Influence of Induced Blood Pressure Variability on the Assessment of Cerebral Autoregulation in Patients after Cardiac Arrest.

OBJECTIVE: To determine if increasing variability of blood pressure influences determination of cerebral autoregulation. METHODS: A prospective observational study was performed at the ICU of a university hospital in the Netherlands. 13 comatose patients after cardiac arrest underwent baseline and intervention (tilting of bed) measurements. Mean flow velocity (MFV) in the middle cerebral artery and mean arterial pressure (MAP) were measured. Coefficient of variation (CV) was used as a standardized measure of dispersion in the time domain. In the frequency domain, coherence, gain, and phase were calculated in the very low and low frequency bands. RESULTS: The CV of MAP was significantly higher during intervention compared to baseline. On individual level, coherence in the VLF band changed in 5 of 21 measurements from unreliable to reliable and in 6 of 21 measurements from reliable to unreliable. In the LF band 1 of 21 measurements changed from unreliable to reliable and 3 of 21 measurements from reliable to unreliable. Gain in the VLF and LF band was lower during intervention compared to baseline. CONCLUSIONS: For the ICU setting, more attention should be paid to the exact experimental protocol, since changes in experimental settings strongly influence results of estimation of cerebral autoregulation.

Cerebral Perfusion and Cerebral Autoregulation after Cardiac Arrest.

Out of hospital cardiac arrest is the leading cause of death in industrialized countries. Recovery of hemodynamics does not necessarily lead to recovery of cerebral perfusion. The neurological injury induced by a circulatory arrest mainly determines the prognosis of patients after cardiac arrest and rates of survival with a favourable neurological outcome are low. This review focuses on the temporal course of cerebral perfusion and changes in cerebral autoregulation after out of hospital cardiac arrest. In the early phase after cardiac arrest, patients have a low cerebral blood flow that gradually restores towards normal values during the first 72 hours after cardiac arrest. Whether modification of the cerebral blood flow after return of spontaneous circulation impacts patient outcome remains to be determined.

Low spontaneous variability in cerebral blood flow velocity in non-survivors after cardiac arrest.

OBJECTIVE: To investigate spontaneous variability in the time and frequency domain in mean flow velocity (MFV) and mean arterial pressure (MAP) in comatose patients after cardiac arrest, and determine possible differences between survivors and non-survivors. METHODS: A prospective observational study was performed at the ICU of a tertiary care university hospital in the Netherlands. We studied 11 comatose patients and 10 controls. MFV in the middle cerebral artery was measured with simultaneously recording of MAP. Coefficient of variation (CV) was used as a standardized measure of dispersion in the time domain. In the frequency domain, the average spectral power of MAP and MFV were calculated in the very low, low and high frequency bands. RESULTS: In survivors CV of MFV increased from 4.66 [3.92-6.28] to 7.52 [5.52-15.23] % at T=72h. In non-survivors CV of MFV decreased from 9.02 [1.70-9.36] to 1.97 [1.97-1.97] %. CV of MAP was low immediately after admission (1.46 [1.09-2.25] %) and remained low at 72h (3.05 [1.87-3.63] %) (p=0.13). There were no differences in CV of MAP between survivors and non-survivors (p=0.30). We noticed significant differences between survivors and non-survivors in the VLF band for average spectral power of MAP (p=0.03) and MFV (p=0.003), whereby the power of both MAP and MFV increased in survivors during admission, while remaining low in non-survivors. CONCLUSIONS: Cerebral blood flow is altered after cardiac arrest, with decreased spontaneous fluctuations in non-survivors. Most likely, these changes are the consequence of impaired intrinsic myogenic vascular function and autonomic dysregulation.

[Captopril test for detecting renal artery stenosis: changes in plasma renin concentration]. / Test au captopril en vue de la détection d'une sténose de l'artère rénale: variations de la concentration en rénine plasmatique.

The aim of this study was to demonstrate the diagnostic value of changes in active renin concentration during the captopril test (measurements of plasmatic active renin concentrations, before 12.5 or 37.5 mg of captopril p.o., and 30 and 90 minutes after) in order to screen a significant renal artery stenosis. After a renal angiography, 88 hypertensive patients suspected of renovascular hypertension were classified according to the percentage of stenosis in the main renal artery: class I (< 30% - n = 50), II (30 to < 75% - n = 21), III (75 to < 90% - n = 8) and IV (90 to 100% - n = 11). The results of the captopril test were compared to those of renal angiography. The active renin before the test (basal AR), the greater increase in active renin after captopril (max AR), the difference between max AR and basal AR (DIF) and the active renin relative change after the test (RC) were compared in the 4 classes (ANOVA). There were no differences in diastolic blood pressure (> or = 90 mmHg) natriuresis (100 mmol/24 h in mean) between these different classes. The basal AR, the max AR, the DIF and the RC significantly differed between the 4 classes. They were greater in class III and IV than in class I. The positive criteria for the captopril test were max AR, DIF and RC. The positivity thresholds were max AR > or = 70 ng/l, DIF > or = 50 ng/l and RC > or = 165% (upper limit in the class I 95% confidence interval for each criterion).(ABSTRACT TRUNCATED AT 250 WORDS)

[MRI study of parathyroid adenoma. Value of T2-weighted sequences]. / Exploration IRM de l'adénome parathyroïdien. Intérêt des séquences pondérées en T2.

The authors report a series of 22 patients operated for primary hyperparathyroidism. The parathyroid adenoma was located preoperatively by MRI and ultrasonography. Measurement of the relaxation time was performed in vitro at 37 degrees C in a 0.47 Tesla field during the 30 minutes following resection. The relaxation times obtained at a precession frequency of 20 mHz were 0.844 +/- 0.16 sec for T1 and 0.082 +/- 0.025 sec for T2. MRI had a sensitivity of 73% and a specificity of 88% for the localization of the parathyroid adenoma, while ultrasonography had a sensitivity of 73% and a specificity of 98%.

[Primary hyperparathyroidism. Apropos of 102 recent exploratory cervicotomies: diagnostic and clinical pitfalls]. / Hyperparathyroïdisme primaire. A propos de 102 cervicotomies exploratrices récentes: pièges diagnostiques et cliniques.

The authors report on various diagnostic pitfalls on 102 patients having undergone exploratory cervicotomy for primary hyperparathyroidism. A false positive diagnostic error was made on 2% of the cases, bringing to 100 the number of patients with a confirmed diagnosis of primary hyperparathyroidism. False negative diagnosis was made on 4% of the patients: two late diagnoses leading to an acute toxic state and death postoperatively in both cases; two pure psychiatric variants leading to repetitive hospitalizations in psychiatry. Error in diagnosis because of a masking effect was made in 4% of the cases:--one association with a clear cell nephro--epithelioma--one association with a multiple myeloma--two associations with a benign monoclonal gammapathy. The absence of hypercalcemia, a diagnostic pitfall in the modern form of this disease was found in 7% of the cases. PTH hypersecretion which is virtually a constant finding in the normocalcemic form of the disease obviates in most cases the need of a bone biopsy and quantitative histomorphometric analysis. The association with another endocrinopathy was found in 12% of the cases (2 MEN I, 1 MEN II, 9 hyperthyroidism). Because of its high frequency in the aged (22% greater than 75 years) the diagnosis of this disease is difficult for its signs are mimicked as well by the aging process. The preoperative topographic diagnostic error is avoided since there doesn't seem to be any test which would preclude the normal surgical procedure of carefully exploring all 4 topographic sites of the parathyroid. Surgical errors can be numerous but minimized with the increasing experience of the operator. Histological errors are seen mainly in the normocalcemic variety where only electron microscopy can detect the typical signs of cellular hyperactivity.

[Does echography contribute to the diagnosis and treatment of acute unknown, tied or bilateral torsion of testis?]. / L'échographie apporte-t-elle quelque chose dans le diagnostic et le traitement des torsions aiguës méconnues, unies ou bilatérales du testicule?

The authors present three cases of testicular torsion lately seen after a mistaken diagnosis. The interpretation of scrotal ultrasonographic examination was difficult. The authors insist to a carefully interpretation of an ultrasonographic examination in this cases particularly.

[Radiological exploration of the inferior vena cava in nephroepithelioma]. / L'exploration radiologique de la veine cave inférieure dans les néphroépithéliomes.

The development of non-invasive procedures, namely ultrasonography and computed tomography, has modified the strategy for evaluating the spread of a nephroepithelioma to the inferior vena cava. When a complete study can be performed, ultrasonography is the most informative method. Angiographic studies are only performed as the second choice.

[Perspectives of hyperthermia in the treatment of tumors of the maxillofacial region]. / Perspectives de l'hyperthermie dans le traitement des tumeurs de la sphère maxillo-faciale.

Hyperthermia used alone or in association with radiotherapy and chemotherapy opens new perspectives in the treatment of tumours. Its application in the maxillo-facial area has special features by virtue of the inhomogeneity of the tissues and the sensitivity of some of them. The region is suitable for the use of interstitial and endocavitary techniques which provide localised and uniform heating. Preliminary clinical study was aimed essentially at the improvement of the technique and the evaluation of tolerance. The effects seen on tumours are encouraging and study is being continued with more routine association of hyperthermia and irradiation.

[Hyperthermia main techniques (author's transl)]. / Techniques de chauffage pour l'hyperthermie.

Superficial tumours with a small thickness can be correctly heated by various techniques. Some difficulties arise for a uniform heating across tumours several centimeters thick; they are considerably increased for deep located tumours. The possibilities of various methods of diathermy are discussed with consideration of blood flow and controlled surface cooling. A peculiar attention is devoted to conductive methods using electrodes supplied by 1 MHz current generator, and placed in contact (tubes, plates) or inside (needles) the tumour.