Adding Gabapentin to a multimodal regimen does not reduce acute pain, opioid consumption or chronic pain after total hip arthroplasty

Background: Gabapentin (GPN) is effective in reducing post‐operative pain and opioid consumption, but its effects with regional anesthesia for total hip arthroplasty (THA) are not known. We designed this study to determine whether (1) gabapentin administration reduces pain and opioid use after THA using a multimodal analgesic regimen including spinal anesthesia; (2) pre‐operative administration of gabapentin is more effective than post‐operative administration. Methods: After REB approval and informed consent, 126 patients were enrolled in a double‐blinded, randomized‐controlled study. Patients received acetaminophen 1 g per os (p.o.), celecoxib 400 mg p.o. and dexamethasone 8 mg intravenously, 1–2 h pre‐operatively. Patients were randomly assigned to one of three treatment groups (G1: Placebo/Placebo; G2: GPN/Placebo; G3: Placebo/GPN). Patients received gabapentin 600 mg (G2) or placebo (G1 and G3) 2 h before surgery. All patients had spinal anesthesia [15 mg (3cc) of 0.5% hypobaric bupivacaine with 10 μg of fentanyl]. In the post‐anesthetic care unit, patients received gabapentin 600 mg (G3) or placebo (G1 and G2). On the ward, patients received acetaminophen 1000 mg p.o. q6h, celecoxib 200 mg p.o. q12h and a morphine PCA device. Patients were interviewed 6 months post‐surgery to determine the incidence and severity of chronic post‐surgical pain. Results: Mean±SD cumulative morphine (mg) consumption (G1=49.4±24.8, G2=47.2±30.1 and G3=56.1±38.2) at 48 h and pain scores at 12, 24, 36 and 48 h post‐surgery were not significantly different among the groups [G1 (n=38), G2 (n=38) and G3 (n=38)]. Side effect profiles were similar across groups. Six months after surgery, the number of patients who reported chronic post‐surgical pain (G1=10, G2=12 and G3=9) and the severity of the pain (G1=4.2±2.9, G2=4.1±2.2 and G3=4.9±2.2) did not differ significantly among the groups (P>0.05). Conclusions: A single 600 mg dose of gabapentin given pre‐operatively or post‐operatively does not reduce morphine consumption or pain scores in hospital or at 6 months after hip arthroplasty within the context of spinal anesthesia and a robust multimodal analgesia regimen.     

Clinical Evaluation of a New Single Pass Lead VDD Pacing System

Twenty-five patients with second- to third-degree AV block and normal sinus function (16 males, mean age 60 ± 18; range 15–78 years) underwent implantation of WD pacemakers (THERA VDD, Medtronic, Inc.) with a single pass (SP) lead. Results: During implantation the mean amplitude of the atrial (A) signal was 3.9 ±1.4 mV (range 2.0–7.8 mV). Stable, acceptable A-signals during implantation were usually observed in the mid- or lower part of the right atrium. The lead tip electrical parameters were not compro mised in any patient in order to obtain an acceptable A-signal. To verify VDD device function, patients underwent pacing system analysis on the second day and again 1, 3, and 6 months after implantation. Acute and chronic electrical measurements in the ventricle were similar to those with regular steroid leads. During follow-up tests, stable atrial sensing (A ≥ 0.7mV) was found in all but one patient (in whom A was 0.25–0.5 mV and an intermittent loss of atriai sensing occurred). There was no difference between serial measurements of A-signal amplitudes on the second day or 1, 3, and 6 months after implantation: 1.9 ± 1.3 mV, 1.5 ± 0.6 mV, 1.3 ± 0.8 mV, and 1.5 ± 1.1 mV, respectively. The mean implantation time was 54.0 ± 17 minutes and the mean fluoroscopy time was 3.2 ±1.3 minutes. Conclusions: SP lead VDD pacing is reliable and easy to manage with dependable atriai sensing and ventricular pacing. The significant reduction in atriai postimplantation amplitude is related to the different techniques used for measuring acute and chronic atriai signals.     

Single Lead VDD Pacing: Multicenter Study

Optimal treatment for patients with AV block and normal sinoatrial node (SA) function entails atrial sensing and ventricular pacing (VDD mode). Single-lead VDD pacing preserves AV synchrony, precludes the need to insert two leads, and makes the implanter's work simpler and quicker. Our objectives were to verify the performance of the Thera(tm) VDD pacing system (Medtronic, Inc., Minneapolis, MN, USA), and evaluate the effectiveness of its atrial sensing and its ventricular sensing and pacing. In 165 patients, 150 adults (mean age 62 ± 18 years) and 15 children (mean age 7 ± 5 years) with 1°–3° AV block and normal SA node function, a Thera VDD system (Models 8948 or 8968) was implanted. Intraoperative ventricular electrical measurements were not significantly different from those of VVI pacemakers. The mean amplitude of the atrial signal during implantation was 4.1 ± 1.9 mV. Optimal atrial signals during implantation were usually obtained in the mid or lower part of the right atrium by using a special technique. Adequate atrial measurements remained stable throughout 24 months. There was no difference between serial measurements of atrial signal amplitudes at predischarge and during follow-up visits. Reposition of the lead was done in 2 patients (1.4%), and reprogramming to VVI in 7 patients: due to atrial fibrillation in 3 (1.8%) and due to atrial undersensing in 4 patients (2.4%). Thera VDD pacing is reliable and easy to manage with dependable atrial sensing and ventricular pacing. The survival rate of VDD pacing at 2 years was 96%.     

Serum Electrolytes and Catecholamines After Cardioversion From Ventricular Tachycardia and Atrial Fibrillation

We have observed hypokalemia after cardioversion from spontaneous out-of-hospital ventricular fibrillation and induced ventricular tachycardia. To test the hypothesis that the hormone response to the hemodynamic stress of the arrhythmia initiated the change in potassium, we compared the electrolytes and hormones in three groups of patients. We observed a decrease in serum potassium and magnesium after cardioversion from ventricular tachycardia induced by programmed Stimulation but not after normal programmed stimulation of the ventricle or after cardioversion from stable atrial fibrillation. These changes were preceded first by a rise in norepinephrine and epinephrine then a rise in glucose, followed by a rise in insulin. The stimulus for these changes was probably the hypotension associated with ventricular tachycardia. The sequence of changes suggests that the decrease of potassium and magnesium after ventricular tachycardia was due to a shift of the electrolytes into cells related to the insulin-mediated movement of glucose from the blood into cells.     

Memory for spatial location in retarded and nonretarded persons

ABSTRACT. Item memory and memory for spatial location were examined in college students, mildly retarded persons and moderately retarded persons. They performed under semantic or nonsemantic encoding instructions to remember pictures presented in a large book. Recall and relocation (unexpected) tests followed immediately after studying the pictures and, again, 24 h later. Mildly retarded persons were deficient in memory for items (effortful processing), but not in memory for location (automatic processing). Moderately retarded persons were deficient in both types of memory. Additionally, there were IQ-related differences in the long-term memory of location information, as well as item information. Location memory, as opposed to item memory, was shown to be (1) sensitive to encoding instruction, (2) insensitive to differences in intelligence, and (3) more sensitive to long-term forgetfulness.