Vol. 86, Issue 1, 306-312, January 1999
Acute response of the lung mechanics of the rabbit to hypoxia
H.
Sakai1,
M.
Fukui2,
Y.
Nakano1,
K.
Endo1,
T.
Hirai3,
Y.
Oku4, and
M.
Mishima5
Departments of 1 Experimental
Pathology and 4 Medical Systems
Control, Institute for Frontier Medical Sciences, and
5 Department of Physical
Therapeutics, Kyoto University Hospital, Kyoto University, Kyoto
606-8397; 2 Shiga Medical
Center for Adults, Shiga 524-0022, Japan; and
3 Meakins-Christie Laboratories,
McGill University, Montreal, Quebec, Canada H2X 2P2
We measured the
change in total lung resistance
(RL) and that in total lung
elastance (EL) induced by
hypoxia (n = 7) and compared the
results with those by intravenous histamine bolus (n = 5) at three different positive
end-expiratory pressure (PEEP) levels (2, 5, and 8 hPa) in open-chest
and vagotomized rabbits. The percent increase ratio of
RL
(PIRR) and
EL
(PIRE) was defined as the change
in RL and
EL, respectively, induced by
hypoxia compared with that in the normoxic condition, expressed as a
percentage. PIR values for the change in
RL and
EL induced by bolus injection of
histamine were also calculated. The
PIRR and
PIRE induced by hypoxia and by
histamine were positive by a statistically significant amount at every
PEEP level, except for the PIRE
value at 8-hPa PEEP in the hypoxic challenge. The
PIRE-to-PIRR
ratio values in the hypoxic challenge at 2-hPa PEEP were significantly
larger than those in the histamine challenge (hypoxia: 0.91 ± 0.23%; histamine: 0.37 ± 0.065%,
P < 0.05). The increase
in EL induced by histamine in
the acute phase has been reported to be mainly derived from tissue
distortion secondary to bronchial constriction. Thus our results
suggest that a part of the increase in
EL by hypoxia was originated in
different parenchymal responses from histamine and imply that this
hypoxic response of lung parenchyma is sensitive to the increase in
parenchymal tethering at high PEEP levels.
lung resistance; lung elastance; histamine
