Respiratory mechanics in sedated and nonsedated adult llamas.
OBJECTIVE
To validate the use of noninvasive pulmonary function testing in sedated and nonsedated llamas and establish reference range parameters of respiratory mechanical function.


METHODS
10 healthy adult llamas.


METHODS
Pulmonary function testing in llamas included the following: measurement of functional residual capacity (FRC) via helium dilution, respiratory inductance plethysmography (RIP) to assess breathing pattern and flow limitations, esophageal-balloon pneumotachography, and a monofrequency forced oscillatory technique (FOT; 1 to 7 Hz) before and after IM administration of xylazine (0.2 mg/kg).


RESULTS
The following mean +/- SD measurements of respiratory function were obtained in nonsedated llamas: FRC (5.60 +/- 1.24 L), tidal volume (1.03 +/- 0.3 L), dynamic compliance (0.83 +/- 0.4 L/cm H(2)O), pulmonary resistance (R(L); 1.42 +/- 0.54 cm H(2)O/L/s), and respiratory system resistance (2.4 +/- 0.9, 2.3 +/- 0.7, 2.2 +/- 0.6, 2.7 +/- 0.7, and 2.5 +/- 0.5 cm H(2)O/L/s at 1, 2, 3, 5, and 7 Hz, respectively) by use of FOT. Measurements of flow limitations via RIP were comparable to other species. Sedation with xylazine induced significant increases in R(L) and maximum change in transpulmonary pressure. Following sedation, a mean 127% increase in R(L) and mean 116% increase in respiratory system resistance were observed across 1 to 7 Hz. The magnitude of change in respiratory system resistance increased with decreasing impulse frequency, suggesting bronchoconstriction.


CONCLUSIONS
Noninvasive pulmonary function testing is well tolerated in untrained unsedated llamas. These techniques have clinical applications in the diagnosis and treatment of respiratory tract disease, although testing should not be performed after sedation with xylazine.
Lascola
Kara M
KM
Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA 01536, USA.
Hoffman
Andrew M
AM
Mazan
Melissa R
MR
Bedenice
Daniela
D
D000375:Aging; D000818:Animals; D002161:Camelids, New World / Q000502:physiology*; D005260:Female; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D012016:Reference Values; D012143:Respiratory Physiological Phenomena
D006993:Hypnotics and Sedatives