An interventional study of High thoracic paravertebral block in Breast Cancer Surgery, Breast Cancer Surgery Pain and Hemidiaphragmatic Paralysis, sponsored by Ciusss de L'Est de l'Île de Montréal. Not yet recruiting at 1 site in Canada. Open to participants aged 18 Years to 80 Years. Per ClinicalTrials.gov, last updated 2026-10-30.
Sponsored by Ciusss de L'Est de l'Île de Montréal · Not applicable, Interventional, and Treatment
The high thoracic paravertebral block is a regional anesthesia technique commonly used for oncologic breast surgery. Local anesthetic is injected into the paravertebral space to provide anesthesia and pain relief. Case reports suggest that cephalad spread of local anesthetic may occasionally affect the phrenic nerve and lead to temporary hemidiaphragmatic dysfunction, but the incidence of this complication is unknown. The goal of this prospective interventional study is to evaluate the impact of high thoracic paravertebral block on diaphragmatic function in patients undergoing unilateral oncologic breast surgery. Diaphragmatic function will be assessed using ultrasound before and after the block. The study will also evaluate postoperative pain, opioid consumption, respiratory symptoms, and other postoperative outcomes.
High thoracic paravertebral block (PVB) is a regional anesthesia technique widely used for oncologic breast surgery. By injecting local anesthetic into the thoracic paravertebral space, it provides unilateral somatic and sympathetic blockade, allowing surgery to be performed with excellent analgesia while reducing postoperative pain and opioid requirements.
The thoracic paravertebral space is not an anatomically closed compartment. Anatomical and imaging studies have demonstrated continuity between the paravertebral space and adjacent structures, allowing local anesthetic to spread beyond the intended thoracic dermatomes. Following high thoracic PVB, cephalad spread of local anesthetic has been associated with unintended blockade of neighboring neural structures, including the brachial plexus and cervical sympathetic chain. Case reports have also described ipsilateral hemidiaphragmatic paresis following high thoracic PVB, suggesting possible involvement of the phrenic nerve.
Despite the widespread use of high thoracic PVB, the incidence of hemidiaphragmatic dysfunction remains unknown because diaphragmatic function is not routinely assessed in clinical practice. As a result, transient or subclinical diaphragmatic dysfunction may be underrecognized.
Diaphragm ultrasonography is a non-invasive and validated method for assessing diaphragmatic function. Measurements such as diaphragmatic excursion and diaphragmatic thickening fraction can be obtained at the bedside and provide objective information regarding diaphragmatic motion and contractility.
The objective of this prospective single-center interventional study is to determine the incidence of ipsilateral hemidiaphragmatic dysfunction following high thoracic PVB in patients undergoing unilateral oncologic breast surgery. Diaphragmatic function will be evaluated using standardized ultrasound measurements performed before block placement and after surgery. Secondary outcomes will include changes in diaphragmatic excursion, postoperative respiratory symptoms and adverse events, postoperative pain scores, opioid consumption, and the incidence of inadvertent brachial plexus blockade. The results of this study will improve understanding of the respiratory effects and safety profile of high thoracic paravertebral block.
14,825 studies on the registry are indexed under Breast Neoplasms; 3,319 are open to participants now.
This study's planned enrollment of 40 is below the median of 72 across 10,896 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →Ciusss de L'Est de l'Île de Montréal is the lead sponsor of 90 studies on the registry; 32 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants undergoing unilateral oncologic breast surgery will receive an ultrasound-guided high thoracic paravertebral block using a standardized two-injection technique. After baseline diaphragmatic ultrasound assessment, a regional anesthesiologist will perform the block at the T1-T2 level and at a second thoracic level selected according to the surgical site using a total of 30 mL of local anesthetic (15 mL per injection). The block will be performed with the ultrasound transducer in the sagittal position about 2.5 to 3 centimeters (cm) lateral to the spinous process using a caudal to cranial in-plane needle approach. The thoracic vertebral levels will be identified by finding the first rib under ultrasound guidance and counting down levels appropriately. The needle (80 mm 22-gauge echogenic SonoPlex needle from Pajunk) will be introduced in-plane in a caudal to cranial. Diaphragmatic ultrasound measurements will be repeated in the post-anesthesia care unit following surgery.
Procedure: High thoracic paravertebral block
already described in arm description
Incidence of ipsilateral hemidiaphragmatic dysfunction determined by diaphragm ultrasonography
The incidence of ipsilateral hemidiaphragmatic paralysis following high thoracic paravertebral block, assessed by diaphragm ultrasonography using the diaphragmatic thickening fraction (DTF).
Time frame: Postoperative assessment in the PACU, approximately 1-3 hours after block placement.
Change in ipsilateral diaphragmatic excursion
Change in ipsilateral diaphragmatic excursion from baseline (pre-block) to postoperative assessment measured by diaphragm ultrasonography.
Time frame: Baseline (before block) and postoperative assessment in the PACU, approximately 1-3 hours after block placement.
Postoperative dyspnea
Incidence and intensity of dyspnea assessed in the PACU using a numerical rating scale (NRS 0-10).
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Oxygen desaturation
Incidence of oxygen desaturation episodes, defined as oxygen saturation below 92%.
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Supplemental oxygen requirement
Requirement for supplemental oxygen during PACU stay.
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Postoperative pain intensity
Pain intensity assessed in the PACU using a numerical rating scale (NRS 0-10).
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Postoperative opioid consumption
Total postoperative opioid consumption in the PACU, expressed as morphine milligram equivalents (MME).
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Inadvertent brachial plexus block
Incidence of inadvertent brachial plexus block following high thoracic paravertebral block.
Time frame: After block placement until discharge from the PACU (approximately 1-3 hours).
Plan to share: No — Protected health information will not be re-used or disclosed to a third party except as required by law, for authorized oversight of the research, or as permitted by an authorization signed by the research subject.
No publications or documents are linked to this record.
Start is estimated for Sep 2026; primary completion for May 2027, 8 months later.
Of 2,661 non-industry interventional studies with no phase under Breast Neoplasms, half reached primary completion within 33 months of starting (the median), counting those still running; a quarter within 16 and three quarters within 66. This study's planned 8 months is below that.
Counting every sponsor, half of 2,771 studies reached it within 33 months; a quarter within 15 and three quarters within 66.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Ciusss de L'Est de l'Île de Montréal