Optimal Temperature for Radiofrequency Ablation of Lumbar Medial Branches for Treatment of Facet-Mediated Back Pain.

BACKGROUND: Radiofrequency ablation (RFA) of the medial branch nerves that innervate the facet joints is a well-established treatment modality; however, studies to determine the optimal radiofrequency ablation temperature are lacking. A wide range (70 to 90°C) has been used. This study aimed to compare outcomes with two set temperatures for the lumbar facet medial branch ablation, 90 and 80°C. METHODS: This retrospective study compared the degree of patient self-reported functional improvement relief, postoperative opioid dose changes, as well as duration among lumbar facet medial branch (RFA) patients who had the procedures performed at 80 or 90°C. RESULTS: Patients who underwent the procedure at 90°C had 3.1 (95% CI 1.7, 6.5) times the odds (P = 0.0004) of reporting functional improvement of at least 50% when compared to those who underwent neurotomy at 80°C. For self-reported functional improvement greater or equal to 75%, the results were sustained with an odds ratio of 2.8 (95% CI 1.2, 5.7) favoring those with 90°C temperature neurotomy (P = 0.002). CONCLUSION: There seems to be significant functional improvement associated with temp of 90°C compared to 80°C, with no added risk of complications. Randomized controlled studies are warranted.

Pulmonary characteristics in COPD and mechanisms of increased work of breathing.

Mechanical characteristics and gas exchange inefficiencies of the lungs contribute to increased work of ventilation in chronic obstructive pulmonary disease (COPD) at rest and exercise, and the energy cost of ventilation is increased in COPD at any external work level. Assuming typical ventilatory variables and respiratory characteristics, we estimated the relative contributions of inspiratory and expiratory resistance, dynamic elastance, intrinsic positive end-expiratory pressure, and gas exchange inefficiency to the work of breathing, finding that the last of these is likely to be of major importance. Dynamic hyperinflation can be seen as both an impediment to inspiratory muscle function and an essential component of adaptation to severe obstruction. Extrinsic restriction, in which the chest wall fails to achieve and maintain abnormally high lung volumes in COPD, can limit ventilatory function and contribute to disability.