Biomedical subjects

Koji Ban

Publications and source records attributed to Koji Ban.

4 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.

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PubMed2004

Successful coil embolization for spontaneous arterial rupture in association with Ehlers-Danlos syndrome type IV: report of a case.

When a patient with Ehlers-Danlos syndrome (EDS) presents with a vascular emergency, performing life-saving surgery can be difficult because of the profound fragility of the arterial tissue. We report the case of a 27-year-old woman with EDS in whom a spontaneous arterial rupture was successfully treated with transcatheter embolization. The patient was brought to our hospital in shock, with left lower abdominal pain. She had been diagnosed with EDS type IV following a colonic rupture 8 years earlier. An emergency angiogram revealed rupture of the left external iliac artery. The active bleeding was managed by transarterial embolization of the ruptured artery using stainless steel coils, which took 30 min to achieve. The patient has not suffered any further vascular complications during the year since this procedure. Transcatheter coil embolization may be a reliable option for treating sudden arterial rupture in patients with this syndrome.

Adult↗

PubMed2003

Retro-sartorius bypass in the treatment of graft infection after peripheral vascular surgery.

Extra-anatomic bypass is preferred for revascularization after removal of infected vascular grafts. The obturator canal technique has been used to bypass an infected field in the groin, although this method has not always been definitive because of several drawbacks. We present a unique method of extra-anatomic revascularization for use in such a situation. An autogenous graft is placed just below the sartorius muscle in the thigh and penetrates the iliacus muscle near the lateral end of the inguinal ligament. Limb loss and recurrent infection are prevented postoperatively. This retro-sartorius bypass technique may be a useful alternative to obturator bypass grafting in selected patients.

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