{
  "abstract": "Background and Aims In 2020 we initiated a prospective cohort study on the application of posterior quadratus lumborum block (QLB) in patients with chronic hip pain. Subsequently, an attempt was made to identify local anaesthetic diffusion with ultrasound.Methods Blocks were performed with the patient in the lateral decubitus position on the healthy hip. A medial to lateral approach was made placing 20 ml of local anaesthetic in the fascial space at the posterior aspect of the quadratus lumborum muscle. ( Figure 1). We observed a different distribution of sensitivity in patients receiving the posterior QLB , an hypoaesthesia in the lower-lateral side of the abdomen, posterior thorax or towards the lumbar and gluteal region. We wondered whether it would be possible to perform an ultrasound scan of the diffusion of the local anaesthetic along the fascial plane.For this purpose, the patients were kept in lateral position after the block and a scan was performed at 15 and 30 minutes later.we added the local anaesthetic diffusion values on the data collection sheet.Results The results of the 30 patients evaluated showed anterior diffusion in 60% (18/29) and posterior diffusion in 40% (12/30). Figure 2 and 3. These diffusions coincided with the distribution of hypoaesthesias shown by the patients. 15 patients showed a caudal diffusion, coinciding with the clinical hypoaesthesia in the upper gluteal region (cluneal nerve block), 7 of them had also shown a cephalic diffusion up to rib 12. With regard to the clinical implications of these findings, we found that those patients with the greatest improvement coincided with anterior diffusion.Abstract P164 Figure 1Abstract P164 Figure 2Abstract P164 Figure 3Conclusions Our results show that it is possible to assess local anaesthetic diffusion. Although most of the patients who showed improvement had anterior diffusion, we cannot conclude that the mechanism in the control of chronic hip pain is the block of anterior branches of lumbar plexus.",
  "authors": [
    {
      "affiliations": [
        "Anesthesiology, Río Hortega University Hospital, Valladolid, Spain"
      ],
      "name": "Ana Melero"
    },
    {
      "affiliations": [
        "Anesthesiology, Río Hortega University Hospital, Valladolid, Spain"
      ],
      "name": "Cristina Barbosa"
    },
    {
      "affiliations": [
        "Anesthesiology, Río Hortega University Hospital, Valladolid, Spain"
      ],
      "name": "Teresa Camacho"
    },
    {
      "affiliations": [
        "Anesthesiology, Río Hortega University Hospital, Valladolid, Spain"
      ],
      "name": "Elena Laita"
    },
    {
      "affiliations": [
        "Anesthesiology, Río Hortega University Hospital, Valladolid, Spain"
      ],
      "name": "María Teresa Fernández"
    }
  ],
  "title": "P164 Posterior quadratus lumborum block: a diffusion ultrasound study",
  "uid": "236384d8-295f-5ce8-9665-e4cf45e6859a"
}