Spontaneous rupture of the normal spleen: diagnosis by computerized tomography.
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Female↗
Biomedical subjects
R N Baird
Publications and source records attributed to R N Baird.
Segmental air plethysmography during arterial reconstruction.
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Arteries↗
Pulsed Doppler angiography in lower limb arterial ischemia.
A 30-channel pulsed Doppler vessel imaging system (MAVIS, GEC Medical, Middlesex, England), was used to obtain images and maximal Doppler velocity time waveforms in the diagnosis of stenosis of the origin of the profunda femoris artery (PFA) and in the detection of structural changes within Dacron arterial grafts. In PFA scans of 33 limbs in 22 patients (mean age, 52 years), PFA stenosis of more than 50% at operation was invariably associated with a damping factor of the maximal Doppler velocity-time waveform of greater than 1.5 (eight limbs). In 12 limbs with a normal PFA at operation, the damping factor was always less than 1.4, and in 13 limbs of normal patients without arterial disease, the damping factor was always less than 1.34. In studies of 10 mm arterial grafts, the internal diameter of 14 iliopopliteal grafts scanned just above the popliteal anastomosis was strikingly reduced as compared with the femoral anastomosis of 14 aortoiliofemoral grafts and seven axillobifemoral grafts. These preliminary results suggest that MAVIS studies can be used noninvasively to detect PFA stenosis and to identify luminal narrowing of iliopopliteal grafts.
Angiography↗
Vein grafts: an historical perspective.
The use of autogenous vein for vascular grafting has been traced historically. Although vein remains the graft of chocie for smaller vessels, the results are imperfect and the need to identify an "ideal" graft is becoming critical.
Angiography↗
Elasticity and compliance of canine femoral and jugular vein segments.
In this study, the pressure/strain and stress/strain relatioships of 44 jugular and 31 femoral canine vein segments were compared with 17 carotid artery specimens, latex rubber, and a synthetic graft material, expanded polytetrafluoroethylene. A method is described for comparing the elastic properties of vein wall specimens of varying thicknesses such as occur after implantation into the arterial circulation. A flat sheet of opened vessel wall, fexed between retention rings at one end of a saline-filled steel cylinder, was biaxially distended to form a bubble shape. Compliance ratio and stress modulus were computed at 20-mmHg increments from 20 to 200 mmHg. In the "arterial" pressure range, vein was less compliant than artery. Vein also had a higher stress modulus E (dyn/cm2 X 10(6)) +/- SE at a chamber pressure 120 mmHg than artery (E = 11 +/- 0.6), and jugular vein was stiffer (E = 65 +/- 3.6) than femoral vein (E = 41.5 +/- 2.0). Changes in the structural properties of vein grafts measured using this technique are potentially important factors leading to graft failure.
Animals↗
Dynamic compliance of arterial grafts.
A cantilever transducer has been developed which allows measurements of diastolic diameter and diameter change in response to pulse pressure in dissected blood vessels during sterile procedures. Preliminary results indicate that it will detect subtle changes in wall elastic properties of arterial grafts at subtle changes in wall elastic properties of arterial grafts at and following implantation, which changes may influence graft function. Compliance, the percentage change in volume per unit pressure, was greater in normal canine femoral artery than in autogenous vein grafts (AVG). Two new graft materials were tested. Mesh-covered modified human umbilical cord vein (DBM) was similar in compliance to AVG but more compliant than double-velour Dacron. Diastolic diameter changes were also recorded. After 2 wk, all three graft materials had increased in diameter: AVG by 8%, DBM by 6%, and Dacron by 5%. After 3 mo, AVG diameter increased by 24%.
Animals↗
Pulsatile blood-flow in arterial grafts.
The distensibility of arterial wall is an important factor in the haemodynamics of pulsatile blood-flow. Autogenous-vein grafts have a dynamic response to the arterial pressure pulse (compliance) which approaches that of normal arterial wall, whereas synthetic prostheses are generally incompliant, or become so shortly after implantation. Although synthetic grafts have little effect on steady-state flow, their lack of compliance greatly interferes with pulsatile flow and this may be an important factor in explaining their lack of success as replacements for medium and small sized arteries.
Arterial Occlusive Diseases↗
Renal carcinoma in a cadaver kidney graft donor.
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Cadaver↗
Initial intensive care in an accident and emergency department.
The work in the resuscitation room is initial intensive care. This must be always available independent of inpatient resources. This demands investment in adequate equipment and staffing. Much of the work is medical rather than surgical and appropriate for physicians to treat. Our experience might help others to plan for the future.
Accidents, Traffic↗
Red-blood-cell survival after splenectomy in congenital spherocytosis.
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Adolescent↗
Physiological interpretation of Doppler shift waveforms: the femorodistal segment in combined disease.
A new method is presented for assessing the femorodistal segment in multisegmental arterial disease, using the Laplace transform technique of Doppler waveform analysis. Blood velocity/time waveforms were obtained at femoral and ankle levels in three groups of limbs--50 without arterial disease, 12 with isolated aortoiliac stenoses, and 32 with femoropopliteal occlusions, with and without proximal disease. The waveforms were analysed for Laplace transform and pulsatility index values. The omega 0 coefficients of the Laplace transform analysis at femoral and ankle levels were compared in each subject, as the omega 0 gradient (femoral/ankle omega 0): and pulsatility index damping factor (femoral/ankle P1) was also calculated. The omega 0 gradient was shown to detect femoropopliteal occlusion in the presence of multisegmental arterial disease and to give some indication of its haemodynamic significance. The diagnostic accuracy of the omega 0 gradient was superior to that of pulsatility index damping factor. When combined with its existing ability to detect aortoiliac stenosis, this new application of the Laplace transform method offers the possibility both of a system for complete localisation of significant arterial lesions, and potential for follow-up of vascular surgical procedures in the lower limb, from two simple Doppler recordings.
Aortic Valve Stenosis↗
Variability and reproducibility of arterial Doppler waveforms.
The variability and reproducibility of arterial Doppler waveforms are influenced by factors such as operator experience, physiological changes in the patient, and the type of Doppler processing system. Some aspects of these were studied using Laplace transform analysis of waveforms from the femoral and posterior tibial arteries of normal subjects and arteriopaths. Five consecutive waveforms were obtained from the femoral and posterior tibial arteries of normal subjects during about 1 hr of supine rest. Group 1 (n = 20) was studied 9 months before Group 2 (n = 11), early in the operator's experience of waveform recording. Variability (root mean square) of femoral and posterior Laplace delta decreased from 16.9 to 12.5%, and 23.3 to 17.9% respectively (P less than 0.05 in each case). In arteriopaths (n = 8) there was a trend to more variable results at femoral level (only significant in the case of Laplace omega 0 - P less than 0.05), while posterior tibial results tended to be less variable. Normal subjects examined in the longer term (n = 4), with a mean interval of 28 days between recordings, did not show significantly greater variability than those examined over 1 hr. There was no significant difference in variability of results in normal subjects (n = 30) using instantaneous average Doppler processing compared with maximum frequency processing, except in the case of posterior tibial Laplace omega 0 (maximum frequency more variable - P less than 0.05).
Adult↗
Detection of arterial stenosis: increased accuracy using biplanar angiography and Doppler signal analysis.
Femoral artery Doppler signals were analysed from 68 patients with lower limb ischaemia undergoing biplanar angiography. These studies (pulsatility index, P.I. and LaPlace transform damping, LTD) were compared with clinical examination using this biplanar angiographic standard. Accuracy of femoral pulse palpation in predicting upstream stenosis was 67%. Biplanar angiography unmasked single plane stenosis underestimates in 21% of patients. In a subgroup of 39 lower limbs with aorto-iliac stenoses between 26 and 85% femoral LTD was the best predictor, being 84% accurate: whereas PI did not improve upon clinical examination. The need for biplanar angiography is underlined and the place of Doppler signal analysis in the assessment of arterial stenosis is confirmed.
Adult↗
Monitoring arterial surgery: a comparison of pulse volume recording and electromagnetic flowmetering in aortofemoral reconstruction.
Intraoperative monitoring of aortofemoral reconstruction using Pulse Volume Recordings (PVR) and Doppler ankle systolic pressure indices (ASPI) is compared with volume blood flow obtained by electromagnetic flowmetering (EMF). Twenty-five patients aged 45-78 with limb ischaemia or abdominal aortic aneurysm were studied before and 20 minutes after reconstruction. Reconstruction of isolated iliac occlusions (25 limbs) produced immediate improvement in PVR results. PVR waveform pulsatility (upstroke time shortened; 249-183 msec, p = less than .001) was more sensitive than amplitude which was restored to pre-reconstruction levels (16.1 to 17.5 mm). Similar trends were seen in multisegment disease. PVR transit time was not as sensitive. EMFlow was increased in both groups (229-600 and 160-308 mls/min). ASPI was not useful. Both PVR amplitude and pulsatility were significantly correlated with EMF volume flow, but pulsatility was more sensitive and was a superior predictor of successful arterial revascularisation. Technical errors were detected and corrected, and 94% of grafts were patent on discharge. These results show a correlation between PVR pulse waveform shape and EMFlow to such an extent that PVR results may be taken as a useful indicator of successful arterial reconstruction.
Aged↗
A simple Doppler test for haemodynamically significant carotid artery disease.
A 10 MHz directional Doppler velocimeter was used to assess carotid atherosclerosis in 41 patients with cerebro-vascular disease. There were 30 men and 11 women with a mean age of 58 years. The arterial waveform pulsatility indices of the common carotid (CC), temporal (T), supratrochlear (ST), and central retinal artery (CRA) were compared with triplanar arteriograms in detecting internal carotid artery stenosis. The results were that Doppler signal ratios were able to differentiate less than 70% from greater than 70% stenosis and complete occlusion. For the diagnosis of internal carotid stenosis the ratio ST/CC had a sensitivity of 90%, a specificity of 93.5% and an accuracy of 93%. The CRA/CC ratio showed a sensitivity of 90% specificity of 72% and accuracy of 76%, and central retinal artery signals were difficult to detect. The T/CC ratio diagnosed external carotid artery stenosis of greater than 70% with a sensitivity of 90%, a specificity of 87% and an accuracy of 96%. The ST/CC and T/CC ratios were easy to perform, and employed routinely available Doppler velocimeters.
Adult↗
Local neurological complication during carotid endarterectomy.
In a prospective study of 52 carotid endarterectomies there were 13 temporary cranial nerve injuries in 12 patients (25%); 7 hypoglossal nerve injuries (13.5%), 3 were asymptomatic (5.8%), 2 had mild speech difficulty (3.8%) and 2 had severe difficulty with deglutition and articulation (3.8%). A full recovery was made within 3 months in all 7 patients. Although 10 patients (19.2%) developed a hoarse voice, indirect laryngoscopy only indicated damage to the ipsilateral recurrent laryngeal nerve in 3 patients (5.8%). Both the voice and vocal cord movement returned to normal within 6 months in 2 patients and a 9 months in the third. The marginal mandibular branch of the facial nerve was injured in 3 patients (5.8%) and all recovered completely within 3 months. Following injury to the great auricular and the transverse cervical nerves injury, 13 patients (25%) had persistent irritation and paraesthesia during shaving and in cold weather lasting up to 18 months after operation. Carotid endarterectomy is associated with a much higher incidence of local nerve injury than retrospective surveys would indicate.
Aged↗
Prostaglandin E1 infusion for small vessel arterial ischaemia.
The effects on severe arterial ischaemia of infusions of Prostaglandin E1 (PGE1) a vasodilator and inhibitor of platelet aggregation, were studied in 49 patients (aged 17-80). Criteria for patient selection included rest pain and/or digital ulceration and gangrene secondary to predominantly small vessel disease. PGE1 was infused at a low (6 ng/kg/min), intermediate (10 ng/kg/min) or high (14 ng/kg/min) dose rate via a central venous cannula on 52 occasions without serious side effects. Doppler studies, pulse volume recordings and infra red radiometry were used to quantify the clinical effects. Improvements in digital perfusion were demonstrated by increased pulse volume amplitude (7.1 +/- 1.1 to 21.6 +/- 2.7 mm mean +/- SEM) which remained significantly raised at 6 weeks (14.2 +/- 2.9 mm; P = less than 0.001 paired t test). Infra red digital temperatures were also significantly raised 6 weeks post infusion (27.2 +/- 0.6 degrees C to 29.5 +/- 0.6 degrees C; P less than 0.001). The majority of patients reported improvement in pain, and two thirds of 12 superficial ulcers healed in 6 weeks. These results show that PGE1, improves digital perfusion for several weeks in patients with severe arterial ischaemia.
Adolescent↗
Femoral artery doppler signal analysis in lower limb ischaemia.
The functional significance of the iliac artery stenosis was assessed non invasively using femoral artery Doppler signals and a new method of blood velocity waveform quantification. This mathematical analysis provided an index, the Laplace Transform Damping (LTD), which was compared with Pulsatility Index (PI) of 263 limbs, in patients with iliac occlusive atherosclerosis was demonstrated by arteriogram and in normal volunteers. Normal LTD results ranged from 0.26 to 0.43 with detection of minor iliac stenosis (less than 50%) at 0.51 (0.38 to 0.63) and major stenosis (greater than 50%) at 0.83 (0.55 to 0.99). LTD was not affected by raised distal impedance associated with superficial femoral artery (SFA) occlusion. PI however was poor at predicting the severity of iliac lesions in the presence of SFA occlusion. LTD and PI specificities and sensitivities were examined using receiver operator curves. At a value of 0.6 LTD was more sensitive than PI in separating major from minor iliac stenoses and at 0.4 LTD separated normals from the early disease group with a sensitivity of 81% and specificity of 88%. This preliminary experience with Laplace Transform Damping analysis suggests that it will improve the assessment of iliac stenosis especially in the presence of femoro-popliteal disease.
Adult↗