Measurement of tidal volume using respiratory ultrasonic plethysmography in anaesthetized, mechanically ventilated horses.
OBJECTIVE
To compare tidal volume estimations obtained from Respiratory Ultrasonic Plethysmography (RUP) with simultaneous spirometric measurements in anaesthetized, mechanically ventilated horses.


METHODS
Prospective randomized experimental study.


METHODS
Five experimental horses.


METHODS
Five horses were anaesthetized twice (1 week apart) in random order in lateral and in dorsal recumbency. Nine ventilation modes (treatments) were scheduled in random order (each lasting 4 minutes) applying combinations of different tidal volumes (8, 10, 12 mL kg(-1)) and positive end-expiratory pressures (PEEP) (0, 10, 20 cm H(2)O). Baseline ventilation mode (tidal volume=15 mL kg(-1), PEEP=0 cm H(2)O) was applied for 4 minutes between all treatments. Spirometry and RUP data were downloaded to personal computers. Linear regression analyses (RUP versus spirometric tidal volume) were performed using different subsets of data. Additonally RUP was calibrated against spirometry using a regression equation for all RUP signal values (thoracic, abdominal and combined) with all data collectively and also by an individually determined best regression equation (highest R(2)) for each experiment (horse versus recumbency) separately. Agreement between methods was assessed with Bland-Altman analyses.


RESULTS
The highest correlation of RUP and spirometric tidal volume (R(2)=0.81) was found with the combined RUP signal in horses in lateral recumbency and ventilated without PEEP. The bias ±2 SD was 0±2.66 L when RUP was calibrated for collective data, but decreased to 0±0.87 L when RUP was calibrated with individual data.


CONCLUSIONS
A possible use of RUP for tidal volume measurement during IPPV needs individual calibration to obtain limits of agreement within ±20%.
Anaesthesiology and Perioperative Intensive Care-Medicine, Department of Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria. elena.russold@vetmeduni.ac.at
Elena
E
Russold
Tamas D
TD
Ambrisko
Johannes P
JP
Schramel
Ulrike
U
Auer
Rene
R
Van Den Hoven
Yves P
YP
Moens
D000758:Anesthesia / Q000662:veterinary; D000818:Animals; D006736:Horses / Q000502:physiology*; D010991:Plethysmography / Q000379:methods / Q000662:veterinary*; D011175:Positive-Pressure Respiration / Q000379:methods / Q000662:veterinary; D012121:Respiration, Artificial / Q000662:veterinary*; D013147:Spirometry / Q000662:veterinary; D013990:Tidal Volume / Q000502:physiology*; D014463:Ultrasonography / Q000379:methods / Q000662:veterinary