Reversal of profound and "deep" residual rocuronium-induced neuromuscular blockade by sugammadex: a neurophysiological study.

BACKGROUND: Sugammadex is the first of a new class of selective relaxant binding drugs developed for the rapid and complete reversal of neuromuscular blockade (NMB) induced by the aminosteroid neuromuscular blocking drugs rocuronium and vecuronium. Neuromuscular blocking drugs block the transmission from the peripheral nerve to the muscle units, with reduction and disappearance of the evoked electromyographic activity. Usually, neuromuscular monitoring for the investigational reversal drug is performed by calibrated acceleromyography. The efficacy of sugammadex in reversing profound and "deep" residual rocuronium-induced NMB using myogenic motor evoked potentials (mMEPs) monitoring was evaluated. METHODS: In this prospective trial, 30 consenting patients undergoing propofol-remifentanil anesthesia for spine surgery were enrolled and divided into two groups: Group 1, reversal of profound NMB (sugammadex 16 mg/Kg, 3 minutes after rocuronium 1.2 mg/Kg) and Group 2, reversal of "deep" residual NMB (sugammadex 4 mg/Kg, 15 minutes after rocuronium 0.6 mg/Kg). Myogenic MEPs registrations of upper and lower limbs and the diaphragm were performed, as well as TOF monitoring. RESULTS: After injection of 4 mg/Kg of sugammadex, the means of recovery time of the basal mMEPs amplitudes (diaphragm, and lower limbs and upper limbs) were 124±9.6, 143±163, 151±207 sec, respectively whereas after 16 mg/Kg of sugammadex the times were 109±13.8, 124±0.6, and 135±14.1 sec. Times to TOF ratio 0.9 were 114±75 and 186±105 sec in Group 1 and 2, respectively. No serious adverse effects related to sugammadex and to electrical stimulation were reported. No reoccurrence of neuromuscular block was observed. CONCLUSION: Neurophysiological monitoring using mMEPs confirmed that sugammadex provided a complete recovery from profound and "deep" residual rocuronium-induced neuromuscular blockade.

The optimal dose of local anaesthetic in the orthogonal two-needle technique. Extent of sensory block after the injection of 20, 30 and 40 mL of anaesthetic solution.

Ninety patients undergoing scheduled upper limb orthopaedic surgery were studied to determine the optimal anaesthetic dose using the 'orthogonal two-needle technique'. The patients were randomly assigned to one of three groups to receive one of three different volumes (20, 30 and 40 mL) (n = 30) of anaesthetic solution (a mixture of equal parts of 0.5% bupivacaine with adrenaline 1:200,000 and 2% lignocaine). A significant correlation was found between the volume injected and the anaesthetic spread for all tested areas. A better analgesic spread to all the major branches of the plexus was obtained when increased volumes of anaesthetic solution were injected. The comparisons between the 20 mL group and the other two groups are significant in all the tested areas, as well as the comparisons between 30 and 40 mL groups in the areas innervated by radial and musculocutaneous nerves. Only the area innervated by the axillary nerve showed a weaker volume-analgesia relation, confirming the elusiveness of this area to anaesthesia in the axillary approaches. The improved results observed using greater amounts of anaesthetic solution might result from a higher intrasheath pressure with disruption of sheath septa, or from a greater availability of drug for all the terminal branches of brachial plexus, or both.

[Treatment of intracranial aneurysm in interventional neuroradiology. What problems for the anesthetist?]. / Il trattamento degli aneurismi intracranici in neuroradiologia interventistica. Quali i problemi per l'anestesista?

AIM: To outline the most occurring complications during endovascular treatment of intracranial aneurysms. DESIGN: Retrospective review of thirty-four patients treated from October 1994 to February 1996 with the placement of mechanically detachable microcoils inside the aneurysmal sac. SETTING: Interventional neuroradiology suite equipped for anesthetic care. PATIENTS: Thirty-four patients with ruptured (88%) or unruptured (12%) intracranial aneurysm submitted to elective (38%) or emergency (62%) endovascular treatment. Aneurysms were located in the anterior circulation in twenty-six patients (76%) and in the posterior circulation in eight patients (24%). INTERVENTIONS: A microcatheter was introduced into the arterial cerebral circulation to deliver tungsten microcoils to aneurysmal sac. The transfemoral approach was used in most cases. All patients were treated under general anesthesia with tracheal intubation, conventional mechanical ventilation and neuromuscular blockade. The procedure was performed under anticoagulation with heparin and intravenous nimodipine administration. MEASUREMENTS: Neurological assessment was performed at the time of treatment (H&H 1) and six hours after the end of intervention (H&H 2) using Hunt and Hess classification system. The outcome was scored at four weeks following treatment using Glasgow Outcome Scale (GOS). RESULTS: Twenty-two (65%) interventions were successful. Attempted embolization failed in twelve (35%) patients due to intraoperative complications (17.6%) or technical difficulties (17.6%). Failures were more frequently determinated by vasospasm and haemorrhage. CONCLUSIONS: The time of intervention, the use of heparin and the patient medical conditions need to be considered in preventing the complications of endovascular treatment.

Postspinal headache in Taylor's approach: a comparison between 21- and 25-gauge needles in orthopaedic patients.

A randomized study was carried out on 160 patients aged 30-60 years with the aim of finding a method of preventing postdural puncture headache (PDPH). In Taylor's lumbosacral approach to the subarachnoid space, two different needle sizes were used (21-gauge versus 25-gauge) for injecting the anaesthetic solution. Our results show an overall incidence of PDPH in nearly 8% of patients, with no significant difference related to the size of the needle employed. Patients with PDPH showed mild symptoms which disappeared in a short time and none needed epidural blood patching. The possibility of using larger needles, facilitating the execution of the block without increasing PDPH incidence, renders this technique particularly attractive in patients where the midline approach is not feasible, or when pencil-point needles are not available.

Effect of injection speed on anaesthetic spread during axillary block using the orthogonal two-needle technique.

One hundred patients undergoing scheduled upper limb orthopaedic surgery were studied to determine if the speed of injection of the local anaesthetic solution could modify the extent and depth of anaesthesia with the axillary approach to the brachial plexus. The blocks were performed using the 'orthogonal two-needle technique' in which two needles are positioned on the upper and on the lower aspect of the axillary artery, orthogonal to the neurovascular bundle and directed towards the fascial compartment containing the radial nerve. The patients were randomly assigned to one of three groups to receive one of three injection rates (10, 20 and 30 s) (n = 30). In consequence to the results obtained in these patients, a further group of 10 patients was a posteriori added for whom the injection time for each single shot of anaesthetic solution was increased to 1 min. In each group the same mixture and volume of anaesthetic solution (a 30 mL mixture of equal parts of 0.5% bupivacaine with adrenaline 1:200,000 and 2% lignocaine) was injected in two separate boluses of 15 mL each through the two positioned needles. A significant association was found between the injection rate and the anaesthetic spread for all tested areas with the exception of the regions supplied by the median nerve. A greater speed of injection was associated with less anaesthetic spread and more frequent block failure. A clear association between the anaesthetic spread to all branches of the brachial plexus and a slower injection rate of the local anaesthetic was found.

[Intracardial knotting of a Swan-Ganz catheter. Description of a clinical case]. / Annodamento intracardiaco del catetere di Swan-Ganz. Descrizione di un caso clinico.

A 79 year old female was admitted to CTO Intensive Care Unit in the immediate postoperative period of orthopedic surgery. A Swan-Ganz fiber optic catheter was inserted through the right internal jugular vein but it was not possible to obtain a satisfactory tracing off pulmonary artery occlusion pressure. We experienced a remarkable trouble to withdraw the catheter in order to repeat the insertion. A chest-X-ray was performed and it showed a knot of the catheter in the right ventricle. It was possible to extract the knotted catheter through original venotomy so avoiding surgery. We want to emphasize that it is of fundamental importance in the insertion of the Swan-Ganz catheter to respect the recommended distances and to avoid repeated attempts to advance and withdraw the catheter.

How many interscalenic blocks are there? A comparison between the lateral and posterior approach.

This study compares the areas of analgesia obtained with the lateral and posterior approaches to the interscalene space after injection of equal volumes of anaesthetic solution (40 ml of a mixture of 0.5% bupivacaine with adrenaline 1:200,000 and 2% lignocaine in equal parts). There was a significant difference in the distribution of the areas of analgesia between the two approaches. With the posterior approach, the region supplied by the radial, medial and ulnar nerves and the post-axial border of the upper limb were more frequently involved, whilst with the lateral approach the area of analgesia was usually confined to the regions supplied by the most caudal roots of the cervical plexus and the upper trunk of the brachial plexus (pre-axial border of the upper limb). On these grounds it appears that two different types of interscalene block are possible.

[The external jugular vein course as surface landmark in subclavian perivascular block]. / Il decorso della vena giugulare esterna quale punto di repere di superficie nel blocco perivascolare succlavio.

A study of 88 orthopaedic patients undergoing upper limb surgery, was carried out using the external jugular vein as surface landmark of the brachial plexus in subclavian perivascular technique. A significant statistical relationship was found between the insertion point of the needle, relatively to the external jugular vein course, and the block outcome. The best results were observed when the needle was inserted on the postero-lateral side of the vein or when the insertion point coincided with the vein course. Worse results were obtained by foreward insertion. So the external jugular vein could be used as surface landmark to improve the plexus localization in the subclavian perivascular technique of brachial plexus anaesthesia.

[How many interscalene blocks are there? Reflections on 109 cases studied with various techniques]. / Quanti sono i blocchi interscalenici? Riflessioni su 109 casi eseguiti con tecniche diverse.

The effects of interscalene block were studied on 109 patients undergoing upper extremity elective orthopaedic surgery. Blocks were performed in a non-randomized manner with three different techniques, the site where anaesthetic solution was injected being the main distinguishing mark. The anaesthetic solution was injected into the interscalenic compartment both in the case of patients where classic technique had been carried out and in the group where the nerve stimulator had been used. In the "double needle" technique group, on the contrary, the anaesthetic solution was injected close to the vertebral column. The spread of analgesia involves the caudal portion of the cervical plexus and the cranial portion of the brachial plexus, but with the cervical plexus is almost certain to be involved, the brachial is not. Block outcome was related to the surgical procedure (surgery or orthopaedic manipulation), the site of surgery, paraesthesia elicitation, prolonged surgery and height, weight, age and sex of patients. Results also different according to the technique used. When the anaesthetic solution was injected close to the vertebral column analgesic cover was more widespread and lesser amounts of anaesthetic needed. When the block was performed within the interscalenic compartment, the analgesic cover was usually restricted to the area supplied by the primary superior trunk of the brachial plexus. The different results were explained by the presence of fibrous sheaths within the interscalenic compartment limiting spread of the anaesthetic, which are absent close to the vertebral column. Therefore two types of interscalene block were postulated: an intrascalene or troncular block within the interscalenic compartment and a radicular or paravertebral block close the vertebral column.