The effects of 45 degree head up tilt on the lumbar puncture success rate in children undergoing spinal anesthesia.

BACKGROUND: There are few studies for procedural techniques of lumbar puncture (LP) for spinal anesthesia in children. There are no controlled studies on the effect of patient positioning. We designed this prospective, randomized study to compare the success rates of LP of the lateral decubitus and lateral decubitus position with a 45 degree head up tilt in children undergoing spinal anesthesia. METHODS: Study was conducted in 180 children aged between one month to twelve years. The LP was performed under general anesthesia using sevoflurane with a 26-gauge, atraumatic needle either in the standard lateral decubitus, knee-chest position (group I, n = 90) or lateral decubitus, knee-chest position with a 45 degree head up tilt (group II, n = 90). The free flow of clear cerebrospinal fluid (CSF) at first attempt was considered to evidence a successful LP. RESULTS: The two groups were similar in age and weight. Total LP success rate was higher in group II than in group I (P < 0.05). When the significance between the groups was evaluated according to age, the increase in LP success rate was significant in children aged <12 months of age but not significant in children older than 12 months of age. CONCLUSIONS: Because of higher success rate, lateral decubitus, knee-chest position with 45 degree head up tilt may be the preferred position for spinal anesthesia in infants.

A new reversible ischemic neurologic deficit model in dogs.

BACKGROUND: The aim of this study was to produce an internal carotid artery (ICA) occlusion model in dogs that can be used for studying the effects of surgical revascularization procedures. MATERIAL/METHODS: After left frontoparietal craniectomy, the ICA and arterial circle of the brain were coagulated and transected, letting the middle cerebral artery be perfused by the contralateral ICA by way of the rostral cerebral artery in five mongrel dogs. Magnetic resonance imaging (MRI) and brain single-photon emission computed tomography (SPECT) were performed during the first 24 to 48 hours and 7 to 10 days after the operation. Paired t and Wilcoxon matched pair tests were used for statistics (p<0.05). RESULTS: All the dogs had postoperative hemiparesis that returned to normal after 7 to 10 days. Early MRI showed cerebral ischemia in the left parietal cortical area extending to the subcortical white matter, sparing the basal ganglion and the internal capsule. Early brain SPECT demonstrated hypoperfusion corresponding to the same area. This area became significantly restricted to a small cortical area in late MRI and SPECT images (p<0.05). CONCLUSIONS: It is concluded that, as symptoms resolved spontaneously, this model can be used as a "reversible ischemic neurological deficit" model for diagnostic imaging and pharmacological studies.

Wrist tourniquet: the most patient-friendly way of bloodless hand surgery.

BACKGROUND: The literature is scarce on wrist tourniquets. In this study, three well-established locations of tourniquet setting including upper arm, proximal forearm, and wrist were compared on the same limb using both clinical as well as biochemical variables in paramedical volunteers. METHODS: Twenty unmedicated, healthy, paramedical, right-hand dominant volunteers participated in the study. The left upper arms were used for monitoring. Blood pressures and heart rates were monitored and recorded before (baseline) and immediately after the application of the tourniquet, every 5 minutes, and at the time the patient requested deflation. An intravenous cannula (22 G) was placed on the right hand to obtain samples, which were taken at baseline and immediately after deflation of the tourniquet to evaluate the levels of pO2, pCO2, O2 saturation, pH, bicarbonate, blood sugar, lactate, hematocrit, and electrolytes. The tourniquets were applied to the right upper arm, forearm, and wrist of each subject with 5-day intervals between each trial. Subjective discomfort and tourniquet pain levels were recorded. For each trial, tourniquet tolerance and details of discomfort were recorded. Statistical analysis was performed as appropriate. RESULTS: Twenty volunteers aged 20 to 44 years were included. For each trial, in the first 10 minutes after inflation of the tourniquet, the heart rate and systolic blood pressure were increased compared with baseline values. Diastolic blood pressure was elevated immediately after inflation and remained so until deflation in each trial. Diastolic blood pressure values were higher in the upper-arm tourniquet group compared with wrist. Then pH, pO2, and O2 saturation values were decreased and pCO2 and lactate levels were increased compared with baseline values in each trial. Blood sugar was decreased significantly in the arm group. The decrease in pH, pO2, O2 saturation, and blood sugar in the upper arm group was significantly higher compared with wrist and forearm groups. The lactate value was higher in the upper arm group compared with wrist. Visual analog scale and numerical rating scores were lower in the wrist group compared with others at all times. The longest tourniquet tolerance was in the wrist group. In the wrist group, curling was observed in all subjects but the fingers could easily be extended. CONCLUSION: The wrist tourniquet is the most comfortable technique of bloodless surgery for procedures limited to the hand region.

The concomitant presence of two anomalous muscles in the forearm.

This article describes the concomitant presence of two anomalous forearm muscles in a 20-year-old man, discovered accidentally during an operation for a forearm injury. The first one was similar to a reverse palmaris longus muscle except for its direction to the Guyon's canal. The second one originated from the radial antebrachial fascia, superficial to all other forearm muscles in the lower half of the forearm, then diverged medially and extended into the Guyon's canal and was innervated by the ulnar nerve. The patient had no symptoms related to overcrowding of the Guyon's canal before the injury. A hand surgeon should be well informed about the anatomic variations of the hand to be comfortable during surgical practice.

Prediction of arterial blood gas values from venous blood gas values in patients with acute exacerbation of chronic obstructive pulmonary disease.

Arterial blood gas (ABG) analysis has an important role in the clinical assessment of patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, arterial puncture or insertion of an arterial catheter has many drawbacks. The aim of this study was to evaluate whether venous blood gas (VBG) values of pH, partial pressure of carbon dioxide (PCO(2)) and oxygen (PO(2)), bicarbonate (HCO(3)), and oxygen saturation (SO(2)) can reliably predict ABG levels in patients with AECOPD. One hundred and thirty-two patients with a prior diagnosis of COPD presenting with acute exacerbation according to AECOPD criteria were included in this prospective study. AECOPD is defined as a recent increase in cough, wheezing, the volume and purulence of sputum or shortness of breath necessitating a change in regular medication, including corticosteroids or antibiotics. ABG samples were taken immediately after venous sampling, and both were analyzed. Linear regression analysis was performed and equations were established for the estimation of arterial values. The Pearson correlation coefficients for pH, PCO(2), HCO(3), PO(2), and SO(2) were 0.934, 0.908, 0.927, 0.252, and 0.296, respectively. There was a significant correlation between ABG and VBG values of pH, PCO(2), and HCO(3) (p < 0.001). Linear regression equations for the estimation of pH, PCO(2), and HCO(3) were as follows: arterial pH = 1.004 x venous pH; arterial PCO(2) = 0.873 x venous PCO(2); and arterial HCO(3) = 0.951 x venous HCO(3). VBG analysis can reliably predict the ABG values of pH, PCO(2) and HCO(3) in patients with AECOPD.

The mechanisms of the direct vascular effects of fentanyl on isolated human saphenous veins in vitro.

OBJECTIVE: The purpose of this study was to determine the mechanism of the direct effects of fentanyl on human veins in vitro. DESIGN: In vitro, prospective with repeated measures. SETTING: University research laboratory. INTERVENTIONS: Dose-response curves were obtained for cumulative doses of fentanyl (10(-9)-10(-5) mol/L) on saphenous vein strips precontracted with (10(-6) mol/L) 5-hydroxytryptamine incubated with either naloxone (10(-4) mol/L), Nomega-nitroL-arginine-methyl ester (L-NAME) (10(-4) mol/L), indomethacin (10(-5) mol/L), glibenclamide (10(-4) mol/L), tetraethylammonium (10(-4) mol/L), or ouabain (10(-5) mol/L). Vein strips were also exposed to a Ca++-free solution and 0.1 mmol/L of ethylene glycol-bis-(b-aminoethylether) N,N'-tetraacetic acid; 5-hydroxytryptamine (10(-6) mol/L) was added to the bath before cumulative Ca++ (10(-4)-10(-2) mol/L). The same procedure was repeated in the presence of fentanyl (10(-6) , 3 x 10(-6) , or 10(-5) mol/L) (p < 0.05 = significant). MEASUREMENTS AND MAIN RESULTS: Preincubation of vein strips with naloxone, L-NAME, or indomethacin did not influence the relaxant responses to fentanyl (p > 0.05). Tetraethylammonium, glibenclamide, and ouabain reduced the relaxation response to fentanyl (p < 0.05). A stepwise increase in tension was recorded with cumulative doses of Ca++ (p < 0.05). CONCLUSIONS: The present results show that fentanyl causes vasodilatation via both endothelium- and opioid receptor-independent mechanisms in the human saphenous vein. The relaxant effects of fentanyl are probably via activation of K+ channel and Na+K+-adenosine trisphosphatase and inhibition of Ca++ channel.

Gabapentin is a first line drug for the treatment of neuropathic pain in spinal cord injury.

STUDY DESIGN: Prospective, randomized, double blind, placebo-controlled, crossover clinical trial. OBJECTIVES: To determine the efficacy of gabapentin in the treatment of neuropathic pain related to spinal cord injury. SUMMARY OF BACKGROUND DATA: Neuropathic pain is initiated or caused by a primary lesion or dysfunction in the nervous system. Neuropathic pain associated with spinal cord injury is quite refractory, and current treatments are not effective. Gabapentin, an anticonvulsant, has become the first choice in the treatment of neuropathic pain. The place of gabapentin in the treatment of spinal cord injury-related neuropathic pain was questioned in only a few recent reports; however, they are retrospectively designed, nonstandardized, and uncontrolled studies, or involve a very small series of patients using less than optimum doses. METHODS: A total of 18-week study period included a 4-week medication/placebo titration period. This was followed by a 4-week stable dosing period when the patients continued to receive maximum tolerated doses, a 2-week washout period, then a crossover of 4 weeks of medication/placebo titration, and another 4 weeks of stable dosing period. Twenty paraplegic patients (female/male: 7/13) with complete spinal cord injury at the thoracic and lumbar level, aged between 20 and 65 years, with neuropathic pain for more than 6 months were recruited for the study. RESULTS: All patients completed the study. Gabapentin reduced the intensity as well as the frequency of pain, relieved all neuropathic pain descriptors except the itchy, sensitive, dull, and cold types, and improved the quality of life (P < 0.05). CONCLUSIONS: Gabapentin can be added to the list of first-line medications for the treatment of chronic neuropathic pain in spinal cord injury patients. It is a promising new agent and offers advantages over currently available treatments.

The in vitro effects of remifentanil and fentanyl on isolated human right atria and saphenous veins.

OBJECTIVE: To determine the myocardial and vascular effects of remifentanil and fentanyl in human atria and saphenous veins. DESIGN: In vitro, prospective with repeated measures. SETTING: University research laboratory. INTERVENTIONS: The direct effects of remifentanil and fentanyl on the electrical stimulation-induced contraction of nonfailing human atrium and saphenous veins contracted with 5-hydroxytryptamine were studied. MEASUREMENTS AND MAIN RESULTS: In human atrial trabeculae, cumulative (10(-9)-10(-5) mol/L) added remifentanil had no effect on contractile force, compared with untreated muscles (p > 0.05). The force of contraction was significantly less than control values with concentrations of fentanyl ranging from 10(-8) to 10(-5) mol/L (p < 0.05). At the highest concentration (10(-5) mol/L), the inhibition by fentanyl of the electrical stimulation-induced contraction was 40.6% +/- 6.32%. In human saphenous vein strips preconstricted with 5-hydroxytryptamine, remifentanil (10(-8)-10(-5) mol/L) and fentanyl (10(-8)-10(-5) mol/L) produced "concentration-dependent" relaxation when compared with the control contraction value (p < 0.05). The IC(50) was similar with remifentanil and fentanyl and the E(max) of fentanyl was significantly higher than remifentanil (p < 0.05). The venodilatory effects of remifentanil and fentanyl were similar on veins with or without endothelium (p > 0.05). CONCLUSIONS: Remifentanil has no direct effect on the contraction of myocardium. Fentanyl inhibits the electrical stimulation-induced contraction in human right atrial muscles in vitro. Remifentanil and fentanyl produce "concentration-dependent" relaxation in human saphenous vein strips independent from the endothelium.

Vertebral artery loop formation: a frequent cause of cervicobrachial pain.

STUDY DESIGN: Patients with cervicobrachial pain were examined in detail with special attention to vertebral artery loop formation. OBJECTIVES: To determine the incidence, short-time natural course and response to a conservative approach to vertebral artery loop formation in a group of patients with cervicobrachial pain. SUMMARY OF THE BACKGROUND DATA: Vertebral artery loop formation is reported to be a rare cause of cervicobrachial neuralgia, discovered incidentally during the search for its cause. It can be congenital or acquired, occurring equally in both sexes. Surgical decompression has been the preferred method in the majority of reported cases, with favorable results. METHODS: One hundred seventy-three patients with cervicobrachial pain were examined in a period of 7 months using physical examination, radiography, and magnetic resonance imaging with or without angiography. RESULTS: Thirteen patients with a mean age of 43.9 +/- 13.5 years were diagnosed with vertebral artery loop formation. The most common level was C6-C7. Four patients presented with loop formation at two levels. None of the patients had symptoms attributable to intervertebral disc pathology. The complaints were in accordance with the level of the vascular pathology. Complete relief or decrease in pain was observed in all patients with the conservative approach. CONCLUSIONS: In patients with cervicobrachialgic symptoms and without established discopathy, during the examination of sagittal magnetic resonance images, vertebral artery loop formation should be kept in mind, and in suspected cases, the vertebral artery should be visualized using three-dimensional time of flight magnetic resonance angiography. Vertebral artery-nerve root relation should also be demonstrated using the multiplanar reformatting method from time of flight images. A conservative course of treatment has a favorable outcome.

Correlation between tissue lactate levels and electroencephalogram in evaluating the severity of experimental head trauma.

OBJECTIVE: The objective of this study was to develop an electroencephalographic grading scale for evaluating the severity of head trauma and assessing the correlation of this scale with brain tissue lactate concentrations. DESIGN: Animal experiment. SETTING: Animal research laboratory in a university hospital. SUBJECTS: Thirty New Zealand rabbits were divided into three groups. INTERVENTIONS: Rabbits were anesthetized, and bilateral frontoparietal craniectomy was performed. An electroencephalogram was recorded over the dura from both sides. After electroencephalographic recording, unilateral trauma was produced by using the weight drop method with a calculated force of 400 g.cm and 800 g.cm in group 2 (n = 10) and group 3 (n = 10), whereas in group 1 (n = 10) only craniectomy was performed. Electroencephalographic recording was repeated 60 mins after trauma or craniectomy, and cortical tissue samples were resected from both sides to evaluate tissue lactate concentrations in all three groups. MEASUREMENTS AND MAIN RESULTS: Electroencephalographic recordings from both sides of the brain were evaluated together by using a 6-point scale (1 = best to 6 = worst) that was based on the presence or absence of electroencephalographic activity and the decrease in amplitude or frequency band of the electroencephalogram. Lactate was measured in resected tissue by using spectrophotometric enzymatic methods. One-way analysis of variance for repeated measures, Bonferroni-adjusted paired Student's -test, Kruskal Wallis analysis of variance, Bonferroni-adjusted Mann-Whitney-U, and Spearman's correlation tests were used as appropriate for statistical analysis. We considered p<.05 to be significant. The difference in lactate concentrations was significant between the three groups ( p<.05). Electroencephalographic grades were significantly different between the pretraumatic and posttraumatic recordings ( p<.05) and between the three groups after craniectomy or trauma ( p<.001). There was a positive high correlation between lactate concentrations and electroencephalographic grades. CONCLUSIONS: Tissue lactate concentrations and electroencephalograhic grades change with the severity of the trauma, and there is a strong positive correlation between tissue lactate concentrations and electroencephalographic grades.