Diaphragmatic dysfunction secondary to experimental lower torso ischaemia-reperfusion injury is attenuated by thermal preconditioning.
BACKGROUND
Preconditioning describes the process whereby tissue exposure to a subcritical stress confers protection from subsequent injuries. This study assessed diaphragmatic muscle function after lower torso ischaemia-reperfusion (IR) and the role of thermal preconditioning in attenuation of this injury.


METHODS
Sprague-Dawley rats were randomized into three groups (24 per group): a control group, an IR group that had aortic cross-clamping for 1 h followed by reperfusion, and a third group that received thermal preconditioning 18 h before IR. Diaphragmatic function was assessed at 24 h, 48 h and 7 days.


RESULTS
IR resulted in significant diaphragmatic twitch and tetanic dysfunction compared with control muscle. Thermal preconditioning significantly attenuated this injury (P < 0.05). Mean(s.e.m.) muscle twitch and tetanic forces in the IR group were 204.9(17.2) and 282.7(19.2) g respectively at 24 h. Corresponding twitch and tetanic forces in preconditioned muscle were 270.4(25.1) and 552.0(35.2) g.


CONCLUSIONS
This study demonstrated that systemic IR injury produced a respiratory muscle mechanical dysfunction that was attenuated by thermal preconditioning, at 24 h, 48 h and 7 days. Preconditioning may have a role in clinical practice, particularly before elective surgery.
McLaughlin
R
R
Department of Surgery, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland.
Kelly
C J
CJ
Kay
E
E
Bouchier-Hayes
D
D
D000818:Animals; D003250:Constriction; D003964:Diaphragm / Q000503:physiopathology; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006979:Hyperthermia, Induced; D009135:Muscular Diseases / Q000503:physiopathology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology*
D006360:Heat-Shock Proteins