[Occurrence of carotid stenosis in patients with cerebrovascular symptoms]. / Forekomsten af carotisstenose hos patienter med cerebrovaskulaere symptomer.

Stenosis of the internal carotid artery is a well known risk factor and is estimated to be the cause of 20-30% of all strokes. As ultrasonography easily can demonstrate arterial stenosis and causal surgical treatment is available we found it of interest to investigate the occurrence of stenosis found among consecutive non selected patients with focal neurological symptoms. Results of duplex scanning from consecutive patients with various symptoms were collected. Seventeen percent of the patients who had had transient ischaemic attacks were found to have stenosis of 50% or greater. For the patients with persistent central neurological symptoms (stroke) we found stenosis greater than 50% in 23%. Only a few patients with uncharacteristic, non focal symptoms were found to have stenoses. Carotid stenosis is found in approximately 20% of patients with focal neurological symptoms. Hence ultrasound investigation is indicated for patients suited for surgical treatment.

The cellular clearance theory does not explain the post-dialytic small molecule rebound.

AIM: (a) To determine the normalized cellular clearance (Kcn) of urea, creatinine and phosphate in patients undergoing maintenance hemodialysis; (b) To identify the factors, particularly circulatory, which determine Kcn; (c) To evaluate whether intra-dialytic blood sampling can predict the size of the post-dialytic solute concentration rebound. METHODS: Kinetic modelling of urea, creatinine and phosphate, using a two-pool variable volume computer simulation, was performed on two occasions on 34 patients undergoing maintenance dialysis. The cellular clearance was determined (a) from the size of the rebound 50 min after the end of dialysis; (b) from a mid-dialytic blood sample. Conventional two-dimensional M-mode echocardiography and Doppler peripheral blood pressure measurement were performed. RESULTS: The model produced accurate measurements of rebound Kc for urea in 93% of measurements, creatinine in 49% and phosphate in 13%. The corresponding figures for mid-dialysis Kcn were 76%, 39% and 0%. The rebound Kcn was, for urea, 8.31 +/- 4.31 ml/kg/min, and for creatinine 4.07 +/- 2.98. The mid-dialysis Kcn was, for urea, 8.57 +/- 4.25 ml/kg/min, and for creatinine 5.06 +/- 3.36. High post-dialytic rebounds (and low Kcn values) were associated with erythropoietin use (p < 0.05) and occurrence of end-dialytic hypotension (p < 0.02). Patients treated with calcium antagonists had a significantly (p < 0.001) higher Kcn. There was no correlation between mid-dialysis and rebound Kcn. Circulatory indices had no influence on Kcn. CONCLUSIONS: The two-pool cellular clearance model is compatible with urea kinetics, but not creatinine or phosphate. It is therefore unlikely that it is the correct model for small molecule kinetics. The post-dialytic solute rebound may be partly an iatrogenic phenomenon and can be reduced by preventing post-dialytic hypotension and by calcium antagonist treatment, both of which improve regional blood flow. The size of the rebound cannot be predicted by intra-dialytic blood sampling.

Antibodies to cardiolipin may increase the risk of failure of peripheral vein bypasses.

OBJECTIVES: To assess the association between antibodies to cardiolipin and infrainguinal vein graft patency. MATERIALS AND METHODS: Plasma levels of antibodies to cardiolipin, haemostatic factors, lipids and the smoking marker carboxyhaemoglobin were determined preoperatively and 6 weeks postoperatively in 80 patients undergoing infrainguinal vein bypass surgery. Bypass patency was assessed by ankle blood pressure measurements and ultrasound duplex scanning at 1 week, 6 weeks, 3, 6, 9 and 12 months. A localised increase in the graft peak systolic velocity by a factor of 2.5 or more was considered to indicate a significant stenosis. RESULTS: Antibodies to cardiolipin were identified in seven (9%) patients preoperatively. In four of these seven patients the bypasses thrombosed within 3 months after surgery and another two developed stenoses. At 6 months the primary bypass patency, i.e. patency without stenosis, was 14% (95% confidence interval (CI) 0-33%) in patients with antibodies to cardiolipin, as opposed to 57% (95% CI 45-69%) in patients without these antibodies (log rank test: p = 0.03). Diabetes mellitus was also associated with a reduced 6 months primary bypass patency (38% (95% CI 16-60%) vs. 58% (95% CI 45-71%), p = 0.006). A Cox regression analysis showed that both the presence of antibodies to cardiolipin and diabetes independently contributed towards predicting the overall risk of bypass failure. CONCLUSION: Antibodies to cardiolipin were identified in 9% of patients undergoing infrainguinal vein bypass surgery and appeared to be associated with increased risk of bypass failure.

Late postoperative nocturnal episodic hypoxaemia and associated sleep pattern.

Ten patients undergoing major abdominal surgery under general anaesthesia were monitored with a pulse oximeter, electroencephalogram, electromyogram, electrocardiogram and eye and hand movement sensors two nights before and three nights after surgery. Episodic hypoxaemic events were increased significantly after surgery (P < 0.05). Rapid eye movement (REM) sleep decreased significantly on the first night after operation (P < 0.05). Seven patients had increased amounts of REM sleep (rebound) on the second, third or both nights after operation compared with the preoperative night. Slow wave sleep was depressed significantly on the first two nights after operation (P < 0.05). REM sleep-associated hypoxaemic episodes for individual patients increased about three-fold on the second and third nights after operation compared with the night before operation (P < 0.05). We conclude that postoperative sleep pattern is disturbed severely with early depression of REM and slow wave sleep and with rebound of REM sleep on the second and third nights. Postoperative rebound of REM sleep may contribute to the development of sleep disordered breathing and nocturnal episodic hypoxaemia.

Doppler spectral characteristics of infrainguinal vein bypasses.

With the aim of assessing the velocity profile of femoropopliteal and femorocrural vein bypasses, 128 patients undergoing infrainguinal vein bypass surgery entered a postoperative Duplex surveillance protocol, which included clinical assessment and Duplex scanning, using Doppler spectral analysis. Doppler spectra were obtained at three sites in each graft and the following waveform parameters recorded: maximum systolic velocity, minimum diastolic velocity and resistance index. In patent reconstructions systolic velocity decreased by 30% during the first 6 months after surgery. In the absence of arteriovenous fistulas the initially antegrade diastolic velocity was replaced by a retrograde flow within 3 months, whereas a forward flow in diastole was sustained in grafts with patent fistulas. Abnormal Duplex findings in 31 patients led to angiography and revision in 13 cases. Four revised grafts failed, while nine remained patent at follow-up 1-12 months later. Ten (56%) of 18 non-revised bypasses with abnormal Duplex findings failed within 9 months compared to 1 (1%) of 76 bypasses with a normal velocity profile (p < 0.00001). In conclusion, Ultrasound Duplex scanning with spectral analysis provides valuable information concerning haemodynamics of infrainguinal vein bypasses and identifies grafts at risk of thrombosis. Inclusion of low resistance index (< 0.75) as an additional criteria for detection of stenoses appears to improve the sensitivity of Duplex scanning.

[Earlier experiences with duplex scanning of femoropopliteal and crural vein bypass]. / Tidlige erfaringer med duplexovervågning af femoropopliteale og -krurale vene-bypass.

Identification and correction of graft stenoses in femoropopliteal and -crural vein bypasses can prevent reconstruction failure. Sixty six consecutive vein bypasses entered a postoperative surveillance protocol, which implied clinical assessment, measurement of ankle blood pressure and duplex-scanning every three months. In 15 cases the duplex-scanning indicated graft stenoses. Seven were revised, five of which remain patent after a median follow-up of three months. Eight stenoses were observed without intervention. Five of these uncorrected stenoses (63%) thrombosed and the function of the bypass could not be reestablished. Of the 34 bypasses with normal duplex-scans only 2 (6%) thrombosed (p < 0.01 compared to observed but not revised stenosis). Neither clinical evaluation or ankle blood pressure measurement could reliably predict graft failure. This study indicates that duplex-scanning effectively identifies grafts at risk and can be expected to improve long-term patency of infrainguinal vein bypasses.

[Doppler ultrasonography in arteriosclerosis of the lower extremities]. / Doppler-ultralydundersøgelse af underekstremitetsarteriosklerose.

Arteriography, which requires resources and is not entirely without risk, has hitherto been a prerequisite for reconstructive surgery in cases of symptom-producing arteriosclerosis in the lower limbs. As an alternative, indirect Doppler ultrasonic examination has been employed but does not appear to be suitable in the clinical routine. On the basis of a review of the literature, it is suggested that, employing a combination of ultrasonic picture scanning and Doppler ultrasonic duplex scanning, it may be possible to diagnose significant solitary stenoses or short occlusions in the aorto-iliac segment and in the femoral artery but that this does not appear to be employable at present in cases of multiple lesions. Examination of the popliteal artery is still too unreliable and reasonably certain assessment of the crural arteries is not possible with the present technique. Duplex scanning can thus not replace arteriography as yet for examination of patients with ischaemia in the lower limbs.

[Intravagal paragangliomas]. / Intravagale paragangliomer.

Two patients with vascular tumors adjacent to the carotid branch of the vagus nerve are presented. Contrary to expectations, the tumours proved to be intravagal paragangliomata. Both were treated surgically.

[Postoperative duplex ultrasonic surveillance of infrainguinal arterial reconstructions]. / Ultralyd-duplex-overvågning af infraingvinale arterielle rekonstruktioner.

Postoperative bypass surveillance can identify graft-related stenoses in 25% of grafts during the first two years after surgery. Correction of the stenoses before they lead to graft occlusion improves the patency significantly. Clinical assessment including distal pressure measurements is of poor sensitivity. Surveillance is best performed with color duplex scanning. Ideally, grafts are examined first after one to two months, thereafter every three months and, after one year, at intervals of six months. Graft surveillance beyond two years is hardly justified, as is the case with prosthetic grafts. Symptom-producing and tight stenoses should be corrected. Percutaneous transluminal angioplasty is appropriate for short stenoses, whereas stenoses longer than 2 to 3 cm are best treated surgically.

Late postoperative episodic and constant hypoxaemia and associated ECG abnormalities.

Twenty-two patients without cardiopulmonary disease and undergoing elective major abdominal surgery were monitored continuously with a Holter tape recorder and a pulse oximeter on one night before operation and the first two nights after operation (23:00 to 07:00), without oxygen therapy. Mean heart rate increased 16 beat min-1 (P less than 0.001) and mean oxygen saturation (SaO2) decreased 2.6% (P less than 0.001) after operation. Episodic oxygen desaturation to less than 80% occurred in four patients before operation, but in 13 patients after operation (P less than 0.05). ECG abnormalities were observed in 10 patients before operation and in 16 patients after operation (ns). Individual maximum ST depression was more pronounced after than before operation (P less than 0.05). Episodic desaturation was related closely to tachycardia in six patients before operation and one patient after operation; before operation to atrioventricular block in one patient, and after operation to ST depression in two patients. Mean SaO2 on the second night after operation correlated with total dose of opioid for pain relief (rs = -0.48; P less than 0.05), and postoperative decrease in SaO2 correlated with postoperative increase in heart rate (rs = -0.43; P less than 0.05). No patient had postoperative cardiac complications indicating treatment.