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Biomedical subjects

F Bonnet

Publications and source records attributed to F Bonnet.

At least 37 records · Page 2Linked to original sources
PubMed1992

[The treatment of severe dysplasias by CO2 laser: the respective indications for vaporization and conization. 84 cases].

Fifty-nine conisations and 25 vaporizations were carried out using laser CO2 in order to treat a series of 84 cases of severe dysplasias (CIN III). After a follow-up of 4 and 12 months (median period of observation 25 months) it was found that out of 74 patients that were followed up in this way 72 had benefitted from the use of the treatment. There were 5 cases however of recurrence of dysplasia (1 CIN I, 2 CIN II, 2 CIN III). These had further treatment with laser. Four of those were controlled properly, the fifth had to have surgery. Complications of treatment did not occur when vaporization was used and only rarely when conisation was used. With vaporisation it is not possible to obtain a piece for histological examination, but if it is done according to precise criteria it is safe (7 mm depth at least and vaporisation carried out to 3 mm beyond the lesions). It can be used particularly in young patients who have never been pregnant. If these have been examined carefully with directed biopsies taken colposcopically and where the lesion is strictly limited to the exocervix and the transformation zone has been seen and the lesion is small (2 cm of less), 84% were controlled therapeutically and using Bruhat's criteria the success rate was 96%. Conisation was effective for every one of the other cases. Laser CO2 probably lessens local complications of the procedure and if vaporization is carried out on the rim of the cervix better control of the condition is obtained (98% controlled in the period under review).

Adult↗
PubMed1991

Effects of clonidine on variation of arterial blood pressure and heart rate during carotid artery surgery.

The effect of oral premedication with 300 micrograms of clonidine on systemic arterial pressure, heart rate, and plasma norepinephrine levels was assessed in a double-blinded, placebo-controlled study conducted in 29 patients subjected to carotid artery surgery (CAS). Anesthesia was induced with thiopental, 6 mg/kg, and alfentanil, 0.05 mg/kg, and maintained with alfentanil and 0.6% isoflurane in 50% N20/O2. The study was divided into five periods as follows: (1) anesthesia to start of surgery; (2) surgery to carotid artery clamping; (3) carotid artery clamping to unclamping; (4) carotid artery unclamping to the end of surgery; and (5) the first 4 postoperative hours in the recovery room. In the clonidine group (n = 14), plasma norepinephrine concentrations were significantly lower before induction of anesthesia and during the operative period. Heart rate and systemic arterial pressure were lower (P less than 0.01) in the clonidine group at 3 different time intervals (control, carotid clamping, carotid unclamping). However, during each of the previously defined periods, the variability of heart rate and systemic arterial pressure, assessed by the coefficient of variation, was not different between the two groups. The lability of these hemodynamic parameters, expressed as the percentage of values, which increased or decreased more than 20% of control values during the corresponding period, was also comparable between the two groups. The number of patients who experienced at least one episode of hypertension (systolic arterial pressure greater than 180 mm Hg), hypotension (systolic arterial pressure less than 100 mm Hg), or bradycardia less than 45 beats/min was not different between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

[Analysis of failures of spinal anesthesia as a function of practice development in a university hospital].

This study is a retrospective analysis of 303 consecutive spinal anaesthesia performed in orthopaedic patients of a University Hospital between January and December 1990. Failure of spinal anaesthesia was defined as the requirement for general anaesthesia to perform surgery. The parameters studied as possible risk factors of failure were patients demographics, local anaesthetic agents and solutions and techniques of spinal anaesthesia (single injection versus continuous spinal anaesthesia). Failures were related to inadequate or incomplete extension of sensory blockade or to difficulties to perform spinal injection. Continuous spinal anaesthesia was performed in 209 patients mostly with 0.5% isobaric bupivacaine, while 94 patients received a single injection of either hyperbaric 0.5% tetracaine with adrenaline or 0.5% bupivacaine or 5% lidocaine. Failures occurred in 6.3% of the cases but were significantly less frequent with continuous spinal anaesthesia (4.8%) than with the conventional technique (9.6%). The incidence of failure was higher with hyperbaric tetracaine (11.1%) confirming its poor reliability. Inadequate extension of the anaesthetic block was the main cause of failure whatever the spinal anaesthetic technique. These results point out the reliability of continuous spinal anaesthesia but problems may occasionally occur due to spinal catheter misplacement.

Academic Medical Centers↗
PubMed1991

Effect of clonidine on the circulation and vasoactive hormones after aortic surgery.

After completion of abdominal aortic graft, 29 patients received an i.v. infusion of placebo (n = 16) or clonidine 7 micrograms kg-1 (n = 13) over 120 min in a double-blind study. Cardiovascular variables were measured and plasma samples obtained up to 5 h after arrival in the recovery room, for assay of noradrenaline, adrenaline, vasopressin and renin concentrations. Noradrenaline, adrenaline and vasopressin concentrations decreased in the clonidine group throughout recovery (P less than 0.001, 0.05 and 0.05, respectively, vs placebo). Heart rate was less in the clonidine group (P less than 0.01). There was no significant difference in mean arterial pressure between groups. Stroke volume was larger (P less than 0.01) and there were fewer episodes of hypertension (P less than 0.05) and tachycardia in the clonidine group. In addition, a reduction in the number of circulatory interventions (P less than 0.05) and episodes of shivering was noted in the clonidine group. Mean (SD) postoperative volume requirements were larger in the clonidine group (total postoperative input: clonidine 1462 (604) ml; placebo 1064 (348) ml (P less than 0.05]. These data are consistent with the observation that clonidine modifies endocrine and circulatory status after major surgery.

Aorta, Abdominal↗
PubMed1991

Clonidine does not delay recovery from anaesthesia.

Clonidine is known to reduce anaesthetic requirements and improve haemodynamic stability when given as premedication. This study, of 46 ASA I-II patients undergoing thyroid surgery, was designed to assess if clonidine interferes with recovery from anaesthesia. Patients were allocated randomly to three groups to receive, 2 h before surgery, flunitrazepam 1 mg, clonidine 150 micrograms, or both drugs. Anaesthesia comprised thiopentone, alfentanil, isoflurane and 70% nitrous oxide in oxygen. Recovery from anaesthesia was assessed using a clinical score, electro-oculographic measurements and reaction times to auditory stimuli. Psychomotor tests were performed the day before surgery and 30, 60, 120 and 240 min after arrival of the patient in the recovery room. Psychomotor performance was decreased significantly after operation in the three groups (P less than 0.05) and returned to baseline at 240 min. There was no significant difference between the three groups. This study indicates that clonidine 150 micrograms orally before surgery does not delay recovery from anaesthesia.

Adolescent↗
PubMed1991

Clonidine decreases postoperative oxygen consumption in patients recovering from general anaesthesia.

Twenty ASA I patients, undergoing thyroid surgery were allocated randomly to receive at the end of surgery either an isotonic saline solution or clonidine 2 micrograms kg-1 i.v. administered over 20 min. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured during recovery in patients breathing spontaneously with a head canopy system. Clonidine was found to attenuate the increase in VO2 and VCO2 associated with recovery from anaesthesia. The effect of clonidine was associated with a reduction in shivering. Sedative and analgesic properties of clonidine may also contribute to the reduction in metabolic demand during recovery from anaesthesia.

Adult↗
PubMed1991

Pressure support ventilation using a new tracheal gas injection tube.

In order to explore new types of jet ventilation, we tested a tracheal gas injection tube (TGIT) which included six thin capillaries and provided high pressure injection. The driving pressure was chosen to yield a plateau of inspiratory tracheal pressure of 10 cm H2O. An original controller was built to monitor spirometry and trigger injection in order to deliver both pressure controlled ventilation (PCVTGIT) and a new mode of inspiratory pressure support jet ventilation (IPSTGIT). The PVCTGIT mode maintained the same end-tidal carbon dioxide concentration as conventional ventilation with the same tidal and minute ventilation. We studied 10 patients after abdominal surgery. During spontaneous breathing, the patients were allowed to breathe through the tube, successively with and without IPSTGIT. IPSTGIT, compared with spontaneous breathing increased minute ventilation (from 5.7 (SD 1.6) to 7.1 (1.7) litre min-1) (P less than 0.001). It reduced the total work of breathing (from 0.625 (0.223) to 0.263 (0.151) J litre-1, respectively) (P less than 0.01) and the occlusion pressure (from 2.62 (1.28) to 1.36 (0.74) cm H2O, respectively) (P less than 0.01). It is concluded that this TGIT used with a specific system for sensing and triggering ventilation allows inspiratory pressure support during low frequency jet ventilation.

Female↗
PubMed1991

Effect of epidural clonidine on analgesia and pharmacokinetics of epidural fentanyl in postoperative patients.

Epidural clonidine produces postoperative analgesia in patients and potentiates opioid analgesia in animals. The aim of the current study was to assess the effect of epidural clonidine on the plasma concentrations and analgesic effect of fentanyl after epidural administration. Twenty ASA physical status 2 or 3 patients recovering from abdominal surgery were allocated randomly to receive either epidural fentanyl (100 micrograms in 10 ml isotonic saline; EF group) or epidural fentanyl (same dose) plus epidural clonidine (150 micrograms; EF + C group) in isotonic saline solution. Analgesia was assessed over a period of 12 h after epidural injection. Venous samples were obtained until 360 min after epidural injection for radioimmunoassay determination of plasma fentanyl concentration. Onset of analgesia was similar in the two groups of patients (13 +/- 6 and 13 +/- 3 min, respectively, after injection), but duration was more than doubled in the patients receiving clonidine (543 +/- 183 vs. 250 +/- 64 min). Peak plasma fentanyl concentrations (Fmax) and the time to reach Cmax (Tmax) were comparable in the two groups (0.29 +/- 0.15 ng.ml-1 at 16.2 +/- 14.8 min in the EF group and 0.27 +/- 0.11 ng.ml-1 at 8.3 +/- 5.5 min in the EF + C group), as were plasma concentrations at each definite time of measurement. Drowsiness and hypotension were noticed in the EF + C group. Thus, epidural clonidine appears to prolong epidural fentanyl analgesia without affecting its plasma concentration.

Aged↗
PubMed1991

[Pharmacology and mechanism of action of opiates administered by the subarachnoid route].

The sites of action of spinally administered opiates are specific receptors (mu kappa delta) located in the spinal dorsal horn. Pharmacokinetics of spinally administered opiates are determined by their lipophilic property. Morphine has a weak octanol-water partition coefficient and remains in the CSF during a long period following the cephalic movements of lumbar CSF to the supraspinal structures. More lipophilic opiates are rapidly eliminated from the CSF. Nevertheless, significant pethidine concentrations are documented in the ventricular CSF, due to vascular absorption of the drug. Pharmacokinetics features of different opiates determine the duration of analgesia and the risk of respiratory depression after spinal injection.

Analgesics, Opioid↗
PubMed1991

[Patient-controlled analgesia].

Patient controlled analgesia (PCA) has been introduced to improve postoperative pain treatment. This review firstly emphasizes the reasons why postoperative analgesia is commonly inappropriately conducted. Secondly the principle of PCA and the practical realisation are explained. Safety and efficacy of the techniques require cooperation of the patients and of the nursing staff who need to be carefully educated.

Analgesia, Patient-Controlled↗
PubMed1990

Cervical epidural anaesthesia for carotid artery surgery.

A series of 394 patients (251 men, 143 women; mean age 70.0 +/- 8.4 yr) selected for carotid artery surgery (CAS) performed under cervical epidural anaesthesia (CEA) was analysed retrospectively. Carotid endarterectomy was performed in 326 patients and saphenous vein bypass in 68. The cervical epidural administration of 15 ml 0.5 per cent bupivacaine or 0.37-0.40 per cent bupivacaine plus fentanyl (50-100 micrograms) resulted in an effective sensory blockade from C2 to T4-T8. Patients were maintained awake during the surgical procedure in comfortable condition. Serious complications included dural puncture in two patients, epidural venipuncture in six patients and respiratory muscle paralysis in three patients. Hypotension (10.9 per cent) and bradycardia (2.8 per cent) were the most frequent side-effects of CEA. Transient neurological events were noticed in 84 patients during the surgical procedure. A definite neurological deficit occurred postoperatively in 12 patients. Three patients suffered postoperative myocardial infarction. The mortality rate was 2.3 per cent (nine patients). Carotid artery surgery may be performed under CEA but haemodynamic variables should be monitored closely and managed closely during the procedure.

Aged↗
PubMed1990

[Comparison between conventional and continuous spinal anesthesia using bupivacaine].

A study was carried out to find out whether dividing the dose of local anaesthetic would give a better control of the spread and duration of sensory blockade due to spinal anaesthesia. It was carried out in 34 patients (mean age 62 years) scheduled for elective limb vascular surgery. All were classed ASA 2 or 3. Sensory blockade was assessed using a fine needle, and the degree of motor blockade with Bromage's scale. This was carried out every 5 min for the first 30 min, and thereafter, every 15 min until recovery from anaesthesia was complete. In the first group of patients (n = 16), spinal anaesthesia was obtained with a 26 gauge needle, the patient lying on his side; 4 ml of 0.5% bupivacaine were injected (1 ml every 10 seconds) before putting the patient supine. In the second group (n = 18), the catheter for continuous spinal anaesthesia was set up with the patient in the same position as for the first group. Once a length of 1 cm had been introduced in the subarachnoid space, the patient was placed supine and 2 ml of 0.5% bupivacaine were injected. If 15 min later sensory blockade did not reach T10, further 0.5 ml aliquots were given every 10 min so as to obtain a level of sensory blockade between T9 and T11. Maximum extension of sensory blockade was 15.1 +/- 2.3 metamers in group 1, with an extension to T3 in 2 patients. In group 2, 12.9 +/- 3.1 mg bupivacaine anaesthetized 14.2 +/- 1.9 metamers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Diagnosis of severe pulmonary embolism by transesophageal echocardiography].

A 56-year-old woman was admitted to the Emergency Department for profuse diarrhoea, associated with hypokaliemia and dehydration. A subclavian venous catheter was inserted after she had a cardiac arrest. Six days later, the subclavian and innominate veins were thrombosed. Prophylactic low molecular weight heparin was then replaced by sodium heparinate. The patient's platelet count decreased to 65 G.1-1. It was nevertheless decided to remove her villous tumour. After the operation, the patient became shocked, with worsening thrombocytopaenia (15 G.1-1). She was unresponsive to fluid replacement. Transoesophageal echocardiography (TEE) was carried out, as pulmonary arterial catheterization was considered too dangerous. A "white" thromboembolus was discovered in the right pulmonary artery. Embolectomy was successfully performed without extracorporeal circulation. Flow was completely restored in the main pulmonary artery, but only partially in the right branch. Oral anticoagulation was started postoperatively. It is concluded that TEE might be a very helpful technique to promptly diagnose acute pulmonary embolism; moreover, it could be an alternative to pulmonary angiography, especially in patients in a poor state.

Drug Hypersensitivity↗
PubMed1990

[Opening of a foramen ovale during liver transplantation. The value of transesophageal echocardiography].

A case is reported of a foramen ovale becoming patent during orthotopic liver transplantation (OLT). The patient had a hepatoma secondary to post-hepatitis cirrhosis. Monitoring included transesophageal echocardiography (TEE). A veno-venous shunt between the right femoral, portal and left axillary veins was used so as to maintain the venous return during portal and caval clamping. The patient's haemodynamic state remained quite stable throughout this period, and no vasoactive drug was required. Five min after graft reperfusion, pulmonary arterial pressure increased suddenly (mean PAP: 27 mmHg). TEE revealed paradoxical movements of the atrial septum. Colour coded Doppler ultrasound showed blood flowing from the right to the left atrium through a patent foramen ovale. Fifteen min later, mean PAP decreased (18 mmHg) and TEE no longer showed any flow between the two atria. Several studies have reported transient pulmonary hypertension after unclamping when the donor liver is reperfused. This could induce right ventricular failure, with transient inversion of the atrial pressure gradient, which, in turn, could result in a right-to-left shunt through a patent foramen ovale. TEE can monitor regional and overall left ventricular function as well as the atrial septum. This technique might therefore to be useful for cardiac monitoring during OLT.

Cardiomyopathies↗
PubMed1990

Clonidine-induced analgesia in postoperative patients: epidural versus intramuscular administration.

To compare the analgesic efficacy and plasma concentration of intramuscular (IM) versus epidural (EP) clonidine, 20 patients recovering from orthopedic or perineal surgery were randomly divided into two groups of ten. Clonidine (2 micrograms/kg) was administered epidurally in group 1 and intramuscularly in group 2. Analgesia was assessed using a visual analog scale (VAS) over a period of 6 h following clonidine administration. Venous blood samples were obtained at specific intervals for radioimmunoassay determination of plasma clonidine concentrations. The maximum reduction in VAS pain score was 78.5 +/- 20.6% in the EP group and 68.1 +/- 31.5% in the IM group (NS). Onset of analgesia was similar (within 15 min of injection), but duration tended to be longer after epidural than intramuscular administration (208 +/- 87 min vs. 168 +/- 95 min, mean +/- SD, P greater than 0.05). The peak plasma clonidine concentration after EP injection was 0.82 +/- 0.22 ng/ml and 1.02 +/- 0.76 ng/ml after IM injection. Hypotension, bradycardia, and drowsiness occurred with both methods of administration. None of these effects required treatment. Thus, in postoperative patients clonidine produces similar analgesia and side effects after parenteral or EP administration.

Adult↗