The effects of the Trendelenburg position and intrathoracic pressure on the subclavian cross-sectional area and distance from the subclavian vein to pleura in anesthetized patients.

BACKGROUND: The effects of maneuvers to increase intrathoracic pressure and of Trendelenburg position on the cross-sectional area (CSA) of the subclavian vein (SCV) and the relationship between the SCV and adjacent structures have not been investigated. METHODS: In ultrasonography-guided SCV catheterization (N = 30), the CSA of the SCV and the distance between the SCV and pleura (DSCV-pleura) were determined during 10-second airway opening, and 10-second positive inspiratory hold with 20 cm H2O in the supine position (S-0, and S-20) and the 10° Trendelenburg position (T-0, and T-20). In addition to a statistical significance of P < 0.05, CSA and DSCV-pleura differences of ≥15% were defined as clinically relevant changes. RESULTS: CSA (mean [95% confidence interval]) in S-20, T-0, and T-20 (1.02 [0.95-1.14] cm(2), 1.04 [0.95-1.15] cm(2), and 1.14 [1.04-1.24] cm(2), respectively) was significantly larger than a CSA in S-0 (0.93 [0.86-1.00] cm(2), all P < 0.001). However, only the increase of CSA in T-20 vs S-0 (0.21 cm(2), 23.2%) was clinically meaningful (≥15%). The number of patients who showed CSA increase ≥15% was more in S-0 to T-20 (57%) compared with those in S-0 to S-20 (23%) and S-0 to T-0 (27%). DSCV-pleura measurements (mean) in S-20 and T-20 (0.61 and 0.60 cm) were significantly shorter than those in S-0 (0.70 cm, all P < 0.001), but the reductions of DSCV-pleura were not clinically meaningful (≥15%). CONCLUSIONS: The combined application of inspiratory hold and Trendelenburg position provided a greater and more relevant degree of CSA increase without compromising DSCV-pleura, which may facilitate SCV catheterization. Further investigations are needed to determine whether these results affect the success rate of catheterization and the risk of procedural injury.

Subacromial patient-controlled analgesia with ropivacaine provides effective pain control after arthroscopic rotator cuff repair.

PURPOSE: To investigate the postoperative analgesic effect of subacromial patient-controlled analgesia (SA-PCA) with ropivacaine in comparison with intravenous patient-controlled analgesia (IV-PCA) after arthroscopic rotator cuff repair. METHODS: Sixty patients were prospectively randomized into one of the two types of analgesics for 48 h after the operation. In the SA-PCA group, patients received 0.5% ropivacaine at a rate of 2 ml/h with a patient-controlled bolus dose of 2 ml. In the IV-PCA group, patients received intravenous patient-controlled analgesia. Pain relief was regularly assessed using visual analog scale (VAS) for 48 h, and side effects were noted. RESULTS: The postoperative pain VAS at 1 h after the operation was lower for the SA-PCA group (4.3 ± 2.7) than for the IV-PCA group (6.3 ± 2.6, P = 0.009). The frequency of requested bolus doses by patients in the IV-PCA (19 ± 19) was higher than in the SA-PCA (7 ± 10, P = 0.04). Rescue opioid or NSAID requirements were not different. More patients in the IV-PCA (17/30) experienced nausea than in the SA-PCA (7/30, P = 0.03). Patient satisfaction was higher in the SA-PCA than in the IV-PCA [6.7 (3-10) vs. 5.6 (0-8), P = 0.04]. The mean total venous plasma concentration of ropivacaine at 8 and 24 h was below the maximum tolerated venous plasma concentration, and symptoms of systemic toxicity were not noted during 48 h in the SA-PCA. CONCLUSIONS: The analgesic effect of subacromial patient-controlled analgesia with ropivacaine was better than intravenous analgesia during the immediate postoperative period with fewer side effects. LEVEL OF EVIDENCE: Therapeutic study, Level I.