A New Model of Intraabdominal Abscess: Usefulness for Hydrosaline Metabolism Studies in Parenteral Nutrition Associated with Sepsis

García-Domingo, M.; Lladó, Laura; Franch-Arcas, Guzmán; Oliva, Antonio; Muñoz, A.; Sitges‐Serra, Antonio

doi:10.1006/jsre.1995.1220

Cited by 11 publications

(3 citation statements)

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“…This would be difficult or impossible in human subjects, as any damage to the abscess wall could result in abscess rupture and sepsis. However, animal models of abscess formation do exist in rabbits (Guirao et al 1995 ) and sheep (Sellera et al 2016 ). These model systems could be used to quantify MB depth penetration, similarly to what has been done for other photosensitizers in various sites (Svaasand et al 1996 , Gerritsen et al 2008 , Kosarieh et al 2016 ).…”

Section: Discussionmentioning

confidence: 99%

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Li,

Hannan,

Sharma

et al. 2024

Phys. Med. Biol.

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Photodynamic therapy (PDT) is an effective antimicrobial therapy that we used to treat human abscess cavities in a Phase 1 clinical trial. This trial included pre-PDT measurements of abscess optical properties, which affect light dose (light fluence) at the abscess wall and PDT response. This study simulated PDT treatment planning for 13 subjects that received optical spectroscopy prior to clinical PDT, to determine the impact of measured optical properties on ability to achieve fluence rate targets in 95% of the abscess wall. Retrospective treatment plans were evaluated for 3 conditions: (1) clinically delivered laser power and assumed, homogeneous optical properties, (2) clinically delivered laser power and measured, homogeneous optical properties, and (3) with patient-specific treatment planning using measured, homogeneous optical properties. Treatment plans modified delivered laser power, intra-cavity Intralipid (scatterer) concentration, and laser fiber type. Using flat-cleaved laser fibers, the proportion of subjects achieving 95% abscess wall coverage decreased significantly relative to assumed optical properties when using measured values for 4 mW/cm2 (92% vs. 38%, p=0.01) and 20 mW/cm2 (62% vs. 15%, p=0.04) thresholds. When measured optical properties were incorporated into treatment planning, the 4 mW/cm2 target was achieved for all cases. After treatment planning, optimal Intralipid concentration across subjects was 0.14 ± 0.09%, whereas 1% was used clinically. Required laser power to achieve the 4 mW/cm2 target was significantly correlated with measured abscess wall absorption (ρ=0.7, p=0.008), but not abscess surface area (ρ=0.2, p=0.53). When using spherical diffuser fibers for illumination, both optimal Intralipid concentration (p=0.0005) and required laser power (p=0.0002) decreased compared to flat cleaved fibers. At 0% Intralipid concentration, the 4 mW/cm2 target could only be achieved for 69% of subjects for flat-cleaved fibers, compared to 100% for spherical diffusers. Based on large inter-subject variations in optical properties, individualized treatment planning is essential for abscess photodynamic therapy.

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Section: Discussionmentioning

confidence: 99%

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Li,

Hannan,

Sharma

et al. 2024

Phys. Med. Biol.

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show abstract

“…This would be difficult or impossible in human subjects, as any damage to the abscess wall could result in abscess rupture and sepsis. However, animal models of abscess formation do exist in rabbits 38 and sheep 39 . These model systems could be used to quantify MB depth penetration, similarly to what has been done for other photosensitizers in various sites [40][41][42] .…”

Section: Discussionmentioning

confidence: 99%

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Li,

Hannan,

Sharma

et al. 2023

Preprint

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Background: Photodynamic therapy (PDT) is an effective antimicrobial therapy that we used to treat human abscess cavities in a recently completed Phase 1 clinical trial. This trial included pre-PDT measurements of abscess optical properties, which affect the expected light dose to the abscess wall and eventual PDT response. Purpose: The objective of this study was to simulate PDT treatment planning for the 13 subjects that received optical spectroscopy prior to clinical abscess PDT. Our goal was to determine the impact of these measured optical properties on our ability to achieve fluence rate targets in 95% of the abscess wall. Methods: During a Phase 1 clinical trial, 13 subjects received diffuse reflectance spectroscopy prior to PDT in order to determine the optical properties of their abscess wall. Retrospective treatment plans seeking to achieve fluence rate targets in 95% of the abscess wall were generated for all subjects for 3 conditions: (1) at the laser power delivered clinically with assumed optical properties, (2) at the laser power delivered clinically with measured optical properties, and (3) with patient-specific treatment planning using these measured optical properties. Factors modified in treatment planning included delivered laser power and intra-cavity Intralipid (scatterer) concentration. The effects of laser fiber type were also simulated. Results: Using a flat-cleaved laser fiber, the proportion of subjects that achieved 95% abscess wall coverage decreased significantly when incorporating measured optical properties for both the 4 mW/cm^2 (92% vs. 38%, p=0.01) and 20 mW/cm^2 (62% vs. 15%, p=0.04) fluence rate thresholds. However, when measured optical properties were incorporated into treatment planning, a fluence rate of 4 mW/cm^2 was achieved in 95% of the abscess wall for all cases. In treatment planning, the optimal Intralipid concentration across subjects was found to be 0.14 +/- 0.09% and the optimal laser power varied from that delivered clinically but with no clear trend (p=0.4). The required laser power to achieve 4 mW/cm^2 in 95% of the abscess wall was significantly correlated with measured absorption at the abscess wall (rho=0.7, p=0.008), but not abscess surface area (rho=0.2, p=0.53). When using spherical diffuser fibers as the illumination source, the optimal intralipid concentration decreased to 0.028 +/- 0.026% (p=0.0003), and the required laser power decreased also (p=0.021), compared to flat cleaved fibers. If the intra-cavity lipid emulsion (Intralipid) was replaced with a non-scattering fluid, all subjects could achieve the 4 mW/cm^2 fluence rate threshold in 95% of the abscess wall using a spherical diffuser, while only 69% of subjects could reach the same criterion using a flat cleaved fiber. Conclusions: The range of optical properties measured in human abscesses reduced coverage of the abscess wall at desirable fluence rates. Patient-specific treatment planning including these measured optical properties could bring the coverage back to desirable levels by altering the Intralipid concentration and delivered optical power. These results motivate a future Phase 2 clinical trial to directly compare the efficacy of patient-specific-treatment planning with fixed doses of Intralipid and light.

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“…Experimental data have shown that the septic animal with an intraabdominal abscess is also susceptible to suffering a further expansion of the ECW by high-volume and high-glucose TPN and that, in sepsis, ECW expansion is favored by the hypoalbuminemia already present at the start of intravenous feeding [47].…”

Section: Water and Sodium Retention And Hypoalbuminemiamentioning

confidence: 99%

Water and Sodium Balance: A Nutritional Goal

Sitges‐Serra

2004

Metabolic Issues of Clinical Nutrition

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A New Model of Intraabdominal Abscess: Usefulness for Hydrosaline Metabolism Studies in Parenteral Nutrition Associated with Sepsis

Cited by 11 publications

References 0 publications

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Treatment planning for photodynamic therapy of abscess cavities using patient-specific optical properties measured prior to illumination

Water and Sodium Balance: A Nutritional Goal

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