# Effects of rhomboid intercostal and sub-serratus plane block on perioperative analgesic efficacy and diaphragm excursion in video-assisted thoracic surgery: a prospective, randomized controlled trial

## TL;DR

A new nerve block technique called RISS helps reduce pain and improves diaphragm movement after lung surgery, according to a clinical trial.

## Contribution

This study provides empirical evidence on the analgesic and functional benefits of ultrasound-guided RISS block in thoracic surgery patients.

## Key findings

- Patients receiving RISS block had significantly lower pain scores at rest and during movement post-surgery.
- RISS block reduced sufentanil consumption and improved diaphragmatic excursion compared to standard care.
- No significant adverse effects were observed in the RISS group.

## Abstract

Rhomboid intercostal and sub-serratus plane (RISS) block is a novel nerve block technique that provides good analgesia, but overall research is scarce. This study aimed to investigate the effect of ultrasound-guided RISS block on postoperative analgesia and diaphragmatic excursion (DE) after video-assisted thoracic surgery (VATS) for lung cancer.

One hundred patients who underwent VATS lung resection participated in this study and were randomized to a RISS group (Group R) or a control group (Group C). Group R underwent ultrasound-guided RISS block with 0.25% ropivacaine hydrochloride 0.5 ml/kg immediately after surgery. Group C was given standard general anaesthesia, and patient-controlled intravenous analgesia (PCIA) was used in the postoperative period in both groups. The visual analogue scores (VAS) at rest and during movement at 2 hours(h), 24 h, and 48 h postoperatively were used as the primary outcome measures. Secondary outcomes included postoperative consumption of sufentanil; preoperative and postoperative left and right-sided DE during calm and deep breathing, and the occurrence of adverse effects such as postoperative nausea and vomiting (PONV), dizziness, somnolence, puncture site infection, and hematoma.

At 2 h, 24 h, and 48 h postoperatively, patients in Group R had lower VAS scores at rest (median [Q1, Q3]: 1.00 [1.00, 1.00]; 1.00 [1.00, 1.00]; 0.00 [0.00, 1.00]) and during movement (2.00 [2.00, 3.00]; 2.00 [2.00, 2.00]; 2.00 [1.00, 2.00]) than those in Group C (resting: 2.00 [2.00, 2.00]; 2.00 [2.00, 2.00]; 1.00 [1.00, 2.00]; movement: 3.00 [3.00, 4.00]; 3.00 [3.00, 4.00]; 3.00 [2.00, 4.00]) (all P < 0.0001). Sufentanil consumption at 2 h, 24 h, and 48 h postoperatively was also significantly lower in Group R (P = 0.0002, P < 0.0001, P < 0.0001). Preoperatively, no significant difference in DE existed between the groups (P > 0.05). At 30 min post-extubation and 2 h and 24 h postoperatively, during both calm and deep breathing on both sides, Group R had significantly greater DE than Group C (P < 0.05). At 48 h postoperatively, the right-sided DE during calm breathing showed no significant difference between the groups. PONV incidences did not differ significantly (P = 0.2662), and Group R had less dizziness, somnolence, higher satisfaction post-surgery, and showed no cases of puncture site infection or hematoma.

Ultrasound-guided RISS block can modestly reduce postoperative pain in patients undergoing VATS, with clinically relevant benefits, and may help alleviate diaphragmatic dysfunction caused by surgical or anesthetic factors.

The trial was registered at the China Clinical Trial Registry (http://www.chictr.org.cn, ChiCTR2300070842) on 24/04/2023.

The online version contains supplementary material available at 10.1186/s12871-025-03556-3.