Biomedical subjects

C T Araki

Publications and source records attributed to C T Araki.

At least 19 recordsLinked to original sources

PubMed1998

A strategy for increasing use of autogenous hemodialysis access procedures: impact of preoperative noninvasive evaluation.

PURPOSE: We studied the efficacy of preoperative noninvasive assessment of the upper extremity to identify arteries and veins suitable for hemodialysis access to increase our use of autogenous fistulas (AF). METHODS: From Sep. 1, 1994, to Apr. 1, 1997, 172 patients who required chronic hemodialysis underwent segmental upper extremity Doppler pressures and duplex ultrasound with mapping of arteries and veins. The following criteria were necessary for satisfactory arterial inflow: absence of a pressure gradient between arms, patent palmar arch, and arterial lumen diameter 2.0 mm or more. The criteria necessary for satisfactory venous outflow were venous luminal diameter greater than or equal to 2.5 mm for AF and greater than or equal to 4.0 mm for synthetic bridging grafts (BG) and continuity with distal superficial veins in the arm. Intraoperative and duplex ultrasound measurements were compared. Contemporary experience was compared with the 2-year period (1992 to 1994) before implementation of the protocol. RESULTS: During the period from Sep. 1, 1994, to Apr. 1, 1997, 108 patients (63%) had AF, 52 (30%) had prosthetic BG, and 12 (7%) had permanent catheters (PC) placed. Early failure was seen in 8.3% of AFs. Primary cumulative patency rates were 83% for AF and 74% for BG at 1 year (p < 0.05), with a mean clinical follow-up of 15.2 months. No postoperative infections were observed with AF, whereas six infections (12%) were observed with BG and two (17%) with PC insertion. During the period from June 1, 1992, to Aug. 31, 1994, 183 procedures were performed with a distribution of 14% AF, 62% BG, and 24% PC. In this earlier period the AF early failure rate was 36%, and the patency rates were 48%, 63%, and 48% for AF, BG, and PC, respectively (mean follow-up, 13.8 months). CONCLUSION: A protocol of noninvasive assessment increased use of AFs. The cumulative patency rate of AFs was improved, and early failure rates were reduced when compared with the preceding institutional experience. Routine noninvasive assessment is recommended to document adequacy of arterial inflow and delineate venous outflow to maximize opportunities for AF.

Arm↗

PubMed1997

Vein transposition in the forearm for autogenous hemodialysis access.

PURPOSE: We describe a technique of superficial venous transposition in the forearm used for the formation of an arteriovenous fistula for hemodialysis access. These modifications of the single-incision radiocephalic fistula are designed to increase options for arteriovenous fistulas by using veins and arteries that are suitable for use but are not in immediate proximity. METHODS: Arteries and veins suitable for a primary arteriovenous fistula were identified and mapped using duplex ultrasound in 89 patients. Separate incisions were used in the majority of cases, and the selected forearm vein was mobilized, angiodilated, and transposed into a subcutaneous tunnel on the volar aspect of the forearm. Before initiation of hemodialysis, duplex ultrasound scanning was performed, and the location that was most suitable for cannulation was identified. Repeat scans were performed at 3-month intervals for analysis of patency. RESULTS: Superficial venous transpositions were performed using a single incision in 13 instances in which the vein was in immediate proximity to the radial artery (type A). Dorsal-to-volar forearm transposition (type B) was performed in 30 veins with anastomoses to the radial (n = 26), ulnar (n = 2), or brachial (n = 2) arteries. Volar-to-volar forearm transposition (type C) was performed in the remaining 46 veins, with anastomoses to the radial (n = 42), ulnar (n = 2), or brachial arteries (n = 2). Successful hemodialysis was accomplished in 81 of 89 patients (91%). The primary cumulative patency rate was 84% at 1 year and 69% at 2 years. The mean duration of follow-up was 14.3 months. CONCLUSIONS: The use of superficial venous transposition for the formation of autogenous hemoaccess was associated with ease of cannulation by dialysis personnel, high maturation rates, reduced early failure rates, and enhanced patency rates. We recommended the use of these technical modifications to increase the use of autogenous fistulas in the forearm.

Adult↗

PubMed1996

Hemodynamic and clinical improvement after superficial vein ablation in primary combined venous insufficiency with ulceration.

PURPOSE: This study was undertaken to determine the degree of clinical and hemodynamic improvement after surgical ablation of incompetent superficial and perforator veins in limbs with combined deep and superficial venous incompetence manifested by chronic dermal ulceration. METHODS: Eleven limbs in 10 patients with class 5 or 6 venous insufficiency (ulceration) were assessed by CEAP (clinical, etiologic, anatomic, pathophysiologic) clinical scores, air plethysmography, color duplex ultrasonography, and phlebography (both ascending and descending). Surgical ablation of superficial and perforating veins was performed, followed by repeat clinical, air plethysmographic, and color duplex ultrasonographic examinations. RESULTS: All 11 limbs had combined deep and superficial vein reflux on the preoperative color duplex ultrasound scan. Clinical symptom scores decreased from 10 to 1.4 after operation. Postoperative air plethysmography demonstrated significant reduction in reflux as measured by the mean venous filling index, which decreased from 12 +/- 5 ml/sec to 2.7 +/- 1 ml/sec after surgery. Calf pump function was also significantly improved, with a mean ejection fraction that increased from 43% +/- 11 to 59% +/- 13 and mean residual volume fraction that decreased from 56% +/- 15 to 33% +/- 16. Each of these measures was significantly different from the preoperative value (p < 0.05). Similar improvement characterized subgroups of limbs with three or more incompetent deep segments (n = 6) or popliteal segment incompetence (n = 6). CONCLUSIONS: Superficial and perforating vein incompetence accounts for a substantial and correctable component of venous insufficiency in limbs with combined deep and superficial vein reflux and venous ulceration. These data indicate that surgical correction of this component significantly improves clinical symptoms and venous hemodynamics. Superficial and perforator ablation is an appropriate initial step in the management of combined deep and superficial venous incompetence.

Aged↗

PubMed1996

A program of operative angioplasty: endovascular intervention and the vascular surgeon.

PURPOSE: Vascular surgeons are ideally suited to select and perform endovascular interventions either as primary therapy or as an adjunct to bypass surgery. Attaining proficiency in endovascular techniques is an important goal in the training of vascular surgeons. We report our initial experience with a program of endovascular intervention performed in the operating room by vascular surgeons. METHODS: During the previous three years, we performed 109 angioplasty procedures, 60 aortoiliac (55%), 32 femoropopliteal (29%), and 17 popliteal/tibial (16%), using guidewires and angioplasty balloons directed by intraoperative digital subtraction C-arm arteriography with road-mapping capabilities. Indications for angioplasty included disabling claudication in 59 patients (54%), rest pain in 18 (17%), and tissue loss in 32 (29%). Angioplasty was accompanied by stent placement in 39 of 60 aortoiliac procedures (65%) and in two of 32 femoral procedures (6%). In 16 cases (15%), the endovascular procedure was performed in conjunction with a bypass procedure. In selected cases (15, 14%), duplex scanning was the sole diagnostic method used before surgery to identify the lesion, eliminating the need for preoperative arteriographic scans. Segmental pressure measurements, duplex ultrasound scans, and treadmill exercise testing as indicated were performed before and after surgery. The efficacy of the endovascular intervention was assessed at 3-month intervals during the first year and at 6-month intervals thereafter. RESULTS: A successful results was defined using criteria recommended by the Ad Hoc Subcommittee on Reporting Standards for Endovascular Procedures from the Society for Vascular Surgery/International Society for Cardiovascular Surgery. This included the combination of symptomatic improvement, obtaining an anatomically successful result with < 30% residual lumen stenosis, and elimination of the translesion gradient with an improvement in high thigh-brachial index or ankle-brachial index greater than 0.15. Initial success was achieved in 55 of 60 aortoiliac (92%), 28 of 32 femoropopliteal (88%), and 16 of 17 popliteal/tibial (94%) angioplasty procedures. Clinical follow-up has been achieved in all cases, with continued clinical success rates of 80%, 75%, and 82% for aortoiliac, femoropopliteal, and popliteal/tibial angioplasty procedures, respectively, with a mean follow-up of 15.7 months. CONCLUSION: These results confirm the value of a program in which C-arm technology was used by vascular surgeons in the performance of angioplasty and stenting procedures in the operating room. This experience in therapeutic endovascular intervention will facilitate the credentialing process for future vascular surgeons.

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PubMed1995

Role of leukocyte activation in patients with venous stasis ulcers.

Alteration in leukocyte activation has been implicated as an etiological factor in the development of chronic venous stasis ulcers (CVSU). The purpose of this study was to determine differences in expression of cell surface activation markers on circulating leukocytes and systemic, soluble, serum cytokine levels between healthy controls and patients with CVSU. Twenty-three patients were separated into two groups. Group I consisted of 12 healthy, adult, age-matched male patients with no venous disease. Group II consisted of 11 adult male patients with CVSU who underwent air plethysmography (APG) and duplex scanning to determine the severity of venous insufficiency. All patients had measurements of systemic, serum-based, soluble IL-1 beta, IL-2, IL-6, TNF-alpha, and beta 2 microglobulin levels. Using fluorescence flow cytometry, we measured the percentage of lymphocytes (CD3), monocytes (CD14), and granulocytes (CD15) expressing various cell surface activation markers. By APG and duplex scan, all group II patients exhibited venous insufficiency, with a mean venous filling index of 6.9 +/- 3.9 sec. Relative to group I, group II patients demonstrated a decreased expression of the CD3+/DR+ (13.3 +/- 1.5, P < or = 0.01) and CD3+/CD38+ (31.1 +/- 2.1, P < or = 0.04) markers on T-lymphocytes and an increased expression of CD14+/CD38+ (99.6 +/- 0.2, P < or = 0.008) markers on monocytes. Circulating neutrophils showed no evidence of activation. In addition, a significant elevation in the T-helper to T-suppressor ratio (2.9 +/- 0.6, P < or = 0.0001) between groups I and II was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1995

Limited range of motion is a significant factor in venous ulceration.

PURPOSE: Calf muscle pump dysfunction is a recognized factor in chronic venous insufficiency (CVI). We investigated the hypothesis that limbs with CVI have a reduced ankle range of motion (ROM) that may be responsible for the poor calf pump function associated with venous ulceration. METHODS: Ankle ROM and calf pump function were assessed in 32 limbs of 26 adult men. Limbs were selected on the basis of clinical presentation: normal (n = 6 limbs), class 1 or 2 CVI with no history of ulceration (n = 9 limbs), class 3 CVI with healed ulceration (n = 9 limbs), and class 3 CVI with active ulceration (n = 8 limbs). ROM was determined by goniometry during maximal plantar flexion and dorsiflexion of the ankle. Calf pump function was determined by air plethysmographic measurement of ejection fraction (EF) and residual volume fraction (RVF). RESULTS: Ankle ROM was significantly (p < 0.05) reduced in each CVI group compared with age-matched control subjects, because of decreases in both plantar flexion and dorsiflexion. Calf pump function was significantly impaired (decreased EF and increased RVF) in ulcerated limbs. ROM was significantly correlated to EF and RVF. Impairment of ROM and calf pump function was associated with deterioration in the clinical classification of venous disease. CONCLUSIONS: Limbs with CVI have a limited ankle ROM that decreases with increasing severity of clinical symptoms. This decreased ROM is associated with, and may contribute to, poor calf pump function.

Aged↗

PubMed1995

Diminished mononuclear cell function is associated with chronic venous insufficiency.

PURPOSE: With clinical progression of chronic venous insufficiency (CVI), dermal infiltration of mononuclear cells increases. Because these cells regulate chronic inflammatory responses and modulate wound healing, cellular dysfunction could explain alterations in wound healing with CVI. The purpose of this study was to determine whether monocytes in patients with CVI are dysfunctional. METHODS: Mononuclear cell function was measured as the degree of proliferation in response to a mitogenic challenge. Fifty patients were separated into four groups: group 1, 14 patients with normal limbs; group 2, 10 patients with class 2 CVI; group 3, 15 patients with active venous ulcers; group 4, 11 patients with healed venous ulcers and current evidence of lipodermatosclerosis. Duplex scanning and air plethysmography correlated with the clinical classification of CVI. Systemically circulating monocytes and lymphocytes were obtained by antecubital venipuncture from groups 1 to 4. Cells were cultured in the presence of staphylococcal enterotoxins A, B, C1, D, and E (mitogens) at 1, 8, 31, and 125 micrograms/well on the basis of previous dose-response experiments. Phytohemagglutinin (PHA), 5 micrograms/well, served as a control mitogen. The dose-response curves indicated that 8 micrograms/well elicited the greatest degree of cell proliferation. Proliferative responses at 8 micrograms/well were analyzed for statistical significance among groups 1 to 4. Comparisons among groups were performed by use of the nonparametric Mann Whitney U post tests and a one-tailed unpaired t test. Results were considered significant at p < or = 0.05. RESULTS: Proliferative responses to PHA indicate that lymphocytes and monocytes from patients with CVI are not globally depressed. However, patients in group 2 did not exhibit the same degree of proliferation to PHA as did groups 1, 3 and 4. Proliferative responses between groups 2 and 1 (44.38 +/- 43.9 vs 118.87 +/- 27.1, p < or = 0.05) and groups 2 and 3 (44.38 +/- 43.9 vs 105.95 +/- 60.99, p < or = 0.05) were significant. Challenges with staphylococcal enterotoxin A and B reveal significant diminution of proliferative responses in groups 2 (42.73 +/- 11.55, p < or = 0.05) and 3 (45.57 +/- 9.1, p < or = 0.05) and groups 3 (36.81 +/- 6.9, p < or = 0.05) and 4 (35.04 +/- 7.5, p < or = 0.05), compared with staphylococcal enterotoxin A controls (68.68 +/- 9.9) and staphylococcal enterotoxin B controls (66.25 +/- 13.56), respectively. A trend of diminished mononuclear cell function with progression of CVI was observed with staphylococcal enterotoxins B, C1, D, and E, strongly suggesting biologic significance. Furthermore, patients with lipodermatosclerosis uniformly exhibited the poorest proliferative responses. CONCLUSIONS: Deterioration of mononuclear cell function is associated with CVI. A trend of diminishing proliferative responses with clinical disease progression is observed and suggests biologic significance. The decreased capacity for mononuclear cell proliferation in response to various challenges may manifest itself clinically as poor and prolonged wound healing.

Aged↗

PubMed1994

The significance of calf muscle pump function in venous ulceration.

PURPOSE: Patients with clinically evident chronic venous insufficiency were evaluated to relate the degree of insufficiency and calf muscle pump dysfunction to venous ulceration. METHODS: Sixty-nine limbs in 55 patients with chronic venous insufficiency by Society for Vascular Surgery/International Society for Cardiovascular Surgery Classification were compared in three groups: classes 1 and 2 with no history of ulceration (19 limbs); class 3 with healed ulceration (20 limbs); and class 3 with active ulcers (30 limbs). Air plethysmography measurements of outflow fraction, venous volume, venous filling time, venous filling index, ejection fraction, ejection volume, residual volume fraction, and residual volume were made. In 62 of the 69 limbs, color-flow duplex ultrasonography was used to determine the pattern of reflux. RESULTS: The outflow fraction was normal in 84%, 75%, and 77% of nonulcerated, healed, and ulcerated limbs. The venous filling index was abnormal in most limbs (nonulcerated 95%, healed 90%, ulcerated 98%) but not significantly different among groups. Differences in calf muscle pump function were significant. Ulcerated limbs had significantly poorer ejection fractions (p = 0.0002) and greater residual volume fractions (p = 0.0006) than nonulcerated or healed limbs. By ultrasonography, deep and superficial vein incompetence was present in most limbs and was not statistically different among groups. Although venous insufficiency was not measurably different among groups, limbs with active venous ulcers had significantly poorer calf muscle pump function than those with healed ulcers or with no history of ulceration. CONCLUSION: Venous insufficiency is necessary but not sufficient to cause ulceration, and a deficiency of the calf muscle pump is significant to the severity of venous ulceration.

Adult↗

PubMed1993

Refinements in the ultrasonic detection of popliteal vein reflux.

Color-flow and duplex ultrasonography were used to determine the optimal method for documenting venous valvular reflux. Popliteal veins were examined in 10 normal limbs and 11 limbs with clinical evidence of chronic venous insufficiency (CVI). Peak reflux velocity (spectral) and duration of reflux (spectral and color) were measured with the patient in supine and standing positions, with manual and pneumatic compression applied sequentially to thigh and calf. Manual and pneumatic compression produced equivalent reflux velocity and duration. In normal limbs peak reflux velocity was always less than 22 cm/sec, with a mean reverse flow duration of 0.3 sec +/- 0.03 (SEM). In limbs with CVI, reflux velocity varied widely among protocols. Reflux duration and velocity were greater in the supine position than in the standing position for both normal limbs and limbs with CVI (p < 0.04). Duration was significantly increased for thigh versus calf compression in normal limbs (p < 0.001) but decreased in limbs with CVI (p < 0.003). Methods that used thigh compression or supine position were less capable of discriminating normal limbs from limbs with CVI. Standing calf compression provided the greatest rates of sensitivity (91%), specificity (100%), and accuracy (95%). Compared with spectral Doppler scanning, color-flow ultrasonography produced a consistently shorter reflux duration (p < 0.001). In limbs with CVI with a mean spectral duration of 2.5 sec +/- 0.2 (SEM), mean color Doppler duration was 0.7 sec shorter. Our results demonstrate that popliteal vein incompetence is identified optimally by reflux duration after standing calf compression; adequate manual compression is sufficient to identify reflux; color-flow Doppler ultrasonography may underestimate reflux duration.

Adult↗

PubMed1991

Cerebrovascular hemodynamic changes associated with carotid endarterectomy.

To evaluate the effect of carotid surgery on the cerebral circulation, transcranial Doppler sonography and ocular pneumoplethysmography were performed on 36 patients who underwent unilateral carotid endarterectomy. Ocular pneumoplethysmography and transcranial Doppler sonography tests were performed within a week before and after operation, and transcranial Doppler sonography was repeated greater than or equal to 30 days after operation. Middle and anterior cerebral arteries were insonated bilaterally, and flow velocities ipsilateral (iMCAFV or iACAFV) and contralateral (cMCAFV or cACAFV) to the side of surgery were recorded. The iMCAFV and iACAFV increased significantly in the immediate postoperative period, and the iMCAFV remained elevated on the second follow-up study. Patients with greater than or equal to 75% ipsilateral carotid stenosis (N = 23) had increased iMCAFV, iACAFV, and decreased cACAFV after operation, whereas those with less than 75% stenosis (N = 13) had no significant transcranial Doppler sonography changes. Those with greater than or equal to 75% contralateral carotid stenosis (N = 17) had significant increases in iMCAFV, cMCAFV, and iACAFV after operation, whereas those with less than 75% contralateral carotid stenosis had no significant transcranial Doppler sonography changes. A subset of patients (N = 13) did not increase iMCAFV after surgery. The ocular pneumoplethysmography changes were significantly different in both groups when preoperative and postoperative values were compared. We conclude that carotid endarterectomy can cause lasting cerebral hemodynamic changes, but that its effects are not uniform among all patients.

Aged↗

PubMed1991

Distribution of valvular incompetence in patients with venous stasis ulceration.

Valvular incompetence associated with venous ulceration can occur in the superficial, deep, or perforating systems. Duplex imaging was used to evaluate 95 extremities (78 patients) with current venous ulceration to determine the location of incompetence in each extremity. In addition, in 91 of the 95 extremities the area of the venous ulcer was evaluated for the presence of perforating veins or any other superficial veins or both conditions. Sixty-three (66.3%) of the 95 extremities had multisystem incompetence (superficial and perforating plus superficial and deep plus perforating and deep plus superficial and perforating and deep), whereas single system incompetence (superficial plus perforating plus deep) was seen in only 26 (27.3%). Isolated deep incompetence was identified in only two extremities (2.1%). Furthermore, 45% (41/91) of the ulcers had no duplex evidence of any venous abnormality in the ulcer bed. These data show that the site of valvular incompetence occurred in multiple locations, that isolated valvular incompetence of the deep venous system was uncommon, and that perforating veins were not always in the ulcer bed itself. Because standard venous surgery has traditionally been directed toward only one system, this may provide one explanation for ulcer recurrence. Therefore complete venous evaluation with duplex imaging allowing for surgical intervention directed specifically to the sites of involvement in each system is recommended.

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PubMed1989

Postischemic hypothermia diminishes skeletal muscle reperfusion edema.

The mechanisms of ischemia-reperfusion injury in skeletal muscle remain controversial. We investigated the ability of postischemic hypothermia to diminish reperfusion edema and improve skeletal muscle pH in a bilateral, in vivo isolated canine gracilis muscle model. In five anesthetized animals, both gracilis muscles were subjected to 6 hr of ischemia followed by 1 hr of reperfusion. After 5 hr of warm ischemia, one gracilis muscle was cooled to 21 degrees C (cold reperfusion, CR) while the contralateral gracilis muscle was maintained at ambient temperature (warm reperfusion, WR). Reperfusion muscle edema was quantitated by measurement of gracilis muscle weight gain. Interstitial muscle pH was monitored by glass microelectrodes. Vascular permeability was measured by analysis of albumin (125I-Alb) leak. Results are presented as the means +/- SEM. (table; see text) Postischemic hypothermia significantly increased the interstitial muscle pH and significantly reduced postreperfusion muscle edema, without changing the vascular permeability to albumin. These data suggest that hypothermia may provide a clinical method for salvaging ischemic skeletal muscle from the postreperfusion edema that can lead to compartment syndromes, reperfusion injury, and subsequent limb loss.

Animals↗

PubMed1987

Poststenotic flow velocity changes as a function of stenosis geometry.

We used an in vitro pulsatile flow model to examine the velocity profile distal to a variable nonaxisymmetric stenosis. Using a continuous-wave Doppler velocimeter, the peak systolic frequency was determined distal to the stenosis and in planes parallel and perpendicular to the long axis of the stenosis. In both planes, an exponential regression best describes the relationship between peak systolic frequency and reduction in cross-sectional area. Regressions at each point of insonation diverged as a direct function of reduction in cross-sectional area and as an indirect function of distance from the stenosis. At each point of insonation, regressions representing the relationship in the mutually perpendicular planes diverged in direct proportion to reduction in cross-sectional area. Slopes were greater in parallel planes of insonation. These data demonstrate that two variables, distance and geometry, may influence the results of spectral analytic studies.

Arterial Occlusive Diseases↗

PubMed1987

Head angulation and variations in the maxillomandibular relationship. Part II: The effects on facial contour and lip support.

Twelve edentulous patients were evaluated for changes in facial contour and lip support when the head was progressively tilted backward. The mandibular facial contour changes did not occur in a progressive cause and effect type of relationship. A trend pattern could not be discerned. The maxillary facial contour did have a significant progressive cause and effect relationship in two of the 12 patients and was a positive relationship. As the angles were increased, the displacement of the maxillary facial contour increased anteriorly. The question as to why the maxillary facial contour had a significant progressive cause-and-effect relationship in two of the 12 patients and the mandibular facial contour did not remain unresolved. In a practical sense, it seems reasonable to establish the maxillomandibular relationship with the patient in a comfortable position. This and the ease of recording by the dentist are the primary considerations.

Adult↗

PubMed1987

Head angulation and variations in the maxillomandibular relationship. Part I: The effects on the vertical dimension of occlusion.

A study of a small patient sample sought to assess the effects of head angulation on the vertical dimension of occlusion. In some patients, increasing the head angulations showed a positive tendency of displacement, whereas in others the displacements were negative. Most displacements were mixed and irregular. A mathematical analysis revealed no correlation and no significance in the relationship of displacement versus the progressive changes in head angulation. The tested hypothesis was that the vertical dimension of occlusion would increase (or progressively alter) as the angulation of the head was progressively increased. Twelve attempts failed to produce a recognizable and mathematically acceptable pattern of distortion. This experiment failed to support the widely held hypothesis that the patient should be seated in an upright position to prevent distortion of the recording of VDO. It appears that the best recommendation for patient posture during the establishment of the maxillomandibular relationship is one that is comfortable for the patient and is easy for the dentist to obtain the recording.

Adult↗

PubMed1986

Doppler-derived percentage systolic window and the quantitation of arterial stenosis.

Peak systolic frequency (PSF) and percentage systolic window (%SW) are spectral parameters used to characterize poststenotic flow velocity patterns. The PSF, obtained using a continuous-wave (CW) Doppler velocimeter, has been used more frequently, however, in the quantitation of carotid occlusive disease. The authors have employed a microprocessor-driven pulsatile flow model to evaluate more completely the relationship between stenosis and the %SW. Using an 8 MHz CW Doppler probe, the Doppler-shifted frequencies were recorded at 1, 2, 3, 4, and 5 diameters distal to a variable, nonaxisymmetric stenosis, which reduced the cross-sectional area (CSA) 25, 40, 50, 60, 70, 85, and 97 per cent. Four sets of observations were made and the %SW derived using a spectrum analyzer. At one diameter from the stenosis, the relationship between the %SW (Y) and the reduction in CSA (X) is best described by two first-order regressions (Y = MX + B). The slope of the relationship from 0 to 60 per cent reduction in CSA is nearly flat, -0.052, while there is a significant (P less than 0.05) decrease in the slope, -1.538, when the CSA is further reduced from 60 to 97 per cent. Beyond 1 diameter, the relationship is best described by a single linear regression, the gradual slope of which does not permit clinically useful comparisons. These data explain the lack of strong correlation between CSA and %SW when the data are evaluated over the entire range of stenoses. However, they do indicate that the %SW may be a useful correlate if it is obtained within one diameter of the stenosis.

Arterial Occlusive Diseases↗

PubMed1985

Diurnal temperature patterns of early lactating cows with milking parlor cooling.

Ten cows in early stages of lactation (less than 100 days postpartum) were used to test the effect of sprinkler/fan cooling on vaginal temperature patterns. Cows were assigned to two groups matched according to milk production. The trial was divided into three periods: period 1, when one group was treated and the other group was not, period 2, when neither group was treated, and period 3, when treatment was switched from period 1 between groups. Treatment consisted of forced air misting in a premilking holding pen, fan cooling during milking, and forced air-sprinkling in a postmilking holding area. Weather conditions were measured by dry bulb, wet bulb, and black globe temperatures. Black globe temperatures in pre- and postmilking holding areas were used to estimate treatment magnitude. All measures were obtained through radiotelemetry at 15-min intervals for 31 days. Animals were milked twice a day. Animals spent an average of 140 min in treatment at each milking. In both morning and afternoon milking, treatment caused a transient increase of body temperature. However, this was followed in the afternoon by low vaginal temperatures for 1 to 2 h beyond treatment with lower temperatures throughout the day.

Air Conditioning↗

PubMed1984

Effect of lactation on diurnal temperature patterns of dairy cattle in hot environments.

Vaginal temperature patterns were obtained from 15 Holstein cows through radiotelemetry. Animals were divided into three groups with five animals per group: 1) cows in early lactation, less than 100 days postpartum, 2) cows in late lactation, greater than 240 days postpartum, and 3) dry cows. Animal temperatures, dry bulb, wet bulb, and black globe temperatures were monitored every 15 min for 17 days. Analysis of variance showed no significant difference for daily mean vaginal temperature between lactation groups. However, on hotter days, lactating cows had higher temperatures than dry cows. Daily mean vaginal temperatures of cows in early lactation were correlated with daily mean dry bulb temperature, black globe temperature, and relative humidity. Comparison of group temperature patterns isolated differences to specific times of day. In groups with early and late lactations, temperatures were lower in either group after milking. Vaginal temperatures were higher in lactating cows than in dry cows through most of the day. Results were 1) diurnal temperature patterns differ among groups; 2) lactating cows are sensitive to environmental changes; and 3) animal management can affect patterns of animal temperature.

Animals↗