Coronary Artery Disease, Postoperative Pain
Conditions
Keywords
artificial intelligence, multimodal AI, ultrasonography, regional anaesthesia, pecto-intercostal fascial plane block, coronary artery bypass grafting, postoperative pain, reader study
Brief summary
This prospective observational cohort with a nested archived-image reader study compared the sonographic pecto-intercostal fascial plane block classifications of five general-purpose multimodal artificial-intelligence configurations and three expert anaesthesiologists against a separate senior anaesthesiologist's single-expert reference. Adults undergoing elective isolated coronary artery bypass grafting through median sternotomy were enrolled consecutively on days when the consultant anaesthesiologist responsible for block performance and ultrasound acquisition was available. Standardised left-sided ultrasound videos were recorded in 120 consented participants. Bilateral pecto-intercostal fascial plane block was performed in 115 participants; five participants who declined the block consented to standardised ultrasound imaging and served as no-block image controls. Eight to ten representative de-identified frames from each video were assessed independently by all readers. Associations between reference-defined sonographic spread and postoperative pain were secondary and observational.
Detailed description
This single-centre prospective observational cohort included 120 consenting adults undergoing elective isolated coronary artery bypass grafting through median sternotomy. At the end of surgery, after complete sternal and skin closure, 115 participants received bilateral ultrasound-guided pecto-intercostal fascial plane block with 20 mL of 0.25% bupivacaine on each side (40 mL and 100 mg in total). Five participants declined the block but consented to Ethics Committee-authorised standardised ultrasound imaging, storage and subsequent de-identified human/AI assessment; no needle was inserted and no local anaesthetic was administered in this group. Ultrasound videos were acquired from the left side with an M5 portable ultrasound system and a 7L4s linear-array transducer at a nominal frequency of 7.5 MHz using standardised settings. Eight to ten representative frames were selected from each video across the pre-block view, needle advancement, local-anaesthetic spread and final post-injection view, as applicable. The same frame set and fixed participant order were shown to every reader. After participant follow-up had ended, five general-purpose multimodal AI configurations, three expert anaesthesiologists and one separate senior reference anaesthesiologist independently classified each image set as successful, patchy/inadequate or failed/no local anaesthetic. The evaluated configurations were Gemini 3.5 Flash, Claude Sonnet 4.6, GPT-5.5 Instant in ChatGPT, Grok 4.3 and Kimi K2.6. They were accessed through free, non-subscription consumer accounts using their standard web interfaces and default response and data-use settings. For each system-participant pair, a new conversation was opened, the same fixed prompt and image set were submitted, and the first response was recorded without regeneration or re-prompting. The visible conversation was deleted before the next assessment, although this did not establish provider-side deletion. Each configuration assessed each participant once; within-system repeatability was not evaluated. The number and identities of the five consumer configurations were fixed before any reader output was observed; no bespoke AI model was developed or trained. The separate senior anaesthesiologist was a pragmatic single-expert reference and not an objective gold standard. The study was not designed as an equivalence or non-inferiority analysis. Postoperative Numerical Rating Scale pain at rest and during coughing was scheduled at 6, 12, 24 and 48 hours. The 6-hour assessment was applicable only to participants who had already been extubated at that time. Rescue analgesic administration during the first 48 hours, intensive-care and hospital length of stay, complications and mortality were also recorded. Pain associations were secondary, observational and non-causal. The ClinicalTrials.gov record was first submitted on 6 May 2026 and first posted on 12 May 2026, after the study had begun but while recruitment, image acquisition and clinical follow-up were still ongoing. Registration was therefore retrospective relative to study start. Image acquisition ended on 27 May 2026 and participant clinical follow-up ended on 1 June 2026.
Interventions
PROCEDUREPecto-Intercostal Fascial Plane Block
Bilateral ultrasound-guided PIFB performed after complete sternal and skin closure as routine clinical care, using 20 mL of 0.25% bupivacaine on each side (40 mL; 100 mg total).
Sponsors
Bursa Yuksek Ihtisas Training and Research Hospital
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
* Age 18-80 years * American Society of Anesthesiologists physical status III * Scheduled for elective isolated coronary artery bypass grafting through median sternotomy * Written informed consent for study participation and research/AI assessment of de-identified ultrasound images
Exclusion criteria
* Emergency surgery * Redo sternotomy * Minimally invasive or thoracotomy surgical approach * Allergy to local anaesthetics * International normalised ratio greater than 1.5 or platelet count below 80,000 per microlitre * Infection at the planned injection site * Chronic opioid use for more than 3 months * Cognitive dysfunction * Pregnancy
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Balanced Accuracy of Binary PIFB Classification Against a Single-Expert Reference | June 2026; each archived image set was assessed once by each reader. | Among 115 participants who received pecto-intercostal fascial plane block, binary classifications from each of five general-purpose multimodal artificial-intelligence configurations and three expert anaesthesiologists were compared separately with the classification of a senior anaesthesiologist serving as a pragmatic single-expert reference. Successful was the positive category; patchy/inadequate and failed/no local anaesthetic were combined as not successful. Balanced accuracy was calculated as (sensitivity + specificity)/2 and reported from 0 to 1, with higher values indicating closer agreement with the reference. The reference was not an objective gold standard, and no equivalence or non-inferiority hypothesis was tested. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Sensitivity of AI and Expert Binary PIFB Classifications Against a Single-Expert Reference | June 2026; each archived image set was assessed once by each reader. | Sensitivity was the percentage of image sets classified as successful by a reader among image sets classified as successful by the pragmatic single-expert reference. It was calculated separately for each of the five artificial-intelligence configurations and three expert anaesthesiologists in the 115 PIFB-treated participants. Possible values range from 0 to 100 percent; higher values indicate closer agreement with the reference. |
| Specificity of AI and Expert Binary PIFB Classifications Against a Single-Expert Reference | June 2026; each archived image set was assessed once by each reader. | Specificity was the percentage of image sets classified as not successful by a reader among image sets classified as not successful by the pragmatic single-expert reference. Patchy/inadequate and failed/no local anaesthetic were grouped as not successful. It was calculated separately for each of the five artificial-intelligence configurations and three expert anaesthesiologists in the 115 PIFB-treated participants. Possible values range from 0 to 100 percent; higher values indicate closer agreement with the reference. |
| Positive Predictive Value of AI and Expert Binary PIFB Classifications Against a Single-Expert Reference | June 2026; each archived image set was assessed once by each reader. | Positive predictive value was the percentage of image sets classified as successful by a reader that were also classified as successful by the pragmatic single-expert reference. It was calculated separately for each of the five artificial-intelligence configurations and three expert anaesthesiologists in the 115 PIFB-treated participants. Possible values range from 0 to 100 percent; higher values indicate closer agreement with the reference. |
| Negative Predictive Value of AI and Expert Binary PIFB Classifications Against a Single-Expert Reference | June 2026; each archived image set was assessed once by each reader. | Negative predictive value was the percentage of image sets classified as not successful by a reader that were also classified as not successful by the pragmatic single-expert reference. Patchy/inadequate and failed/no local anaesthetic were grouped as not successful. It was calculated separately for each of the five artificial-intelligence configurations and three expert anaesthesiologists in the 115 PIFB-treated participants. Possible values range from 0 to 100 percent; higher values indicate closer agreement with the reference. |
| Overall Accuracy of AI and Expert Binary PIFB Classifications Against a Single-Expert Reference | June 2026; each archived image set was assessed once by each reader. | Overall accuracy was the percentage of the 115 PIFB-treated image sets for which a reader's binary successful or not-successful classification matched the pragmatic single-expert reference. It was calculated separately for each of the five artificial-intelligence configurations and three expert anaesthesiologists. Possible values range from 0 to 100 percent; higher values indicate closer agreement with the reference. |
| Linear-Weighted Cohen Kappa for Three-Category Agreement With the Single-Expert Reference | June 2026; each archived image set was assessed once by each reader. | Across all 120 image sets, linear-weighted Cohen kappa was calculated separately for each of the five artificial-intelligence configurations and three non-reference expert anaesthesiologists against the pragmatic single-expert reference using the ordered categories successful, patchy/inadequate and failed/no local anaesthetic. Values range from -1 to 1; 1 indicates perfect agreement, 0 indicates agreement expected by chance and negative values indicate less agreement than expected by chance. Each reader assessed each image set once. |
| Fleiss Kappa Among AI Configurations and Among Expert Anaesthesiologists | June 2026; each archived image set was assessed once by each reader. | Across all 120 image sets, Fleiss kappa was calculated separately among the five artificial-intelligence configurations and among the three non-reference expert anaesthesiologists using the categories successful, patchy/inadequate and failed/no local anaesthetic. Values range from -1 to 1; 1 indicates perfect agreement, 0 indicates agreement expected by chance and negative values indicate less agreement than expected by chance. Each reader assessed each image set once; within-reader and within-system repeatability were not evaluated. |
| Median Postoperative Resting Pain Score on the Numerical Rating Scale | 6, 12, 24 and 48 hours after surgery | Resting pain was reported verbally as a whole number on an 11-point Numerical Rating Scale from 0 (no pain) to 10 (worst imaginable pain); higher scores indicate worse pain. Scores were summarised as median and interquartile range at each scheduled time point. Assessment required the participant to be extubated and able to respond. The planned 6-hour assessment was applicable only when the participant had already been extubated. |
| Median Postoperative Cough-Evoked Pain Score on the Numerical Rating Scale | 6, 12, 24 and 48 hours after surgery | Pain during coughing was reported verbally as a whole number on an 11-point Numerical Rating Scale from 0 (no pain) to 10 (worst imaginable pain); higher scores indicate worse pain. Scores were summarised as median and interquartile range at each scheduled time point. Assessment required the participant to be extubated and able to respond. The planned 6-hour assessment was applicable only when the participant had already been extubated. |
| Number of Participants Receiving Additional Rescue Paracetamol | During the first 48 hours after surgery | In the 115 participants who received PIFB, rescue paracetamol administration was recorded as a participant-level yes/no measure and was to be summarised as the number and percentage of participants receiving at least one rescue dose. Rescue treatment was administered when NRS exceeded 4 at the attending physician's discretion. |
| Number of Participants Receiving Rescue Tramadol | During the first 48 hours after surgery | In the 115 participants who received PIFB, rescue tramadol administration was recorded as a participant-level yes/no measure and was to be summarised as the number and percentage of participants receiving at least one rescue dose. Rescue treatment was administered when NRS exceeded 4 at the attending physician's discretion. |
| Number of Participants Receiving Rescue Pethidine | During the first 48 hours after surgery | In the 115 participants who received PIFB, rescue pethidine administration was recorded as a participant-level yes/no measure and was to be summarised as the number and percentage of participants receiving at least one rescue dose. Rescue treatment was administered when NRS exceeded 4 at the attending physician's discretion. |
| Median Intensive Care Unit Length of Stay in Days | From postoperative intensive-care admission to intensive-care discharge, up to 13 days after surgery | Intensive-care length of stay was the recorded number of days from postoperative intensive-care admission until intensive-care discharge and was summarised as median and interquartile range in the PIFB-treated cohort. |
| Median Index Hospital Length of Stay in Days | From surgery to hospital discharge, up to 25 days after surgery | Hospital length of stay was the recorded number of days from coronary artery bypass grafting until discharge from the index hospital admission and was summarised as median and interquartile range in the PIFB-treated cohort. |
| Number of Participants With at Least One Postoperative Complication | From surgery through hospital discharge during the index admission, up to 25 days after surgery | In the 115 participants who received PIFB, postoperative complications recorded during the index hospital admission were summarised as the number and percentage of participants with at least one event. |
| Number of Participants Who Died During the Index Hospital Admission | From surgery through hospital discharge during the index admission, up to 25 days after surgery | In the 115 participants who received PIFB, mortality was summarised as the number and percentage of participants who died before discharge from the index hospital admission. |
Countries
Turkey (Türkiye)
Outcome results
None listed