Cardiovascular effects of atropine and neostigmine in man

Comparison of neostigmine and sugammadex for hemodynamic parameters in neurointerventional anesthesia

Introduction

Hemodynamic stability is important during neurointerventional procedures. However, ICP or blood pressure may increase due to endotracheal extubation. The aim of this study was to compare the hemodynamic effects of sugammadex and neostigmine with atropine in neurointerventional procedures during emergence from anesthesia.

Methods

Patients undergoing neurointerventional procedures were allocated to the sugammadex group (Group S) and the neostigmine group (Group N). Group S was administered IV 2 mg/kg sugammadex when a train-of-four (TOF) count of 2 was present, and Group N was administered neostigmine 50 mcg/kg with atropine 0.2 mg/kg at a TOF count of 2. We recorded heart rate, systolic blood pressure, diastolic blood pressure, mean blood pressure (MAP), and peripheral arterial oxygen saturation during administration of the reverse agent and at 2, 5, 10, 15, 30, 120 min, and 24 h thereafter. The primary outcome was blood pressure and heart rate change after the reversal agent was given. The secondary outcomes were systolic blood pressure variability standard deviation (a measure of the amount of variation or dispersion of a set of values), systolic blood pressure variability-successive variation (square root of the average squared difference between successive blood pressure measurements), nicardipine use, time-to-TOF ratio ≥0.9 after the administration of reversal agent, and time from the administration of the reversal agent to tracheal extubation.

Results

A total of 31 patients were randomized to sugammadex, and 30 patients were randomized to neostigmine. Except for anesthesia time, there were no significant differences in any of the clinical characteristics between the two groups. The results demonstrated that the increase in MAP from period A to B was significantly greater in Group N than in Group S (regression coefficient = -10, 95% confidence interval = -17.3 to -2.7, P = 0.007). The MAP level was significantly increased from period A to B in the neostigmine group (95.1 vs. 102.4 mm Hg, P = 0.015), but it was not altered in Group S. In contrast, the change in HR from periods A to B was not significantly different between groups.

Conclusion

We suggest that sugammadex is a better option than neostigmine in interventional neuroradiological procedures due to the shorter extubation time and more stable hemodynamic change during emergence.

Comparative study between sugammadex and neostigmine in neurosurgical anesthesia in pediatric patients

BACKGROUND

Postoperative recurarization remains a risk following the use of the conventional neuromuscular blocking agents. In addition, none of the commonly used reversal agents, such as neostigmine or edrophonium are capable of reliably reversing profound blockade. The present comparative and randomized study investigated the use of sugammadex for reversing profound neuromuscular blockade (NMB) in pediatric neurosurgical patients undergone posterior fossa tumor excision.

PATIENTS AND METHODS

Forty pediatric patients undergoing elective craniotomy for posterior fossa tumor excision were randomly divided into either of neostigmine or sugammadex group in which muscle relaxant was reversed at the end of anesthesia either with neostigmine 0.04 mg/kg added to atropine 0.02 mg/kg or sugammadex 4 mg/kg alone, respectively. The primary endpoint was the time from the administration of sugammadex or neostigmine to recovery of the train of four (TOF) ratio to 90% after rocuronium-induced neuromuscular block. Unpaired t-test was used to compare continuous variables between groups. Meanwhile, repeated ANOVA was used to detect intragroup differences.

RESULTS

Patients in sugammadex group attained a TOF ratio 90% in statistically shorter time (1.4 ± 1.2 min) than those in neostigmine group (25.16 ± 6.49 min) for reversal of the rocuronium. Mean arterial pressure and heart rate were significantly higher in neostigmine group at 2, 5 and 10 min after administration of the reversal agents and returned nonsignificantly different after that. With no recurarization in any patient throughout the study period.

CONCLUSION

Sugammadex rapidly and effectively reverses rocuronium-induced NMB in pediatric patients undergoing neurosurgery when administered at reappearance of T2 of TOF at dose 4 mg/kg.

Org 25969 (sugammadex), a selective relaxant binding agent for antagonism of prolonged rocuronium-induced neuromuscular block

BACKGROUND

Org 25969 is a cyclodextrin compound designed to reverse a rocuronium-induced neuromuscular block. The aim of this study was to explore the efficacy, dose-response relation and safety of Org 25969 for reversal of a prolonged rocuronium-induced neuromuscular block.

METHODS

Thirty anaesthetized adult patients received rocuronium 0.6 mg kg(-1) as an initial dose followed by increments to maintain a deep block at a level of <10 PTCs (post-tetanic counts) recorded every 6 min. Neuromuscular monitoring was carried out using accelerometry, in a train-of-four (TOF) mode using TOF-WatchSX. At recovery of T2, following at least 2 h of neuromuscular block, patients received their randomly assigned dose of 0.5, 1.0, 2.0, 4.0 or 6.0 mg kg(-1) of Org 25969. Anaesthesia and neuromuscular monitoring were continued for a minimum period of 30 min after Org 25969 administration. The main end-point of the study was the time to achieve a sustained recovery of TOF ratio to 0.9. Patients were followed up for 7 days after anaesthesia.

RESULTS

The results showed a dose-related decrease in the average time taken to attain a TOF ratio of 0.9 from 6:49 (min:s) with the 0.5 mg kg(-1) dose to 1:22 with the 4.0 mg kg(-1) dose. Weighted non-linear regression analysis showed the fastest achievable time to TOF ratio of 0.9 to be 1:35. Org 25969 produced no major adverse effects.

CONCLUSION

Org 25969 effectively reversed a deep and prolonged neuromuscular block induced by rocuronium. The effective reversal dose appears to be 2-4 mg kg(-1).

Development of a near anesthetic-free isolated canine hindlimb model. The effects of halothane and atropine sulfate on vascular resistance

A denervated, isolated canine hindlimb (HL) model was developed to minimize residual anesthetic contamination. To test the preparation, we determined the peripheral arterial vascular effects of atropine sulfate and the effect of the basal anesthetic on arterial resistance. In four dogs that were under halothane and oxygen anesthesia, the HL was prepared to allow either vascular isolation of the limb or continuity with the systemic circulation. During isolation the HL was perfused by roller pump at a preset flow rate through an infant oxygenator. Inspired gas fed to the oxygenator contained either 0%, 1.25%, or 2.5% halothane to determine that anesthetic's effect on HL arterial vascular resistance. No halothane (0%) was used in the oxygenator inflow during the atropine measurements. Vascular resistance was calculated from HL arterial pressure at constant flow. Halothane caused a significant stepwise fall in vascular resistance, with a decrease of 68% at 2.5% inspired concentration (p less than 0.01). Atropine produced a progressive attenuation of resistance that decreased by 18% after the 2.5 mg/kg dose (p less than 0.01). The model proved stable over time and demonstrated an apparent direct, dose-dependent vasodilating effect of both atropine and halothane in the canine HL muscle arterial bed.

Pressor and depressor responses after cholinergic blockade in humans

To determine whether cholinergic mechanisms contribute to blood pressure responses during arterial baroreflex inhibition and stimulation, we assessed the effects of atropine on pressor and depressor responses during and after release of the Valsalva maneuver, upon administration of intravenous phenylephrine and nitroglycerin, and during neck suction in 12 healthy people. Atropinization augmented the depressor response during the Valsalva maneuver (269%), the pressor response after release of the maneuver (544%), the pressor response to phenylephrine (109%), and the depressor response to nitroglycerin (76%), whereas the depressor response to externally applied neck suction was attenuated or abolished in all subjects. Cardiac output as indicated by impedance cardiography was unchanged during carotid baroreceptor stimulation. The results are best explained by inhibition by atropine of compensatory cholinergic heart rate, vasodilator, and negative inotropic responses.

Effects on muscarinic receptors of various agents in reversal of neuro-muscular blockade: a study evaluating atropine, glycopyrron, neostigmine and pyridostigmine

The effects were studied of various drug combinations, recommended for use in reversal of neuromuscular blockade, on heart rate and salivary secretions in 80 healthy patients anaesthetized with nitrous oxide-oxygen-halothane and relaxed with d-tubocurarine. The drug combinations were mixtures of atropine 1 mg--neostigmine 2.5 mg, atropine 1 mg--pyridostigmine 15 mg, glycopyrron 0.5 mg--neostigmine 2.5 mg, and glycopyrron 0.5 mg--pyridostigmine 15 mg, respectively. It was found that administration of the atropine-containing mixtures induced more pronounced initial increases and delayed decreases in heart rate than the mixtures containing glycopyrron. Pyridostigmine-containing mixtures elicited a somewhat more pronounced initial increase in heart rate than neostigmine-containing mixtures, but a less pronounced and delayed decrease in heart rate. Supraventricular arrhythmias occurred less frequently in the pyridostigmine groups than in the neostigmine groups. No such difference was found between the atropine and glycopyrron groups. Glycopyrron caused a more intense dryness of the mouth than atropine. A differential attitude towards the use of drugs for reversal of neuromuscular blockade, based on the cardiovascular state of the particular patient, might be recommendable.

Sinoatrial block. Autonomic influences and clinical assessment

Seventeen patient with sinoatrial block and 16 healthy volunteers were investigated with recently developed autonomic tests of atrial pacemaker function. Only one patients was found to be entirely normal in comparison with normal subjects, while another patients had supernormal responses. Fifteen patients had reduced responses relative to the controls implying impaired atrial pacemaker function or sinoatrial disease. It is suggested that while in some cases sinoatrial block may be of physiological origin, it is more often due to sinoatrial disease. The latter group are liable to Adams-Stokes syncope and may have additional atricventricular conduction abnormalities. The possible mechanisms and treatment of sinoatrial block are discussed relative to the autonomic and pacemaker function abnormalities described.