Auxiliary diagnosis of aerobic forearm exercise in mitochondriai myopathy and encephalopathy

Objective To investigate blood gas analysis and lactic acid evaluation in aerobic forearm exercise and the significance of aerobic forearm exercise for the auxiliary diagnosis of mitochondrial myopathy and encephalopathy patients.Methods Forty-two patients with mitochondrial myopathy and encephalopathy patients, 40 healthy control, and 40 patients control were studied.They performed a protocol under aerobic exercise conditions, consisting of intermittent forearm exercise for 4 minutes at 40% of intented maximal voluntary contraction force.Blood samples were collected to monitor blood gas and plasma lactate before, during arid after exercise.Results During exercise venous PO_2(mm Hg, 1 mm Hg=0.133 kPa)decreased in mitochondrial myopathy and encephalopathy patients from 41.2±12.6 to 39.5±16.2, whereas PO_2 fell from 50.5±14.4 to 30.8±13.1 in healthy control and from 50.1±7.9 to 44.3±35.5 in patient control.Venous PO_2 decreased much more in healthy control group than the other 2 groups(F= 6.34,P0.01).During exercise venous SO_2 dropped in mitochondrial myopathy and encephalopathy patients from 70.5%±15.8% to 64.4%±15.2%, from 82.4%±10.0% to 47.2%±11.7% in healthy control and from 84.6%±6.3% to 51.1%±9.3% in patient control.Venous SO_2 decreased much less in mitochondrial myopathy and encephalopathy patients than the other 2 groups(F=91.95, P0.01). Recovery venous PO_2 and SO_2 were similar in all subjects.During exercise resting plasma lactate(mmol/L) rose from 2.7±3.2 to 5.1±3.8 in mitochondrial myopathy and eneephalopathy patients, from 1.1±0.5 to 3.1±1.9 in healthy control and from 1.3±0.8 to 3.5±1.8 in patient control.Recovery plasma lactate in mitochondrial myopathy and encephalopathy patients was 3.8±3.5, 1.8±1.0 in healthy control ,2.3±1.4 in patient control.Recovery plasma lactate in mitoehondrial myopathy and encephalopathy patients was higher than the other 2 groups(F=8.50, P0.01).Conclusions The oxygen uptake ability during exercise of mitochondrial myopathy and encephalopathy patients decreases compared with healthy people and other myopathy patients.Aerobic forearm exercise is a valuable method in auxiliary diagnosis of mitochondrial myopathy and encephalopathy patients by means of monitor blood gas and plasma lactate with high sensitivity and specificity are high.