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Biomedical subjects

J Hamza

Publications and source records attributed to J Hamza.

At least 19 recordsLinked to original sources
PubMed1997

Preclinical studies for cell transplantation: isolation of primate fetal hepatocytes, their cryopreservation, and efficient retroviral transduction.

Fetal hepatocytes are an attractive target for in utero cellular transplantation. Their use could provide a very efficient way for implanting normal or transduced cells into the livers of affected fetuses. Marking cells with recombinant retroviruses is a powerful tool for evaluating the chimerism of grafted animals. The technique relies on the ex vivo transduction efficiency of the engrafted cells. We have isolated fetal primary hepatocytes from nonhuman primates. The cells were cultured and transduced with a retroviral vector carrying the Escherichia coli beta-galactosidase gene. Optimal gene transfer efficiency was obtained 48-60 hr after plating and was as high as 90%. Cryopreservation had little effect on cell viability and infectivity: The viability of thawed hepatocytes remained high (75-85%) and the infection efficiency was identical to that of freshly isolated cells. Efficient ex vivo retroviral gene transfer into fetal hepatocytes provides an appropriate system for testing allogenic grafting and for modifying immunogenicity of engrafted cells. These results open up new perspectives for cell transplantation through cell banking.

Animals↗
PubMed1996

[Acute fetal distress. The anesthesiologist's point of view].

Foetal distress is a non-specific and imprecise diagnose sometimes associated with surgical delivery of a normal newborn. As this type of delivery is usually considered urgent, emergent anaesthesia is required. General anaesthesia is usually chosen in these cases because it is the quickest anaesthetic technique and because of fears concerning the haemodynamic consequences of regional techniques. Maternal risks of general anaesthesia which is the leading cause of anaesthesia-related maternal mortality (difficult intubation and Mendelson's syndrome) but also neonatal consequences (increased need for neonatal resuscitation) have challenged this policy. Indeed, spinal anaesthesia and extension of a pre-existing epidural analgesia are more and more used during emergency Caesarean section. A better evaluation of the patient's problems based upon a pre-anaesthetic outpatient visit during the last trimester of pregnancy allows a more rational approach to meet the patient's requirements should an emergency. Caesarean section be necessary. For example, a "prophylactic" epidural instituted soon after the beginning of labour may be lifesaving in a patient with obvious signs of difficult intubation. A clear definition of safe standards of equipment and practices either to prevent. Mendelson's syndrome or to cope with a failed intubation drill is of greatest importance. Finally, comprehensive communication between the anaesthetic and obstetrical teams is one of the most useful ways to facilitate safer approach of the management of obstetric emergencies studies. Caesarean section for foetal distress.

Acute Disease↗
PubMed1995

Parturient's posture during epidural puncture affects the distance from skin to epidural space.

STUDY OBJECTIVE: To assess the factors affecting the distance from skin to epidural space. DESIGN: Prospective observational study of consecutive cases over a 2-year period. SETTING: Inpatient obstetric unit in a French university hospital. PATIENTS: 2,123 consecutive term parturients who received epidural anesthesia for cesarean section or epidural analgesia for labor and vaginal delivery. INTERVENTIONS: At the time of epidural puncture, the interspace used and the patient's posture (sitting or left lateral decubitus) were recorded, and the distance from the skin to the epidural space (DS-ES) was measured to the nearest 0.5 cm using a marked epidural needle. MEASUREMENTS AND MAIN RESULTS: The relationship between patient factors [height, weight, body mass index (BMI; weight/height2), presence of scoliosis] and technical factors (interspace, patient's posture at puncture) versus DS-ES was investigated using multiple regression analysis. DS-ES correlated positively with the parturient's weight and BMI. In addition, DS-ES was significantly greater when epidural puncture was performed in the lateral position as compared with the sitting position. CONCLUSION: Both the patient's weight and position during epidural needle placement are important factors influencing DS-ES. A change from the sitting to the lateral position may increase DS-ES, causing catheter dislodgment and consequent inadequate analgesia. Clinical studies relating DS-ES to inadequate analgesia must take these factors into account.

Adult↗
PubMed1995

Sevoflurane elimination kinetics in children.

We compared the rates of elimination of sevoflurane and halothane in 29 children, aged between one and seven years, undergoing ambulatory anaesthesia. Analgesia was provided by fentanyl and muscle relaxation by atracurium. Anaesthesia was maintained by inhalation of one MAC of either sevoflurane or halothane, based on an equipotent concentration of each agent for the age of the child. Following simultaneous discontinuation of N2O and the inhalational agent, the equation describing N2O washout was identical in the presence of halothane and sevoflurane, showing that there was no effect of the volatile agent on the rate of N2O elimination. The elimination of sevoflurane and N2O give similar types of equations. Halothane elimination gives a logarithmic type of equation, showing a slower release, corresponding to residual tissue content.

Ambulatory Surgical Procedures↗
PubMed1994

[Use of Diprivan in gynecology].

1. Propofol as an induction agent At a dose of 2 to 2.5 mg.kg-1, as a bolus injection over 30 to 60 seconds, for gynaecological procedures of short duration (abortion, D and C), propofol can be characterized as follows when compared with other induction agents: ADVANTAGES OVER METHOHEXITONE AND ETOMIDATE: decreased incidence of hiccups and abnormal movements, increased quality of induction, similar to that obtained with thiopentone, decreased postoperative nausea and vomiting. ADVANTAGES OVER THIOPENTONE: shorter recovery period, more rapid recovery of consciousness and orientation. DISADVANTAGES WHEN COMPARED WITH THIOPENTONE: more frequent pain at the injection site, however its prevention is possible, more frequent apnoea, but may be avoided by slowly injecting the drug, higher cost. The main advantage of propofol over thiopentone (shorter recovery period), makes day-case gynaecological procedures one of its major indications. This concerns young, healthy women, whose professional and family lives are important and who may benefit from minimal disruption in their way of life. 2. Propofol as a maintenance agent Propofol is given as a continuous infusion at a dose ranging from 6 to 12 mg.kg-1.h-1 for maintenance of prolonged procedures (abdominal surgery, hysterectomy) and can be characterized as follows with respect to halogenated anaesthetics: ADVANTAGES OVER ENFLURANE AND ISOFLURANE: decreased postoperative nausea and vomiting, increased recovery scores (1st hour). COMPARED WITH DESFLURANE: shorter induction time than desflurane, less respiratory problems at induction, similar recovery period, same incidence of nausea and vomiting. The administration of propofol for maintenance of anaesthesia has the main advantage of reducing the incidence of postoperative nausea and vomiting when compared to conventional halogenated anaesthetics. Respective costs of the various techniques, using propofol or the new halogenated anaesthetics, may be a criterion for choice in the future.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Intravenous↗
PubMed1994

Addition of oral clonidine to postoperative patient-controlled analgesia with i.v. morphine.

Using a randomized, double-blind, placebo-controlled design, we have investigated, in 40 patients undergoing major abdominal surgery, the effect of oral clonidine 300 micrograms, 1 h before and 12 h after surgery on postoperative morphine requirements (evaluated by PCA). During the 24 h of the study, pain scores measured every 6 h did not differ significantly. Morphine requirements tended to be reduced in the clonidine group but the difference was not significant. There were no significant differences also in mean arterial pressure, ventilatory frequency and the incidence of pruritus and nausea. Heart rate was significantly lower until 18 h after surgery and sedation was significantly more pronounced in patients receiving clonidine. We cannot recommend routine oral administration of clonidine before surgery to improve postoperative analgesia.

Administration, Oral↗
PubMed1994

Anaesthesia for caesarean section in a patient receiving high dose amiodarone for fetal supraventricular tachycardia.

We report the anaesthetic management of a Caesarean section in a woman treated with high dose amiodarone for fetal supraventricular tachycardia. Most of the interactions between anaesthesia and amiodarone therapy previously reported were observed during general anaesthesia. We therefore chose epidural anaesthesia using incremental doses of lignocaine 2% with adrenaline and fentanyl. This technique appeared to be safe, but since severe refractory vasodilation with hypotension may occur, potent vasopressor agents should be immediately available.

Adult↗
PubMed1994

[Emergency cesarean section: role of locoregional anesthesia].

Emergency cesarean section is sometimes required for acute fetal distress but also for some maternal vital emergencies. In spite of its maternal (Mendelson's syndrome, difficult intubation) and fetal (neonatal depression) risks, general anaesthesia was classically used. The arguments in favor of regional anaesthesia techniques for emergency cesarean section and the respective advantages of spinal and epidural anaesthesia are developed in this text. The already functioning epidural catheter can be used to rapidly convert analgesia for labor to anaesthesia for cesarean section: this situation is probably the simplest to manage but requires that parturients at risk for cesarean section were recognized in early labor, especially all the parturients with a suspected difficult airway. In case of patchy or unilateral analgesia, it is particularly important to resite the catheter to avoid the need for emergency general anaesthesia to solve an inadequate epidural anaesthesia for cesarean section. Spinal anaesthesia is the technique of choice for its rapidity of action but its hemodynamic risks need a prior careful evaluation of maternal hemodynamics. General anaesthesia will be always indispensable in some cases; therefore, every anaesthetist should maintain sufficient experience and skills in the management of some of its complications, especially intubation difficulties.

Adult↗
PubMed1994

[Polytraumatised children].

Trauma is the leading cause of mortality in children between the ages of 1 and 14 years. It represents a major health problem in all industrialized countries. A well coordinated organization of the whole chain of cares is essential, from the initial management at the scene of the accident until the long term neurological rehabilitation of the child. During the initial examination, the presence of anoxia, hypovolemia or neurological distress was systematically evaluated. Emergency therapeutic measures should be ensured. At the term of this initial management: if the haemodynamic state is unstable, an emergency operative procedure may be required; if the haemodynamic state remains stable, one can realize a complete clinical and radiological assessment. The clinical and biological supervision must continue during this evaluation while sedation and analgesia are essential to limit an increase in intracranial pressure (ICP). At the term of this complete assessment, if one or several surgical lesions are identified, an operative program with a precise hierarchy is scheduled; if an intensive medical support is required, the child is then transferred to the pediatric intensive care unit. Most often, children with a serious head trauma do not have neurosurgical lesions but a "brain-swelling" or cerebral edema. Elevated ICP is one of the main risk for cerebral ischemia. Therefore, continuous assessment of ICP is essential. Thoracic trauma is most often a closed trauma in the child: pneumothorax and pulmonary contusion are the problems most frequently met. An emergency laparotomy is required if the abdomen volume increases rapidly associated to the persistence of a unstable haemodynamic status despite an important fluid expansion. However, the presence of intraperitoneal blood is no longer a formal indication to surgery. Frequent examination of liver and splenic lesions with abdominal tomodensitometry allows to avoid surgery in more than 90% of cases at the price of a very rigorous haemodynamic supervision. Intestinal perforations are rare and difficult to diagnose: peritoneal dialysis, if it reveals the presence of a leucocytosis greater than 500/mm3 or bacteria justifies the surgery.(ABSTRACT TRUNCATED AT 400 WORDS)

Child↗
PubMed1994

[Anesthesia for acute fetal distress].

Anaesthesia for fetal distress is usually indicated for emergency caesarean section. General anaesthesia, which is the classical technique in these cases, remains the leading cause of anaesthesia-related maternal mortality. Difficult intubation and Mendelson's syndrome are mostly responsible for these fatalities. Nevertheless there are several answers to this problem. A better evaluation of the patient's problems based upon a preanaesthetic outpatient visit during the last term of pregnancy allows a more rational approach to meet the patient's requirements should an emergency caesarean section occur. For example, a "prophylactic" epidural instituted soon after the beginning of labor may be lifesaving in a patient with obvious signs of difficult intubation. A clear definition of safe standards of equipment and practices both to prevent Mendelson's syndrome or to cope with a failed intubation through a "failed intubation drill" is of paramount importance. Finally, a comprehensive communication between anesthetic and obstetrical teams is one of the most useful ways to allow a safer approach of the management of obstetric emergencies such as caesarean section for fetal distress.

Acute Disease↗
PubMed1994

[Effect of epidural anesthesia on the fetus and the neonate].

The placental transfer of local anaesthetics (LA) depends on maternal factors (LA dosage, degree of protein binding, blood pH), placental factors (surface of placental exchange, placenta thickness) and fetal factors (maternal-fetal gradient of pH, fetal hepatic metabolism of the LA, redistribution of the cardiac output in case of fetal hypoxia). The assessment of effects of LA and epidural anaesthesia (EA) on the fetus is based on the monitoring of the fetal heart rate and the measurement of the fetal pH allowing to rapidly detect an acute fetal distress. Apgar score, analysis of blood gases in the umbilical artery and neurobehavioral tests (such as Brazelton test (NBAS). Early Neonatal Neurobehavioral Scale (ENNS) and Neurologic and Adaptative Capacity Score (NACS) allow an evaluation of the drugs effects on the neonate. Direct effects of LA: although a diminution of variability of the fetal heart rate has been reported little after the beginning of an EA using lidocaine, no significant modification of the fetal heart rate after EA using bupivacaine or lidocaine with epinephrine has been shown. Fetal neurological toxicity is rare and there are very little alterations of neurobehavioral scores after EA. Indirects effects on the uteroplacental blood flow (UBF): in high concentration, LA entail a vasoconstriction of uterine arteries but the main feared effect is maternal arterial hypotension that impedes directly the uteroplacental blood flow: fetal consequences depend on the importance and duration of the UBF decrease, the preliminary state of the utero-placental circulation and haemodynamic adaptative capacities of the fetus: when the former are exceeded, fetal hypoxia occurs and myocardial and brain oxygenation can be rapidly impaired if the haemodynamic state is not corrected.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1993

[Ambulatory anesthesia in gynecologic surgery].

Surgical gynecologic procedures are among the best clinical indications of ambulatory surgery as the patients are usually young and healthy. The beneficial effects of this type of organization (economical, medical and psychological) are numerous. A rational approach of the main objectives of ambulatory surgery and anesthesia is needed to choose the more logical anesthetic agents to allow rapid patient's recovery with a minimal rate of postoperative problems. These issues are therefore briefly developed in this text.

Ambulatory Surgical Procedures↗
PubMed1993

[Pediatric surgery and anesthesia in a day hospital].

Day care surgery is an increasing service in our health structures. If we return to the source, we find the first important series has been published in 1906 (8,900 cases) without accident. Child is an ideal patient. So, more than 60% of paediatric surgery could benefit by ambulatory surgery. Recovery of mental abilities following general anaesthesia has not the same significance as in adult. Many studies confirm the safety of paediatric outpatient anaesthesia, but can we assert that children older than five years prefer ambulatory surgery? In the same way, are we sure that the cost cannot be cut and maybe other options used?

Ambulatory Surgical Procedures↗
PubMed1993

[Vascular filling and vasopressors: effects on the fetus and the newborn infant].

Epidural analgesia and anaesthesia are more and more commonly used in modern obstetrical anaesthesia practice leading to the frequent use of fluid infusion and vasopressors. Fetal and neonatal effects of these treatments are reviewed here and may be summarized as follows: 1) Prolonged and/or severe maternal arterial hypotension may induce fetal hypoxia and acidosis, especially when fetal status is already compromised (uteroplacental insufficiency). 2) Preventive fluid hydratation with crystalloids associated with left uterine displacement are always useful to avoid maternal hypotension. 3) Dextrose-containing solutions are undesirable for the prevention of treatment of maternal hypotension as they may induce delayed neonatal hypoglycemia. 4) When the parturient is correctly hydrated, the rapid use of intravenous ephedrine is efficient in restoring normal maternal arterial pressure and has no deleterious effect on the fetus and the newborn. Finally, rapid, repetitive and non-invasive monitoring of maternal arterial pressure is the prerequisite to a rapid management of maternal hypotension which is essential to avoid any deleterious effect to the fetus and the neonate.

Anesthesia, Epidural↗