This clinical study confirms user acceptability of PAPR during surgery both at operating room tea... more This clinical study confirms user acceptability of PAPR during surgery both at operating room team level as well as by groups of surgeons, anaesthesiologists and nursing level. While some care is needed in the use of this equipment, surgery can be performed safely with satisfactory user experience. Therefore PAPR is useable for surgery but scope exists for improvement.
Introduction Indocyanine green (ICG) quantification and assessment by machine learning (ML) could... more Introduction Indocyanine green (ICG) quantification and assessment by machine learning (ML) could discriminate tissue types through perfusion characterisation, including delineation of malignancy. Here, we detail the important challenges overcome before effective clinical validation of such capability in a prospective patient series of quantitative fluorescence angiograms regarding primary and secondary colorectal neoplasia. Methods ICG perfusion videos from 50 patients (37 with benign (13) and malignant (24) rectal tumours and 13 with colorectal liver metastases) of between 2- and 15-min duration following intravenously administered ICG were formally studied (clinicaltrials.gov: NCT04220242). Video quality with respect to interpretative ML reliability was studied observing practical, technical and technological aspects of fluorescence signal acquisition. Investigated parameters included ICG dosing and administration, distance–intensity fluorescent signal variation, tissue and camer...
Background There is a substantial gap in provision of adequate surgical care in many low- and mid... more Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality wa...
The wide availability of near infrared light sources in interventional medical imaging stacks ena... more The wide availability of near infrared light sources in interventional medical imaging stacks enables non-invasive quantification of perfusion by using fluorescent dyes, typically Indocyanine Green (ICG). Due to their often leaky and chaotic vasculatures, intravenously administered ICG perfuses through cancerous tissues differently. We investigate here how a few characteristic values derived from the time series of fluorescence can be used in simple machine learning algorithms to distinguish benign lesions from cancers. These features capture the initial uptake of ICG in the colon, its peak fluorescence, and its early wash-out. By using simple, explainable algorithms we demonstrate, in clinical cases, that sensitivity (specificity) rates of over 95% (95%) for cancer classification can be achieved.
Introduction The advent of the COVID-19 pandemic led to recommendations aimed at minimizing the r... more Introduction The advent of the COVID-19 pandemic led to recommendations aimed at minimizing the risk of gas leaks at laparoscopy. As this has continuing relevance including regarding operating room pollution, we empirically quantified carbon dioxide (CO2) leak jet velocity (important for particle propulsion) occurring with different instruments inserted into differing trocars repeated across a range of intra-abdominal pressures (IAPs) and modern insufflators in an experimental model. Method Laparoscopic gas plume leak velocity (metres/second) was computationally enumerated from schlieren optical flow videography on a porcine cadaveric laparoscopic model with IAPs of 4–5, 7–8, 12–15 and 24–25 mmHg (repeated with 5 different insufflators) during simulated operative use of laparoscopic clip appliers, scissors, energy device, camera and staplers as well as Veres needle (positive control) and trocar obturator (negative control) in fresh 5 mm and 12 mm ports. Results Close-fitting solid i...
Background COVID-19 has greatly impacted medical students’ clinical education. This study evaluat... more Background COVID-19 has greatly impacted medical students’ clinical education. This study evaluates the usefulness of a rapidly implemented on-site simulation programme deployed to supplement our disrupted curriculum. Methods Students on surgical rotations received 4-hour tutor-led simulated patient sessions (involving mannikins with remote audio-visual observation) respecting hospital and public health protocols. Attitudes were questionnaire-assessed before and after. Independent, blinded, nonacademic clinicians scored students’ clinical competencies by observing real patient interactions using the surgical ward assessment tool in a representative sample versus those completing same duration medicine clinical rotations without simulation (Mann–Whitney U testing, p < 0.05 denoting significance) with all students receiving the same surgical e-learning resources and didactic teaching. Results A total of 220 students underwent simulation training, comprising 96 hours of scheduled di...
Introduction Indocyanine green fluorescence angiography (ICGFA) is commonly used in colorectal an... more Introduction Indocyanine green fluorescence angiography (ICGFA) is commonly used in colorectal anastomotic practice with limited pre-training. Recent work has shown that there is considerable inconsistency in signal interpretation between surgeons with minimal or no experience versus those consciously invested in mastery of the technique. Here, we deconstruct the fluorescence signal patterns of expert-annotated surgical ICGFA videos to understand better their correlation and combine this with structured interviews to ascertain whether such interpretative capability is conscious or unconscious. Methods For fluorescence signal analysis, expert-annotated ICGFA videos (n = 24) were quantitatively interrogated using a boutique intensity tracker (IBM Research) to generate signal time plots. Such fluorescence intensity data were examined for inter-observer correlation (Intraclass Correlation Coefficients, ICC) at specific curve milestones: the maximum fluorescence signal (Fmax), the times ...
Summary Indocyanine Green Fluorescence Angiography (ICGFA) has been deployed to tackle malperfusi... more Summary Indocyanine Green Fluorescence Angiography (ICGFA) has been deployed to tackle malperfusion-related anastomotic complications. This study assesses variations in operator interpretation of pre-anastomotic ICGFA inflow in the gastric conduit. Utilizing an innovative online interactive multimedia platform (Mindstamp), esophageal surgeons completed a baseline opinion-practice questionnaire and proceeded to interpret, and then digitally assign, a distal transection point on 8 ICGFA videos of esophageal resections (6 Ivor Lewis, 2 McKeown). Annotations regarding gastric conduit transection by ICGFA were compared between expert users versus non-expert participants using ImageJ to delineate longitudinal distances with Shapiro Wilk and t-tests to ascertain significance. Expert versus non-expert correlation was assessed via Intraclass Correlation Coefficients (ICC). Thirty participants (13 consultants, 6 ICGFA experts) completed the study in all aspects. Of these, a high majority (29 ...
As indocyanine green (ICG) with near-infrared (NIR) endoscopy enhances real-time intraoperative t... more As indocyanine green (ICG) with near-infrared (NIR) endoscopy enhances real-time intraoperative tissue microperfusion appreciation, it may also dynamically reveal neoplasia distinctively from normal tissue especially with video software fluorescence analysis. Colorectal tumours of patients were imaged mucosally following ICG administration (0.25 mg/kg i.v.) using an endo-laparoscopic NIR system (PINPOINT Endoscopic Fluorescence System, Stryker) including immediate, continuous in situ visualization of rectal lesions transanally for up to 20 min. Spot and dynamic temporal fluorescence intensities (FI) were quantified using ImageJ (including videos at one frame/second, fps) and by a bespoke MATLAB® application that provided digitalized video tracking and signal logging at 30fps (Fluorescence Tracker App downloadable via MATLAB® file exchange). Statistical analysis of FI-time plots compared tumours (benign and malignant) against control during FI curve rise, peak and decline from apex. ...
Despite increasing endorsement of near-infrared perfusion assessment using indocyanine green (ICG... more Despite increasing endorsement of near-infrared perfusion assessment using indocyanine green (ICG) during colorectal surgery, little work has yet been done regarding learning curve and interobserver variation most especially on surgical video reflective of real-world usage. Surgeons with established expertise in ICG usage were invited to participate in the study along with others without such experience including trainees. All participants completed an opinion questionnaire and interpreted video presentations of fluorescence angiograms in a variety of colorectal case scenarios. An interactive video platform (Mindstamp) enabled dynamic annotation. Statistical analysis of data was performed using Kruskal–Wallis and Mann–Whitney testing as well as Intraclass Correlation Coefficients and Fleiss Multi-rater Kappa Scoring. Forty participants (six experts) completed questionnaire data and provided judgement of 14 videos (nine showing proximal colonic transection site perfusion, four showing completed anastomoses and one an acutely strangulated bowel). 70% felt > 10 cases were needed for competency in use with the majority of experts advocating > 50 (p < 0.05). Overall agreement among experts was “good” for videos showing colonic transection perfusion (versus “moderate” among in-experts) with experts clustering more distally. In contrast, there was no interpretation concordance among experts or in-experts when judging ICG perfusion sufficiency on a yes/no basis. Significant experience is recommended before reliance on ICG perfusion angiograms. ICG fluorescence assessment is prone to variable interpretation and influenced by experience and, perhaps, knowledge of preassessment operative steps suggesting a role for objective flow analysis with artificial intelligence methods as the next phase of this technology.
This clinical study confirms user acceptability of PAPR during surgery both at operating room tea... more This clinical study confirms user acceptability of PAPR during surgery both at operating room team level as well as by groups of surgeons, anaesthesiologists and nursing level. While some care is needed in the use of this equipment, surgery can be performed safely with satisfactory user experience. Therefore PAPR is useable for surgery but scope exists for improvement.
Introduction Indocyanine green (ICG) quantification and assessment by machine learning (ML) could... more Introduction Indocyanine green (ICG) quantification and assessment by machine learning (ML) could discriminate tissue types through perfusion characterisation, including delineation of malignancy. Here, we detail the important challenges overcome before effective clinical validation of such capability in a prospective patient series of quantitative fluorescence angiograms regarding primary and secondary colorectal neoplasia. Methods ICG perfusion videos from 50 patients (37 with benign (13) and malignant (24) rectal tumours and 13 with colorectal liver metastases) of between 2- and 15-min duration following intravenously administered ICG were formally studied (clinicaltrials.gov: NCT04220242). Video quality with respect to interpretative ML reliability was studied observing practical, technical and technological aspects of fluorescence signal acquisition. Investigated parameters included ICG dosing and administration, distance–intensity fluorescent signal variation, tissue and camer...
Background There is a substantial gap in provision of adequate surgical care in many low- and mid... more Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality wa...
The wide availability of near infrared light sources in interventional medical imaging stacks ena... more The wide availability of near infrared light sources in interventional medical imaging stacks enables non-invasive quantification of perfusion by using fluorescent dyes, typically Indocyanine Green (ICG). Due to their often leaky and chaotic vasculatures, intravenously administered ICG perfuses through cancerous tissues differently. We investigate here how a few characteristic values derived from the time series of fluorescence can be used in simple machine learning algorithms to distinguish benign lesions from cancers. These features capture the initial uptake of ICG in the colon, its peak fluorescence, and its early wash-out. By using simple, explainable algorithms we demonstrate, in clinical cases, that sensitivity (specificity) rates of over 95% (95%) for cancer classification can be achieved.
Introduction The advent of the COVID-19 pandemic led to recommendations aimed at minimizing the r... more Introduction The advent of the COVID-19 pandemic led to recommendations aimed at minimizing the risk of gas leaks at laparoscopy. As this has continuing relevance including regarding operating room pollution, we empirically quantified carbon dioxide (CO2) leak jet velocity (important for particle propulsion) occurring with different instruments inserted into differing trocars repeated across a range of intra-abdominal pressures (IAPs) and modern insufflators in an experimental model. Method Laparoscopic gas plume leak velocity (metres/second) was computationally enumerated from schlieren optical flow videography on a porcine cadaveric laparoscopic model with IAPs of 4–5, 7–8, 12–15 and 24–25 mmHg (repeated with 5 different insufflators) during simulated operative use of laparoscopic clip appliers, scissors, energy device, camera and staplers as well as Veres needle (positive control) and trocar obturator (negative control) in fresh 5 mm and 12 mm ports. Results Close-fitting solid i...
Background COVID-19 has greatly impacted medical students’ clinical education. This study evaluat... more Background COVID-19 has greatly impacted medical students’ clinical education. This study evaluates the usefulness of a rapidly implemented on-site simulation programme deployed to supplement our disrupted curriculum. Methods Students on surgical rotations received 4-hour tutor-led simulated patient sessions (involving mannikins with remote audio-visual observation) respecting hospital and public health protocols. Attitudes were questionnaire-assessed before and after. Independent, blinded, nonacademic clinicians scored students’ clinical competencies by observing real patient interactions using the surgical ward assessment tool in a representative sample versus those completing same duration medicine clinical rotations without simulation (Mann–Whitney U testing, p < 0.05 denoting significance) with all students receiving the same surgical e-learning resources and didactic teaching. Results A total of 220 students underwent simulation training, comprising 96 hours of scheduled di...
Introduction Indocyanine green fluorescence angiography (ICGFA) is commonly used in colorectal an... more Introduction Indocyanine green fluorescence angiography (ICGFA) is commonly used in colorectal anastomotic practice with limited pre-training. Recent work has shown that there is considerable inconsistency in signal interpretation between surgeons with minimal or no experience versus those consciously invested in mastery of the technique. Here, we deconstruct the fluorescence signal patterns of expert-annotated surgical ICGFA videos to understand better their correlation and combine this with structured interviews to ascertain whether such interpretative capability is conscious or unconscious. Methods For fluorescence signal analysis, expert-annotated ICGFA videos (n = 24) were quantitatively interrogated using a boutique intensity tracker (IBM Research) to generate signal time plots. Such fluorescence intensity data were examined for inter-observer correlation (Intraclass Correlation Coefficients, ICC) at specific curve milestones: the maximum fluorescence signal (Fmax), the times ...
Summary Indocyanine Green Fluorescence Angiography (ICGFA) has been deployed to tackle malperfusi... more Summary Indocyanine Green Fluorescence Angiography (ICGFA) has been deployed to tackle malperfusion-related anastomotic complications. This study assesses variations in operator interpretation of pre-anastomotic ICGFA inflow in the gastric conduit. Utilizing an innovative online interactive multimedia platform (Mindstamp), esophageal surgeons completed a baseline opinion-practice questionnaire and proceeded to interpret, and then digitally assign, a distal transection point on 8 ICGFA videos of esophageal resections (6 Ivor Lewis, 2 McKeown). Annotations regarding gastric conduit transection by ICGFA were compared between expert users versus non-expert participants using ImageJ to delineate longitudinal distances with Shapiro Wilk and t-tests to ascertain significance. Expert versus non-expert correlation was assessed via Intraclass Correlation Coefficients (ICC). Thirty participants (13 consultants, 6 ICGFA experts) completed the study in all aspects. Of these, a high majority (29 ...
As indocyanine green (ICG) with near-infrared (NIR) endoscopy enhances real-time intraoperative t... more As indocyanine green (ICG) with near-infrared (NIR) endoscopy enhances real-time intraoperative tissue microperfusion appreciation, it may also dynamically reveal neoplasia distinctively from normal tissue especially with video software fluorescence analysis. Colorectal tumours of patients were imaged mucosally following ICG administration (0.25 mg/kg i.v.) using an endo-laparoscopic NIR system (PINPOINT Endoscopic Fluorescence System, Stryker) including immediate, continuous in situ visualization of rectal lesions transanally for up to 20 min. Spot and dynamic temporal fluorescence intensities (FI) were quantified using ImageJ (including videos at one frame/second, fps) and by a bespoke MATLAB® application that provided digitalized video tracking and signal logging at 30fps (Fluorescence Tracker App downloadable via MATLAB® file exchange). Statistical analysis of FI-time plots compared tumours (benign and malignant) against control during FI curve rise, peak and decline from apex. ...
Despite increasing endorsement of near-infrared perfusion assessment using indocyanine green (ICG... more Despite increasing endorsement of near-infrared perfusion assessment using indocyanine green (ICG) during colorectal surgery, little work has yet been done regarding learning curve and interobserver variation most especially on surgical video reflective of real-world usage. Surgeons with established expertise in ICG usage were invited to participate in the study along with others without such experience including trainees. All participants completed an opinion questionnaire and interpreted video presentations of fluorescence angiograms in a variety of colorectal case scenarios. An interactive video platform (Mindstamp) enabled dynamic annotation. Statistical analysis of data was performed using Kruskal–Wallis and Mann–Whitney testing as well as Intraclass Correlation Coefficients and Fleiss Multi-rater Kappa Scoring. Forty participants (six experts) completed questionnaire data and provided judgement of 14 videos (nine showing proximal colonic transection site perfusion, four showing completed anastomoses and one an acutely strangulated bowel). 70% felt > 10 cases were needed for competency in use with the majority of experts advocating > 50 (p < 0.05). Overall agreement among experts was “good” for videos showing colonic transection perfusion (versus “moderate” among in-experts) with experts clustering more distally. In contrast, there was no interpretation concordance among experts or in-experts when judging ICG perfusion sufficiency on a yes/no basis. Significant experience is recommended before reliance on ICG perfusion angiograms. ICG fluorescence assessment is prone to variable interpretation and influenced by experience and, perhaps, knowledge of preassessment operative steps suggesting a role for objective flow analysis with artificial intelligence methods as the next phase of this technology.
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Papers by Jeffrey Dalli