Efficacy of Pectoral Nerve Block Type II for Breast-Conserving Surgery and Sentinel Lymph Node Biopsy: A Prospective Randomized Controlled Study

Abstract

Objectives: The pectoral nerve block type II (PECS II block) is widely used for postoperative analgesia after breast surgery. This study evaluated the analgesic efficacy of PECS II block in patients undergoing breast-conserving surgery (BCS) and sentinel lymph node biopsy (SNB).

Methods: Patients were randomized to the control group (n=40) and the PECS II group (n=40). An ultrasound-guided PECS II block was performed after induction of anesthesia. The primary outcome measure was opioid consumption, and the secondary outcome was pain at the breast and axillary measured using the Numerical Rating Scale (NRS) 24 hours after surgery. Opioid requirement was assessed according to tumor location.

Results: Opioid requirement was lower in the PECS II than in the control group (43.8 ± 28.5 µg versus 77.0 ± 41.9 µg, p < 0.001). However, the frequency of rescue analgesics did not differ between these groups. Opioid consumption in the PECS II group was significantly lower in patients with tumors in the outer area than that in patients with tumors in the inner area (32.5 ± 23.0 µg versus 58.0 ± 29.3 µg, p=0.007). The axillary NRS was consistently lower through 24 hr in the PECS II group.

Conclusion: Although the PECS II block seemed to reduce pain intensity and opioid requirements for 24 h after BCS and SNB, these reductions may not be clinically significant. This trial is registered with Clinical Research Information Service KCT0002509.

Figures

Figure 1

Ultrasound images of the introduction of a PECS II block. (a) Target areas of the PECS II block. (b) First injection of the PECS II block, showing spreading of local anesthetic in the interfascial plane between the pectoralis major and pectoralis minor muscles. (c) Second injection of the PECS II block, showing spreading of local anesthetic in the interfascial plane between the pectoralis minor and serratus anterior muscles. PM, pectoralis major muscle; Pm, pectoralis minor muscle; SA, serratus anterior muscle; LA, local anesthetic; R3, third rib; R4, fourth rib. The arrow indicates the 23-gauge Quincke needle.

Figure 2

Opioid consumption as a function of breast cancer location. (a) Opioid consumption according to the quadrants of the breast. Patients with cancers located at 12, 3, 6, and 9 o'clock were not excluded because of the ambiguity of location. UOQ, upper outer quadrant; UIQ, upper inner quadrant; LOQ, lower outer quadrant; LIQ, lower inner quadrant; SA, subareolar; Ax, axilla; N, number of patients; values within parentheses denote mean fentanyl consumption. (b) Opioid consumption according to tumor location in the outer and inner areas of the breast, as determined by a line connecting the 12 o'clock and 6 o'clock positions. Patients with cancers located at 12 o'clock and 6 o'clock were not excluded, ∗p value < 0.05. (c) Opioid consumption according to tumor location in the upper and lower areas of the breast, as determined by a line connecting the 3 o'clock and 9 o'clock positions. Patients with cancers located at 3 o'clock and 9 o'clock were not excluded.

Figure 3

Study flow chart.

Figure 4

NRS of the breast (a) and axilla (b) in the PECS II and control groups. Data are expressed as the median (interquartile range). ∗p value < 0.05.

Figure 5

Diagrammatic representation of the nerves innervating the female breast and axilla. MPN, medial pectoral nerve; LPN, lateral pectoral nerve; MBCN, medial brachial cutaneous nerve; ICBN, intercostobrachial nerve; LTN, long thoracic nerve.

Figure 6

Illustration of target areas of the PECS II block. This agent can block the lateral cutaneous branches of the TICN in the interfascial plane between the pectoralis minor and serratus anterior muscles but cannot block the anterior cutaneous branch of the TICN.