Changes of dorsalis pedis artery flow pattern after caudal block in children: observational study using a duplex sonography

Effective dose of dobutamine in augmenting free flap blood flow during reconstructive surgery of the lower extremity

Success of surgical free flap transfer depends on achieving and maintaining adequate perfusion across the microvascular anastomosis. The purpose of this prospective study was to determine the optimal infusion rate of dobutamine to augment duplex ultrasound measured blood flow to the tissue flap during surgery.Twenty-one patients undergoing general anesthesia for lower limb reconstructive surgery were recruited. The optimal dobutamine dose was evaluated using the modified Dixon's up-and-down method, starting at 6 μg·kg·min, and then titrated in increments of 1 μg·kg·min.The optimal dose of dobutamine for improving blood flow to the tissue flap was 3.50 ± 0.57 μg·kg·min in 50% of patients. The 95% effective dose of dobutamine calculated by probit analysis was 4.46 μg·kg·min (95% confidence interval: 3.99-7.00 μg·kg·min).The results of our study suggest that a dobutamine infusion rate less than 5 μg·kg·minprovides significant improvement of blood flow to the tissue flap, while minimizing cardiovascular side effects.

Influence of caudal block on postoperative oliguria in infants undergoing bilateral ureteroneocystostomy: a retrospective analysis

BACKGROUND

Caudal block has been widely used in children undergoing genitourinary surgery. However, the influence of caudal block on postoperative oliguria is unclear.

AIM

The aim of this study was to assess the effect of caudal block on urinary flow through the reimplanted ureter after ureteroneocystostomy and the incidence of postoperative oliguria in infants.

METHODS

This retrospective study analyzed the medical records of 121 infants aged less than 12 months who underwent bilateral ureteroneocystostomy for vesicoureteral reflux at a tertiary medical center. In all study infants, a ureteral catheter was placed in one of the two ureters in order to relieve the clinical consequences of transient ureteral obstruction and a urethral catheter was placed at the end of the ureteroneocystostomy procedure. Urinary output was assessed separately for each catheter. Logistic regression analysis was performed to identify the risk factors for oliguria from the urethral catheter.

RESULTS

Among the 121 patients, 63 (52%) received caudal block (caudal block group) and 58 (48%) did not (no caudal block group). Patient characteristics, preoperative vesicoureteral reflux grade and renal function, and intraoperative profiles were comparable between the groups. The incidence of oliguria from the urethral catheter for 8 h after the surgery was significantly higher in the caudal block group than in the no caudal block group. However, the incidence of oliguria from the ureteral catheter was comparable between the groups. In multivariate analysis, oliguria from the urethral catheter was associated with caudal block, anesthesia duration, and intraoperative dexamethasone administration. The odds for oliguria was 3.069-fold greater in patients who received caudal block than in those who did not (95%CI, 1.303-7.228, P = 0.010). On the other hand, intraoperative dexamethasone reduced the risk of oliguria.

CONCLUSION

Caudal block may be associated with postoperative oliguria in infants undergoing ureteroneocystostomy.

Caudal blocks

Caudal anesthesia is the single most important pediatric regional anesthetic technique. The technique is relatively easy to learn (1), has a remarkable safety record (2), and can be used for a large variety of procedures. The technique has been reviewed in the English (3) and French (4) literature, as well as in German guidelines (5) and in pediatric anesthesia textbooks (6).