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Biomedical subjects

F Donati

Publications and source records attributed to F Donati.

At least 127 records · Page 7Linked to original sources
PubMed1991

Vecuronium is more potent in Montreal than in Paris.

This study was undertaken to compare the potency of vecuronium in patients anaesthetized in Montreal or Paris. Anaesthesia was induced with thiopentone and maintained with N2O, and intermittent boluses of thiopentone and fentanyl in 18 patients in Paris and 19 in Montreal. Neuromuscular blockade was measured using train-of-four stimulation of the ulnar nerve. The force of contraction of the adductor pollicis muscle was measured. Single doses of vecuronium, 20, 30, or 40 micrograms.kg-1 were given by random allocation. Dose response curves were constructed by obtaining the linear regression of the logit of the first response (T1) neuromuscular blockade versus log dose. The patients in Paris required 27% more vecuronium (95% confidence limits 5-53%; P = 0.01) for the same intensity of blockade. In Montreal, the ED50 and ED90 (+/- SEE for the mean) values were 26.0 +/- 1.4 and 44.2 +/- 2.5 micrograms.kg-1 compared with 33.0 +/- 3.3 and 71.9 +/- 7.2 micrograms.kg-1 in Paris respectively. The patients were comparable with respect to age, sex, height and weight. These results confirm, for vecuronium, the transatlantic difference in potency of neuromuscular blocking drugs which was previously observed with d-tubocurarine between London and New York.

Adult↗
PubMed1991

Nitrous oxide potentiates vecuronium neuromuscular blockade in humans.

This study was designed to measure the potency of vecuronium with and without nitrous oxide. Anaesthesia was induced with thiopentone and fentanyl in 56 adult patients. The subjects were randomly assigned to receive nitrous oxide, 70%, or intermittent boluses of thiopentone and fentanyl for maintenance of anaesthesia. Train-of-four stimulation was applied to the ulnar nerve every 20 sec, and the force of contraction of the adductor pollicis muscle was measured. Vecuronium, 20, 30 or 40 micrograms.kg-1 was given by random allocation five minutes after induction of anaesthesia. Maximum depression of the first response (T1) in the train-of-four was measured, and dose-response curves were constructed. In the absence of nitrous oxide, the ED50 and ED95 were mean +/- standard error of the mean (SEM), 29.2 +/- 1.8 and 59.3 +/- 3.6 micrograms.kg-1, respectively. In the group receiving nitrous oxide, these values were 25.3 +/- 1.2 and 42.3 +/- 2.0 micrograms.kg-1 respectively. By analysis of covariance, the dose-response curves were shown to be shifted with respect to one another (P less than 0.05). Administration of nitrous oxide was associated with a 19.5% increase in potency (95% confidence limits: 1.7 to 40.4%). It is concluded that nitrous oxide has a slight potentiating effect on neuromuscular blockade, and that this effect occurs within five to ten minutes after the beginning of its administration.

Adult↗
PubMed1991

Cerebral blood flow velocity in term infants treated with phototherapy.

The relationship between phototherapy and changes in the cerebral circulation was studied in 50 jaundiced newborn infants. The aim of the study was to determine whether important alterations in cerebral hemodynamic occur under blue light therapy. Blood flow velocity, i.e., the pulsatility index (PI) and the area under the velocity curve (AUVC), was measured in the anterior cerebral arteries (ACA) using a Duplex scan technique. No prominent changes compromise flow in the ACA. PI and AUVC values were similar during and after phototherapy (p greater than 0.5) suggesting effective cerebral autoregulation in term infants undergoing light treatment for hyperbilirubinemia.

Cerebral Arteries↗
PubMed1991

Pharmacokinetics and pharmacodynamics of atracurium obtained with arterial and venous blood samples.

To determine the influence of sampling site on atracurium pharmacokinetic-pharmacodynamic relationships, blood was drawn simultaneously from the radial artery and peripheral vein during a 20-minute period after injection of atracurium, 0.2 mg/kg, in eight patients. Atracurium and laudanosine concentrations were measured by HPLC. Neuromuscular blockade was measured at the adductor pollicis, after stimulation of the ulnar nerve. Venous levels were lower than corresponding arterial values for up to 20 minutes, and this difference was marked for the early samples. Neuromuscular blockade was maximum after 5 to 7 minutes, much later than the peak venous concentration (1 to 3 minutes). Nonparametric analysis yielded (mean +/- SEM) a rate constant, concentration for 50% blockade, and slope of the effect-concentration relationship of 0.092 +/- 0.01 min-1, 379 +/- 27 ng/ml, and 7.3 +/- 1.67, respectively, when based on arterial samples. The values were statistically different (0.135 +/- 0.011 min-1, 235 +/- 42 ng/ml, and 3.41 +/- 0.37, respectively) when venous levels were used (p less than 0.05). It is concluded that forearm venous levels do not correspond to adductor pollicis neuromuscular blockade and the kinetics and kinetic-dynamic relationship for atracurium are heavily dependent on sampling site.

Adolescent↗
PubMed1991

Pharmacokinetics and pharmacodynamics of atracurium with and without previous suxamethonium administration.

Suxamethonium increases neuromuscular block produced by non-depolarizing agents administered subsequently. To determine if this effect has a pharmacokinetic or pharmacodynamic origin, 18 ASA physical status I or II adults received atracurium 0.2 mg kg-1, with (n = 10) or without (n = 8) previous injection of suxamethonium 1 mg kg-1, during a thiopentone-nitrous oxide-isoflurane (0.5% end-tidal) anaesthetic. Arterial blood samples were obtained and plasma atracurium concentration measured by HPLC. Train-of-four stimulation was applied to the ulnar nerve and the force of contraction of the adductor pollicis muscle was recorded. Mean (SEM) volume of distribution was slightly greater with previous suxamethonium (143 (13) ml kg-1) than without (109 (5) ml kg-1) (P less than 0.04). Mean elimination half-life was unaffected (20.3 (0.8) min and 20.4 (1.6) min, respectively). Neuromuscular block was more intense and recovery was slower with previous administration of suxamethonium. Atracurium concentration at 50% block (Cpss50) was 305 (30) ng ml-1 with and 454 (25) ng ml-1 without previous suxamethonium (P less than 0.01). It is concluded that suxamethonium may be associated with a slight increase in the volume of distribution of atracurium, but this effect is more than compensated by a decrease in atracurium concentration required for a given effect.

Adult↗
PubMed1991

A method to measure elicited contraction of laryngeal adductor muscles during anesthesia.

The recurrent laryngeal nerve was stimulated with surface electrodes to produce vocal cord adduction, and the response was measured as pressure changes in the inflatable cuff of a tracheal tube positioned between the vocal cords. To test the linearity of the system, a model of the larynx consisting of a syringe barrel was constructed, and weights were applied to two bands of tissue simulating the vocal cords. Tests on Mallinckrodt size-7.5 tubes showed that the pressure increase produced by a given force was independent of baseline pressure in the range 10-30 mmHg. In addition, the pressure inside the inflatable cuff was linear with increasing weight (or force) for a baseline pressure of 10 mmHg. Thirty ASA physical status 1 or 2 adults were anesthetized with propofol and fentanyl. Tracheal intubation was performed in the absence of muscle relaxants, and the inflatable cuff of the tracheal tube was positioned between the vocal cords. Pressure inside the cuff was measured with an air-filled transducer. Stimulation was produced at different sites along the course of the recurrent laryngeal nerve. A surface electrode placed over the notch of the thyroid cartilage produced consistent adduction of the cords, measured as an increase of 8.9 +/- 5.1 mmHg (mean +/- standard deviation [SD]) in the cuff pressure. Neuromuscular blocking drugs produced train-of-four fade, and large doses abolished the response completely, ruling out direct muscle stimulation. It is concluded that this assembly can provide useful information on intrinsic laryngeal muscle function.

Anesthesia↗
PubMed1991

Vecuronium neuromuscular blockade at the adductor muscles of the larynx and adductor pollicis.

The differences between neuromuscular blockade of the adductor muscles of the vocal cords and the adductor pollicis were examined in 20 adult women anesthetized with fentanyl and propofol. Vecuronium 0.04 or 0.07 mg/kg was given as a single bolus by random allocation. The force of contraction of the adductor pollicis was recorded. Laryngeal response was measured as pressure changes in the cuff of the tracheal tube positioned between the vocal cords. Train-of-four stimulation was applied to the recurrent laryngeal nerve at the notch of the thyroid cartilage and to the ulnar nerve at the wrist. Neuromuscular blockade had a faster onset, was less intense, and recovered more rapidly at the vocal cords. With 0.04 mg/kg, maximum blockade of first twitch (T1) was 55 +/- 8 (mean +/- standard error of the mean [SEM]) and 88 +/- 4% at the vocal cords and the adductor pollicis, respectively (P = 0.006). Onset time was 3.3 +/- 0.1 and 5.7 +/- 0.2 min, respectively (P = 0.000001), and time to 90% T1 recovery was 11.3 +/- 1.6 and 26.1 +/- 1.8 min, respectively (P = 0.001). With 0.07 mg/kg, onset time was unchanged; maximum blockade was more intense, being 88 +/- 4 and 98 +/- 1%, respectively (P = 0.04 between muscles); and time to 90% T1 recovery was 23.3 +/- 1.8 min at the vocal cords versus 40.3 +/- 2.9 min at the adductor pollicis (P = 0.001). Approximately 1.73 times as much vecuronium was required at the larynx compared with the dose required at the adductor pollicis for the same intensity of blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1991

Cerebral hemodynamics in low-birth-weight infants treated with phototherapy.

Changes of cerebral blood flow were determined in 20 preterm infants undergoing blue-light phototherapy for hyperbilirubinemia. All were healthy very-low-birth-weight infants (less than 1,500 g) with normal brain sonograms and not under pharmacological treatment at the time of the investigation. Blood flow velocity (pulsatility index and area under velocity curve) was measured by Duplex Scan technique during and after phototherapy. No changes of global cerebral blood flow were observed in the anterior cerebral artery (p less than 0.5). Our results suggest no functional disturbance of cerebral autoregulation in low-birth-weight infants treated with phototherapy.

Blood Flow Velocity↗
PubMed1991

Partial complex epileptic seizures with ictal urogenital manifestation in a child.

Ictal sexual manifestations, like somatosensory genital phenomena, sexual emotions or sexual automatisms during a partial complex seizure, are very rare. So far the literature has above all described cases in adulthood. We report on a 6-year-old boy with partial complex epileptic seizures which led to confusion, oral and genital automatisms and the urge to urinate. During one epileptic seizure with these urogenital manifestations the EEG showed an epileptic rhythmic discharge over the left temporal region.

Automatism↗
PubMed1991

Nitrous oxide potentiates succinylcholine neuromuscular blockade in humans.

Sixty ASA physical status I and II adults received 0.3 mg/kg succinylcholine to determine the effect of prolonged administration of thiopental and that of nitrous oxide on succinylcholine neuromuscular blockade. Succinylcholine was administered either 1 min (group 1) or 6 min (groups 2 and 3) after induction of anesthesia with thiopental. In group 2, anesthesia was maintained with thiopental and the patients' lungs were ventilated with oxygen. In group 3, anesthesia was maintained with only 70% nitrous oxide in oxygen. Train-of-four stimulation of the ulnar nerve was started 30 s before the administration of succinylcholine and repeated every 12 s. The force of contraction of the adductor pollicis muscle was measured. Maximum blockade (mean +/- SEM) did not vary significantly between group 1, where thiopental had been administered for 1 min, and group 2, where it had been administered for 6 min (group 1: 61% +/- 6%; group 2: 54% +/- 8%). However, the addition of nitrous oxide increased neuromuscular blockade (group 3: 80% +/- 6%; P less than 0.05 compared with group 2). The degree of twitch augmentation, i.e., greater than maximal response, and times to twitch augmentation and to maximum blockade did not vary significantly among the groups. It is concluded that nitrous oxide increases succinylcholine neuromuscular blockade and that this is manifest within 6 min. This effect is not due to the duration of the anesthetic because thiopental, administered over a similar time period, did not potentiate succinylcholine.

Drug Synergism↗
PubMed1991

Potentiation of atracurium neuromuscular blockade by enflurane: time-course of effect.

This study was designed to determine the time required for potentiation of atracurium neuromuscular blockade after the introduction of enflurane. Ten ASA physical status I and II adults anesthetized with thiopental, nitrous oxide, and alfentanil were given 0.4 mg/kg atracurium besylate. The force of contraction of the adductor pollicis muscle in response to train-of-four stimulation of the ulnar nerve was recorded. When the first twitch (T1) of the train-of-four recovered to 10% of control, an atracurium infusion was started and adjusted to keep the level of blockade constant. After 15 min of stable blockade, 1.6%-1.7% end-tidal enflurane was started and maintained for up to 2 h. Venous blood samples were drawn and plasma atracurium concentrations were measured 15 min before and 0, 5, 10, 15, 30, 45, 60, 90, and 120 min after the introduction of enflurane. Atracurium plasma concentrations were 730 +/- 127 (SEM) ng/mL at time 0. During the first 30 min, no significant decrease in plasma levels occurred; but at 45 min, concentrations were only 67% +/- 8% of their initial value (P less than 0.01) and 48% +/- 2% at 120 min (P less than 0.01). This suggests that the interaction between enflurane and atracurium is time-dependent. Clinically, the interaction between atracurium and enflurane is negligible during procedures of less than 45 min.

Adult↗
PubMed1991

Postoperative neuromuscular function in pediatric day-care patients.

After anesthesia employing nondepolarizing muscle relaxants, 30%-40% of adult patients demonstrate residual paralysis with a train-of-four ratio less than 70%, but it is not known if the same is true for children. This study was designed to investigate neuromuscular transmission in 91 ASA physical status I or II day-care children (aged 0-10 yr) after halothane anesthesia in which pancuronium (n = 34), atracurium (n = 32), or vecuronium (n = 25) was administered. Peripheral nerve stimulation was used clinically to assess neuromuscular blockade during surgery. In the recovery room, the evoked response of the adductor pollicis muscle was measured by train-of-four stimulation of the ulnar nerve. This measurement was made (mean +/- SEM) at 18.0 +/- 1.5, 15.0 +/- 1.3, and 15.0 +/- 1.7 min after pharmacologic antagonism with 0.02 mg/kg atropine and 0.06 mg/kg neostigmine in the pancuronium, atracurium, and vecuronium groups, respectively. There were no differences in the ages of the patients in the three groups at 4.3 +/- 0.4, 4.0 +/- 0.4, and 5.0 +/- 0.5 yr, with 17 children less than 2 yr. Recovery from neuromuscular blockade in all three groups was almost complete. The train-of-four ratio (height of fourth twitch compared with the first) was similar in patients who had received pancuronium (96.7% +/- 0.9%), atracurium (95.5% +/- 0.9%), or vecuronium (96.3% +/- 1.3%). Therefore, postoperative muscle weakness or respiratory impairment is unlikely in pediatric day-care surgical patients more than 2 yr old when these anesthetic techniques are used.

Ambulatory Surgical Procedures↗
PubMed1991

Neuromuscular effects of succinylcholine on the vocal cords and adductor pollicis muscles.

To quantify the effects of succinylcholine at the laryngeal adductor muscles and the adductor pollicis, 17 adult patients were studied during propofol-fentanyl anesthesia. Train-of-four stimulation was applied to the ulnar nerve at the wrist and the recurrent laryngeal nerve at the notch of the thyroid cartilage. Laryngeal response was measured as pressure changes in the cuff of the tracheal tube positioned between the vocal cords. The force of contraction of the laryngeal adductor muscles and of the adductor pollicis were compared after administration of 0.25 or 0.5 mg/kg of succinylcholine. With 0.25 mg/kg, maximum blockade of first twitch (T1) was 66% +/- 10% (mean +/- SEM) and 45% +/- 13% at the vocal cords and the adductor pollicis, respectively (P less than 0.01). After 0.5 mg/kg, maximum blockade at the vocal cords (93% +/- 2%) and the adductor pollicis (84% +/- 6%) did not differ significantly. For both doses, time to maximal blockade was shorter for the vocal cords (0.9 +/- 0.1 min) than for the adductor pollicis (1.7 +/- 0.2 min; P less than 0.01). Time to 90% recovery of T1 after a bolus of 0.5 mg/kg was similar at the vocal cords (4.3 +/- 0.5 min) and the adductor pollicis (5.2 +/- 0.8 min) (NS). The ED50 was less at the laryngeal adductors (0.170 mg/kg) than at the adductor pollicis (0.278 mg/kg). It is concluded that, in adults, succinylcholine-induced blockade is more rapid and more intense at the laryngeal muscles than at the adductor pollicis.

Adolescent↗
PubMed1990

Edrophonium priming for antagonism of atracurium neuromuscular blockade.

Edrophonium administered in divided doses has been reported to accelerate antagonism of neuromuscular blockade, i.e., a "priming" effect. Since measured onset times can be affected by the type of stimulation used, this effect was studied using both train-of-four (TOF) and single twitch (ST) stimulation. During thiopentone-nitrous oxide-enflurane anaesthesia 20 adults were given atracurium 0.5 mg.kg-1. Both ulnar nerves were stimulated with TOF every 12 sec until one per cent recovery of first twitch (T1). At this time, ST stimulation was applied to one arm, selected at random. When the mean value of T1 and ST reached ten per cent of control, edrophonium, 1 mg.kg-1, preceded by atropine was given either as a single dose, or in two doses consisting of 0.2 mg.kg-1 followed by 0.8 mg.kg-1 three minutes later. No statistically significant differences were observed between T1 and ST for the next ten minutes, whether edrophonium had been given in single or divided doses. Giving edrophonium in divided doses did not improve recovery significantly, measured with either T1, ST or train-of-four ratio (T4/T1). Five minutes after the first administration of edrophonium, T1 was (mean +/- SEM) 86 +/- 3 and 86 +/- 2 per cent control in the single and divided dose groups respectively. Corresponding values for ST were 89 +/- 1 and 89 +/- 2 per cent (NS), and for TOF, 49 +/- 3 and 57 +/- 3 per cent (NS), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Dose-related effects of succinylcholine on the adductor pollicis and masseter muscles in children.

This study was performed to determine the effects of various doses of succinylcholine on resting tension and evoked twitch height at the masseter and adductor pollicis muscles in children. Twenty patients, aged 3-10 yr, ASA physical status I or II, were randomly assigned to receive succinylcholine 0.15, 0.25, 0.50 or 1.00 mg.kg-1, during halothane-nitrous oxide anaesthesia. Supramaximal train-of-four stimulation was applied simultaneously to the ulnar nerve and the nerve to the masseter. Transducers recorded force at the jaw and the thumb. Maximum blockade of the first twitch (T1) and maximum resting tension change were measured. Potency of succinylcholine at the two muscles was estimated by linear regression of the logit transformation of T1 versus log dose. The relationship between resting tension change and log dose was established by linear regression. The masseter muscle was more sensitive to succinylcholine than the adductor pollicis with an ED95 of 0.28 +/- 0.02 (mean +/- SEM) vs 0.44 +/- 0.05 mg.kg-1 (P less than 0.05). Onset of neuromuscular blockade was faster at the masseter, and recovery occurred simultaneously in both muscles. A dose-related increase in resting tension was observed in both muscles, but its magnitude was five times greater at the masseter. With succinylcholine, 1 mg.kg-1, this increase was 51.6 +/- 16.8 g at the masseter and 9.1 +/- 2.3 g at the adductor pollicis. Tension returned to baseline within 1-2 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1990

Potency of atracurium on masseter and adductor pollicis muscles in children.

The sensitivity of the masseter to atracurium was measured in ten children aged 3-10 yr undergoing elective surgery, and compared with that of the adductor pollicis. During nitrous oxide-halothane anaesthesia and mechanical ventilation, supramaximal nerve stimulation was applied to the ulnar nerve at the elbow and to the nerve to the masseter, at a point inferior to the zygomatic arch, anterior to the mandibular condyle. Jaw closure was measured by a force displacement transducer system attached to an oral airway and connected to a metal frame fixed to the operating table 10 cm caudad to the chin. Cumulative dose-response curves for atracurium were obtained by the injection of doses followed by an infusion to compensate for elimination. The mean ED50s and ED95s were similar at the masseter and the adductor pollicis. At the masseter, these were 0.150 +/- 0.013, mean +/- SEM, mg.kg-1 and 0.254 +/- 0.021 mg.kg-1, respectively. At the adductor pollicis, corresponding values were 0.145 +/- 0.009 mg.kg-1, and 0.259 +/- 0.016 mg.kg-1. However, this relationship was not constant in every patient, and in some patients the masseter was much more sensitive than the adductor pollicis. The time from injection of the first dose of atracurium to maximum blockade was 2.5 +/- 0.2 min at the masseter and 3.2 +/- 0.2 min at the adductor pollicis (P less than 0.05). It is concluded that when atracurium is administered to paediatric patients, neuromuscular blockade is usually of the same intensity at each muscle but occurs sooner at the masseter than at the adductor pollicis.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1990

Pharmacokinetics of alfentanil and clinical responses during cardiac surgery.

This study assessed the pharmacokinetic and pharmacodynamic behaviour of alfentanil during and after coronary artery bypass grafting (CABG). Twenty-eight patients with good ventricular function having CABG were divided into three groups and premedicated with morphine 0.1 mg.kg-1 IM, scopolamine 0.005 mg.kg-1 IM and diazepam 0.1 mg.kg-1 PO. Group I patients received an infusion of 250 micrograms.kg-1 of alfentanil over one hour coincidental with a second infusion at 2.5 micrograms.kg-1.min-1 which was continued to the end of surgery. Patients in group II received 300 micrograms.kg-1 and 3.0 micrograms.kg-1.min-1 and patients in group III 350 micrograms.kg-1 and 3.5 micrograms.kg-1.min-1. The tracheas of all patients were intubated after receiving alfentanil 96 micrograms.kg-1 and pancuronium 0.15 micrograms.kg-1. Haemodynamic responses to intubation and surgical stimuli (greater than or equal to 20 per cent increase in heart rate and/or systolic blood pressure from control) were treated with isoflurane, one to two per cent inspired, until abolished. Blood samples were taken during and after surgery for plasma alfentanil concentrations which were determined by radioimmunoassay. After surgery the times to awakening and extubation, and alfentanil elimination half-life (t1/2B = 0.693/-k) were determined for each patient. Haemodynamic responses occurred in 20 patients. There were no significant differences in any variable among the groups. The times to awakening and extubation for all patients were 3.2 +/- 0.6 and 8.8 +/- 1.2 hr (mean +/- SEM) respectively. The elimination half-life for all patients was 5.1 +/- 1.0 hr (mean +/- SEM).(ABSTRACT TRUNCATED AT 250 WORDS)

Alfentanil↗