Biomedical subjects

G Dhonneur

Publications and source records attributed to G Dhonneur.

7 recordsLinked to original sources

PubMed2000

The effects of residual pain on oxygenation and breathing pattern during morphine analgesia.

UNLABELLED: To determine the influence of pain on opioid-induced respiratory depression, we studied oxygenation and breathing patterns in 40 patients scheduled for knee surgery during postoperative patient-controlled analgesia (PCA). After 1 h of morphine PCA, patients were randomized to receive either 20 mL of placebo or bupivacaine 0.25% through a crural nerve catheter and allowed to use PCA for one more hour. Abnormal breathing events were identified and characterized by using the Edentrace II device (Nellcor, Jouy-en-Josas, France). The Spo2 below which the patient spent 25% and 50% of a studied period was calculated (Spo2(25), Spo2(50)). Pain relief with regional analgesia increased the incidence of abnormal respiratory events associated with oxygen desaturation: during the second period, the pain score was lower in the bupivacaine group (0.7+/-1 vs 4.1+/-1.2), morphine consumption was larger in the placebo group (4.2+/-1.3 vs 0.7+/-1.4 mg), and there were more abnormal obstructive breathing events in the bupivacaine group (11+/-16 vs 3.7+/-4.3). Spo2(25) and Spo2(50) were lower in the bupivacaine than in placebo group (91.5%+/-2.8% vs 93.1%+/-2.1%, 92.9%+/-2.4% vs 94.2%+/-1.8%). IMPLICATIONS: Pain relief with regional analgesia in patients previously treated with opioids increases the incidence of abnormal respiratory events associated with oxygen desaturation.

Analgesia, Patient-Controlled↗

PubMed1999

Postoperative obstructive apnea.

UNLABELLED: We studied electromyography (EMG) of the geniohyoid muscle (Gh) and diaphragm (Di) in 12 postoperative, premedicated (flunitrazepam 2 mg PO), asymptomatic patients who snored after recovering from general anesthesia, the induction of which was partly achieved by i.v. midazolam. After extubation of the trachea, integrated EMG activity of Gh (E-Gh(MTA)) and Di (E-Di(MTA)) were measured. For Gh, tonic and phasic activity were distinguished. Patients were studied during obstructive apnea, at the end of apnea, while breathing through an artificial Guedel airway, and during quiet breathing 5 min after flumazemil. All patients experienced episodes of postoperative upper airway obstruction and nine became apneic. Flumazenil restored consciousness and predominant tonic E-GhMTA associated with upper airway patency in all patients. Reduced tonic E-GhMTA characterized postoperative obstructive apnea. Resolution of apnea required a burst of both tonic and phasic E-GhMTA associated with intense E-Di(MTA). Breathing through the Guedal airway resulted in patent airway in 8 of 10 patients and was associated with low tonic and phasic E-GhMTA and reduced E-Di(MTA). In this study, we demonstrated that the tonic pharyngeal muscular support modulates airway patency in the postoperative period. Because it is reversed by flumazemil, benzodiazepines are certainly the main cause of airway obstruction in these patients. IMPLICATIONS: Upper airway obstruction during recovery from general anesthesia induced by i.v. midazolam is associated with low tonic pharyngeal muscular support, which modulates upper airway patency in the postoperative period.

Adult↗

PubMed1999

A comparison of two techniques for cervical plexus blockade: evaluation of efficacy and systemic toxicity.

UNLABELLED: We compared two techniques of cervical plexus blockade (CPB) for carotid endarterectomy. Cervical plexus nerve block was performed with a combination of bupivacaine and lidocaine, with injections at the C2-C3, C3-C4, and C4-C5 transverse processes in 11 patients (classical CPB) or with a single injection after localization of the cervical plexus with a nerve stimulator in 12 patients (interscalene CPB). Pain scores were obtained during block placement and at predetermined phases of the operation. Arterial blood was sampled before and 3, 5, 8, 10, 15, 25, 40, and 60 min after CPB for measurement of bupivacaine and lidocaine concentrations. Interscalene CPB was less painful than classical CPB. The techniques appeared equally effective. Patients in both groups required equivalent supplementation with IV fentanyl and additional local infiltration with lidocaine during the most painful stages of surgery. The maximal concentration of bupivacaine was lower in interscalene CPB compared with classical CPB (1.0 microg/mL versus 1.5 microg/mL, P < 0.01). The time required to reach the maximal concentration of bupivacaine was 15 (10-40) min in interscalene CPB and 10 (5-17) min in classical CPB (P < 0.05). Lidocaine maximal concentration was similar in both groups, however the time required to reach the maximal concentration was longer (P < 0.05) in interscalene CPB (15 [10-60] min) than in classical CPB (10 [8-20] min). We conclude that the interscalene CPB is as effective as the classical CPB as a regional technique for carotid endarterectomy and may be associated with a lower systemic absorption of bupivacaine. IMPLICATIONS: Cervical plexus blockade for carotid endarterectomy can be effectively performed with a single injection after localization of the cervical plexus with a nerve stimulator. This technique is simple and was associated with less systemic absorption of local anesthetic than the multiple-injection technique.

Aged↗

PubMed1999

Effects of an intubating dose of succinylcholine and rocuronium on the larynx and diaphragm: an electromyographic study in humans.

BACKGROUND: Paralysis of the vocal cords is one objective of using relaxants to facilitate tracheal intubation. This study compares the neuromuscular blocking effect of succinylcholine and rocuronium on the larynx, the diaphragm, and the adductor pollicis muscle. METHODS: Electromyographic response was used to compare the neuromuscular blocking effect of succinylcholine and rocuronium on the laryngeal adductor muscles, the diaphragm, and the adductor pollicis muscle. Sixteen patients undergoing elective surgery were anesthetized with propofol and fentanyl, and their tracheas were intubated without neuromuscular blocking agents. The recurrent laryngeal and phrenic nerves were stimulated at the neck. The electromyographic response was recorded from electrodes placed on the endotracheal tube and intercostally before and after administration of 1 mg/kg succinylcholine or 0.6 mg/kg rocuronium. RESULTS: The maximum effect was greater at the adductor pollicis (100 and 99%) than at the larynx (96 and 97%) and the diaphragm (94 and 96%) after administration of succinylcholine and rocuronium, respectively (P < or = 0.05). Onset time was not different between the larynx (58+/-10 s), the diaphragm (57+/-8 s), and the adductor pollicis (54+/-13 s), after succinylcholine (all mean +/- SD). After rocuronium, onset time was 124+/-39 s at the larynx, 130+/-44 s at the diaphragm, and 115+/-21 s at the adductor pollicis. After succinylcholine administration, time to 90% recovery was 8.3+/-3.2, 7.2+/-3.5, and 9.1+/-3.0 min at the larynx, the diaphragm, and the adductor pollicis, respectively. Time to 90% recovery after rocuronium administration was 34.9+/-7.6, 30.4+/-4.2, and 49.1+/-11.4 min at the larynx, the diaphragm, and the adductor pollicis, respectively. CONCLUSION: Neuromuscular blocking effect of muscle relaxants on the larynx can be measured noninvasively by electromyography. Although the larynx appears to be resistant to muscle relaxants, we could not demonstrate that its onset time differed from that of peripheral muscles.

Adult↗

PubMed1998

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

BACKGROUND: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. METHODS: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg.kg-1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg.kg-1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg.kg-1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. RESULTS: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). CONCLUSION: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.

Adult↗

PubMed1996

Neostigmine reversal of vecuronium neuromuscular block and the influence of renal failure.

The duration of clinical relaxation induced by vecuronium and reversal by neostigmine was studied in 40 patients with renal failure (RF) and 40 patients with normal renal function (NL) under general anesthesia. Patients were premedicated with flunitrazepam, and anesthesia commenced with fentanyl 1-2 micrograms/kg, thiopental 5-8 mg/kg, and vecuronium 0.1 mg/kg. Anesthesia was maintained with 60% nitrous oxide in oxygen, isoflurane 0.3%-1.0% end-tidal concentration, and 1 microgram/kg fentanyl every 20-30 min. Neuromuscular block was reversed by the administration of intravenous neostigmine 40 mg/kg at the time of reappearance of either two or four responses to the train-of-four (TOF) stimulation. Monitoring of neuromuscular function consisted of supramaximal TOF stimulation of the ulnar nerve and the evoked thumb response was registered using a force transducer. Spontaneous recovery time, reversal time, and the time to recovery of TOF ratio to 0.7 were recorded. RF did not prolong the vecuronium neuromuscular blocking effect, reversal was achieved at the same rate in NL as in RF, and the duration of reversal of neuromuscular blocking effect of vecuronium was not influenced by the time of administration of neostigmine. Therefore, the neuromuscular blocking effect of a tracheal intubating dose of vecuronium can be reversed at the same rate in patients with end-stage RF as in patients with normal kidney function.

Adult↗

PubMed1996

A comparison of the neuromuscular blocking effects of atracurium, mivacurium, and vecuronium on the adductor pollicis and the orbicularis oculi muscle in humans.

Both the orbicularis oculi (OO) and the adductor pollicis (AP) muscles have been used to indirectly quantify the extent of neuromuscular block of the respiratory muscles. To clarify any differences in response of these muscles to neuromuscular blocking drugs, the effects of two different doses of atracurium, mivacurium, and vecuronium on the AP and OO were studied. A new technique was used to measure the evoked mechanical response of the OO with accelerometry. Fifty premedicated patients were anesthetized with 5-8 mg/kg thiopental and 2 micrograms/kg fentanyl intravenously (i.v.). They were randomly allocated to receive a single dose of either 300 or 500 micrograms/kg atracurium, 150 or 250 micrograms/kg mivacurium, or 60 or 100 micrograms/kg vecuronium i.v. After orotracheal intubation, anesthesia was maintained with nitrous oxide 60% in oxygen, isoflurane 0.5%-1.5% end-tidal, and 1-2 micrograms/kg fentanyl boluses as required. The evoked response of the AP after ulnar nerve stimulation was measured using a force transducer, and that of the OO after facial nerve stimulation was measured with accelerometry using a piezoelectric probe fixed to the eyelid. The following variables were recorded for each muscle: the maximum depression of the first twitch response to the train-of-four (EMAX), the time to achievement of EMAX (TMAX), the time to recovery of the first twitch response to 25%, 50%, 75%, and 90% of control value (TH25, TH50, TH75, and TH90, respectively) and the time to recovery of the train-of-four response to a ratio of 70% (TOF 0.7). The smaller dose of each relaxant was significantly less potent than the larger dose at the OO. TMAX was shorter for the OO than for the AP at the larger dose of each drug. TH 25 was shorter at the OO than at the AP with 0.5 mg/kg atracurium, but there was no significant difference with 0.25 mg/kg atracurium. TH25 and TH50 were both faster at the OO than at the AP with mivacurium, but there was no difference with vecuronium. TOF 0.7 was shorter with the smaller dose of each drug, but there was no difference with the higher doses. It is concluded that it is possible to record the mechanical response of the OO muscle using a noninvasive method. There are differences between the responses of the OO and the AP to neuromuscular blockers that depend upon both the specific drug itself and the dose used.

Adult↗