Heterogeneity of intrapleural pressures during exercise.
We determined whether the caudodorsal region of the intrapleural space in exercising horses experiences larger pressure fluctuations than other regions and whether systematic phase-shifting of peak intrapleural pressures along the length of the thorax suggests the existence of locomotor-induced intrapleural pressure waves. We utilised percutaneous introducers and solid-state pressure-tip transducers implanted along the dorsal aspect of the thorax, mid-thorax or oesophagus to measure regional intrapleural pressures while 3 horses galloped on a flat treadmill at 13-14 m/s, then recorded pressures from the same catheters when horses exercised intensely (heart rate 170-190 beats/min) while swimming with no ground concussion. Pressure excursions in the caudodorsal region did not vary systematically from other regions during galloping or swimming, nor more than a few torr between different locations. During swimming, peak expiratory pressures were higher than during galloping (68-79 vs. 26-32 torr), and horses breathed explosively at frequencies 5 times slower than while galloping (28 vs. 120/min). During galloping, individual catheter locations registered locomotor concussion; however, this was variable and did not indicate a systematic pressure wave passing through the lung or intrapleural space.
Jones
J H
JH
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis 95616, USA.
Cox
K S
KS
Takahashi
T
T
Hiraga
A
A
Yarbrough
T B
TB
Pascoe
J R
JR
D000818:Animals; D002404:Catheterization / Q000379:methods / Q000662:veterinary; D005080:Exercise Test / Q000662:veterinary; D006736:Horses / Q000502:physiology*; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D035422:Pleural Cavity / Q000502:physiology*; D011312:Pressure; D012420:Running; D013550:Swimming