Overview

The purpose of this study is to compare the effects of three different doses of hydromorphone combined with ropivacaine and sufentanil combined with ropivacaine in epidural labor analgesia through prospective clinical trials, so as to explore whether hydromorphone combined with ropivacaine has advantages in epidural labor analgesia, and find out the optimal dose of hydromorphone.

Participants will be randomly allocated to four groups : Group 1, Group 2, Group 3 and Group 4. For those in Group 1 : they will be administered with 15 ug/ml hydromorphone and 0.08% ropivacaine for epidural labor analgesia, For those in Group 2 : they will be administered with17.5 ug/ml hydromorphone and 0.08% ropivacaine for epidural labor analgesia, For those in Group 3 : they will be administered with 20 ug/ml hydromorphone and 0.08% ropivacaine for epidural labor analgesia, For those in Group 4 : they will be administered with 0.4 ug/ml sufentanil and 0.08% ropivacaine for epidural labor analgesia.

The goal of this clinical trial is to provide a new treatment option for pregnant women in epidural labor analgesia, and to provide a basis for hydromorphone combined with ropivacaine in epidural labor analgesia.

Eligibility

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status II
• a single fetus
• competent to provide informed consent

Exclusion Criteria:

• severe respiratory diseases including hypoxemia, respiratory failure and severe pneumonia
• severe circulatory diseases including acute decompensated heart failure and peripartum cardiomyopathy
• placenta previa