Analgesia nociception index as a tool to assess the effectiveness of paravertebral block in total mastectomy: a prospective cohort study
Índice de analgesia–nocicepção como ferramenta para avaliar a eficácia do bloqueio paravertebral na mastectomia total: um estudo de coorte prospectivo
Julien Raft, Anne-Sophie Lamotte, Cécile Huin Schohn, Caroline Fritz, Philippe Richebé
Abstract
Background
Single-injection Paravertebral Block (PVB) is commonly used for analgesia in major breast surgery; however, its sensory effectiveness may be variable. This study investigated whether intraoperative changes in the Analgesia Nociception Index (ANI) are associated with PVB effectiveness.
Methods
This prospective observational study included 100 women scheduled for total mastectomy. A single-injection PVB was performed preoperatively under ultrasound guidance at the T3 level. Sensory testing was performed from T1 to T10, but block effectiveness was evaluated in the surgical field (T2−T6). PVBs were classified as effective (complete loss of cold sensation in all T2‒T6 dermatomes) or incomplete (partial cold sensation in this range). ANI variations, intraoperative remifentanil consumption, postoperative pain scores, and morphine use were compared.
Results
Ninety-three patients were analyzed. PVB was effective in 75% and incomplete in 25%. The mean ANI variation was significantly greater in the effective group (+1.4 § 10.3) compared to the incomplete group (-11.0 § 7.1), with a mean difference of 12.4 (95% CI: 8.8 to 16.0; p < 0.0001). Remifentanil consumption was higher in the incomplete group (0.072 § 0.018 mg.kg1.min1 vs. 0.054 § 0.008 mg.kg1.min1), mean difference 0.018 (95% CI: 0.010 to 0.026; p < 0.0001). Pain score and morphine consumption were significantly higher for patients with incomplete PVB.
Conclusion
In this observational study, a significant decrease in ANI values following skin dissection was associated with incomplete PVB. Early ANI monitoring may help identify insufficient regional block during total mastectomy, thus guiding intraoperative analgesic adjustment to improve patient comfort.
Keywords
Resumo
Introdução
O Bloqueio Paravertebral (PVB) por injeção única é amplamente utilizado para analgesia em cirurgias mamárias de grande porte, porém sua eficácia sensorial pode ser variável. Este estudo investigou se alterações intraoperatórias no Analgesia Nociception Index (ANI) estão associadas à eficácia do PVB.
Métodos
Este estudo observacional prospectivo incluiu 100 mulheres programadas para mastectomia total. Um PVB de injeção única foi realizado no pré-operatório, guiado por ultrassom, ao nível de T3. O teste sensorial foi realizado de T1 a T10, mas a eficácia do bloqueio foi avaliada no campo cirúrgico (T2–T6). Os PVBs foram classificados como eficazes (perda completa da sensação de frio em todos os dermátomos T2‒T6) ou incompletos (sensação parcial de frio nessa área). As variações do ANI, o consumo intraoperatório de remifentanil, os escores de dor no pós-operatório e o uso de morfina foram comparados.
Resultados
Noventa e três pacientes foram analisadas. O PVB foi eficaz em 75% e incompleto em 25%. A variação média do ANI foi significativamente maior no grupo eficaz (+1,4 ± 10,3) em comparação com o grupo incompleto (–11,0 ± 7,1), com diferença média de 12,4 (CI 95%: 8,8 a 16,0; p < 0,0001). O consumo de remifentanil foi maior no grupo incompleto (0,072 ± 0,018 µg·kg⁻¹·min⁻¹ vs. 0,054 ± 0,008 µg·kg⁻¹·min⁻¹), com diferença média de 0,018 (CI 95%: 0,010 a 0,026; p < 0,0001). Os escores de dor e o consumo de morfina foram significativamente maiores nas pacientes com PVB incompleto.
Conclusion
Neste estudo observacional, uma redução significativa nos valores de ANI após a dissecção da pele esteve associada ao PVB incompleto. O monitoramento precoce do ANI pode ajudar a identificar bloqueios regionais insuficientes durante a mastectomia total e, assim, orientar o ajuste da analgesia intraoperatória para melhorar o conforto da paciente.
Palavras-chave
Referencias
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Submitted date:
08/06/2025
Accepted date:
23/10/2025
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