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This study evaluates the movement of the diaphragm (which is the main muscle used for breathing). It will compare two ultrasound modalities: linear ultrasound versus curvilinear ultrasound, at measuring diaphragm motion. The proposed measurement method with linear ultrasound is novel, and will be compared against the established method with curvilinear ultrasound. The investigators hypothesize that the novel method will have several potential advantages, including: it may be easier to learn, quicker to perform, and have a lower failure rate.
Full description
Background:
Multiple pathologies cause diaphragmatic dysfunction, including: respiratory, abdominal and neurological disease. Established clinical tests of diaphragmatic function, include: the transdiaphragmatic pressure, the maximal static inspiratory pressure, the sniff inspiratory pressure, pulmonary function tests, electromyography, a chest radiograph or fluoroscopy.
However ultrasound assessment of diaphragmatic function is a non-invasive, radiation-free technique that has gained traction in clinical practice in recent years. Several different methods have been described, that examine motion in two different areas of the diaphragm, either the zone of apposition, or the dome of the diaphragm, however no one method has emerged as the standard of care.
The current conventional technique (using B-mode or M-mode ultrasound via a phased array or curvilinear probe) in the subcostal region, has several limitations:
The investigators propose a novel method, using linear ultrasound to examine the zone of apposition, and determine diaphragmatic excursion at end inspiration and expiration. In theory this technique may have a number of advantages over the conventional method. It is likely easier to learn, quicker to perform, and has a lower failure rate for imaging the diaphragm on both sides during deep breathing. The investigators will compare this method to the conventional method, i.e. a curvilinear probe as described above.
Hypothesis:
Diaphragmatic motion can be assessed more rapidly, and more reliably via a linear high frequency ultrasound probe, than a curved low frequency probe.
Primary Objective:
Secondary Objectives:
This prospective observational study, will involve patients undergoing elective surgery, and will consist of two phases:
Phase 1:
The first phase will be to evaluate a new lung ultrasound technique to measure diaphragmatic excursion using a linear probe in the mid-axillary line. This will involve scanning 75 healthy patients undergoing elective surgery to determine normal reference values for this technique in men and women.
Phase 2:
The second phase will involve 100 patients who are undergoing an inter-scalene, upper trunk of cervical plexus, or supraclavicular brachial plexus block as part of their perioperative analgesic management for shoulder or arm surgery. This cohort of patient is likely to develop phrenic nerve palsy as a side effect of the brachial plexus block. The resultant phrenic nerve palsy, will result in reduced diaphragmatic motion, and the aim will be to evaluate the ability of using a linear probe technique to measure this reduction as compared to the conventional method of measurement.
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Inclusion criteria
Phase 1 Any healthy adult patient undergoing elective surgery
Phase 2 Any adult patient, undergoing elective upper limb surgery that involves an interscalene or supraclavicular brachial plexus block.
Exclusion criteria
(i) Inability to obtain an informed consent (e.g. language barrier) (ii) BMI > 35 (iii) Known pre-existing diaphragmatic dysfunction (iv) Existing lung pathology
Additional Criteria for Phase 2 Any contraindication to an interscalene or supraclavicular brachial plexus block
175 participants in 2 patient groups
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Central trial contact
Anahi Perlas, MD; Jayanta Chowdhury
Data sourced from clinicaltrials.gov
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