Plasma Catecholamines During Surgical Stress: Differences Between Neurolept and Enflurane Anaesthesia

To evaluate the influence of enflurane and neurolept anaesthesia on the sympatho-adrenal response to surgery, arterial plasma concentrations of adrenaline and noradrenaline were measured at 11 carefully defined events before, during and after cholecystectomy in two groups of five patients. During steady-state anaesthesia prior to operation and after cholangiography, when the operative procedure had been interrupted for 10 min, adrenaline concentrations were similar in the two groups. During periods of stress such as intubation, skin incision and abdominal exploration, adrenaline levels were 4–6 times higher in the neurolept patients compared to the enflurane patients ( p <0.01), in whom adrenaline levels were very stable. Noradrenaline levels also varied with stress but without difference between the two groups. Systolic blood pressure was approximately 20 mmHg higher during operation in the neurolept group than in the enflurane group ( P <0.05). It is concluded that enflurane blocks the sympatho-adrenal response to surgical stress more effectively than conventional neurolept anaesthesia.     

Anaesthesia for closed embolisation of cerebral arteriovenous malformations

Cerebral arteriovenous malformation embolisation is a therapeutic, neuroradiological procedure involving injection of bucrylate glue into the nidus of the AV malformation to obliterate the abnormal vascular network. These procedures may involve significant risks, are often long and thereby necessitate the need for some form of sedation and for adequate monitoring of the cerebral, cardiovascular and respiratory systems. The anaesthetic management of a series of twenty patients undergoing embolisation of a cerebral arteriovenous malformation is outlined, seven general and nineteen neurolept anaesthetics being administered. Neurolept anaesthesia is the preferred technique as neurological assessment during the procedure is possible and complications may be diagnosed immediately. Systemic arterial hypotension may facilitate the embolisation process and various agents, including glyceryl trinitrate and sodium nitroprusside, have been employed for this purpose.     

Delayed post-traumatic cervical instability

BACKGROUND

Cervical spine instability is a clinical entity whose biomechanical and radiological features have been widely discussed by many authors. On the other hand, the subject of delayed post-traumatic cervical instability is often surrounded by confusion due to its difficult nosologic framing; the aim of this study is to contribute to the matter.

METHODS

A cooperative study was organized by the Study Group for Spinal Surgery of the Italian Society of Neurosurgery to evaluate cervical trauma patients surgically treated more than 20 days after the traumatic event. From a total number of 172 patients, twenty-five were admitted to the study, because neuroradiological investigations performed during the acute phase had shown either an absence of traumatic lesions or only minimal lesions judged to be stable. For this reason these 25 patients had not been treated by either surgery or immobilization in a halo vest. Some time after trauma, this group of patients clearly demonstrated evidence of unstable lesions requiring surgical treatment, following the appearance of new clinical signs or on neuroradiological follow-up.

RESULTS

Re-examination of the neuroradiological investigations performed during the acute phase made it possible to identify elements that might have led us to suspect the presence of ligamental lesions: microfractures, dislocations less than 3 mm, and inversion of physiological lordosis.

CONCLUSIONS

This review clearly indicates that patients with even mild cervical trauma must be scrupulously evaluated during the acute phase and that in some cases it is advisable to perform a more detailed neuroradiological investigation.     

Hemodynamics of coronary surgery patients under isoflurane and neuroleptanalgesia

The haemodynamic effects of isoflurane- and modified neurolept-anaesthesia were evaluated in 24 patients undergoing coronary artery bypass grafting. 12 patients (isoflurane group) were anaesthetized after an induction with 1.5 mg/kg methohexital and a unique dose of 0.005 mg/kg fentanyl with isoflurane (0.5-1.5 Vol%), N2O/O2 and pancuronium. 12 patients (neurolept group) received fentanyl (0.04 mg/kg), flunitrazepam, pancuronium and N2O/O2. Haemodynamic measurements were made before anaesthesia, in steady state anaesthesia, after sternotomy, after extracorporal circulation, after thoracic closure and one, two and four hours after the end of the operation. Between both groups we could not find significant differences in the haemodynamic parameters RAP, PAP, PCWP, PVR, CI, SVI, AP and CPP. However in the isoflurane group the peripheral vascular resistance (TPR) was significantly lower in steady state anaesthesia and after sternotomy. In the neurolept group the heart rate (HR) was significantly higher after bypass than in the isoflurane group. We believe, that at this time fentanyl analgesia was reduced. Before extracorporal bypass, patients with isoflurane anaesthesia had a lower arterio-mixed venous oxygen content difference (AVDO2) than patients with neurolept anaesthesia. Therefore it can be supposed that isoflurane lowers the oxygen demand more than neurolept anaesthesia. After surgery neurolept anaesthetized patients showed postanaesthetic shivering more frequently than those in the isoflurane group. We suggest that the vasodilating effect of isoflurane induces a homogeneous heat gain during warming the patients up, and that, therefore, in patients of the isoflurane-group AVDO2 and TPR were lower than in the patients of the neurolept-group during the first postoperative hours.(ABSTRACT TRUNCATED AT 250 WORDS)     

The cerebral arterio-venous oxygen content differences (AVDo2) during halothane and neurolept anaesthesia in patients subjected to craniotomy

In 20 patients subjected to craniotomy for supratentorial cerebral tumours, the haemodynamic changes during halothane and neurolept anaesthesia were evaluated by measuring mean arterial blood pressure (MABP) and cerebral arterio-venous oxygen content differences (AVDO2) repeatedly during the operation. Ten patients were given 0.5% halothane anaesthesia and ten patients neurolept anaesthesia. MABP, AVDO2 and PaCO2 were measured after induction of anaesthesia, before and after incision, after opening and closure of the dura, at the time of extubation and 1 h later. Concerning MABP and PaCO2, no significant difference between the two groups was found. In both groups an increase in MABP was observed after incision (P less than 0.01 in the neurolept group and P less than 0.05 in the halothane group) and in the neurolept group after extubation (P less than 0.01). In both groups a decrease in AVDO2 was observed after incision (P less than 0.01) and after extubation (P less than 0.01 in the neurolept group and P less than 0.05 in the halothane group). During the operation AVDO2 values were significantly higher in the neurolept group (P less than 0.05). The results indicate that even a moderate increase in MABP after incision during neuroanaesthesia affects AVDO2 values, suggesting an increase in cerebral blood flow. The study suggests that autoregulation of cerebral blood flow might be better preserved during neurolept anaesthesia. A state of hyperperfusion of the brain after extubation was unveiled in both groups.     

A new infusion design for atracurium and vecuronium

An infusion technique, designed to reduce the duration of period of no response to nerve stimulation following atracurium (Group I) and vecuronium (Group 2), was studied in 30 patients during neurolept anaesthesia. For intubation a combination of a small bolus injection of the relaxant (ED50) and a continuous infusion were administered. The tactile response to nerve stimulation was used to quantify the degree of relaxation and to adjust the speed of infusion. On the other arm the mechanical twitch was recorded blindly for control. Good to excellent intubation conditions were obtained in 4.3 min with atracurium and in 4.0 min with vecuronium. The total dose given for intubation was 0.36 mg kg-1 atracurium (0.24-0.49 mg kg-1) and 0.064 mg kg-1 vecuronium (0.046-0.084 mg kg-1). The period of no response was zero in seven patients in Group I and in four patients in Group 2. In the remaining patients in Group I the period of no response ranged from 5.0-25.0 min, median 10.9 min, and in Group 2 from 2.5-15.6 min, median 9.5 min. At the time of extubation the train-of-four ratio was 0.71 and 0.72 in Group I and 2, respectively. It is concluded that it is possible to achieve a stable, adjustable, and easily reversible block with this technique, even during surgery of short duration.     

Postoperative Ventilatory Response to Carbon Dioxide Following Neurolept Anaesthesia

In order to investigate the duration of respiratory depression following neurolept anaesthesia, 21 patients who had hemilaminectomia performed were subjected to ventilation-carbon dioxide response tests by a rebreathing method in the post-operative period. Up to 3 1/2 h after start of anaesthesia all patients had a decreased ventilatory response to carbon dioxide. After this period some patients showed a normal respiratory response, while others remained depressed for up to 6 h, the period for which the investigation lasted. Most patients in the depressed group were premedicated with pethidine. We conclude that additional narcotics are contraindicated for a period of 3 1/2 h following the start of neurolept anaesthesia for surgical procedures lasting 1-2 h, while clinical control is still necessary before administration of additional narcotics within 6 h, especially if narcotics have been used as premedication.     

Assessment of neuromuscular transmission by the evoked acceleration response

This paper presents preliminary observations on an acceleration-responsive transducer designed to monitor neuromuscular transmission. Simultaneously evoked acceleration and tension responses of the adductor pollicis muscles were studied. Registrations were obtained during recovery from atracurium-induced block in 29 individuals in neurolept II anaesthesia (Group I) and in 4 ICU patients (Group II) sedated with pentobarbital or midazolam. Regression analysis of 1567 train-of-four (TOF) registrations, in regard to TOF-ratio (T4/T1) and first twitch ratio (T1/T0), demonstrated regression coefficients (b) and correlation coefficients (r) in the range 0.91-1.06 and 0.89-0.98, respectively. During 1 Hz single twitch stimulation and post-tetanic count stimulation, b and r were in the range 0.85-1.03 and 0.77-0.90, respectively. Following administration of edrophonium (n = 6, Group I) a deviation of T1/T0 regression values was observed in four individuals, i.e. 0.48 (b) and 0.56 (r). This investigation proved a good level of accuracy of the acceleration transducer compared to the force displacement transducer during spontaneous and neostigmine-induced recovery from atracurium block. The acceleration transducer-based system does not require a rigid suspension and seems to have a good monitoring potential in clinical assessment of neuromuscular transmission.     

Epilepsy in patients with spina bifida in the lumbosacral region

This study aimed to assess the relevance of epilepsy and spina bifida in the lumbosacral region. We evaluated 75 patients with spina bifida admitted to the Kyushu University Hospital from 1980 to 2004. Patients were classified as having meningocele (MC, 4 cases), myelomeningocele (MMC, 6), myeloschisis (MS, 45), and lumbosacral lipoma (LL, 20). Nine cases had epileptic disorders, and all showed MS. Meticulous neuroradiological investigations revealed cerebral abnormalities such as polymicrogyria or hypogenesis of the corpus callosum in all epileptic cases. Locations of cerebral abnormalities topographically correlated with areas of interictal EEG abnormalities. Although all epileptic cases had ventriculoperitoneal (VP) shunt for hydrocephalus before the onset of epilepsy, interictal EEG abnormalities could not be explained by location of the VP shunt. In all LL patients, neither history of epilepsy nor cerebral abnormalities were noted on magnetic resonance imaging (MRI). Epileptogenesis in spina bifida patients seemed to correlate with coexisting cerebral abnormalities in MS patients rather than with the VP shunt. However, not all spina bifida patients associated with cerebral abnormalities had epilepsy, and not all cerebral abnormalities were epileptogenic, suggesting that epilepsy in spina bifida patients was multifactorial.     

Propofol anaesthesia versus paracervical blockade with alfentanil and midazolam sedation for outpatient abortion

Propofol anaesthesia was compared with paracervical blockade in a prospective, randomized study of 59 abortion patients. All the patients received alfentanil 0.01 mg/kg i.v. at the start of anaesthesia and were randomized into two groups. Group R (regional, 31 patients): midazolam 0.1 mg/kg i.v. and paracervical blockade with 2 x 10 ml of mepivacaine 20 mg/ml + adrenaline 0.005 mg/ml. Group G (general, 28 patients): propofol 2.0 mg/kg i.v. induction and 75% nitrous oxide in oxygen spontaneous respiration. In 10 patients from the R-group venous blood samples were taken regularly for 30 min for serum concentration measurements (gas chromatography) of mepivacaine. Pain during induction of anaesthesia was remembered by 17% in Group G and 4% in Group R, whereas 8% in Group R remembered pain during the procedure compared with none in Group G. Of the patients in Group G, 25% had apnoea compared with none in Group R. In Group R the patients slept for 2.5 +/- 3.8 min (mean +/- s.d.) after induction compared with 12 +/- 4.0 min in Group G. Except for a better p-deletion score 30 min after the procedure in Group G, there was no difference in recovery function between the groups. Of the patients in Group G, 67% experienced postoperative pain compared with 23% in Group R. Maximum serum mepivacaine concentration (Group R) was reached at 15-30 min, range 1.5-5 micrograms/ml.     

Clinical analysis of ossified thoracic ligaments and thoracic disc hernia]

Thoracic lesions present several clinical problems, particularly in their diagnosis and treatment, compared with cervical or lumbar lesions. Since 1983, 18 cases of thoracic space lesions, excluding spinal tumors or trauma have been experienced: nine cases of ossification of yellow ligament (OYL), five of ossification of posterior longitudinal ligament (OPLL), and four of disc hernia (DH). In these 18 patients, problems of clinical manifestations, neuroradiological examination, and surgical approaches are analyzed and discussed. As clinical manifestations, there was a preponderant occurrence in males in the OYL group, while in the OPLL group all the patients were females. OYL and DH occurred at lower thoracic levels. Thirteen of the 18 patients showed combined lesions either in the cervical or in the lumbar regions, such as cervical OPLL, cervical spondylosis, lumbar DH, and lumbar canal stenosis. In the neuroradiological examinations diagnosis of the upper thoracic lesions was difficult. Computed tomography (CT) scan with intrathecal metrizamide injection seemed essential for examination of ossified thoracic lesions. However, because CT imaging of the entire spine is impractical, efficient use of this examination requires previous localization of the offending vertebral level from either the neurological findings or other neuroradiological examinations such as myelography. Magnetic resonance imaging seemed most useful for ruling out the thoracic compressing lesions. As for surgical approaches, posterior decompression was effective for OYL and the anterior approach was useful for OPLL and DH. In patients with "tandem lesions," neurological and neuroradiological findings played an important role in deciding the responsible site.     

Avoiding Psychic Adverse Effects during Induction of Neurolept Anaesthesia with Levomepromazine A Double-Blind Study of Levomepromazine and Droperidol

Levomepromazine 0.1 μg/kg or droperidol 0.15 mg/kg for induction of neurolept anaesthesia were compared in a double-blind prospective study of 60 patients undergoing upper abdominal surgery. On the morning after surgery, eight of 30 patients (26.7%) who received droperidol remembered having had unpleasant anxiety, or nightmarish or panicky experiences during induction of anaesthesia, whereas only one of 30 patients (3.3%) receiving levomepromazine experienced such unpleasant adverse effects ( P <0.0l). During anaesthesia, the patients induced with levomepromazine needed somewhat less fentanyl, had somewhat less pain intensity, during the first 3 h after surgery, and they required the first postoperative dose of morphine 1.5 h later than the patients receiving droperidol ( p <0.02). There was no difference in the number of patients receiving naloxone at the end of anaesthesia in the two groups. However, 21 of 30 patients (70%) in the levomepromazine group and only seven of 30 patients (23.3%) in the droperidol group were given physostigmine for arousal at the end of anaesthesia ( p <0.0l). There was no difference between the two groups in the occurrence of postoperative nausea, restlessness, hallucinations, or sedation in the recovery ward. This study shows that levomepromazine is superior to droperidol for induction of neurolept anaesthesia because it gives less psychic adverse effects. more analgesia, and a deeper sedation, which is easily reversed with physostigmine at the end of anaesthesia.     

Effect of injections of contrast media on regional uptake of (14C)-2-deoxyglucose by the rat brain

Mechanisms contributing to the rare but consistent neurotoxicity of contrast media currently in clinical use for the radiological examination of the subarachnoid space remain to be isolated. We assessed, by means of the (¹⁴C)-2-deoxy-D-glucose (2-DG) autoradiographic method, the effect of three non-ionic, low-osmolar contrast media, namely metrizamide, iopamidol and iohexol, on the local cerebral glucose utilization in the rat brain after intracisternal application.

A significant (- 30%) global reduction of the brain's metabolic activity occurred following intracisternal metrizamide injection. When compared with the mock-CSF control group the greater relative changes were observed in the supratentorial grey matter structures. In contrast, no significant changes were observed in metabolic brain activity in rats treated intracisternally with iopamidol and iohexol.

These findings were consistent with the hypothesis that metrizamide is a competitive inhibitor of human brain hexokinase. The apparent lack of interference on neural tissue metabolism makes the second generation contrast media less neurotoxic and more suitable for neuroradiological subarachnoid investigations in clinical settings. The present experimental work establishes the 2-DG method as a viable laboratory approach to investigate aspects of neuronal dysfunction induced by contrast media.     

A myoclonic seizure during propofol-alfentanil anesthesia?]

Total intravenous anaesthesia with propofol and alfentanil is an established alternative to inhalation anaesthesia for intracranial neurosurgical procedures. Its usefulness has been somewhat overshadowed by reports of seizure-like movements, both during anaesthesia and in the recovery period. These can be related to the use of either anaesthetic agent, but true epileptogenic properties still remain to be demonstrated in man. Opioid-induced rigidity is a well known phenomenon and must not be mistaken for an epileptic seizure. Myoclonic motor activity can be observed even under physiological conditions, e.g. sleep. Almost all anaesthetic agents have been found to produce "epileptic" EEG changes (spikes, polyspikes, spike-wave complexes), but in man these have never been correlated to motor reactions. Propofol's pro- or anticonvulsive action is unclear. While some groups found shortened convulsing times in patients undergoing electroconvulsive therapy with propofol instead of methohexitone, others have reported activation of epileptogenic foci in the EEGs of known epileptic patients. A synergistic effect of propofol and alfentanil in the generation of seizure-like movements cannot be excluded. Whether seizure-like movements indicate a true "epileptogenic potency" of the anaesthetic drugs or are related to other phenomena remains to be studied. Electro-encephalographic monitoring during anaesthesia as well as careful observation and documentation of motor reactions may contribute to elucidation of the problem. We report a case of seizure-like movements during propofol-alfentanil anaesthesia for an elective craniotomy. A 52-year-old patient presented with a history of headaches of increasing frequency. A CT brain scan demonstrated a tumor in the left occipital region.(ABSTRACT TRUNCATED AT 250 WORDS)     

Thromboembolic complications after major abdominal surgery: effect of thoracic epidural analgesia

In a prospective study of 50 patients subjected to major abdominal surgery, the frequencies of postoperative deep vein thrombosis and pulmonary embolism were analysed. The patients were randomized to one of two groups receiving either neurolept anaesthesia or neurolept anaesthesia combined with thoracic epidural analgesia. Five patients were excluded. No special anti-thrombotic prophylaxis was administered. Deep vein thrombosis was diagnosed with the 125I-fibrinogen test and pulmonary embolism with pre- and postoperative lung perfusion scintigraphy combined with lung X-ray. Patients with positive scintigraphy were subjected to pulmonary angiography for verification of the diagnosis. Deep vein thrombosis was treated when diagnosed. The frequency of deep vein thrombosis was equal in both groups (38%). No patient with pulmonary embolism was recorded during the first seven days after operation. It is concluded that the addition of thoracic epidural analgesia to neurolept anaesthesia does not alter the postoperative frequency of deep vein thrombosis in patients subjected to major abdominal surgery. Early diagnosis and treatment of postoperative deep vein thrombosis might prevent pulmonary embolism. Problems encountered in the diagnosis of postoperative pulmonary embolism are discussed.     

Renal Function During Neurolept Anaesthesia

Renal function and central haemodynamics were studied in eight patients, without known histories of renal or cardiovascular disease, during and immediately after upper abdominal surgery under neurolept anaesthesia. Inulin and PAH clearance, fractional sodium and fractional osmolar excretion decreased, while fractional free water reabsorption increased under anaesthesia. Cardiac output, mean systemic arterial pressure and systemic vascular resistance remained virtually unchanged both per- and postoperatively. Renal haemodynamics were promptly restored postoperatively, while fractional sodium and fractional osmolal excretion were unaltered and antidiuresis increased. It is concluded that neurolept anaesthesia, as far as renal function is concerned, is well suited for the anaesthetic management of the poor-risk patient.     

Haemodynamic Effects of Calcium Chloride Administered Intravenously to Patients with and without Cardiac Disease during Neurolept Anaesthesia

During neurolept anaesthesia, calcium chloride (15 mg/kg) was administered intravenously to two different groups of patients undergoing vascular surgery on the abdominal aorta. The patients in group I all suffered from cardiac disease and were treated with digoxin, while the patients in group II had no cardiac symptoms. Cardiovascular measurements were made during steady-state anaesthesia. In group I, CaCl₂ increased cardiac index (CI) significantly while systemic vascular resistance index (SVRI) remained unchanged. Mean arterial pressure (MAP) increased. In group II, both MAP and SVRI increased while CI remained unchanged. No significant changes in heart rate were observed and no arrhythmias occurred. It is concluded that CaCl₂ administered intravenously is an effective means of improving cardiac function when it is depressed by anaesthesia, underlying cardiac disease, or both.     

Bacterial filters - are they necessary on anaesthetic machines?

At the Vancouver General Hospital the effectiveness of the system for decontamination of anaesthetic equipment was evaluated to determine the need for bacterial filters on anaesthetic machines. Two groups of patients were studied. Group I consisted of 33 patients, none of whom had clinical symptoms of respiratory tract disease. Group II consisted of 17 patients who had lower respiratory tract secretions. In the latter group 16 had chronic bronchitis and had cystic fibrosis. Of 550 bacterial cultures taken from the anaesthetic equipment immediately before and after anaesthesia in our 50 patients, only five yielded a growth of non-pathogenic bacteria. The results of this study indicate that bacterial colonization of anaesthetic equipment is of a low order and is adequately controlled by pasteurization even after use in patients with chronic lower respiratory tract disease. The use of bacterial filters does not appear justified if a strict regimen of cleaning and pasteurization is followed.     

Hyperbaric bupivacaine affects the doses of midazolam required for sedation after spinal anaesthesia

BACKGROUND AND OBJECTIVE: Patients having spinal anaesthesia with hyperbaric bupivacaine may become sensitive to sedative drugs but no data exists about any dose-related effect of the local anaesthetic on the sedative requirement. We aimed to investigate whether hyperbaric bupivacaine dose in spinal anaesthesia has any effect on midazolam requirements. METHODS: Sixty unpremedicated patients were allocated to three equal groups. Patients in Groups I and II received hyperbaric bupivacaine 0.5% 10 and 17.5 mg respectively for spinal anaesthesia and Group III was a control group without spinal anaesthesia. In Groups I and II, after the evaluation of sensory block, patients received intravenous midazolam 1 mg per 30 s until the Ramsay sedation score reached 3 (drowsy but responsive to command). In Group III, general anaesthesia was induced after sedation score had reached 3 using midazolam. The total dose of midazolam (mg kg(-1)) given to each patient, the level of sensory block and complications were recorded. RESULTS: The level of sensory block was higher in Group II (T7) than Group I (T9) (P < 0.01). The doses of midazolam were 0.063 mg kg(-1) in Group I, 0.065 mg kg(-1) in Group II and 0.101 mg kg(-1) in Group III (P < 0.001). There was no correlation between level of sensory block and dose of midazolam in Group I (r = -0.293, P = 0.21) and Group II (r = 0.204, P = 0.39). CONCLUSIONS: Different doses of hyperbaric bupivacaine for spinal anaesthesia do not affect the midazolam requirements for sedation. However, spinal anaesthesia with hyperbaric bupivacaine with a maximum spread in the middle thoracic dermatomes may be associated with sedative effects and thus a reduced need for further sedation with midazolam.     

Anaesthetic techniques and thromboembolism in total hip arthroplasty

Sixty patients who were scheduled for total hip replacement were randomly allocated to receive either epidural blockade or neurolept anaesthesia. All patients received dextran 70. The blood loss during surgery and the mean arterial blood pressure were lower following epidural anaesthesia. However, the frequency of deep venous thrombosis and pulmonary embolism, as diagnosed by ascending phlebography and pulmonary scintigraphy, was the same in the two groups. It is concluded that, although epidural anaesthesia may be considered for other reasons, there is no reduction in thromboembolic complications with this anaesthetic technique in patients who receive dextran.