Xenakis and coworkers (1995) reported beneits using an incremen tal oxytocin regimen starting at 4 m U / min. In another study, 816 women were randomly assigned for labor induction and 816 for augmentation with incremental oxytocin gihen at either 1.5 or 4.5 mU/min (Merrill, 1999). Women randomized to the 4.5 mU/min dosage had signiicantly shorter mean durations of induction-to-second-stage labor and inductionto-delivery times. Nulliparas randomized to the 4.5 mU/min dosage had a signiicantly lower cesarean delivery rate for dystocia compared with those given 1.5 mU/min dosage-6 versus 12 percent. Thus, benefits favor higher-dose regimens of 4.5 to 6 mU/min compared with lower dosages of 0.5 to 1.5 mU/min.
In 1990 at Parkland Hospital, routine use of the 6-mU/min oxytocin beginning and incremental dosage was incorporated and continues through today. In other labor units, a 2-mU/min beginning and incremental oxytocin regimen is preferred and administered. With either regimen, dosages are employed for either labor induction or augmentation. Although a Cochrane metaanalysis of randomized and quasi-randomized trials comparing high-dose versus low-dose regimens for labor induction at term reported no benefit of higher dosing, the metaanalysis included studies judged to have high potential bias. The authors concluded that the results might be confounded by these poorquality studies (Budden, 2014).
Interval between Incremental Dosing. Intervals to increase oxytocin doses vary from 15 to 40 minutes (see Table 26-3). Satin and associates (1994) addressed this aspect with a 6-mU/ min regimen providing increases at either 20-or 40-minute intervals. Women assigned to the 20-minute interval regimen for labor augmentation had a significantly reduced cesarean delivery rate for dystocia compared with that for the 40-minute interval regimen-8 versus 12 percent. As perhaps expected, uterine tachysystole was significantly more frequent with the 20-minute escalation regimen.
Other investigators reported even more frequent incremental increases. F rigoletto (1995) and Xenakis (1995) and their coworkers gave oxytocin at 4 mU/min with increases as needed every 15 minutes. Merrill and Zlatnik (1999) started with 4.5 mU/min doses and increased this every 30 minutes. L6pez-Zeno and associates (1992) used 6 mU/min doses and 15-minute intervals. Thus, there are several acceptable oxytocin protocols that at least appear dissimilar. But, a comparison of protocols from two institutions indicates that this is not so: 1.
The Parkland Hospital protocol uses a starting dose of oxytocin at 6 mU/min, which is increased by 6-mU/min every 40 minutes, and employs flexible dosing based on uterine tachysystole.
2.
The University of Alabama at Birmingham Hospital protocol begins oxytocin at 2 mU/min and increases it as needed every 15 minutes to 4,8, 12, 16,i20,25, and 30 mU/min.
hus, although the regimens at first appear disparate, if there is no uterine activity, either regimen is delivering 12 mU/ min by 45 minutes into the infusion.