Kazuo Tsuyuki

Oxygen uptake efficiency slope as a useful measure of cardiorespiratory functional reserve in adult cardiac patients.

Abstract In this study we aimed to elucidate the validity and usefulness of the oxygen uptake efficiency slope (OUES) in the evaluation of adult cardiac patients. Cardiopulmonary exercise tests were performed on a treadmill by 50 adult patients with chronic heart failure. The OUES was calculated from data for the first 75%, 90%, and 100% of exercise duration. The OUES is derived from the following equation: V˙O2=a× logV˙E+b, where V˙O2 is oxygen uptake (ml/kg/min), V˙E is minute ventilation (l/kg/min), and the constant “a” represents OUES. We also determined the ventilatory anaerobic threshold (VAT). The correlation coefficient of the logarithmic curve-fitting model was [mean (SD)] 0.986 (0.009). The OUES could be used to discriminate effectively between New York Heart Association functional classes (P < 0.001). OUES and maximum V˙O2 were significantly correlated (r=0.78, P < 0.01). Agreement between the OUES values for the first 90%, 75%, and 100% of the exercise was excellent (intraclass correlation coefficient = 0.99). Our results suggest that OUES is applicable to adult cardiac patients as an objective, effort-independent estimation of cardiorespiratory functional reserve.

Oxygen Uptake Efficiency Slope as Monitoring Tool for Physical Training in Chronic Hemodialysis Patients

Abstract:  The purpose of this study was to clarify the utility of oxygen uptake efficiency slope (OUES) as a monitoring tool, and to investigate the effects of physical training in chronic hemodialysis (HD) patients. Seventeen patients (Trained Group) received physical training 2–3 times per week for 20 weeks at the intervals between exercise tests. Patients underwent a combination training of bicycle ergometry, walking and jogging for 30 min duration. The intensity of physical training was adjusted to maintain the exercising heart rate at between 50 and 60% of the peak heart rate. Twelve patients (Control Group) lived without physical training throughout the 20 weeks. Both the Groups received the symptom limited exercise tests before and after the 20 week physical training. Minute ventilation (V̇E), carbon dioxide output (V̇CO2) and oxygen uptake (V̇O2) were continuously measured during the exercise tests. Oxygen uptake efficiency slope was derived from the logarithmic relation between V̇O2 and V̇E during an incremental exercise test. In the Trained Group, OUES after physical training (30.1 ± 5.8) was significantly (P < 0.01) higher than that before physical training (25.2 ± 2.6), while in the Control Group, OUES did not change in this study period of 20 weeks. In the Trained Group, changes in OUES correlated with those in the maximum oxygen uptake (r = 0.78, P < 0.001) and the anaerobic threshold (r = 0.61, P < 0.01). It was suggested that OUES was applicable as a monitoring tool for cardiorespiratory functional reserve during physical training in HD patients.

Exercise-Ankle Brachial Pressure Index with One-Minute Treadmill Walking in Patients on Maintenance Hemodialysis

BACKGROUND The ankle-brachial pressure index (ABI) is widely used as a standard screening method for arterial occlusive lesion above the knee. However, the sensitivity of ABI is low in hemodialysis (HD) patients. Exercise stress (Ex-ABI) may reduce the false negative results. PATIENTS AND METHODS After measuring resting ABI and toe-brachial pressure index (TBI), ankle pressure and ABI immediately after walking (Post-AP, Post-ABI) were measured using one-minute treadmill walking in 52 lower limbs of 26 HD patients. The definition of peripheral arterial occlusive disease (PAD) required an ABI value of less than 0.90, TBI value of less than 0.60, and decrease of more than 15% of the Post-ABI value and 20 mmHg of Post-AP in Ex-ABI. Computed tomographic angiography (CTA) was performed in 32 lower limbs of 16 HD patients. PAD is defined as presence of stenosis of more than 75% in the case of lesions from an iliac artery to knee on CTA. RESULTS The accuracy of Ex-ABI (Sensitivity, 85.7%; Specificity, 77.7%) was higher than those of ABI (Sensitivity, 42.9%; Specificity, 83.3%) or TBI (Sensitivity, 78.6%; Specificity, 61.1%). CONCLUSION Ex-ABI with one-minute treadmill walking is the most useful tool for the screening of arterial occlusive lesions above the knee in maintenance HD patients.

Comparison of Diagnostic Accuracy between Pulse Volume Recording Parameters and Exercise-Ankle-Brachial Pressure Index in Patients with Ankle-Brachial Pressure Index above 0.91

Objective: The objective of this study was to clarify whether or not pulse volume recoding (PVR) parameters have screening capability equivalent to ankle-brachial pressure index after walking (Ex-ABI) for patients with 0.91 or higher ABI. Patients and Methods: The subjects were 87 patients (147 limbs) with symptoms of lower extremities with 0.91 or higher ABI. In all patients, upstroke time (UT), percentage of mean artery pressure (%MAP) of PVR and Ex-ABI were measured, and computed tomographic angiography (CTA) was concomitantly performed. Results: Area under the curve (AUC) of receiver operating characteristics (ROC) curves of Ex-ABI, %MAP, and UT were 0.90, 0.70, and 0.81, respectively. A significant difference was noted in AUC between Ex-ABI and %MAP (p <0.001). When the cut-off values were set at %MAP ≥45% and UT ≥180 msec, the accuracies of %MAP and UT were markedly lower than that of Ex-ABI. When the cut-off values were corrected to the values determined from the ROC curves (%MAP ≥41, UT ≥164 msec), the diagnostic accuracy of UT increased markedly. Conclusion: In patients with 0.91 or higher ABI, screening capability of PVR parameters was markedly lower than that of Ex-ABI, but UT has screening capability close to that of Ex-ABI when the cut-off value is corrected downward.

Circulatory Response During Isokinetic Training on Upper Extremity in Coronary Heart Disease Patients

The purpose of this study was to investigate the circulatory response during muscular training in coronary heart disease patients. Thirty-five male patients with effort angina pectoris and a history of myocardial infarction were studied. All patients performed a cardiopulmonary exercise test (SL-GXT) and isokinetic training at elbow flexion. The pressure rate product (PRP) during training approached the PRP level at the endpoint on SL-GXT as myocardial aerobic impairment increased. Additionally, ST changes appeared when PRP during the training equalled or exceeded the PRP endpoint on SL-GXT. In conclusion, patients showing low exercise tolerance and poor cardiac function must be carefully monitored during isokinetic training.

Properties of physical activity and optimum hemoglobin concentration in chronic hemodialysis patients

社会復帰に必要なヘモグロビン (Hb) 濃度や最大運動能力について検討するため, 27例の女性慢性血液透析 (HD) 患者と10例の女性健常者にHb濃度, 日常の歩行数の測定および運動負荷試験を施行し, 下記の成績を得た.HD患者の平均歩行数は, 健常群と比較し26.2%低値であった. 運動群に対し非運動群の歩行数は, 有意に低値であった. 職業群に対し主婦群の歩行数は, 有意に低値であった. HD患者の歩行数と年齢とに有意な負の相関関係が認められた. しかし健常者においては, 歩行数と年齢とに有意な相関関係が認められず, 年齢に関わらず歩行数は一定であった.HD患者における歩行数はHb濃度が上昇するに従い直線的に増加したが, 8.2g/dl以上まで上昇すると健常者と同水準になり, 増加傾向を示さず一定となった. HD患者における歩行数と最大酸素摂取量は, 有意な相関関係が認められた.以上のことから, HD患者の社会復帰に必要なHb濃度は日常の身体活動量を指標にすると, およそ8.2g/dl程度と考えられた. また日常の身体活動量に応じ, 必要となる最大運動能力の推測が可能と考えられた.

Studies of factors limiting maximal aerobic work capacity in patients on chronic hemodialysis

慢性血液透析 (HD) 患者の最大有酸素運動能力の制限因子を検討する目的で, 35例のHD患者と52例の健常者に対して, 心機能および末梢循環機能を評価し, またヘモグロビン濃度を測定した. HD患者は心疾患の合併がなく, β-遮断剤やdigitalis製剤の服用もしていない症例であった. また運動負荷試験の中止理由が心電図異常や血圧異常でない症例であることを厳守した. 全対象において最大運動負荷試験より得られた最大酸素摂取量, 最大pressure rate productからBruceの計算式に従いfunctional aerobic impairment (FAI), left ventricular impairment (LVI) およびperipheral circulatory impairment (PCI) を求めた. HD患者のヘモグロビン濃度は最大運動負荷試験の前に測定した.その結果, 次のような成績が得られた. HD患者のFAI, LVIおよびPCIは, 健常者と比較して有意に高い値を示した. またHD患者のPCIはLVIよりも高値を示した. 健常者のFAIはLVIとPCIの両方に有意な相関関係を認めた. しかしHD患者のFAIはLVIとは相関せず, PCIのみに有意な相関関係を認めた. HD患者のFAIはヘモグロビン濃度との間に有意な相関関係を認めなかった.以上の成績からHD患者の最大有酸素運動能力の制限を決定する因子としては, 心機能の低下よりもヘモグロビン濃度の低下以外の末梢循環系の機能の低下に関係するものと考えられた.