Satoru Takaishi

Heart rate response to breath-holding during supramaximal exercise

SummaryThe cardiovascular responses to breath-holding (BH) during short-lasting supramaximal exercise (415 W) on a cycle ergometer were investigated in 15 healthy male subjects. The arterial oxygen saturation, heart rate (HR), endtidal PO2 and PCO2 were continuously monitored. Firstly, 15 subjects performed exercise during BH, preceded by air breathing (air-BH test), and secondly, exercise without BH. Then 9 of the subjects performed the same procedure as in the air-BH test, except that all subjects breathed 100% O2 for 1 min before apnoea (O2-BH test). In 2 of these subjects, the systemic arterial blood pressure was continuously measured via a catheter in the radial artery and plasma catecholamine concentration [CA] was also measured both during the air-BH and the O2-BH tests. In the later period of the air-BH test, the high HR level became progressively depressed. This response, however, was absent in the O2-BH test. There was a late increase in the arterial blood pressure in both tests, and both tests produced hypercapnia. Only the air-BH test resulted in hypoxia, substantial hypertension and HR-depression. The increase in plasma CA was similar in both tests. The marked HR-depression demonstrated here is ascribed mainly to activation of the peripheral arterial chemoreceptors by asphyxia, and partially to baroreceptor activity due to elevated blood pressure.

Effect of Unilateral Pulmonary Vagotomy on Respiratory Control in Man

We studied the breathing pattern and pulmonary function at rest, and ventilatory responses to progressive hypoxia and hypercapnia in 7 awake patients who had undergone esophageal-carcinoma resection with sectioning of the right pulmonary vagal branch by lymphadenectomy. Twelve control patients, who had received the same surgery without vagotomy, were also studied by the same protocol. Two months after the operation, both patient groups demonstrated substantial depressions in FVC and FEV1.0, and slight augmentations in breathing frequency, minute ventilation, and occlusion pressure at 0.2s (P0.2) at rest. In the vagotomized group, the occlusion pressure responses to hypercapnia (delta P0.2/delta PaCO2) and hypoxia (delta P0.2/delta SaO2) in terms of response curve slope increased from 1.3 +/- 1.2 to 1.9 +/- 1.1 cm H2O/Torr and from 0.29 +/- 0.19 to 0.88 +/- 0.53 cm H2O/% (p less than 0.05), respectively. Contrary to the vagotomized patients, the nonvagotomized control group exhibited no significant changes in ventilatory chemosensitivities. Furthermore, when comparing the control and vagotomized groups, postoperative ventilatory chemosensitivity responses in terms of both hypercapnic and hypoxic occlusion pressure responses were significantly higher in the latter. We suggest that (1) due to the development of the substantial mechanical limitation in pulmonary functions, the Hering-Breuer inflation reflex became activated after surgery, and (2) a diminished Hering-Breuer reflex effect to inhibit the respiratory centers by unilateral vagotomy may have resulted in augmented ventilatory chemosensitivities.

AN OPERATED CASE OF HEMORRHAGIC DUODENAL ULCER AT THE POSTERIOR BULB WITH DIFFICULTY IN DIFFERENTIATION FROM CANCER OF THE PANCREATIC HEAD

症例は55歳,女性.近医で胃潰瘍の加療中,症状が軽快しないため当科を受診.上部消化管内視鏡検査にて上十二指腸角から下行部にかけて,乳頭側3/4周を占める白苔を伴った潰瘍を認めたため入院.腹部超音波検査および造影CTでは膵鈎部に腫瘤を認め,肝外胆管および16番リンパ節の腫脹も認められた.閉塞性黄疸,肝機能異常も出現したため,膵癌あるいは十二指腸癌の可能性も考え,手術を行った.十二指腸下行部および膵頭部は一塊となっており根治切除不能と判断し,十二指腸を球部にて離断し十二指腸球部空腸吻合および胆道バイパスを行った.術後経過は良好で画像上腫瘤は縮小したが, 4カ月後黒色便および貧血が出現したため再手術を行った.十二指腸下行部を切開すると膵側に4cmの潰瘍を認め,中央には血管が露出していたため,膵頭十二指腸切除術を行った.術後経過は良好であった.

Importance of Arterial Chemoreceptors for Cardiorespiratory Responses to Static Exercise in Man

Static isometric exercise leads to a rapid heart rate acceleration and pulmonary hyperventilation (Miyamoto et al., 1987). The heart rate acceleration is known as a muscle-heart reflex, originates in muscle receptors affected by noxious chemical and mechanical stimulation, and is mediated by group III and IV afferents (Gelsema et al., 1983). The mechanism of the hyperpnea is uncertain, as is also the role of chemical drive in both cardiac and respiratory events of static exercise.

Possible Involvement of Peripheral Chemoreceptor Mechanism in Bradycardia Observed During Breath Holding with Supramaximal Exercise

It is often seen that the breath is held during strenous exercise such as 100m or 200m dash. The characteristic features in this maneuver are that exercise intensity is very vigorous and duration is very short. To our knowledge, no detailed observation has been conducted on the cardiopulmonary responses during this particular physical performance.

CO2 Chemoreflex in Spinal Man

In this study we tested the hypothesis that the stimulatory hypercapnic ventilatory response (HCVR) would be less in quadriplegic patients. Apart from the sheer exclusion of a substantial part of the effector of the respiratory control system due to paralysis of the respiratory muscles of the chest and abdominal wall, two lines of evidence suggest such a possibility. First, these muscles contain a rich network of mechanoreceptors, muscle spindles, and tendon organs, which are classified as proprioceptors. There is evidence showing that afferent information from these proprioceptors exerts, via ascending spinal pathways, a reflex effect on the central control of respiration, modulating the descending drive to phrenic and intercostal spinal motoneurons (Shannon, 1986). Second, chemoreceptor afferents might have a facilitatory effect on the descending drive to respiratory muscle neurons independent of the proprioceptive influences. Recent studies have shown that hypercapnia increases both internal intercostal (Fregosi and Bartlett, 1989) and abdominal expiratory (Ledlie et al.,1983) nerve activities in the absence of proprioceptive feedback from the body wall.

Use of stable isotopes in gastrointestinal surgery.

種々の安定同位元素により, 消化器外科患者の全身蛋白代謝, 脂肪消化吸収能, 肝細胞内の個々の機能を測定した. 全身蛋白代謝は加齢とともに低下した. 肝硬変患老では蛋白合成速度が著明に低下している症例が認められ, また蛋白合成速度とICG15分値・プロトロンビン時間とには有意の相関が認められた. 膵頭十二指腸切除術後の脂肪消化吸収能は著明に低下していた. 肝硬変患者の肝ミトコンドリア, ureacycle, ミクロゾームの各機能を測定した結果, 肝ミトコンドリア機能の障害は比較的軽度であり, 肝ミクロゾーム機能が強く障害されていた.