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G Boccara

Publications and source records attributed to G Boccara.

35 records · Page 2Linked to original sources
PubMed2000

[Endovascular treatment of aorto-iliac aneurysms. Made-to-measure endoprotheses increase the feasibility].

The authors describe their experience of tailoring endoprostheses for endovascular treatment of aorto-iliac aneurysms with components available on the market. Between January 1996 and December 1999, 188 aorto-iliac aneurysms were treated by tailor-made endoprostheses using self-expanding Z stents made of stainless steel compiled with polyester ligatures and covered with standard commercially available polyester prostheses. These endoprostheses were implanted with an 18 to 24 Fr (usually 20 Fr) introducer and positioned by a surgical approach. This method allows construction of tubular, bifurcated, digressive or occlusive endoprostheses associated with an extra-anatomical bypass graft. It increased the number of endovascular procedures for aorto-iliac aneurysms in the authors' department. This number has been further increased by using endoprostheses with an uncovered proximal or distal stent for cases with particularly short or angled necks and by using hybrid endoprostheses with one or more extremities without a stent, allowing surgical suture of the anastomosis. The authors' results show that tailoring endoprostheses considerably increased the feasibility of endovascular treatment of aorto-iliac aneurysms, even in unselected patients whilst providing an effectiveness and safety to justify the continuation of this experience.

Aortic Aneurysm, Abdominal↗
PubMed1999

Regulation of Ca2+ homeostasis by atypical Na+ currents in cultured human coronary myocytes.

Primary cultured human coronary myocytes (HCMs) derived from ischemic human hearts express an atypical voltage-gated tetrodotoxin (TTX)-sensitive sodium current (I(Na)). The whole-cell patch-clamp technique was used to study the properties of I(Na) in HCMs. The variations of intracellular calcium ([Ca2+]i) and sodium ([Na+]i) were monitored in non-voltage-clamped cells loaded with Fura-2 or benzofuran isophthalate, respectively, using microspectrofluorimetry. The activation and steady-state inactivation properties of I(Na) determined a "window" current between -50 and -10 mV suggestive of a steady-state Na+ influx at the cell resting membrane potential. Consistent with this hypothesis, the resting [Na+]i was decreased by TTX (1 micromol/L). In contrast, it was increased by Na+ channel agonists that also promoted a large rise in [Ca2+]i. Veratridine (10 micromol/L), toxin V from Anemonia sulcata (0.1 micromol/L), and N-bromoacetamide (300 micromol/L) increased [Ca2+]i by 7- to 15-fold. This increase was prevented by prior application of TTX or lidocaine (10 micromol/L) and by the use of Na(+)-free or Ca(2+)-free external solutions. The Ca(2+)-channel antagonist nicardipine (5 micromol/L) blocked the effect of veratridine on [Ca2+]i only partially. The residual component disappeared when external Na+ was replaced by Li+ known to block the Na+/Ca2+ exchanger. The resting [Ca2+]i was decreased by TTX in some cells. In conclusion, I(Na) regulates [Ca2+]i in primary cultured HCMs. This regulation, effective at baseline, involves a tonic control of Ca2+ influx via depolarization-gated Ca2+ channels and, to a lesser extent, via a Na+/Ca2+ exchanger working in the reverse mode.

Adult↗
PubMed1999

[Hemodynamic monitoring using esophageal Doppler ultrasonography during laparoscopic cholecystectomy].

PURPOSE: To evaluate the use of a 4-mHz continuous wave esophageal Doppler monitor in the hemodynamic management of 48 ASA I to III patients undergoing laparoscopic cholecystectomy. METHODS: General anesthesia was induced with fentanyl and propofol, maintained with N20 N20/02 and muscle relaxation was provided with atracurium. The lungs were mechanically ventilated. Non invasive arterial blood pressure, heart rate, capnography, arterial blood gas were monitored during CO2 pneumoperitoneum at 15-mmHg. Using the velocity waveform of descending aortic blood flow, the Doppler device estimated changes in cardiac output and systemic vascular resistances. RESULTS: Peritoneal insufflation resulted in a mean 19% decrease in cardiac output (range -49 to +5%; P < 0.05) and a mean 48% increased in systemic vascular resistances (range -7 to +101%; P < 0.01). There was no relationship between changes in cardiac output and mean arterial pressure or PETCO2. The esophageal Doppler provided, in two patients, details of hypertensive peaks (mean arterial pressure > 140 mmHg) which responded to administration of nicardipine. CONCLUSION: The Esophageal Doppler provided an easy-to-handle and non invasive tool to monitor changes in cardiac output during laparoscopic cholecystectomy. However, further comparison with a thermodilution cardiac output technique is required.

Adult↗
PubMed1999

The relationship among carbon dioxide pneumoperitoneum, vasopressin release, and hemodynamic changes.

UNLABELLED: We assessed the role of vasopressin (VP) for the hemodynamic response to pneumoperitoneum in pigs. Four groups of anesthetized pigs were investigated. Nine pigs were intraabdominally insufflated with CO2 and eight were intraabdominally insufflated with argon; eight pigs received an i.v. injection of 1 mg/kg SR 49059, a VP antagonist, before CO2 insufflation; and six pigs received SR 49059 alone. Hemodynamics, plasma concentrations of VP and vasoactive hormones, and Paco2 were measured. Data were analyzed by using analysis of variance, Student's t-test, and Mann-Whitney U-test. Five minutes after insufflation, changes in systemic vascular resistance (SVR) were significantly correlated with changes in VP (r = 0.72; P = 0.005) but not with changes in epinephrine, norepinephrine, renin activity, or Paco2. SVR increased during CO2 insufflation but not during argon insufflation or CO2 insufflation with a preceding infusion of SR 49059. The SR 49059 injection itself resulted in increases in heart rate and cardiac output and decreases in blood pressure and SVR. We conclude that, during CO2 pneumoperitoneum in pigs, absorbed CO2 initiates a pathophysiological process that stimulates VP release. Hence, VP most likely plays a key role in the hemodynamic response to a CO2-induced pneumoperitoneum. IMPLICATIONS: Intraabdominal insufflation of CO2 is associated with hemodynamic and hormonal changes. Investigating CO2 and argon-insufflated pigs and using a vasopressin antagonist, we found that CO2 insufflation released vasopressin, which, in turn, induced hemodynamic perturbances.

Animals↗
PubMed1999

Changes in occlusion pressure (P0.1) and breathing pattern during pressure support ventilation.

BACKGROUND: The purpose of this study was to investigate changes in breathing pattern, neuromuscular drive (P0.1), and activity of the sternocleidomastoid muscles (SCM) during a gradual reduction in pressure support ventilation (PSV) in patients being weaned off controlled mechanical ventilation. METHODS: Eight non-COPD patients recovering from acute respiratory failure were included in this prospective interventional study. All patients were unable to tolerate discontinuation from mechanical ventilation. Each patient was evaluated during a period of spontaneous breathing and during PSV. Four successive levels of PSV were assessed in the following order: 20 cm H2O (PS20), 15 cm H2O (PS15), 10 cm H2O (PS10), and 5 cm H2O (PS5). RESULTS: When pressure support was reduced from PS20 to PS10 the respiratory rate (f) and the rapid shallow breathing index (f/VT) significantly increased and tidal volume (VT) significantly decreased. These parameters did not vary when pressure support was reduced from PS10 to PS5. Conversely, P0.1 varied negligibly between PS20 and PS15 but increased significantly at low PSV levels. P0.1 values were always greater than 2.9 cm H2O (4.1 (1.1) cm H2O) when SCM activity was present. When contraction of the SCM muscles reappeared the P0.1 was the only parameter that changed significantly. CONCLUSIONS: In postoperative septic patients the value of P0.1 seems to be more useful than breathing pattern parameters for setting the optimal level of pressure assistance during PSV.

Acute Disease↗
PubMed1999

Vasopressin receptors in human adrenal medulla and pheochromocytoma.

The nature of vasopressin (VP) receptors present in normal and tumoral human adrenal was investigated using various experimental approaches. Specific VP-binding sites were detected by autoradiography using [3H]arginine VP as a radioligand in adrenal cortex and medulla. The V1a receptor subtype was expressed in the two parts of the gland, as shown by pharmacological studies and RT-PCR experiments. By contrast, the V1b receptor subtype was only expressed in medullary chromaffin cells. This was confirmed by the characterization of V1b transcripts detected in adrenal medulla tissues. In pheochromocytoma, we also detected functional V1b receptors. These receptors triggered intracellular calcium mobilization from intracellular pools and were involved in catecholamine secretion. Binding experiments performed on pheochromocytoma plasma membrane preparations also revealed V1a vasopressin-binding sites, whose roles and cellular localization have not yet been determined. RT-PCR experiments confirmed these data; 100% and 80% of the five tumors tested exhibited V1a and V1b transcripts, respectively. Perifusion experiments also demonstrated that some pheochromocytomas may secrete large amounts of VP. Our findings imply that VP locally secreted by human adrenal medulla may regulate adrenal function by acting on V1a or V1b receptors. More interestingly, we demonstrate that one pheochromocytoma oversecretes VP. In this particular case, this may contribute to the increase in blood pressure observed.

Adrenal Gland Neoplasms↗
PubMed1998

Vasopressin regulates adrenal functions by acting through different vasopressin receptor subtypes.

In mammals, vasopressin is known to be synthesized in the hypothalamus and released in the blood stream at the pituitary level. This neuropeptide is also synthesized and secreted by the adrenal medulla in many species including human. Moreover, agents like acetylcholine and corticotropin releasing factor stimulates its basal secretion. V1a vasopressin receptors are present in the adrenal cortex and are involved in steroids secretion (aldosterone in the zona glomerulosa and glucocorticoids in the zona fasciculata of some species). These receptors are coupled to phospholipase C beta and to dihydropyridine-sensitive calcium channels via heterotrimeric G proteins differing by their sensitivities to pertussis toxin. The adrenal medulla, from many species, exhibits V1a vasopressin receptors. In rat adrenal medulla, functional V1b vasopressin receptors could also be characterized. These receptors stimulate catecholamines secretion via activation of phospholipase C beta and subsequent mobilization of intracellular calcium. The adrenal medulla secretes AVP and exhibits functional vasopressin receptors. The adrenal cortex also possesses functional vasopressin receptors and is in contact with adrenal medulla via "medullary rays". We may thus reasonably conclude that AVP physiologically regulates adrenal gland functions via autocrine/paracrine mechanisms.

Adrenal Cortex↗
PubMed1998

Improved postoperative analgesia with isoflurane than with propofol anaesthesia.

PURPOSE: The impact of hypnotic drugs on postoperative analgesia has not been evaluated. We compared the influence of the maintenance of anaesthesia with either propofol or isoflurane on postoperative pain. METHODS: Forty ASA 1-2 women, undergoing cosmetic abdominoplasty were randomized to receive either 6-12 mg.kg-1.hr-1 propofol i.v. (P, n = 20) or MAC 1-1.5 isoflurane inhalation (Iso, n = 20). The lungs were ventilated with N2O 60% and O2 40%, and 1 microgram.kg-1 fentanyl i.v. provided intraoperative analgesia. Before surgical closure, 2 g propacetamol i.v. were administered. Postoperative analgesia was provided after hourly assessment of pain (VAS 0-100 mm), with 10 mg nalbuphine i.v. if VAS > or = 50 mm, during the eight hours after surgery. Sedation score (awake 0 to unrousable 4) was also recorded. Analgesia satisfaction score (nil 0 to excellent 4) obtained from the patient on discharge. RESULTS: Sedation scores were similar in both groups except in the first postoperative hour, when it was higher in the Iso group. The VAS at rest (15.4 +/- 18.6 vs 29.7 +/- 19.8 mm, P = 0.0001) and nalbuphine requirements (0.13 +/- 0.35 vs 0.70 +/- 0.80 doses, P = 0.004) were lower in the Iso group during the first six hours, although emesis was more frequent than in P (60 vs 25%; P = 0.03). The incidence of analgesia satisfaction score (> or = 3) was similar between the two groups (P: 95; Iso: 75%). CONCLUSION: These results suggested that isoflurane anaesthesia provides better analgesia than propofol anaesthesia in the first six hours after abdominoplasty.

Abdomen↗
PubMed1998

[Acute myopericarditis following laparoscopic treatment of gastroesophageal reflux].

A 32-year-old patient experienced a postoperative acute myopericarditis following laparoscopic surgery for gastro-oesophageal reflux (Toupet's fundoplication). His medical history was unremarkable, apart from controlled arterial hypertension. Peroperative circulation was stable, except a short hypertensive episode at CO2 insufflation, controlled with nicardipine. A myopericarditis occurred at the fourth postoperative hour, with apical and inferior hypokinesia at ventriculography, ST-segment elevation with unremarkable coronary arteriography. The patient was discharged at day seven, with a NSAIDs treatment. Echocardiography three and nine months later postoperatively, showed an apical akinesia and persistence of the ST-segment modification, without clinical symptoms. Complications of laparoscopic fundoplication is either specific to surgery (gastro-oesophageal injury, diaphragmatic injury, mediastinitis, stenosis) or secondary to pneumoperitoneum (pneumothorax, carbon dioxide embolism). In this case, following an apparently uncomplicated laparoscopy and, except a direct cardiac trauma from a laparoscopic instrument, either coronary artery spasm, or pneumopericardium with CO2, or delayed gas embolism, or preoperative "silent" myopericarditis could be the potential cause of this cardiac complication.

Acute Disease↗
PubMed1997

Argon pneumoperitoneum is more dangerous than CO2 pneumoperitoneum during venous gas embolism.

UNLABELLED: We investigated the possibility of using argon, an inert gas, as a replacement for carbon dioxide (CO2). The tolerance of argon pneumoperitoneum was compared with that of CO2 pneumoperitoneum. Twenty pigs were anesthetized with enflurane 1.5%. Argon (n = 11) or CO2 (n = 9) pneumoperitoneum was created at 15 mm Hg over 20 min, and serial intravenous injections of each gas (ranging from 0.1 to 20 mL/kg) were made. Cardiorespiratory variables were measured. Transesophageal Doppler and capnographic monitoring were assessed in the detection of embolism. During argon pneumoperitoneum, there was no significant change from baseline in arterial pressure and pulmonary excretion of CO2, mean systemic arterial pressure (MAP), mean pulmonary artery pressure (PAP), or systemic and pulmonary vascular resistances, whereas CO2 pneumoperitoneum significantly increased these values (P < 0.05). During the embolic trial and from gas volumes of 2 and 0.2 mL/kg, the decrease in MAP and the increase in PAP were significantly higher with argon than with CO2 (P < 0.05). In contrast to CO2, argon pneumoperitoneum was not associated with significant changes in cardiorespiratory functions. However, argon embolism seems to be more deleterious than CO2 embolism. The possibility of using argon pneumoperitoneum during laparoscopy remains uncertain. IMPLICATIONS: Laparoscopic surgery requires insufflation of gas into the peritoneal cavity. We compared the hemodynamic effects of argon, an inert gas, and carbon dioxide in a pig model of laparoscopic surgery. We conclude that argon carries a high risk factor in the case of an accidental gas embolism.

Animals↗
PubMed1997

The detection of carbon dioxide embolism during laparoscopy in pigs: a comparison of transesophageal Doppler and end-tidal carbon dioxide monitoring.

BACKGROUND: The aim of the study was to compare the value of transesophageal Doppler and end-tidal carbon dioxide monitoring to detect venous carbon dioxide embolism in pigs during laparoscopic cholecystectomy. METHOD: Ten pigs were anesthetized under constant ventilation, and instrumented for laparoscopic cholecystectomy. CO2 pneumoperitoneum was performed at 15 mmHg and then, successive increased intravenous gas boluses of 0.1 to 4 ml/kg injected through the femoral vein using a 55-mm long catheter. The responses indicative of embolism were defined as: 1) a change in Doppler tone placed facing the junction of the right atrium and inferior vena cava; 2) a change in end-tidal CO2 > or = 0.4 kPa. RESULTS: Doppler was more sensitive in detecting 0.1, 0.2 and 0.4 ml/mg of CO2 embolism than end-tidal CO2 (P < 0.05). Over 0.4 ml/mg no differences in sensitivity were found but the Doppler signal modifications occurred earlier than the changes in end-tidal CO2. Moreover, these changes always consisted of a reduction of the value. CONCLUSION: During laparoscopic cholecystectomy in pigs, transesophageal Doppler was a highly sensitive monitor which provided an earlier detection of CO2 embolism and at lower doses than end-tidal CO2 monitoring.

Animals↗
PubMed1997

[Intrinsic sinus node dysfunction in adolescence during anorexia nervosa].

A seventeen year old girl with anorexia nervosa (32 kg; 165 cm) was admitted as an emergency after syncope with severe bradycardia resistant to atropine monitored over a one week period. Autonomic blockade confirmed the intrinsic character of the sinus node dysfunction with chronotropic incompetence on exercise. Secondarily, a Mobitz I second degree AVB was observed. A DDDR pacemaker was implanted with an excellent functional result. With a one year follow-up, the bradycardia persists but body weight has increased. The authors discuss the physiopathology of this case: in the literature, the classical bradycardia of anorexia nervosa is sensitive to vagolytic drugs and only exceptionally as intense as in this patient. Sinus node dysfunction is very rare in the young in the absence of congenital heart disease. It is possible that the bradycardia had become chronic in this case.

Adolescent↗
PubMed1996

Tolerance of laparoscopy for resection of phaeochromocytoma.

We describe two patients who underwent resection of phaeochromocytoma by a laparoscopic approach. Although outcome from surgery was successful, there was marked variability in hormonal and haemodynamic changes. In one patient, despite an infusion of nicardipine, peritoneal insufflation produced a marked increase in catecholamine concentrations associated with transient but intense vasoconstriction, but there was no change in the second patient. In both patients, exsufflation caused no significant haemodynamic changes in spite of the high doses of nicardipine given throughout the procedures.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Vasopressin : a potent autocrine/paracrine regulator of mammal adrenal functions.

The control of adrenal functions by locally secreted neuropeptides or neurotransmitters is of great physiological importance. Vasopressin (VP) is one of these autocrine/paracrine regulators. We demonstrated by RT-PCR and perifusion experiments that rat and human adrenal medulla expressed and released vasopressin under basal conditions and under stimulation by acetylcholine. Intra-adrenal concentrations of VP may be sufficient to activate adrenal VP receptors. In the cortex, only the V1a receptor subtype has been detected. It triggered both steroid secretion and cortical growth. In the medulla, both V1a and V1b receptor subtypes were expressed. V1b receptors were mainly present on chromaffin cells and stimulated catecholamine secretion. The role of the V1a receptor remains unclear. Pathophysiological studies also revealed that human pheochromocytoma did not overexpress vasopressin receptors but might oversecrete vasopressin causing high plasma VP concentrations and elevated blood pressure.

Adrenal Glands↗