Ultrasound-assisted Thoracic Intervertebral Foramen Block. A Cadaveric Study.

BACKGROUND: A thoracic paravertebral block can be a useful opioid-sparing technique for controlling postoperative pain after thoracic and visceral abdominal surgery. OBJECTIVES: Our aim was to assess dye spread into the ventral branch, connecting branch, sympathetic trunk, thoracic paravertebral space, and epidural space after performing a modified ultrasound-assisted thoracic paravertebral block via the intervertebral foramen. STUDY DESIGN: This was a nonrandomized cadaveric study. SETTING: The cadavers were kept at the Department of Anatomopathology of the San Salvatore Academic Hospital of L'Aquila (L'Aquila, Italy). METHODS: We performed a bilateral thoracic paravertebral block via the intervertebral foramen at the second, fifth, ninth, and twelfth thoracic vertebrae. A linear array ultrasound transducer was used. Then, cadaveric dissection was performed. A Tuohy needle was gently inserted in-plane with the ultrasound beam in a lateromedial direction to contact the spinous process. Subsequently, the needle tip was advanced 2 mm along the transverse process of the vertebra, and 5 mL of methylene blue 1% dye was injected at each level. Then, 2 continuous catheter sets were inserted. RESULTS: Forty intervertebral foramen blocks were performed in 5 cadavers. For 38 injection sites, we found dye on both sides of the thoracic paravertebral space and epidural space at each level of puncture. The retropleural organs were also stained. In 2 cases, methylene blue accumulated intramuscularly at the level of the twelfth thoracic vertebra. RESULTS: The spread of dye into the ventral rami, communicating rami, and sympathetic trunk in the thoracic paravertebral space and the epidural space was assessed. We also evaluated the position and the distance (mm) between the catheter tip and the thoracic intervertebral foramen content. Finally, puncturing of intervertebral blood vessels, nerve rootlet and root damage, lung and pleural injuries, and the extent of intramuscular dye accumulation were evaluated and recorded as iatrogenic complications related to the anesthetic procedure. Forty thoracic paravertebral blocks in 5 cadavers were performed. For 38 injection sites, we found dye on both sides of the thoracic paravertebral space and the epidural space at each level of puncture. The ventral rami, the communicating rami, and the sympathetic trunk were also stained. In 2 cases, methylene blue accumulated intramuscularly at the level of the twelfth thoracic vertebra. LIMITATIONS: The first limitation of this study is its small sample size. In addition, the study design did not consider or measure the width of the transverse processes. Another limitation is that the ultrasound beam could not identify the thoracic intervertebral foramen content or the needle tip behind the acoustic shadow of the transverse and vertebral articular processes. CONCLUSION: Paravertebral block via the thoracic intervertebral foramen achieved consistent dye spread into the thoracic paravertebral space and epidural space, capturing retropleural organs.

A Modified Approach for Ultrasound-Guided Thoracic Paravertebral Block via Thoracic Intervertebral Foramen in an Adolescent Patient: A Case Report.

This case report describes a modified approach for a thoracic paravertebral block by performing a bilateral ultrasound-assisted injection of 12 mL of 0.5% levobupivacaine near the thoracic intervertebral foramen, combined with general anesthesia, in a patient who underwent emergent laparotomy for small intestinal volvulus. Two continuous catheter sets were used for a bilateral continuous block with levobupivacaine 0.25% at a rate of 5-8 mL/h. No complications during the execution of the block were recorded. No supplemental opioids were administered and the patient was hemodynamically stable, requiring no pharmacological cardiovascular support during surgery. At the end of the surgical procedure, the patient received a continuous flow of 0.2% levobupivacaine as postoperative analgesia, at a basal flow of 4 mL/h per each side, a bolus of 4 mL, and a lockout time of 60 min was used. The postoperative pain on the Numeric Rating Scale was 2 at rest and it was 4 in motion, without neurological or respiratory sequelae due to block in the first 72 h after surgery.

Arterial Blood Gas and Rotational Thromboelastometry Parameters in Healthy Rescuers Incidentally Exposed to Nitroglycerin, Nitrogen Compounds, and Combustion Products.

INTRODUCTION: Acute exposure to nitrogen compounds combined with a massive inhalation of air pollutants can influence respiratory and cardiovascular symptoms and coagulation abnormalities in accidentally exposed healthy adults during cave detonation operations. METHODS: Italian alpine and cave rescuers widened a cave in the Abisso Luca Kralj in Trieste, Italy. Volunteers inside the cave were accidentally exposed to the fumes from an uncontrolled detonation of blasting gelatin microcharges. We performed a retrospective cohort study on the clinical data, arterial blood gas analysis, and rotational thromboelastometry parameters from the rescuers involved in the accident. RESULTS: Ninety-three healthy rescuers were involved in the uncontrolled detonation: 47 volunteers handled a mixture of nitrogen compounds (blaster group), and 46 volunteers did not (nonblaster group). After the accident, statistically significant differences (P<0.05) in arterial blood gas values were observed between the groups, with a pattern of mild respiratory acidosis with hypercapnia in the nonblaster group and severe mixed acid-base disorder with hypoxia and hypercapnia in the blaster group. Mild hyperfibrinolysis was observed in 44 volunteers in the blaster group, as were associated bleeding symptoms in 34 volunteers; no significant coagulation modifications were recorded in the nonblaster group. CONCLUSIONS: Respiratory acidosis with hypoxia, hypercapnia, a compensatory metabolic response, and mild hyperfibrinolysis were probably related to the combined effect of nitrogen compounds and the inhaled toxic products of detonation. Therefore, each element exerts a determinant effect on promoting the biological toxicity of the others.

Intermediate Cervical Plexus Block in the Management of Persistent Postoperative Pain Post Carotid Endarterectomy: A Prospective, Randomized, Controlled, Clinical Trial.

BACKGROUND: The mechanisms of persistent postoperative pain (PPP) with neuropathic features after carotid endarterectomy (CEA) are multifaceted and are incompletely understood. OBJECTIVES: The aim of this research was to assess whether the ultrasound-guided (USG) intermediate cervical plexus block (ICPB) could provide better control of PPP and neuropathic disturbances (NPDs) after CEA than the USG superficial cervical plexus block (SCPB). STUDY DESIGN: Prospective, randomized, controlled, clinical trial. SETTING: This clinical trial was conducted at the SS Filippo and Nicola Academic Hospital of Avezzano (L'Aquila, Italy). METHODS: Patients who were scheduled for primary CEA were chosen. In the experimental group, the USG-ICPB was performed unilaterally, at the level of the third cervical vertebra. The needle was inserted into the deep lamina of the deep fascia of the neck, between the posterior border of the middle scalene muscle and the anterior border of the posterior scalene muscle. Three milliliters saline solution was injected into the opening of the deep lamina, and 20 mL 0.375% levobupivacaine was injected. In the control group, the anesthetic target was located at the inferior border of the sternocleidomastoid muscle at the level of the third cervical vertebra. The needle was superficially inserted below the skin, and 2 to 3 mL saline solution was injected into the opening of the superficial lamina of the deep fascia of the neck. A total of 20 mL 0.375% isobaric levobupivacaine was subsequently injected.The primary outcome measure was the proportion of patients with PPP on movement and at rest 3 months after surgery. The secondary outcome measures were NPD assessment scores using the von Frey hair test and the Lindblom test, opioid and pregabalin consumption. Adverse effects were also recorded. RESULTS: A total of 98 consecutive patients were enrolled and randomized to receive either a USG-SCPB (control group, n = 49) or a USG-ICPB (experimental group, n = 49). The sensory blockade was longer in the experimental group. Three months after surgery, the proportions of patients with PPP on movement were significantly different between the experimental and control groups (33%, 95% confidence intervals [CI], 20%-47% vs. 71%, 95% CI, 57%-83%; P < 0.001), whereas there were no differences in the proportions of patients with pain at rest between groups (31%, 95% CI, 18%-45% vs. 49%, 95% CI, 34%-64%; P = 0.063). The proportions of patients with NPDs were not different between the groups, whereas the sizes of the areas of interest (cm2) were significantly different. LIMITATIONS: A limitation of this study is that we assessed NPDs for only 3 months using the von Frey hair test and the Lindblom test without additional instrumental techniques. Additionally, there are many risk factors for NPDs after CEA. For this reason, another limitation of this research is that we neglected to consider the relationship between the choice of anesthetic block and the presence of these risk factors. CONCLUSIONS: The USG-ICPB provided long-lasting analgesia during the postoperative period and might mitigate the development of NPDs, thereby decreasing the analgesic drug requirement. KEY WORDS: Carotid endarterectomy, intermediate cervical plexus block, myofascial planes of neck, neuropathic disturbances, persistent postoperative pain, superficial cervical plexus blocks, ultrasound guidance, vascular disease.