Objective—To evaluate the use of a modified whole
body plethysmograph in awake sheep.
Animals—10 healthy adult sheep.
Procedure—Concurrent measurements of specific
airway resistance (sRaw) and pulmonary resistance
(RL) were obtained using a novel noninvasive headout
constant-volume plethysmograph and esophageal
balloon-pneumotachography, respectively. All data
were collected before and after external resistive
loading with 1 and 5.6 cm H20/L/s. Functional residual
capacity (FRC) was measured by helium dilution for
computation of airway resistance (Raw) preloading
(Raw = sRaw/FRC).
Results—The sRaw and RL were closely correlated in
10 adult sheep. Additionally, sRaw and RL accurately
reflected the magnitude of added resistance. The
mean FRC was 52 mL/kg and used to calculate Raw.
At baseline, the values for Raw were significantly correlated
with sRaw and RL.
Conclusions and Clinical Relevance—Precise measurements
of sRaw and Raw at baseline and sRaw after
external resistive loading were obtained by use of this
novel noninvasive plethysmographic technology. This
method should have application to veterinary patients
or animals used in research in which noninvasive rapid
or serial measurements of sRaw in the conscious
state are required. (Am J Vet Res 2004;65:1259–1264)