months. Subjects were assigned to the trained or untrained groups based on the operational definitions of 'trained' vs 'untrained'. A computerized spirometer was used to test forced vital capacity (FVC), forced mid-expiratory flow (FEF25-75%) and maximum voluntary ventilation (MVV) as indicators of respiratory muscle strength, airway patency and respiratory muscle endurance, respectively. Independent t tests and Wilcoxon-Mann-Whitney nonparametric tests revealed no significant differences between the 'trained' and 'untrained' groups for the pulmonary functions. Correlation analysis revealed a moderate relationship (r = 0.498; p < or = 0.0001) between a derived continuous variable called the weighted training equivalent (WTE) and FVC. Regression analysis revealed that WTE and level of injury accounted for approximately 30% of the variance of FVC with WTE contributing 25%. Exercise training may positively affect FVC in persons with quadriplegia.