Consciousness, cognition and brain networks: New perspectives

A detailed analysis of the literature on consciousness and cognition mechanisms based on the neural networks theory is presented. The immune and inflammatory response to the anesthetic-surgical procedure induces modulation of neuronal plasticity by influencing higher cognitive functions. Anesthetic drugs can cause unconsciousness, producing a functional disruption of cortical and thalamic cortical integration complex. The external and internal perceptions are processed through an intricate network of neural connections, involving the higher nervous activity centers, especially the cerebral cortex. This requires an integrated model, formed by neural networks and their interactions with highly specialized regions, through large-scale networks, which are distributed throughout the brain collecting information flow of these perceptions. Functional and effective connectivity between large-scale networks, are essential for consciousness, unconsciousness and cognition. It is what is called the "human connectome" or map neural networks.

National survey on thromboprophylaxis and anticoagulant or antiplatelet management in neurosurgical and neurocritical patients

OBJECTIVES

To determine the protocols used by Spanish anaesthesiologists for thromboprophylaxis and anticoagulant or antiplatelet drugs management in neurosurgical or neurocritical care patients.

MATERIAL AND METHODS

An online survey with 22 questions, with one or multiple options, launched by the Neuroscience Subcommittee of the Spanish Anaesthesia Society and available between June and October 2012.

RESULTS

Of the 73 hospitals included in the National Hospitals Catalogue, a valid response to the online questionnaire was received by 41 anaesthesiologists from 37 sites (response rate 50.7%). Only one response per site was used. A specific protocol was available in 27% of these centres. Mechanical thromboprophylaxis is used, intraoperatively or postoperatively, in 80%, and pharmacological treatment is used by 75% of respondents. Enoxaparin was the most frequent heparin used in craniotomy patients (78%). Craniotomies were performed maintaining acetylsalicylic acid treatment in patients with coronary stents and double anti-platelet treatment in a half of the centres.

CONCLUSIONS

Mechanical thromboprophylaxis is used more frequently than the pharmacological approach in neurosurgical or neurocritical populations in Spanish hospitals. Management of patients under previous anticoagulant treatment was highly heterogeneous among hospitals included in this survey. Previous antiplatelet treatment is modified depending on primary or secondary prescription.

[Comparison of 3 combinations of 0.5% levobupivacaine and 1% mepivacaine in popliteal sciatic block in hallux valgus outpatient surgery]

BACKGROUND

To compare 3 combinations of 0.5% levobupivacaine (L) and 1% mepivacaine (M) for popliteal block for hallux valgus surgery.

METHODS

Prospective, double blind study of 120 patients undergoing unilateral hallux valgus outpatient surgery with posterior popliteal block with ultrasound-guided single injection. Patients were randomly allocated into three groups: G1: 20mL L+10mL M; G2: 10mL L+20mL M; and G3: 15mL L+15mL M. Recorded variables were: time of block, onset and reversal times for tibial and peroneal nerves block; postoperative pain until the 7(th) day by means of visual analogue scale (VAS), simple descriptive scale and the quality of nocturnal rest, complications, and patient satisfaction. ANOVA and chi2 were applied in the statistical analysis, with a P<0.05 considered significant.

RESULTS

Groups were homogeneous for demographic and surgical characteristics. None of the patients required intraoperative complementary analgesia or anaesthesia. Block onset was significantly longer in G1 than in G2 and G3 (39.4±14.7 versus 32.2±16.5 and 33.2±12minutes). Recovery time from sensory and motor block was significantly longer in G1 than in G2 and G3 (29.5±9.3 versus 22.2±8.2 and 24.8±7.9hours). Postoperative pain level was below VAS 30 (1-100) in the three groups; none of the patients experienced severe pain. Maximum pain level appeared at 24h postoperatively. Patient satisfaction was high and there were no complications.

CONCLUSIONS

Block onset time and anaesthetic efficacy was adequate in the three groups. The combination of 20mL levobupivacaine 0.5% with 10mL mepivacaine 1% provide a good alternative for a lasting postoperative analgesia.

[Cerebrovascular accident with haemorrhagic transformation in a patient on antiplatelet treatment subjected to surgery of a hypophyseal macroadenoma]

The case is presented of a 51 year-old woman, proposed for endoscopic endonasal transsphenoidal resection of a hypophyseal macroadenoma diagnosed in the context of a stroke suffered 10 weeks before the date of the surgery. During this time, she had been treated with antiplatelet drugs, which were withdrawn 5 days before the surgery. The surgical procedure was performed without any incidents. On the second day after the surgery, the patient had an ischaemic infarction of the left cerebellar hemisphere, with signs of hydrocephaly and a posterior haemorrhagic transformation, with brain death 5 days after the operation. There are no definitive guidelines on the use of antiplatelet drugs in the perioperative period of neurosurgery. Also, there is no agreement as regards the waiting time between a cerebrovascular event and surgery, it appears that between 4 and 12 weeks would be the most advisable. The importance of an individual assessment of each patient before surgery is emphasised, as well as a review of the antiplatelet management of the patient with a risk of thrombosis in the context of neurosurgery, and their possible postoperative complications.

[Importance of monitoring neuroendoscopic intracranial pressure during anesthesia for neuroendoscopic surgery: review of 101 cases]

OBJECTIVE

The aim of this study was to describe monitoring, anesthetic management, and risk factors for complications in neuroendoscopic surgery.

PATIENTS AND METHODS

Patients who underwent neuroendoscopy between 1994 and 2003 under general anesthesia, with monitoring of intracranial pressure from inside the neuroendoscope, were studied retrospectively. In some patients, the blood flow rate in the middle cerebral artery was monitored using transcranial Doppler ultrasound. Information was collected related to surgical procedure and the development of complications.

RESULTS

Of 101 patients included in the study, transcranial Doppler ultrasound images were available for 20. In 75 patients neuroendoscopic intracranial pressure exceeded 20 mm Hg. Forty-five percent of the patients with available transcranial Doppler ultrasound images showed episodes of reduced diastolic flow rate in the middle cerebral artery during ventricular irrigation. Hemodynamic instability was associated with higher neuroendoscopic intracranial pressures (P < .05). An increase of more than 30 mm Hg in neuroendoscopic intracranial pressure was associated with more postoperative complications, the most common of which was delayed awakening. Procedures that were more complicated than a simple ventriculostomy were performed in 58% of the cases. Mean (SD) neuroendoscopic intracranial pressures in such cases were higher (50.5 [30.9] mm Hg vs 31.8 [25.1 mm Hg] in the simpler procedures) and the postoperative complication rate was higher (P = .003).

CONCLUSIONS

Neuroendoscopic surgery can causes increases in neuroendoscopic intracranial pressure that are associated with disturbances in cerebral blood flow and complications. This situation demonstrates the importance of monitoring intracranial pressure and cerebral blood flow.

[Problem/case-based learning compared to lectures for acquiring knowledge of air embolism in continuing medical education]

OBJECTIVE

The efficacy of continuing medical education in anesthesiology has been examined very little. This study compared the efficacy of a lecture on air embolism to that of a class that used a problem/case-based learning approach.

MATERIAL AND METHODS

Prospective, randomized study enrolling 52 experienced anesthesiologists participating in a professional development course. Twenty-six anesthesiologists attended a lecture on air embolism in anesthesia and 25 attended a problem-based class. The objectives were the same for both groups and had been defined previously. The participants' knowledge was evaluated before and after the instruction with tests based on 2 cases dealing with the same knowledge areas: risk factors and symptoms, diagnosis, monitoring, and treatment.

RESULTS

No significant between-group differences were found for any of the knowledge areas before or after the classes. After instruction, participants who listened to the lecture improved their scores for knowledge of monitoring (P = .03) and treatment (P = .001). Participants in the problem-based learning group also improved their scores for knowledge of treatment (P = .003).

CONCLUSIONS

No between-group differences in participants' knowledge outcomes were detected; improvements were minimal. The study design allowed the knowledge acquired to be evaluated objectively.

[Neuroanesthetic practice in Catalonia. Results of a survey done on 2003]

INTRODUCTION

Health system planning requires the precise knowledge of the activity performed. We present the neuroanesthesic activity results in Catalonia during 2003.

METHODS

A prospective and cross-sectional survey was performed for 14 randomised days during 2003. All hospitals practicing anaesthesia in Catalonia took part in the survey. Data on characteristics of patients, anaesthetic techniques and type of procedure were included.

RESULTS

6909 neuroanesthetic procedures performed in Catalonia in 2003 (95% IC 6022-7847), a 1.28% of total surgical activity. A 74% of procedures were done in the public hospitals and a 26% in private hospitals. Patients mean age was 48 years old (95% IC 45.5-50.6). Scheduled procedures were 79.7%. The most frequent interventions were: Spine surgery 40.1 %; craniotomies for tumour resection 24.1%, for haemorrhage o trauma 7.2% and for aneurysms or AVM surgery 2.3%; ventricular shunts 2.6%. Mean duration of craneotomies for tumour resection was 287 -/+95 min. All patients were distributed postoperatively in a conventional recovery room (55.8 %), in a monitored care unit (19.2%) or in an intensive care unit (24.9 %). Craniotomy patients were admitted to an intensive care unit (41.6%), a monitored care unit (33.7%) or a conventional recovery room (24.7%).

CONCLUSIONS

About seven thousand Neurosurgical procedures were performed in Catalonia in 2003, in public (73.6%) and private (26.4%) hospitals. Spine surgery and craniotomies for tumour resection were the most frequently performed interventions. Craniotomy patients were mainly submitted to an ICU or a Monitored care unit.

Cerebrospinal Fluid Composition Modifications after Neuroendoscopic Procedures

Normal saline solution is currently used as the ventricular irrigation fluid during neuroendoscopic procedures. The aim of this study is to determine the alterations in the cerebrospinal fluid (CSF) composition after neuroendoscopic interventions. Twenty nine patients who underwent a neuroendoscopic procedure under general anaesthesia were studied. Temperature inside the cerebral ventricle was measured and samples of CSF were taken to determinate oxygen and carbon dioxide partial pressures, pH, base excess, ionised calcium, standard bicarbonate, glucose, sodium, potassium, magnesium, total calcium, proteins, chlorine and osmolality before initiating the irrigation and after the neuronavigation. Patient demographics, neuronavigation time, total fluid volume used and temperature of the irrigation solution and complications that appeared in the first 24 hours were collected. Mean age of the patients was 42+/-18 years. The mean neuronavigation time was 21.5+/-15.4 minutes. The mean amount of saline solution used for irrigation was 919.6+/-994.7 mL. All the values studied in the CSF, except osmolality, showed significant variations. There was a significant correlation between the CSF variation of pH, oxygen and carbon dioxide partial pressures, base excess, standard bicarbonate, glucose and total calcium with respect to the total volume of irrigation solution, but not with respect to the neuronavigation time. A cut-off point of 500 mL of irrigation solution (sensitivity 0.7; specificity 0.87) was related with a CSF pH decrease greater than 0.2. The use of saline as irrigation solution during neuroendoscopic procedures produces important changes in CSF.

[Outcome after spontaneous subarachnoid hemorrhage. Relationship between admission glycemia and clinical status on admission and on hospital discharge]

BACKGROUND

To determine the relationship between the glycemia on hospital admission after subarachnoid haemorrhage (SAH) and neurological score.

PATIENTS AND METHODS

On 44 patients we recorded the glycemia value on admission, coma Glasgow scale (CGS) and Hunt and Hess scale grade (HH), on admission, on discharge and six months later.

RESULTS

The patients with HH IV-V and GCS between 3 and 8 had glycemia values higher than patients with HH I-III and GCS between 9 and 15. The patients with HH IV-V on discharge had glycemia values higher than patients with HH I-III.

CONCLUSIONS

Glycemia value on admission is related with the acute injury severity and represents a prognosis factor in spontaneous subarachnoid haemorrhage outcome.

[Learning cardiopulmonary resuscitation using conventional external cardiac massage or active compression-decompression in simulated cardiopulmonary resuscitation]

OBJECTIVE

To compare medical students' simulated learning of two different techniques of cardiopulmonary resuscitation (CPR). One was conventional external cardiac massage (ECM) and the other was active compression-decompression (ACD-CPR).

MATERIAL AND METHODS

The study group (group S) comprised 111 students enrolled in their fourth year of medical studies who had no prior experience of CPR. Group R, the control group, was made up of 32 medical residents in anesthesiology and post-anesthetic intensive care. Before the study, group S received 5 hours of theoretical classes on CPR and both groups saw a video explaining each technique just before performing the test. All subjects applied each method to an adult dummy for one minute. The variables evaluated were frequency of complete and effective thoracic compressions and the body weight of the resuscitator.

RESULTS

Each group performed similarly using the two techniques in terms of frequency of total compressions achieved. For each technique, the number of effective compressions achieved by group S (49.4 +/- 22.9 with ECM and 42.5 +/- 20.7 with ACD-CPR) was significantly lower (p < 0.05) than the number attained by group R (71.2 +/- 18.6 with ECM and 58.8 +/- 12 with ACD-CPR). Group R's frequency of effective compressions was significantly higher (p < 0.05) with CPR than with ACD-CPR. Body weight had no influence on the number of total compressions or efficacy in group R, whereas lower body weight in group S was significantly related to lower frequency of effective compressions with ECM p < 0.05). Neither group achieved a frequency of 80 total compressions in one minute.

CONCLUSIONS

With the present teaching method, the medical students' performance was poor for both types of CPR and was affected by body weight. The residents' performance was less effective with ACD-CPR, a technique that was new to them, than with conventional ECM, with which they were expert and on which body weight had no impact.

[Determinants associated wtih the presence of risk behaviors in HIV infected patients]

BACKGROUND

Determinants associated with risk behaviours are evaluated in a known HIV-infected population not belonging to the great metropolitan nuclei.

PATIENTS AND METHODS

110 unselected HIV+ patients were interviewed, including 77 variables. Their association with sharing needles, and unprotected sex is analysed.

RESULTS

Sharing needles was associated to: low academic achievement (p = 0.045), no children (p = 0.045), any physical limitation (p = 0.004), previous admission to detoxification unit (p = 0.014), and depression. With unprotected sex were associated: low academic achievement (p = 0.005), lesser time of HIV infection (p = 0.009), no family support (p = 0.005), and scanty information about HIV transmission (p = 0.018).

CONCLUSIONS

A cohort of HIV-infected subjects who persist with risk practices is remaining. Some easily recognizable variables may be useful for their early recognition.

Bacterial colonization patterns in mechanically ventilated patients with traumatic and medical head injury. Incidence, risk factors, and association with ventilator-associated pneumonia

We prospectively evaluated the relation of upper airway, lower airway, and gastric colonization patterns with the development of pneumonia and its etiology in 48 patients with surgical (n = 25) and medical (n = 23) head injury. Initial colonization was assessed by cultures of nasal and pharyngeal swabs, tracheobronchial aspirates, gastric juice, and bronchoscopically retrieved protected specimen brush. Follow-up colonization was determined until the end points extubation, suspected ventilator-associated pneumonia (VAP), or death. The initial colonization rate at any site at ICU admission was 39/47 (83%). It mainly accounted for Group I pathogens (Streptococcus pneumoniae, Staphylococcus aureus, Hemophilus influenzae) of the upper and lower airways. At follow-up, colonization rates with Group II pathogens (Gram-negative enteric bacilli and Pseudomonas spp.) increased significantly. The high initial bacterial load with Group I pathogens of the upper airways and trachea decreased during Days 2 to 4, whereas that of Group II pathogens increased. Upper airway colonization was an independent predictor of follow-up tracheobronchial colonization (odds ratio [OR], 9.9; 95% confidence interval [CI], 1.8 to 56.3 for initial colonization with Group I pathogens; OR, 23.9; 95% CI, 3.8 to 153.3 for follow-up colonization with Group II pathogens). Previous (short-term) antibiotics had a protective effect against colonization with Group I pathogens of the lower respiratory tract (OR, 0.2; 95% CI, 0.05 to 0.86), but they were a risk factor for colonization with Group II pathogens (OR, 6.1; 95% CI, 1.3 to 29). Initial tracheobronchial colonization with Group I pathogens was associated with a higher probability of early onset pneumonia (OR, 4. 1; 95% CI, 0.7 to 23.3), whereas prolonged antibiotic treatment (> 24 h) independently predicted late-onset pneumonia (OR, 9.2; 95% CI, 1.7 to 51.3). We conclude that patients with head injury are colonized in the airways mainly by Group I pathogens early in the evolution of illness. The upper airways represent the main reservoir for subsequent lower airway colonization with Group I pathogens. Previous (short-term) antibiotic treatment is protective against initial tracheobronchial colonization with Group I pathogens, but it represents a risk factor for subsequent lower airway colonization by Group II pathogens.

Histopathology of ventilator-associated pneumonia (VAP) and its clinical implications

Ventilator-associated pneumonia (VAP) is a diffuse polymicrobial and dynamic process, with heterogeneous distribution of lesions, showing different degrees of histological evolution predominating in the dependent lung zones, in which microbiology and histology can be dissociated. This might explain why blind endobronchial techniques to collect respiratory secretions have similar accuracy compared to visually guided samples, explaining the difficulties in validating any methods for its diagnosis. In the clinical setting the association of acute lung injury (ALI) and pneumonia is controversial. However, it is rare to detect diffuse alveolar damage (DAD) in absence of histological signs of pneumonia, probably evidencing that ALI favors the development of pneumonia. Histopathologically, it is difficult to distinguish initial and resolution phases of DAD from pneumonia and vice versa. On the other hand, there is a clear relationship between antimicrobial treatment and the decreased lung bacterial burden which strengthens the importance of distal airway sampling before starting antibiotic therapy.

Unilateral trigeminal and facial nerve palsies associated with epidural analgesia in labour

PURPOSE

To report a rare complication related to epidural analgesia for obstetrics: the association of unilateral trigeminal and facial nerve palsies in a patient with the clinical syndrome of intracranial hypotension.

CLINICAL FEATURES

A 38-yr-old woman was admitted in pre-term labour (at 35 wk gestation). She was receiving 40 mg methadone po daily for opioid addiction. Epidural analgesia for labour was established with 9 ml bupivacaine 0.25%. The patient underwent normal vaginal delivery of a 2500 g female infant. She developed post-dural puncture headache (PDPH) on the third postpartum day which was managed by palliative measures: bed rest (patient's position of choice), increased hydration (water: 3 litres po per day), lysine acetyl salicylate (5.4 g po per day) and caffeine (600 mg po per day). She developed paraesthesiae and numbness of the right side of the face one day after the onset of PDPH and unilateral facial nerve palsy two days later. There was no evidence of dural puncture and no cause was found. Treatment of the nerve palsies with epidural blood patch or epidural dextran 40 was not considered to be indicated. Headache disappeared on the 10th postpartum day and trigeminal palsy regressed. At the time of discharge, on the 17th postpartum day, neurological examination showed minimal facial assimetry. The patient refused further exploration and follow-up.

CONCLUSION

Post delivery trigeminal and facial nerve palsy in a 38 yr old woman recovered spontaneously with conservative therapy.

[Outcome of patients who underwent surgical repair of aneurysm after subarachnoid hemorrhage]

BACKGROUND

Follow-up study of patients with surgical repair of aneurysmal subarachnoidal hemorrhage (SAH), looking for clinical outcome predictors.

PATIENTS AND METHODS

Sixty two patients consecutively admitted to a teaching hospital, from January 1992 to December 1995 were included in the study. We studied preoperative, intraoperative and postoperative features looking for their relationship with the outcome. The ultimate outcome was evaluated by means of Glasgow Outcome Scale on discharge and 6 months later.

RESULTS

Smoking (p = 0.0001) and arterial hypertension (AHT) (p = 0.0186) were more frequent in these patients than in general population, but without relationship to the outcome as with the age of the clinical status on admission. The greatest statistical relationship was found between the level of consciousness on postoperative awakening (measured by the Hunt and Hess scale), and the outcome (p = 2.53 x 10(-8). From our results we made an algorithm that correctly assigned 92% of studied patients to their outcome.

CONCLUSIONS

All patients admitted on with aneurysm SAH deserve intensive care treatment besides their clinical grade. The level of consciousness on postoperative awakening was a good outcome predictor.

[Analysis of the current status of neuroanesthesia in Spain using a national survey]

OBJECTIVES

Advances in complementary diagnostic explorations, surgical support technology and the complexity of neurophysiological monitoring require anesthesiologists to acquire specific knowledge for dealing with neurosurgery. We aimed to study the implantation of new anesthetic-surgical techniques in the field of neurosurgery, and the state of neuroanesthesia as a subspecialty in Spain.

MATERIAL AND METHODS

A 20-item postal questionnaire sent to anesthesiology department heads of Spanish hospitals with neurosurgery teams.

RESULTS

We received responses from 62% of the hospitals surveyed. Of these, 69% performed stereotaxic surgery, 30% functional cerebral surgery (for Parkinson's disease and epilepsy) and 21% offered neuroendoscopy. In 38% of the hospitals cerebral metabolism was monitored (hemoglobin oxygen saturation in the jugular or regional cerebral oxygen saturation) and/or cerebral electrophysiology (electroencephalogram, evoked potentials) and in 23.8% flows and pressures were measured (transcranial precordial and/or tracheoesophageal Doppler). Anesthesiologists specializing in neurosurgery are present in 62% of the hospitals. Interventionist neuroradiology is performed in 57%. It was noteworthy that 14.3% do not regularly have an anesthesiologist present during such high risk procedures.

CONCLUSIONS

Although most centers continue performing "classical" neurosurgery with standard monitoring, a substantial proportion of hospitals (38%) show evidence of advancing in anesthetic techniques for neurosurgery in Spain. Anesthesia for neurosurgery as a subspecialty is available in 62% of the responding hospitals.

Value of intracellular bacteria detection in the diagnosis of ventilator associated pneumonia

BACKGROUND

Markers of ventilator associated pneumonia are of interest for confirming the diagnosis and for guiding the initial management of this frequent complication of mechanical ventilation. The detection of intracellular organisms in the polymorphonuclear leucocytes (PMNLs) and/or macrophages of bronchoalveolar lavage (BAL) fluid has been suggested as a specific test for the early indication of an infectious pulmonary process.

METHODS

The diagnostic value of detecting intracellular organisms in two types of BAL fluid--protected (P-BAL) and conventional (C-BAL)--in 25 patients who died in one unit was prospectively studied. Immediately after death both P-BAL and C-BAL were performed bilaterally. Through a minithoracotomy on both sides of the chest bilateral bronchoscopically guided open lung biopsy samples were obtained from the same area, and an average of eight open lung blind biopsy samples (not bronchoscopically guided) were taken from each lung for histological examination. BAL fluid was examined for quantitative cultures (threshold 10(4) cfu/ml) and for the presence of intracellular organisms and extracellular organisms, and differential cell counts were also performed.

RESULTS

Using the histopathology of the bronchoscopically guided open lung biopsies as the gold standard, detection of intracellular organisms in P-BAL (> or = 5%) and C-BAL (> or = 5%) fluids yielded 75% and 57% positive predictive values, and 83% negative predictive values, respectively. Prior treatment with antibiotics decreased the positive and negative predictive values of intracellular organism detection for both types of BAL fluid. The presence of intracellular organisms was correlated with the quantitative cultures of P-BAL and C-BAL samples. Quantitative cultures from P-BAL fluid were less sensitive (22% versus 45%) and more specific (100% versus 55%) than those from C-BAL samples. The percentage of extracellular organisms and the differential cell count in P-BAL and C-BAL samples could not discriminate between the presence or absence of pneumonia.

CONCLUSIONS

The presence of > or = 5% intracellular organisms infecting PMNLs or macrophages in P-BAL or C-BAL fluids is a specific marker of ventilator associated pneumonia.

[Postoperative analgesia in herniated disk surgery. Comparative study of diclofenac , lysine acetylsalicylate, and ketorolac]

INTRODUCTION

Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in treating musculoskeletal pain and are theoretically ideal for treating postoperative pain of the lumbar column.

OBJECTIVES

To compare the analgesic efficacy and side effects of treatment with 3 NSAIDs (lysine acetylsalicylate, ketorolac and diclofenac) in the treatment of pain after surgery for lumbar disc hernia.

PATIENTS AND METHODS

We enrolled 75 ASA I-II patients undergoing discectomy because of lumbar disc hernia; balanced general anesthesia was used in all cases. The patients were randomly distributed in 3 groups based on type of analgesia given in the immediate postoperative period. Group A received lysine acetylsalicylate (1800 mg), group B received ketorolac (30 mg) and group C received diclofenac (75 mg). The analgesics were diluted in 100 mg of saline solution and administered through a peripheral vein over 10 min. We evaluated the analgesia attained on a visual analog scale (VAS) and the physiological response to pain was assessed by monitoring changes in arterial pressure, heart rate and breathing frequency. If analgesia was insufficient 30 min after administration of the drug, 200 mg of lysine cloximate was given as a top-up. The side effects of each drug were also recorded.

RESULTS

VAS evaluation showed significant reductions in pain 60 min after administration in groups A and B and after 120 min in group C. Nine patients in each group required lysine cloximate. There were no significant differences in physiological response among the 3 groups. No patient suffered major side effects. Mild side effects were reported most often in group B.

CONCLUSIONS

The NSAIDs studied were inadequately for treating pain after surgery for lumbar disc hernia. Ketorolac was no better than the other analgesics studied but was associated with a higher number of mild side effects.

[Intravenous anesthesia using propofol during lengthy neurosurgical interventions]

OBJECTIVE

To compare the hemodynamic stability and time to recovery of consciousness after long-duration (> 3 h) neurosurgery with 2 anesthetic protocols: total intravenous anesthesia with propofol as the single hypnotic agent and inhalational anesthesia with isoflurane.

PATIENTS AND METHOD

We studied 58 middle-aged patients (range 40-50 years) scheduled for intracranial surgery. The patients, who all scored over 13 on the Glasgow coma scale before surgery, were randomly divided into two groups: 27 in group I received isoflurane and 31 in group II received propofol. Anesthetic induction was with sodium thiopental 4 mg/kg i.v. in group I and with propofol 2.5 mg/kg i.v. in group II. Both groups then received fentanyl 2 micrograms/kg i.v., lidocaine 1.5 mg/kg i.v. and vecuronium 0.2 mg/kg i.v. Before placement of the Mayfield head grip, with clamps, or before start of surgery in those cases in which the head grip was not used, all patients were given a 3 micrograms/kg i.v. dose of fentanyl. Hypnosis was maintained in group I with concentrations of isoflurane that were adequate for keeping minimum alveolar concentration (MAC) between 0.6 and 1. In group II maintenance was by continuous i.v. perfusion of propofol 10 mg/kg/h for 30 min., followed by 8 mg/kg/h for 30 min. and 6 mg/kg/h until the end of surgery. N2O was never used.

RESULTS

After induction systolic and mean arterial pressures (SAP and MAP) decreased significantly in both groups in comparison with baseline values (SAP: 113.1 +/- 30.0 vs. 140.9 +/- 27.08 mmHg in group I and 109.6 +/- 22.1 vs. 135.0 +/- 19.7 mmHg in group II; MAP: 76.8 +/- 18.7 vs. 95.6 +/- 17.0 mmHg in group I and 74.9 +/- 13.2 vs. 93.4 +/- 13.7 mmHg in group II). The patients in group II showed less tendency to develop arterial hypertension in response to orotracheal intubation (SAP and MAP at the moment of intubation: 156.4 +/- 33.7 and 104.6 +/- 18.1 mmHg, respectively, in group I as compared to 135.1 +/- 31.2 and 93.5 +/- 22.4 mmHg in group II; p < 0.05 between the 2 groups and p < 0.05 for the baseline and intubation pressures in group I). Time to recovery of effective, spontaneous breathing was shorter in group I (5.9 +/- 4.9 and 8.9 +/- 5.7 min.) than in group II (10.9 +/- 9.6 and 13.0 +/- 7.4 min.) and tubes could be extracted earlier from patients in the isoflurane group (10.4 +/- 6.1 min. vs. 17.6 +/- 12.8 min.; p < 0.01). We found no differences between the 2 groups for time until eye opening, response to verbal orders or time until start of spontaneous movement.

CONCLUSIONS

Propofol can be considered an alternative to the traditional thiopental-isoflurane sequence in neurosurgery lasting more than 3 h. In our study the hypertensive response to the stimulus of orotracheal intubation was lower in the propofol group than in the thiopental-isoflurane group.

[Idiopathic hypocalcemia and ventricular fibrillation: report of a case]

We report a 38-year-old female, with past history of syncope and occasional palpitation, who was admitted to our hospital with relapsing episodes of ventricular fibrillation alternating with relapsing runs of ventricular tachycardia of torsade des pointes type, associated with prolonged OT interval and hypocalcemia. These arrhythmias did not respond to any antiarrhthmic drug, and could only be controlled by the insertion of a temporary pacemaker and the normalization of the levels of ionic calcium.

[Hypokalemic effect of salbutamol administered intravenously in the preoperative period]

In 8 healthy patients (ASA I-II) there was analyzed the effect of salbutamol over serum levels of potassium, glucose, insulin, AMPc and GMPc. Also were determined the arterial blood pressure and heart rate. The drug was administered intravenously, as bronchodilator, during the preoperative period. There was a significant decrease in kaliemia (p less than 0.001 immediately after receiving the salbutamol infusion and p less than 0.05 at 60 min). Their plasma potassium levels dropped from 4.03 +/- 25 to 3.45 +/- 0.16 mEq.l-1. The plasma levels of glucose and insulin increased with a significance of p less than 0.001 post salbutamol perfusion. There were no changes in the plasmatic AMPc and GMPc. Heart rate increased from 67 +/- 10.8 to 80.5 +/- 13.7 (p less than 0.01) post perfusion, returning afterwards to their basal values. Arterial blood pressure was unmodified.