Measuring tissue oxygen consumption in patients with mitochondrial myopathy
Kazuo Abe, Kadekawa Jun, Matsuo Yoshimi, Satoru Inoue, Takehiko Yanagihara, Shiro Yorifuji (Osaka University, Osaka, Japan)
[OBJECTIVE] We used a noninvasive tissue oximetry to measure oxygen consumption in the exercising lower limb in normal controls and patients with mitochondrial myopathy.
[METHOD] We analyzed near-infrared spectra of hemoglobin in the quadriceps muscle during bicycle ergometer exercise in normal controls and 3 patients with chronic progressive external ophthalmoplegia (CPEO) and one patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).
[RESULTS AND CONCLUSION] Normal controls showed constant oxygenation during exercise and a rapid recovery after exercise. However, patients with mitochondrial myopathy showed abnormal oxygenation during exercise and a slow recovery after exercise. These results reflected the defect in oxidative phosphorylation system and suppressed oxygen utilization in those patients. Distinctive patterns of imbalance between oxygen delivery and utilization correlated well with the severity of mitochondrial myopathy as judged by the lactate+pyruvate during exercise. The noninvasive tissue oximetry may be useful to investigate the exercise intolerance in patients with mitochondrial myopathy.
Measuring tissue oxygen consumption during ischemic forearm exercise in a patient with mitochondrial myopathy
Jun Kadekawa, Kazuo Abe, Yoshimi Matsuo, Satoru Inoue, and Shiro Yorifuji (Osaka University, Osaka, Japan)
[OBJECTIVE] We investigated tissue oxygen consumption during ischemic forearm exercise in a patient with chronic progressive external ophthalmoplesia (CPEO) by using a tissue oximetry.
[METHODS] The subjects were a 52-year-old male patient with CPEO and 5 normal controls (all men, age 39.6±5.5 years). The tissue oximetry analyzes near-infrared spectra of hemoglobin in the exercising muscle. Each subject was applied with sphygmomanometer cuff around the exercising upper arm, which was inflated to the mean arterial pressure during exercise. The subject squeezed hand manometer 120 times during two minutes.
[RESULTS AND CONCLUSION] Normal controls showed increased deoxygenation of hemoglobin and decreased blood volume during the exercise, and prompt oxygenation and hyperemia after cessation of the exercise. The patient with CPEO, however, didn't show increased deoxygenation of hemoglobin during the exercise but excessive oxygenation after cessation of the exercise. This reflects deficits in oxidative phosphorylation system in the patient with CPEO. The noninvasive tissue oximetry may be useful to investigate the exercise intolerance in patients with CPEO.