Breast Cancer SurgeryNCT07907692
Impact of High Thoracic Paravertebral Block on Diaphragmatic Function: a Prospective Study
A study testing High thoracic paravertebral block in people with Breast Cancer Surgery and Breast Cancer Surgery Pain, run by Ciusss de L'Est de l'Île de Montréal at 1 site in Canada.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- Breast Cancer Surgery, Breast Cancer Surgery Pain, Hemidiaphragmatic Paralysis
- What is being tested?
- High thoracic paravertebral block
- Type of treatment
- Injection or infusion, Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteCanada
- Study dates
- Sep 2026to May 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Fully consented, ASA 1-3 patients from 18yo to 80yo
- Undergoing unilateral oncologic breast surgery under PVBs
Who cannot join
- Patient refusal or inability to consent
- Allergy to medication used in the trial
- Pregnant or breastfeeding women
- Low body weight (under 50 kg)
- BMI over 40
- Moderate to severe COPD or other moderate to severe respiratory condition
- Contraindications to locoregional anesthesia: Infection at the site of blocks, coagulopathy, anatomic distorsion, neuropathy.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site
Maisonneuve-Rosemont Hospital
Montreal, Quebec, H1T 2M4
Ariane Clairoux, MD, 514-222-6743, clairouxariane@gmail.com
About this study
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.
Read the detailed description
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.
- Being tested
- High thoracic paravertebral block
- Keywords
- regional anesthesia, High thoracic paravertebral block, post-operative analgesia, hemidiaphragmatic paralysis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
High thoracic paravertebral blockProcedure or surgery
already described in arm description
| Study group | Role | What they receive |
|---|---|---|
| High thoracic paravertebral block | Experimental | 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. Receives: Procedure: High thoracic paravertebral block |
What is being measured
The primary outcome is the main question the study is designed to answer.
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).
Measured: Postoperative assessment in the PACU, approximately 1-3 hours after block placement.
Secondary outcomes (7)
Change in ipsilateral diaphragmatic excursion
Change in ipsilateral diaphragmatic excursion from baseline (pre-block) to postoperative assessment measured by diaphragm ultrasonography.
Measured: 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).
Measured: From PACU admission to PACU discharge (approximately 1-3 hours).
Oxygen desaturation
Incidence of oxygen desaturation episodes, defined as oxygen saturation below 92%.
Measured: From PACU admission to PACU discharge (approximately 1-3 hours).
Supplemental oxygen requirement
Requirement for supplemental oxygen during PACU stay.
Measured: 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).
Measured: 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).
Measured: 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.
Measured: After block placement until discharge from the PACU (approximately 1-3 hours).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted30 Oct 2026
- Study startSep 2026 (estimated)
- Primary completionMay 2027 (estimated)
- Study completionMay 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Breast Cancer SurgeryStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Single group : Ultrasound-guided high thoracic paravertebral block for oncologic breast surgery
- Masking
- None (open label)
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Ciusss de L'Est de l'Île de Montréal
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Ariane Clairoux, Ciusss de L'Est de l'Île de Montréal
- Investigators
- Ariane Clairoux, MD, Principal investigator, Maisonneuve-Rosemont Hospital / CIUSSS de l'Est-de-l'Île-de-Montréal
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07907692
- Sponsor's protocol ID
- 2027-4391
- Status last verified
- Oct 2026
- First submitted
- 26 Oct 2026
- Last updated
- 30 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- 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.
Study at a glance
From the registry record, last updated by the sponsor on 30 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Impact of High Thoracic Paravertebral Block on Diaphragmatic Function: a Prospective Study
- ClinicalTrials.gov ID
- NCT07907692
- Acronym / sponsor ID
- 2027-4391
- Keywords
- regional anesthesia, High thoracic paravertebral block, post-operative analgesia, hemidiaphragmatic paralysis
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- Ciusss de L'Est de l'Île de MontréalUniversity, hospital or other
- Study start
- Sep 2026 (estimated)
- Primary completion
- May 2027 (estimated)
- Study completion
- May 2027 (estimated)
- First posted
- 30 Oct 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Single group : Ultrasound-guided high thoracic paravertebral block for oncologic breast surgery
| Arm | Type | Receives |
|---|---|---|
| High thoracic paravertebral block | Experimental | Procedure: High thoracic paravertebral blockParticipants 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. |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Fully consented, ASA 1-3 patients from 18yo to 80yo
- Undergoing unilateral oncologic breast surgery under PVBs
Key exclusion criteria (7 listed)
- Patient refusal or inability to consent
- Allergy to medication used in the trial
- Pregnant or breastfeeding women
- Low body weight (under 50 kg)
- BMI over 40
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| High thoracic paravertebral blockalready described in arm description | Procedure or surgery | High thoracic paravertebral block |
Primary outcome
Incidence of ipsilateral hemidiaphragmatic dysfunction determined by diaphragm ultrasonography
Time frame: Postoperative assessment in the PACU, approximately 1-3 hours after block placement.
The incidence of ipsilateral hemidiaphragmatic paralysis following high thoracic paravertebral block, assessed by diaphragm ultrasonography using the diaphragmatic thickening fraction (DTF).
7 secondary outcomes
Change in ipsilateral diaphragmatic excursion
Time frame: Baseline (before block) and postoperative assessment in the PACU, approximately 1-3 hours after block placement.
Postoperative dyspnea
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Oxygen desaturation
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Supplemental oxygen requirement
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Postoperative pain intensity
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Postoperative opioid consumption
Time frame: From PACU admission to PACU discharge (approximately 1-3 hours).
Inadvertent brachial plexus block
Time frame: After block placement until discharge from the PACU (approximately 1-3 hours).
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Oct 2026.
- Individual participant dataSharing planned: 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.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Ariane Clairoux, MD principal investigator
Maisonneuve-Rosemont Hospital / CIUSSS de l'Est-de-l'Île-de-Montréal
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing High thoracic paravertebral block in people with Breast Cancer Surgery and Breast Cancer Surgery Pain, run by Ciusss de L'Est de l'Île de Montréal at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 30 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Ariane Clairoux, MD (514-222-6743, clairouxariane@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Incidence of ipsilateral hemidiaphragmatic dysfunction determined by diaphragm ultrasonography (time frame: Postoperative assessment in the PACU, approximately 1-3 hours after block placement.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Oct 2026; AzTrials last refreshed its copy on 4 Nov 2026.