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Biomedical subjects

M Naguib

Publications and source records attributed to M Naguib.

At least 55 records · Page 3Linked to original sources
PubMed1996

Enzymatic versus pharmacologic antagonism of profound mivacurium- induced neuromuscular blockade.

BACKGROUND: Mivacurium, a nondepolarizing muscle relaxant, is hydrolyzed by butyrylcholinesterase. The use of butyrylcholinesterase for antagonism of profound mivacurium-induced blockade has not been studied in humans. In part 1 of this two-part study, the authors examined the relationship between the posttetanic count (PTC) and recovery from profound mivacurium-induced blockade. In part 2, an attempt was made to antagonize a quantified level of profound mivacurium-induced blockade using either butyrylcholinesterase, edrophonium, or neostigmine. METHODS: Eighty-seven ASA physical status 1 or 2 adult patients were given 0.15 mg.kg-1 mivacurium during fentanyl-thiopental-nitrous oxide-isoflurane anesthesia. They were randomly assigned to eight groups. Neuromuscular function was monitored by recording the mechanomyographic response of the adductor pollicis to PTC and train-of-four (TOF) stimulation in all patients except those in group 1 where the TOF was the only pattern used. In part 1, neuromuscular function was allowed to recover spontaneously in ten patients (group 1; control-TOF) until TOF ratio (the amplitude of the fourth evoked response as a fraction of the first evoked response T4/T1) had reached 0.75. The temporal relationship between PTC and the first reaction to TOF stimulation was determined in another 31 patients, and neuromuscular function in 10 of these patients was allowed to recover spontaneously until TOF ratio had reached 0.75. The temporal relationship between PTC and the first reaction to TOF stimulation was determined in another 21 patients, and neuromuscular function in 10 of these patients was allowed to recover spontaneously, until TOF ratio had reached 0.75 (group 2; control-PTC). In part 2, the antagonism of mivacurium-induced profound (PTC > or = 1; groups 3-6) and 90% block (groups 7-8) of twitch height were investigated in another 56 patients. Groups 3 and 7 received neostigmine 0.06 mg.kg-1 whereas groups 4 and 8 received edrophonium 1 mg.kg-1, respectively. Groups 5 and 6 received exogenous human butyrylcholinesterase equivalent to activity present in 25 or 70 ml.kg-1 of human plasma, respectively. RESULTS: Neither butyrylcholinesterase nor edrophonium shortened the times from first PTC response to TOF = 0.75 compared to group 2. Neostigmine resulted in prolongation of recovery time. There was a linear relationship (r = -0.80; P = 0.00001) between PTC and time of onset of TOF response. CONCLUSIONS: There appears to be no clinical advantage in attempting to antagonize profound mivacurium-induced neuromuscular blockade.

Adolescent↗
PubMed1995

Midazolam for caudal analgesia in children: comparison with caudal bupivacaine.

In a randomized, double-blind study we have examined the analgesic efficacy of caudal administration of midazolam, bupivacaine, or a mixture of both drugs in 45 children, undergoing inguinal herniotomy. They were allocated randomly into three groups (n = 15 in each) to receive a caudal injection of either 0.25% bupivacaine 1 ml.kg-1 with or without midazolam 50 micrograms.kg-1 or midazolam 50 micrograms.kg-1 with normal saline 1 ml.kg-1. There were no differences in quality of pain relief, postoperative behaviour or analgesic requirements between the midazolam group and the other two groups. Times to first analgesic administration (paracetamol suppositories) were longer (P < 0.001) in the bupivacaine-midazolam group than in the other two groups. Further, the bupivacaine-midazolam group received fewer (P < 0.05) doses of paracetamol than the bupivacaine group. Side effects such as motor weakness, respiratory depression or prolonged sedation were not observed in patients who received caudal epidural midazolam only. We conclude that caudal midazolam in a dose of 50 micrograms.kg-1 provides equivalent analgesia to bupivacaine 0.25%, when administered postoperatively in a volume of 1 ml.kg-1 for children following unilateral inguinal herniotomy.

Analgesia, Epidural↗
PubMed1995

Dose-response studies of the interaction between mivacurium and suxamethonium.

We have determined the effect of pretreatment with mivacurium on the potency of suxamethonium and the effect of prior administration of suxamethonium on the potency of mivacurium. We studied 100 ASA I or II patients during thiopentone-fentanyl-nitrous oxide-isoflurane anaesthesia. Neuromuscular block was recorded as the evoked thenar mechanomyographic response to train-of-four stimulation of the ulnar nerve (2 Hz at 12-s intervals). Single dose-response curves were determined by probit analysis. Pretreatment with mivacurium had a marked antagonistic effect on the development of subsequent depolarizing block produced by suxamethonium. The dose-response curves for suxamethonium alone and after pretreatment with mivacurium did not deviate from parallelism, but those constructed after mivacurium were shifted significantly to the right (P < 0.0001). The calculated doses producing 50% depression of T1 (ED50) were 86 (95% confidence intervals 83-88) and 217 (208-225) micrograms kg-1 for suxamethonium alone and after mivacurium, respectively. This study also demonstrated that prior administration of suxamethonium did not appear to influence either the slope of the regression lines or the potency of mivacurium. Combining the results of this study with a previous study (mivacurium ED50 = 20.8 (20.3-21.3) micrograms kg-1 during isoflurane-nitrous oxide anaesthesia), we suggest that the potency of mivacurium did not differ from that observed after suxamethonium (17.4 (16.9-17.9) micrograms kg-1).

Adolescent↗
PubMed1995

Comparative potency of steroidal neuromuscular blocking drugs and isobolographic analysis of the interaction between rocuronium and other aminosteroids.

We have determined the relative potency of rocuronium, pancuronium, pipecuronium and vecuronium, and examined the nature of the interaction of rocuronium with the other three steroidal neuromuscular blocking drugs. We studied the dose-response relationships of each drug and their combination with rocuronium in 200 ASA I or II patients during propofol-fentanyl-nitrous oxide-oxygen anaesthesia. Neuromuscular block was recorded as the evoked thenar mechanomyographic response to single twitch stimulation of the ulnar nerve at 10-s intervals. The dose-response curves were determined by probit analysis. Isobolographic and algebraic (fractional) analyses were used to assess the combined effect of equipotent doses of rocuronium and vecuronium, pipecuronium or pancuronium and to define the type of interaction between these drugs. The isobolograms were constructed by plotting single-drug ED50 points on the dose co-ordinates, and a combined ED50 point in the dose field. The calculated doses producing 50% depression (ED50) of the twitch height for rocuronium, pancuronium, pipecuronium and vecuronium were 144.8 (95% confidence intervals 140.4-149.3), 32.4 (31.7-32.9), 27.1 (26.5-27.6) and 23.7 (22.7-24.8) micrograms kg-1, respectively. Corresponding doses producing 95% depression (ED95) of twitch height were, respectively, 322.1 (307.5-337.3), 58.1 (56.2-60.1), 48.7 (46.9-50.5) and 39.9 (38.4-41.4) micrograms kg-1. Based on the estimate of ED50, the relative potency was 1:4.5:5.4:6, respectively. The interaction between rocuronium and vecuronium, pipecuronium or pancuronium was found to be additive.

Adolescent↗
PubMed1995

Histamine-release haemodynamic changes produced by rocuronium, vecuronium, mivacurium, atracurium and tubocurarine.

We have examined the effects of different benzyl-isoquinolinium and steroidal neuromuscular blocking compounds on plasma concentrations of histamine, heart rate and arterial pressure in surgical patients. A single, rapid (5-s) bolus of mivacurium 0.2 mg kg-1, atracurium 0.6 mg kg-1, tubocurarine 0.5 mg kg-1, vecuronium 0.1 mg kg-1 or rocuronium 0.6 mg kg-1 was administered to 75 patients (n = 15 in each group). Anaesthesia was induced with thiopentone 6 mg kg-1 i.v. and maintained with isoflurane and 70% nitrous oxide in oxygen. Venous blood samples were obtained before induction, 1 min after thiopentone and 1, 3 and 5 min after administration of the neuromuscular blocking drug. Mivacurium, atracurium and tubocurarine caused 370%, 234% and 252% increases in plasma histamine concentrations at 1 min, respectively. Corresponding values at 3 min were 223%, 148% and 157%, respectively. These changes were significant (P < 0.01) at 1 and 3 min. In contrast, the rocuronium and vecuronium groups had no significant changes in either plasma histamine concentrations or haemodynamic variables.

Adolescent↗
PubMed1995

Enzymatic antagonism of mivacurium-induced neuromuscular blockade by human plasma cholinesterase.

BACKGROUND: Mivacurium chloride is a bis-benzylisoquinolinium nondepolarizing neuromuscular blocking agent, hydrolyzed by butyrylcholinesterase (PCHE). The dose-response relationships for PCHE after mivacurium have not been studied. Therefore, this study was designed to establish dose-response relationships for PCHE as an antagonist of mivacurium-induced neuromuscular blockade. METHODS: Forty-eight physical status 1 adults were given 0.15 mg/kg mivacurium during fentanyl-thiopental-nitrous oxide-isoflurane anesthesia. Train-of-four (TOF) stimulation was applied to the ulnar nerve every 12 s, and the force of contraction of the adductor pollicis muscle was recorded. When spontaneous recovery of first twitch height (T1) reached 10% of its initial control value, exogenous PCHE equivalent to activity present in 2.5, 5, 7.5, 15, or 25 ml/kg of human plasma was administered by random allocation to 40 patients. Neuromuscular function in another eight subjects was allowed to recover spontaneously. Two blood samples were taken for determination of plasma cholinesterase activity. The first sample was taken before induction of anesthesia, and the second sample was taken when the TOF ratio had recovered to 0.75. Dibucaine and fluoride numbers were determined from the first assay. RESULTS: Administration of PCHE produced significant increases in PCHE activity in all patients. The larger the dose, the greater was the resultant plasma activity. Human PCHE produced a dose-dependent antagonism of mivacurium-induced neuromuscular blockade and the recovery times correlated inversely with PCHE activity (P < 0.01). The recovery of T1 was greater (P < 0.01) and time to attain a TOF ratio of 0.75 was shorter (P < 0.01) with any dose of PCHE than that observed in the spontaneous recovery group. After the administration of exogenous PCHE equivalent to activity present in 25 ml/kg of human plasma, recovery of TOF ratio to 0.75 or more was observed in all patients in less than 10 min and time to attain a TOF ratio of 0.75 was 55% shorter than the spontaneous recovery group (8.4 [7.1-9.7] vs. 18.7 [15.4-22] min; mean and 95% confidence intervals). CONCLUSIONS: Administration of exogenous PCHE equivalent to activity present in 25 ml/kg of human plasma (in a 65-kg patient, this dose is equivalent to PCHE activity of 1,625 ml of adult human plasma) resulted in reliable antagonism of mivacurium-induced neuromuscular blockade. Nevertheless, because of the prohibitive cost of this compound, this reversal modality is unlikely to have a routine practical application at this time.

Adolescent↗
PubMed1995

Lower skull base: anatomic study with surgical implications.

With advances in the lateral approaches to the skull base and the increasing success of the management of jugular foramen lesions, a thorough knowledge of the anatomy of this region is needed. The purpose of the present work is to study the detailed microsurgical anatomy of the lower skull base and the jugular foramen area as seen through the lateral approaches. Forty preserved skull base specimens and 5 fresh cadavers were dissected. The shape of the jugular bulb and its relationship to nearby structures were recorded. The different venous connections of the bulb were noted. The hypoglossal canal was identified and its contents were observed. The lower cranial nerves were studied at the level of the upper neck, at their exit from the inferior skull base, and in the jugular foramen. The results of the present study showed the complex and variable anatomy of this area. The classic compartments of the jugular foramen were not always present. Cranial nerves IX through XI followed different patterns while passing through the jugular foramen, being separated from the jugular bulb by bone, thick fibrous tissue, or thin connective tissue.

Cadaver↗
PubMed1995

Facial nerve neuromas: diagnosis and management.

Facial nerve neuromas are uncommon tumors that involve the facial nerve. There is no classic presentation of these tumors. This study presents a series of 22 patients with facial neuromas managed from 1977 to 1993. Facial nerve dysfunction was the most common complaint, present in 90.5% of cases. Hearing loss was the second most common complaint and was found in 76.2% of cases. High resolution computed tomography and magnetic resonance imaging with gadolinium proved to be the most accurate methods of preoperative assessment of these tumors and are complementary in selected cases. Different surgical approaches were performed according to tumor location and preoperative hearing level. In all cases long-term follow-up showed no tumor recurrence, and acceptable return of facial function was noted in 80% of cases.

Adolescent↗
PubMed1994

Different priming techniques, including mivacurium, accelerate the onset of rocuronium.

Different priming sequences of equipotent doses of rocuronium and mivacurium on the onset of maximum neuromuscular block and intubating conditions were compared with those obtained after succinylcholine. During thiopentone-fentanylnitrous oxide anaesthesia, 70 patients were randomly assigned into seven groups. Group I received mivacurium 0.15 mg.kg-1 as a single bolus dose. Group II received a priming dose of mivacurium 0.015 mg.kg-1 followed three minutes later by mivacurium 0.135 mg.kg-1. Group III received rocuronium 0.6 mg.kg-1 as a single bolus dose, and Group IV received an initial dose of rocuronium 0.06 mg.kg-1 followed by rocuronium 0.54 mg.kg-1. Group V received a priming dose of mivacurium 0.015 mg.kg-1 followed by rocuronium 0.54 mg.kg-1. Group VI received an initial dose of rocuronium 0.06 mg.kg-1 followed by mivacurium 0.135 mg.kg-1. Group VII received succinylcholine 1.0 mg.kg-1. Groups I, III, and VII received a placebo injection before the administration of the neuromuscular blocking drug. Additional thiopentone 2 mg.kg-1 iv was given 30 sec before intubation. Onset times (mean (95% confidence interval)) after priming a rocuronium block with either rocuronium (73 (57-90) sec) or mivacurium (58 (47-69) sec) were similar to those after succinylcholine (54 (40-68) sec), and were shorter (P < 0.01) than that observed in other groups. Intubating conditions were not different between the groups. The duration of neuromuscular block was shortest with succinylcholine. It is concluded that priming a rocuronium block with either mivacurium or rocuronium resulted in a neuromuscular block comparable to that of succinylcholine in both the onset of action and intubating conditions.

Adult↗
PubMed1994

Surgical anatomy of the extended middle cranial fossa approach.

The extended middle cranial fossa approach includes removal of the petrous bone from its subtemporal surface in order to expose widely the internal auditory canal and the posterior fossa dura around its porus while preserving all the important and closely related anatomical structures. We have dissected 25 temporal bones and five fresh cadavers in order to define the limits of this approach. Measurements were obtained between the different structures to find reliable angles and distances that could guide working in this area. A new method of identification of the internal auditory canal is discussed based on the measurements taken.The results of the present work showed wide variations in the different structures. The arcuate eminence was coincident with the superior semicircular canal in only 48% of bones. Dehiscence of the geniculate ganglion and of the internal carotid artery was noted in 16% and 20% of specimens, respectively. The angles measured between the different structures showed great variations. However, the angle between the internal auditory canal and superior petrosal sinus was constant. Though the extended middle cranial fossa is a versatile approach, it affords a limited access to the cerebellopontine angle. A thorough understanding of the complex and variable anatomy of this area is necessary should this approach be utilized.

Journal Article↗
PubMed1994

Interactions between mivacurium and atracurium.

We have studied the interaction between atracurium and mivacurium. The dose-response relationships of atracurium, mivacurium and their combination were studied in 96 ASA I or II patients during thiopentone-fentanyl-nitrous oxide-isoflurane (1.2% end-tidal) anaesthesia. Neuromuscular block was recorded as the evoked thenar mechanomyographic response to train-of-four stimulation of the ulnar nerve (2 Hz at 12-s intervals). The dose-response curves were determined by probit analysis. Isobolographic and algebraic (fractional) analyses were used to assess quantitatively the combined effect of equipotent doses of atracurium and mivacurium and to define the type of interaction between these drugs. Isobolograms were constructed by plotting single drug ED50 points on the dose co-ordinates and a combined ED50 point in the dose field. The calculated doses producing 50% depression (ED50) of the first twitch height were 50.5 (95% confidence intervals 48.9-52.1) and 20.8 (20.3-21.3) micrograms kg-1 for the atracurium and mivacurium groups, respectively. Isobolographic and fractional analyses of the atracurium-mivacurium combination demonstrated zero interaction (additivism). An additional 26 patients anaesthetized with thiopentone-fentanyl-nitrous oxide-isoflurane were allocated randomly to receive either atracurium 0.5 mg kg-1 (n = 13) or mivacurium 0.15 mg kg-1 (n = 13). Additional maintenance doses of mivacurium 0.1 mg kg-1 were administered to patients in both groups, whenever the first twitch recovered to 10% of control. The duration of the first maintenance dose of mivacurium to 10% recovery of the first twitch was greater (P < 0.0005) after atracurium (25 (21.8-28.5) min) than after mivacurium (14.2 (11.9-16.6) min).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Antinociceptive effects of spinal cholinesterase inhibition and isobolographic analysis of the interaction with mu and alpha 2 receptor systems.

BACKGROUND: Spinal cholinergic receptors have been shown to have a potent antinociceptive action, an effect that can be mimicked by spinal cholinesterase inhibitors. We (1) characterized the cholinergic receptor system through which intrathecally applied cholinesterase inhibitors produce their antinociceptive effect and (2) examined their interaction with spinal mu opioid and alpha 2-adrenergic receptors. METHODS: Rats were prepared with chronic intrathecal catheters and the nociceptive threshold was assessed by the use of the radiant heat-evoked hind paw withdrawal. RESULTS: Spinal administration of neostigmine, edrophonium, carbachol, clonidine, and morphine produced a dose-dependent increase on the thermally evoked hind paw withdrawal latency. The order of potency (dose producing a 50% effect, in nanomoles) was morphine (1.1) = neostigmine (1.2) > clonidine (4.4) > carbachol (15) >> edrophonium (112). Spinal pretreatment with atropine (35 nmol) attenuated the antinociceptive effect of intrathecal carbachol (55 nmol), neostigmine (15 nmol), and edrophonium (500 nmol) but did not affect the potency of intrathecal morphine (15 nmol) or clonidine (435 nmol). In addition, intrathecal pretreatment with naloxone (31 nmol) and yohimbine (28 nmol) attenuated the effects of intrathecally administered morphine and clonidine, respectively, but did not significantly affect the potency of carbachol, neostigmine, or edrophonium. The nicotinic receptor antagonist mecamylamine (60 nmol) did not affect thermal nociception. Isobolographic analysis revealed a synergistic interaction after the coadministration of neostigmine-clonidine (P < 0.001), edrophonium-clonidine (P < 0.0001), and edrophonium-morphine (P < 0.01) mixtures. Neostigmine-morphine exhibited simple additivity. CONCLUSIONS: These data indicate that analgesia after spinal cholinesterase inhibition is mediated through muscarinic, but not nicotinic cholinergic, opioid, or alpha 2-adrenergic receptor systems, and that these spinal effects of cholinesterase inhibition interact synergistically with the antinociceptive effects of intrathecal mu and alpha 2 agonists.

Animals↗
PubMed1994

Neuromuscular effects of rocuronium bromide and mivacurium chloride administered alone and in combination.

BACKGROUND: Rocuronium is a new nondepolarizing neuromuscular blocking agent with a rapid onset but with intermediate duration of action. Mivacurium, on the other hand, is a new short-acting nondepolarizing neuromuscular relaxant, but of slower onset of action. The current study was undertaken to characterize the interaction between rocuronium and mivacurium. METHODS: In the first study, the dose-response relations of rocuronium, mivacurium, and their combination were studied in ASA physical status 1 or 2 patients during thiopental-fentanyl-N2O anesthesia. One hundred ten patients, randomly assigned to 1 of 11 groups of 10 patients each, received mivacurium 30, 50, or 70 micrograms.kg-1; rocuronium 100, 200, 250, or 300 micrograms.kg-1; or an equieffective combination of both drugs (1 ED50 rocuronium + 1 ED50 mivacurium; 1/2 ED50 rocuronium + 1/2 ED50 mivacurium; 1/4 ED50 rocuronium + 1/4 ED50 mivacurium; or 1/8 ED50 rocuronium + 1/8 ED50 mivacurium, where ED50 is the dose producing 50% depression of the first twitch height). In the second study, 50 patients, ASA physical status 1 or 2, anesthetized with thiopental-fentanyl-N2O, were randomly allocated to 5 groups of 10 patients each to receive one of the following neuromuscular blocking drugs or drug combination: rocuronium 600 micrograms.kg-1 (group 1), mivacurium 150 micrograms.kg-1 (group 2) rocuronium 150 micrograms.kg-1 + mivacurium 37.5 micrograms.kg-1 (group 3), rocuronium 300 micrograms.kg-1 + mivacurium 75 micrograms.kg-1 ((group 4), or rocuronium 600 micrograms.kg-1 + mivacurium 150 micrograms.kg-1 (group 5). RESULTS: The calculated ED50 values and their 95% confidence intervals were 125 (122-129) and 37 (36-38) micrograms.kg-1 for the rocuronium and mivacurium groups, respectively. The interaction between rocuronium and mivacurium was found to be synergistic. The measured ED50 of the mixture was only 62% of the predicted value assuming a purely additive interaction. In the second study, rocuronium 600 micrograms.kg-1 group and group 3 had similar onset times (99 [74-123] and 114 [100-128] s, respectively), which were significantly shorter than that observed in the mivacurium 150 micrograms.kg-1 group (178 [149-206] s). Onset times in groups 4 and 5 were significantly shorter than that in each of the other study groups (69 [63-76] and 73 [65-80] s, respectively). Clinical duration of action (recovery of T1 to 25% of baseline twitch height) was significantly greater in group 5 (55 [51-60] min) than with all other doses and agents, and briefest (P < 0.01) with mivacurium 150 micrograms.kg-1 (14.5 [12.6-16.5] min) and group 3 (14.7 [13.4-16] min). CONCLUSIONS: The interaction between rocuronium and mivacurium was found to be synergistic.

Adult↗
PubMed1994

Revision stapes surgery: a critical evaluation.

Fifty-six revision stapes surgeries performed during the last 9 years were evaluated retrospectively for their preoperative symptoms, intraoperative findings, and postoperative results according to the causes of failure, at the Gruppo Otologico, Piacenza, Italy. The most frequent causes of failure were found to be prosthetic misalignments, a reaction to the surgical trauma in the form of excess fibrous tissue reaction or new bony regrowth at the oval window, and ossicular chain problems. The location of the pathology was found to be an important factor in the outcome. Sixty percent of cases resulted in 0- to 20-dB air-bone gap. The causes of these failures, management, and their prevention during primary surgeries are also discussed.

Adult↗
PubMed1994

Giant cell tumor of the lateral skull base: a case report.

Giant cell tumors of the temporal bone are very rare lesions. They should be differentiated from other giant cell lesions of bone, mainly reparative granulomas. A case with a very huge giant cell tumor of the temporal bone extending to the infratemporal fossa, temporomandibular joint, and greater wing of the sphenoid has been presented. Because of their tendency for recurrence, total removal is the treatment of choice for these tumors and was accomplished through the infratemporal fossa approach type B. A follow-up of 2 years and 9 months revealed no evidence of tumor recurrence.

Adult↗