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Kazuhiro Kochi

Publications and source records attributed to Kazuhiro Kochi.

13 recordsLinked to original sources
PubMed2005

A novel endothelial function test using Doppler flow: the snuff-box technique.

Precise measurement of Doppler estimated blood flow volume using the standard technique of flow-mediated vasodilation is not possible because the anatomic course of the brachial or radial artery goes against the principle of Doppler measurements that the insonation angle should be less than 30 degrees . The radial artery in the anatomic snuff-box area is useful for the measurement of Doppler signals as the insonation angle is less than 30 degrees and because the size of the artery allows observation of laminar flow. We introduce the snuff-box technique as a novel endothelial function test that enables measurement of both blood flow and diameter of the radial artery. Changes in diameter and blood flow volume during reactive hyperemia were examined in 15 healthy volunteers. Changes in blood flow determined using the snuff-box technique were compared with changes in forearm blood flow determined by plethysmography. The diameter of the radial artery increased from 2.3 +/- 0.2 mm at baseline to 2.8 +/- 0.4 mm at 60 s after deflation (P = 0.0017), and blood flow increased from 52.3 +/- 21.4 ml/min at baseline to 108.6 +/- 33.1 ml/min at 15 s after deflation (P = 0.0014). Percentile blood flow determined by the snuff-box technique correlated significantly with that determined by plethysmography (r = 0.824, P = 0.0002). Both blood flow volume and artery diameter can be measured with high reliability using the snuff-box technique, as has been shown in subjects with reactive hyperemia.

Adult↗
PubMed2005

Novel Doppler technique to assess systemic vascular resistance: the snuffbox technique.

BACKGROUND: To explore an alternative to the systemic vascular resistance index (SVRI) for monitoring peripheral circulation in patients in the intensive care unit (ICU), the resistive index (RI) in the upper extremity arteries was measured by using surface Doppler ultrasound. METHODS AND RESULTS: The correlation between RI and vascular resistance was assessed in vitro using a vessel phantom in a Donovan-type mock circulation system. In addition, 15 ICU patients who had undergone open-heart surgery were studied. Mean arterial pressure, central venous pressure and cardiac output were measured 30 times at 10 min intervals after patients returned to the ICU following surgery, and the SVRI was calculated from these parameters. At the same time points, 3 parts of the upper extremity arteries (brachial artery in the cubital fossa (BA), radial artery at the wrist (RA), and radial artery at the anatomical snuffbox (SB)) were scanned by Doppler ultrasound, and the resistance index (RI) for each artery region was calculated. In vitro, RI increased with higher vascular resistance, exhibiting a significant correlation (r = 0.982, p < 0.0001). In vivo, the average incidence angles at the BA and RA were larger than 60 degrees , while that at the SB was only 11.5+/-10.8 degrees. The overall correlation between SVRI and RI for all patients was not significant for the BA or RA, but was significant for the SB (p < 0.0001). In individual patients, the correlation of SVRI with RI at the BA or RA was significant in 3 patients only, whereas significant correlation for the SB was observed in all patients. Doppler waveform analysis at the SB revealed diastolic flow reversal with increased SVRI. CONCLUSIONS: Measurement at the SB provides an ideal ultrasound incidence angle for the measurement of blood flow velocity. Hence, RI measured in this way may serve as an indicator of peripheral vascular resistance, and may be effective for the evaluation of peripheral circulatory disturbance.

Aged↗
PubMed2004

Inflammatory aortic arch aneurysm with total occlusion of cervical branches.

We surgically replaced the aortic root and the complex arch in a patient with aortitis syndrome with total occlusion of the cervical branches. Cerebral perfusion was being maintained through the reversed flow of the vertebral artery from the bilateral mammary arteries. Though cerebral perfusion was continued through the prosthetic grafts attached to the subclavian arteries during the procedure, bilateral watershed cerebral infarction corresponding to the most distal part of the anterior- and middle cerebral arterial system developed. With regard to the near infrared spectroscopy as a brain monitoring method, we sought to discuss the limitations.

Aged↗
PubMed2003

Fate of aneurysms of the distal arch and proximal descending thoracic aorta after transaortic endovascular Stent-Grafting.

BACKGROUND: The purpose of this study was to evaluate the midterm results of transaortic stent-grafting for distal aortic arch aneurysms or proximal descending aortic aneurysms and the feasibility of this method for thoracic aortic aneurysm repair. METHODS: Twenty-three patients with true distal aortic arch aneurysms or proximal descending thoracic aortic aneurysms were repaired with the stent-graft introduced through the incision on the proximal arch aorta. Follow-up computed tomography was performed every 6 months in 21 surviving patients. The maximum dimension of the excluded aneurysmal space and the maximum aneurysmal diameter were measured and evaluated to determine whether the aneurysmal space decreased or disappeared after this alternative procedure. RESULTS: There was 1 hospital death (4.3%) due to cerebral embolism. Another patient died of pneumonia 1 year after surgery. Twenty-one patients (91%) survived during the follow-up period, but 1 patient (4.3%) suffered from paraplegia. The follow-up period ranged from 12 to 62 months (average, 34.3 +/- 15.2). There were no instances of aneurysmal rupture during the follow-up period. Postoperative serial computed tomography scans showed disappearance or significant shrinkage of the excluded aneurysmal space in 20 of 21 patients (95%), except for the one patient with endoluminal leakage. CONCLUSIONS: Transaortic endovascular stent-grafting was an effective alternative approach to treating distal aortic arch aneurysms or proximal descending aortic aneurysms. The excluded aneurysm disappeared or shrunk after successful placement of the stent-graft.

Aged↗
PubMed2003

The snuffbox technique: a reliable color Doppler method to assess hand circulation.

OBJECTIVE: Although the Allen test is crude and subjective, an objective color Doppler method has yet to be established in the assessment of hand circulation before radial artery harvesting. Doppler studies so far have neglected the Doppler principle that the insonation angles should be less than 30 degrees and have not been compared with any standard except the crude Allen test. We therefore introduced the snuffbox technique, measuring the radial artery at the anatomic snuffbox, which is the most distal area after harvesting. Color Doppler methods were compared with the stump pressure as a criterion standard. METHODS: Maximal flow velocity and Doppler angles of the snuffbox, palmar artery, and ulnar artery were measured in 20 hands before and after radial artery harvesting. Stump pressure was measured during surgery. RESULTS: Maximal flow velocity in the snuffbox decreased with radial artery compression and after radial artery harvesting. All the flow patterns in the snuffbox technique showed simultaneous reversal. Maximal flow velocity in the ulnar artery increased with radial artery compression and after radial artery harvesting. Maximal flow velocity in the palmar artery did not change significantly with radial artery compression or after radial artery harvesting. Doppler angles were 20.9 degrees +/- 6.0 degrees in the radial artery of the snuffbox, 82.5 degrees +/- 6.1 degrees at the palmar artery, and 81.0 degrees +/- 7.6 degrees at the ulnar artery. The changes in the snuffbox technique were highly correlated with the stump pressure ratio (P <.001). CONCLUSIONS: Among various color Doppler methods, the snuffbox technique was precise and reliable.

Aged↗
PubMed2003

Surgical treatment of aortic coarctation associated with multi-vessel brachiocephalic involvement in takayasu's arteritis.

In Takayasu's arteritis (TA), both atypical coarctation (CO) and brachiocephalic involvement are common features that occasionally require operative correction. A combination of these abnormalities could duplicate underlying illness in patients, posing an increased risk of operative morbidity. We present, herein, two TA patients in which hypertensive heart disease secondary to CO was surgically corrected. Both patients had multi-vessel brachiocephalic disease. One patient who showed occlusion of all brachiocephalic arteries underwent aorto-aortic bypass, while another with two-vessel lesion underwent axillo-bifemoral bypass grafting. Subclavian reconstruction was supplemental to each procedure, resulting in relief of neurologic stigmata. Strategies to avoid intraoperative cerebral ischemia played an important role in the surgical repair of such TA-related extensive vascular lesions.

Aortic Coarctation↗
PubMed2003

Trans-vertebral regional cooling for spinal cord protection during thoracoabdominal aortic surgery: an experimental study.

We developed a simple cooling method for spinal cord protection against ischemic injury during aortic surgery. The neuroprotective effects of our method were investigated using an animal study. Selective spinal hypothermia was produced by means of originally-designed cooling pads placed over the lower thoracic and lumbar vertebral column. Spinal cord ischemia was induced by cross-clamping the thoracic aorta for 60 min in beagle dogs. The neuroprotective effects were evaluated by a multi-modal study. The motor-evoked potentials of the spinal cord resulting from transcranial electric stimulation (MEPs) were recorded during both the ischemic and reperfusion periods. Hindlimb motor function was graded with the Tarlov score, and a histologic examination of the spinal cord injury was performed, at 24 hours after ischemia in animals undergoing hypothermia (hypothermia group: n = 7) or a sham (control group: n = 7). The spinal cord temperatures at the lower thoracic (T10) and lumbar (L3) levels decreased by -9.1 degrees C per hour and -8.1 degrees C per hour, respectively. The amplitude of the MEPs decreased during ischemia in both groups of animals, and significantly recovered during the early phase of aortic reperfusion in the hypothermia group. The Tarlov scores in the hypothermia and control groups were 3.3 +/- 1.0 and 1.1 +/- 1.5 (mean +/- SD, p = 0.015), respectively. Histopathologic study revealed that ischemic injury of the lumbar cord was reduced in the animals undergoing hypothermia. Trans-vertebral regional cooling reduced ischemic spinal cord injury in a canine study. The current method is potentially feasible for clinical use, especially in view of its technical simplicity and few procedure-related complications.

Animals↗
PubMed2002

Severe ischemic early liver injury after cardiac surgery.

BACKGROUND: The epidemiology, pathogenesis and prognosis of severe ischemic early liver injury (SIELI) after cardiac surgery are poorly understood. Accordingly, we studied patients whose alanine transaminase (ALT) concentration acutely increased above 500 IU/l in the immediate postoperative period and compared these patients to two control groups matched for preoperative and immediate postoperative characteristics. METHODS: We used a prospective database of 1,800 consecutive cardiac surgical cases to identify the study groups. Group I was made up of 20 patients with ALT levels above 500 IU/L in the acute postoperative stage (SIELI). Preoperative liver tests were normal in all these patients. Group II was obtained by identifying 20 control cases whose age, type of surgery, NYHA classification, and Parsonnet score matched Group I (preoperative controls). Group III was obtained by identifying 20 patients who developed postoperative acute renal failure and shock (ARF/shock; postoperative controls) but no enzyme evidence of hepatic injury. RESULTS: Acute renal failure, a low cardiac index (CI) state, and mortality were more common in SIELI and ARF/Shock patients compared with preoperative controls (all p values less than 0.01). Peak postoperative pulmonary artery occlusion (PAOP) and central venous (CVP) pressures were also higher in SIELI and ARF/Shock patients than controls (all p values less than 0.02). A higher dose of norepinephrine and milrinone were required to maintain blood pressure and cardiac output in SIELI and ARF/shock patients than preoperative controls (all p values less than 0.005). SIELI patients, however, differed from ARF/Shock patients in that they had a higher preoperative NYHA class and a greater incidence of hypertension and diabetes. Stepwise linear regression analysis identified a postoperative low CI and the presence of diabetes as the only predictors of peak ALT value (p less than 0.05). Multivariate logistic regression analysis identified female gender as being associated with a higher likelihood of SIELI (odds ratio: 6.13; 95% CI 1.08 to 34.82) CONCLUSIONS: SIELI after cardiac surgery carries a high mortality and is strongly associated with a low cardiac output and increased filling pressures, suggesting that liver ischemia induced by a combination of decreased perfusion and congestion is fundamental to its pathogenesis. A history of cardiac failure, diabetes, hypertension, and female gender may represent risk factors for its development and severity in the setting of a postoperative low cardiac output state.

Acute Kidney Injury↗
PubMed2002

Comparative study of noninvasive cerebrovascular monitoring methods in cardiac surgery.

Unfavorable incidents during cardiac operations due to inadequate cerebral perfusion can be avoided by the utilization of noninvasive blood flow monitoring methods. The purpose of this study was to evaluate monitoring systems for cebrovascular perfusion. We compared currently available blood flow monitoring devices including transcranial Doppler (TCD), central retinal artery color Doppler (CRAD) and near-infrared spectroscopy (NIRS). The maximum flow velocity (Vmax) of the right central retinal artery was measured with a 7.5 MHz Doppler system. The Vmax of the right middle cerebral artery was measured with a TCD system. Regional tissue oxygen saturation (rSO2) was continuously measured with a NIRS system. The total number of individual data for each monitoring method collected from 25 patients was 184. The CRAD-Vmax was correlated more closely with the corresponding maximum blood pressure than the TCD-Vmax (r = 0.742 and 0.607, respectively). No missing data were seen in CRAD, but 20 missing data were seen in TCD, mostly during the period of cardiopulmonary bypass with lowered blood pressure. All 184 data were divided into two groups: Group 1 (rSO2 > or = 60 %, n=175) and Group 2 (rSO2 <60 %, n=9 data). The CRAD-Vmax was significantly lower in Group 2 (5.2+/-2.4 cm/s versus 3.0+/-0.4 cm/s, p<0.001). However, there was no significant difference in the TCD-Vmax between these two groups. Thus, CRAD may be superior to TCD in detecting insufficiency of cerebral blood flow correlating to rSO2, and could be used as the first choice monitoring system of cerebral blood flow during cardiac surgery.

Adolescent↗