Does an acute COPD crisis modify the cardiorespiratory and ventilatory adjustments to exercise in horses?

Abstract

The present study was conducted to understand better the mechanisms leading to the decrease in exercise capacity observed in horses suffering from chronic obstructive pulmonary disease (COPD). Five COPD horses were submitted to a standardized submaximal treadmill exercise test while they were in clinical remission or in acute crisis. Respiratory airflow, O2 and CO2 fractions in the respired gas, pleural pressure changes and heart rate were recorded, and arterial and mixed venous blood were analyzed for gas tensions, hemoglobin, and plasma lactate concentrations. O2 consumption, CO2 production, expired minute ventilation, tidal volume, alveolar ventilation, cardiac output, total pulmonary resistance, and mechanical work of breathing were calculated. The results showed that, when submaximally exercised, COPD horses in crisis were significantly more hypoxemic and hypercapnic and that their total pulmonary resistance and mechanical work of breathing were significantly higher and their expired minute ventilation significantly lower than when they were in remission. However, their O2 consumption remained unchanged, which was probably due to the occurrence of compensatory mechanisms, i.e., higher heart rate, cardiac output, and hemoglobin concentration. Last, their net anaerobic metabolism seemed to be more important.

Comparison of inulin with urea as dilutional markers of bronchoalveolar lavage in healthy and heaves-affected horses

“…The following limits were arbitrarily chosen to control whether the animals were healthy or suffering a crisis of heaves: healthy: R L ≤ 0.10 kPa·s·L -1 , C dyn ≥ 10 L·kPa -1 , ∆pplmax ≤ 1.00 kPa; suffering a crisis of heave : R L ≥ 0.25 kPa·s·L -1 , C dyn ≤ 10 L·kPa -1 , ∆pplmax ≥ 2.50 kPa. Further details about the measurement technique are reported elsewhere [1].…”

“…The aims of our study were: (1) to compare the inulin method to the urea method for the calculation of PELF dilution and (2) to examine whether airway disease has an influence on PELF dilution, calculated either by the inulin or the urea method.…”

Obstrução recorrente das vias aéreas em muares: relato de três casos

“…Os hemogramas dos três animais não apresentaram indício de doença de natureza infecciosa, descartando pneumonia como uma possível causa. O aumento observado no valor da hemoglobina está de acordo com os achados de Art et al (1998), estando associada à necessidade de o animal afetado equilibrar a troca gasosa pulmonar deficiente.…”

“…Para compensar a troca gasosa ineficiente, os animais afetados aumentam sua ventilação/minuto por meio do aumento da freqüência respiratória, conforme observado nos três casos descritos. Para inalar o mesmo volume tidal, no mesmo espaço de tempo, há necessidade de uma taxa de fluxo de ar médio mais elevada em face da obstrução das vias aéreas, justificando o surgimento do padrão respiratório típico demonstrado pelo animal afetado (Nyman et al, 1991;Tremblay et al, 1993;Art et al, 1998;Robinson et al, 2000;Holcombe et al, 2001). …”

“…O termo DPOC, utilizado na medicina humana, descreve a doença pulmonar inflamatória em fumantes, com patofisiologia e evolução clínica completamente diferente daquela vista nos eqüinos (Art et al, 1998;Léguillette, 2003). Após constantes esforços de pesquisadores, determinou-se a nomenclatura correta para as doenças inflamatórias das vias aéreas dos eqüinos.…”