Stimulating versus non-stimulating catheter for lumbar plexus continuous infusion after total hip replacement.

BACKGROUND: This study was aimed to investigate whether stimulating catheters for continuous lumbar plexus block reduce local anesthetic consumption after hip arthroplasty if compared with traditional non-stimulating catheters. METHODS: Seventy-two ASA I-III, 18-82-year-old, undergoing primary hip replacement (THA) for osteoarthritis with spinal anesthesia were randomized into two groups: Stim group (stimulating catheter, N.=36) and Nonstim group (non-stimulating catheter, N.=36). After surgery, 15 mL of mepivacaine 1% were administered in both groups through the catheter. An electronic pump was connected to deliver ropivacaine 0.2% (3 mL/h, bolus 3 mL, lock out 15 min) for the first 72 h. Patients were given ketorolac 30 mg IV every 8 h, acetaminophen 1g IV every 8 h and oxycodone 10 mg per os for rescue analgesia. Primary outcome was postoperative local anesthetic consumption. Numerical Rating Scale (NRS), complications, both quadriceps and obturator strength measurements, and opioid requirement were also registered. Mixed effect models (random intercept) were built for repeated measures over time. A difference between groups was considered statistically significant if P<0.05. RESULTS: Local anesthetic consumption and NRS were comparable between groups. Patients in the Nonstim group required significant more rescue opioid analgesia compared with the Stim group during the first 36 h (P=0.002). Quadriceps and adductor muscle strength was equally preserved in the two groups. CONCLUSIONS: The study showed comparable local anesthetic consumption, pain scores and muscle strength preservation between the two groups. The stimulating catheter allowed a significant, although underpowered, reduction in opioid consumption.

Delayed Anaerobic Threshold in Heart Failure Patients With Atrial Fibrillation.

PURPOSE: To assess whether atrial fibrillation (AF) in heart failure (HF) affects oxygen uptake at anaerobic threshold ((Equation is included in full-text article.)O2 AT) and heart rate (HR) kinetics. METHODS: A total of 15 patients with HF and AF and 18 with HF and sinus rhythm (SR) performed a maximal incremental and 2 constant workload cycle ergometer cardiopulmonary exercise tests (below and above AT, at 25% and 75% of maximal workload, respectively). At constant workload tests, kinetics of (Equation is included in full-text article.)O2 and HR were assessed by calculating time constant (τ). RESULTS: HF patients with AF showed a similar peak (Equation is included in full-text article.)O2 to those with SR (16.7 ± 4.5 mL/kg/min vs 16.6 ± 3.9 mL/kg/min). However, (Equation is included in full-text article.)O2 AT (11.3 ± 2.9 mL/kg/min vs 9.3 ± 2.8 mL/kg/min; P < .05), peak HR (149 ± 18.8 bpm vs 116.4 ± 20.4 bpm; P < .001), HR AT (125.3 ± 19.1 bpm vs 90.3 ± 15.5 bpm; P < .001), and HR increase during exercise were greater in HF patients with AF. Finally, τHR and τ(Equation is included in full-text article.)O2 below and above AT were not significantly different. CONCLUSIONS: In HF patients with AF, despite a similar peak (Equation is included in full-text article.)O2 compared with patients with HF and SR, (Equation is included in full-text article.)O2 AT is higher because of a higher HR and a greater HR increase during exercise. One postulated mechanism would be a greater cardiac output increase at the beginning of exercise in HF patients with AF. The delayed AT generates uncertainty about the meaning of a (Equation is included in full-text article.)O2 value at AT in HF patients with AF, because a higher AT is usually associated with better performance and a better prognosis.

ACE-Inhibition Benefit on Lung Function in Heart Failure is Modulated by ACE Insertion/Deletion Polymorphism.

PURPOSE: The benefit of angiotensin converting enzyme (ACE) inhibition in chronic heart failure (HF) is partially due to its effects on pulmonary function and particularly on lung diffusion, the latter being counteracted by acetylsalicylic acid (ASA). Tissue ACE activity is largely determined by an insertion/deletion (I/D) polymorphism resulting in three possible genotypes (DD, ID and II). It is not clear if ACE inhibitor therapy could exert different effects in these genotypes. The aim of the study was to understand whether I/D polymorphism interferes with ACE inhibitor's protection of the lungs in HF during acute fluid overload. METHODS: 100 HF patients (left ventricular ejection fraction ≤40 %) in stable clinical conditions, treated with enalapril but without ASA performed pulmonary function tests including lung diffusion (DLco) and its subcomponents, membrane diffusion (Dm) and capillary volume (Vcap), and a cardiopulmonary exercise test before and immediately after rapid infusion of 500 cc saline. RESULTS: ACE I/D genotype prevalence was: DD = 28, ID =55 and II = 17 cases. No significant differences in major pulmonary function and exercise parameters were observed before saline infusion among ACE genotypes. After fluid challenge, DD patients presented a higher DLco and Dm reduction than ID and II (DLco -2.3 ± 1.3 vs. -0.8 ± 1.9 and -0.6 ± 1 mL/mmHg/min, p < 0.0001 and p < 0.01; Dm -7 ± 5 vs. -3.2 ± 7.4 and -1.3 ± 5 mL/mmHg/min, p < 0.05, respectively) and a higher increase in VE/VCO2 slope than II (1.8 ± 1.9 vs. -0.8 ± 2.3, p = 0.01). CONCLUSIONS: ACE DD genotype is associated with higher vulnerability of the alveolar-capillary membrane to acute fluid overload in HF patients treated with ACE inhibitors.