Lidocaine 0.5% spinal anaesthesia: a hypobaric solution for short-stay perirectal surgery

The efficacy of subarachnoid injection of 8 ml lidocaine 0.5% was assessed in ten outpatients having perirectal surgery in the jackknife position. This solution is hypobaric, with a baricity 0.9985 +/- 0.0003 (mean +/- SD). Injections were made with the patient in the surgical position (with the upper torso at a 15 degrees downward inclination). Sensory level was tested by pinprick. Times to two-segment regression, to complete resolution of sensory analgesia, to urination, and to discharge from the recovery room were recorded. All injections produced effective anaesthesia for surgery. Lidocaine 0.5% behaves clinically as a hypobaric solution. Dermatomal levels remained low (T11 to L5) while the patients were in the surgical position (head down), but rose two to six dermatomes if the patient's head was elevated after surgery. Time to two-segment regression was 97 +/- 36 min, time until regression to S1 was 116 +/- 22 min, time to complete resolution of sensory blockade was 151 +/- 23 min, time to urination was 197 +/- 64 min, and time to discharge from the recovery room was 205 +/- 45 min. Lidocaine 0.5% provides effective spinal anaesthesia of short duration appropriate for outpatient surgical procedures. Dermatomal sensory spread of anaesthesia, and our measurements of specific gravity, indicate that this solution is hypobaric. It appears that changes in position can alter the spread of analgesia for at least one hour after injection and, thus, we caution against elevating the patient's head in the immediate postoperative period.     

Synthesis and transport of GAP-43 in entorhinal cortex neurons and perforant pathway during lesion-induced sprouting and reactive synaptogenesis.

Metabolic labeling and quantitative 2D gel autoradiography were used to assess changes in the synthesis and transport of GAP-43 in entorhinal cortex (EC) neurons and perforant pathway during lesion-induced sprouting and reactive synaptogenesis. In normal adult rats, there is a high constitutive level of GAP-43 synthesis and transport in EC neurons projecting to the hippocampus. Following unilateral EC lesions, there is a 2-fold (100%) increase in the transport of newly synthesized GAP-43 to the contralateral or 'sprouting' hippocampus. The timing of this upregulation (between 6 and 15 days) suggests that changes in GAP-43 expression occur in response to the growth of presynaptic terminals during sprouting.     

Statistical issues in long-term followup studies

The thesis of this article is that since followup studies of patients with schizophrenia have provided a rich body of informative knowledge, emphasis should now be on hypothesis testing in future studies. The consumer of research needs to have a general appreciation of statistical thinking, design, and methods to make an informed synthesis of results presented. This article presents a brief discussion of relevant statistics and statistical issues, as free of jargon as possible. Given the multivariable nature of psychiatric research, the natural focus is on multivariate statistics. A strong background in statistics is not required to understand the methods described and how and why they might be applied. Reference material for more detailed discussions is provided. It is a truism to say that the highest quality scientific work is dependent on an intimate collaboration with the expert in statistics and the expert in clinical methods, and this merits repeating only because it is so often ignored.     

Effect of training frequency and specificity on isometric lumbar extension strength

To investigate the effects of training frequency and specificity of training on isolated lumbar extension strength, 72 men (age = 31 +/- 9 years) and 42 women (age = 28 +/- 9 years) were tested before and after 12 weeks of training. Each test involved the measurement of maximum voluntary isometric torque at 72 degrees, 60 degrees, 48 degrees, 36 degrees, 24 degrees, 12 degrees, and 0 degrees of lumbar flexion. After the pretraining tests, subjects were randomly stratified to groups that trained with variable resistance dynamic exercise every other week (1X/2 weeks, n = 19), once per week (1X/week, n = 22), twice per week (2X/week, n = 23) or three times per week (3X/week, n = 21); a group that trained isometrically once per week (n = 14); or a control group that did not train (n = 15). Analysis of covariance showed that all training groups improved their ability to generate isometric torque at each angle measured when compared with controls (P less than 0.05). There was no statistical difference in adjusted posttraining isometric torques among the groups that trained (P greater than 0.05), but dynamic training weight increased to a lesser extent (P less than 0.08) for the 1X/2 weeks group (26.6%) than for the groups that trained 1X/week, 2X/week, and 3X/week (37.2 to 41.4%). These data indicate that a training frequency as low as 1X/week provides an effective training stimulus for the development of lumbar extension strength. Improvements in strength noted after isometric training suggest that isometric exercise provides an effective alternative for developing lumbar strength.     

Percutaneous absorption of 2,6-di-tert-butyl-4-nitrophenol (DBNP) in isolated perfused porcine skin.

DBNP (2,6-di-tert-butyl-4-nitrophenol) has been reported as a potential contaminant in submarines. This yellow substance forms when lubrication oil mist containing the antioxidant additive 2,6-di-tert-butylphenol passes through an electrostatic precipitator and is nitrated. Percutaneous absorption of 14C-DBNP was assessed in the isolated perfused porcine skin flap (IPPSF). Four treatments were studied (n=4 flaps/treatment): 40.0 microgram/cm(2) in 100% ethanol; 40.0 microgram/cm(2) in 85% ethanol/15% H(2)O; 4.0 microgram/cm(2) in 100% ethanol; and 4.0 microgram/cm(2) in 85% ethanol/15% water. DBNP absorption was minimal across all treatment groups, with the highest absorption detected being only 1.08% applied dose in an aqueous ethanol group. The highest mass of 14C-DBNP absorbed was only 0.5 microgram. The majority of the applied dose remained on the surface of the skin. This suggests that there is minimal dermal exposure of DBNP when exposed topically to skin.     

Induction, Recovery, and Safety Characteristics of Sevoflurane in Children Undergoing Ambulatory Surgery: A Comparison with Halothane

Background: Sevoflurane is an inhalational anesthetic with characteristics suited for use in children. To determine whether the induction, recovery, and safety characteristics of sevoflurane differ from those of halothane, the following open-labeled, multicenter, randomized, controlled, phase III study in children undergoing ambulatory surgery was designed.

Methods: Three hundred seventy-five children, ASA physical status 1 or 2, were randomly assigned in a 2:1 ratio to receive either sevoflurane or halothane, both in 60% N2 O and 40% O2. Anesthesia was induced using a mask with an Ayre's t piece or Bain circuit in four of the centers and a mask with a circle circuit in the fifth center. Maximum inspired concentrations during induction of anesthesia were 7% sevoflurane and 4.3% halothane. Anesthesia was maintained by spontaneous ventilation, without tracheal intubation. End-tidal concentrations of both inhalational anesthetics were adjusted to 1.0 MAC for at least 10 min before the end of surgery. Induction and recovery characteristics and all side effects were recorded. The plasma concentration of inorganic fluoride was measured at induction of and 1 h after anesthesia.

Results: During induction of anesthesia, the time to loss of the eyelash reflex with sevoflurane was 0.3 min faster than with halothane (P < 0.001). The incidence of airway reflex responses was similar, albeit infrequent with both anesthetics. The total MAC *symbol* h exposure to sevoflurane was 11% less than the exposure to halothane (P < 0.013), although the end-tidal MAC multiple during the final 10 min of anesthesia was similar for both groups. Early recovery as evidenced by the time to response to commands after sevoflurane was 33% more rapid than it was after halothane (P < 0.001), although the time to discharge from hospital was similar for both anesthetics. The mean (+/-SD) plasma concentration of inorganic fluoride 1 h after discontinuation of sevoflurane was 10.3+/-3.5 micro Meter. The overall incidence of adverse events attributable to sevoflurane was similar to that of halothane, although the incidence of agitation attributable to sevoflurane was almost threefold greater than that attributable to halothane (P < 0.004).     

Normal pressure hydrocephalus and cerebral blood flow: a PET study of baseline values.

Regional cerebral blood flow (CBF) was studied with O(15)-water positron emission tomography and anatomic region-of-interest analysis on co-registered magnetic resonance in patients with idiopathic (n = 12) and secondary (n = 5) normal pressure hydrocephalus (NPH). Mean CBF was compared with values obtained from healthy volunteers (n = 12) and with clinical parameters. Mean CBF was significantly decreased in the cerebrum and cerebellum of patients with NPH. The regional analysis demonstrated that CBF was reduced in the basal ganglia and the thalamus but not in white matter regions. The results suggest that the role of the basal ganglia and thalamus in NPH may be more prominent than currently appreciated. The implications for theories regarding the pathogenesis of NPH are discussed.