Standardizing the diagnosis of inhalation injury using a descriptive score based on mucosal injury criteria.

INTRODUCTION: Inhalation injury is an important determinant of outcome in patients with major burns. However the diagnostic criteria remain imprecise, preventing objective comparisons of published data. The aims were to evaluate the utility of an inhalation score based on mucosal injury, while assessing separately the oro-pharyngeal sphere (ENT) and tracheobronchial tree (TB) in patients admitted to the ICU with a suspicion of inhalation injury. METHODS: Prospective observational study in 100 patients admitted with suspicion of inhalation injury among 168 consecutive burn admissions to the ICU of a university hospital. Inclusion criteria, endoscopic airway assessment during the first hours. ENT/TB lesion grading was 1: oedema, hyperemia, hypersecretion, 2: bullous mucosal detachment, erosion, exudates, 3: profound ulcers, necrosis. RESULTS: Of the 100 patients (age 42±17 years, burns 23±19%BSA), 79 presented an ENT inhalation injury ≥ENT1 (soot present in 24%): 36 had a tracheobronchial extension, 33 having a grade ≥TB1. Burned vibrissae: 10 patients "without" suffered ENT injury, while 6 patients "with" had no further lesions. Length of mechanical ventilation was strongly associated with the first 24 hrs' fluid resuscitation volume (p<0.0001) and the presence of inhalation injury (p=0.03), while the ICU length of stay was correlated with the %BSA. Soot was associated with prolonged mechanical ventilation (p=0.0115). There was no extubation failure. CONCLUSIONS: The developed inhalation score was simple to use, providing a unified language, and drawing attention to upper airway involvement. Burned vibrissae and suspected history proved to be insufficient diagnostic criteria. Further studies are required to validate the score in a larger population.

Extensive (8 to 12 cm2) noncircumferential endoscopic mucosal resection for early esophageal cancer.

BACKGROUND: Endoscopic mucosal resection (EMR) is an appealing method for treating intramucosal esophageal cancer but must comply with the following stringent requirements: proper preoperative staging, complete resection of the lesion, obtaining a resected specimen for histologic analysis of safety margins, and squamous reepithelialization without stricture formation. METHODS: A rigid esophagoscope was created to resect up to 12 cm(2) of esophageal mucosa in a single specimen and at a constant depth through the submucosa. Under visual control, the esophageal mucosa is sucked into a transparent window and resected with a thin diathermy wire loop in 10 seconds. After extensive preclinical studies in a sheep model, this article reports our early experience in humans. RESULTS: Twenty-one hemi-circumferential EMRs were performed for 11 dysplastic Barrett's esophagi and 10 early squamous cell carcinomas with no perforation, one hemorrhage controlled by embolization of the left gastric artery, and one incomplete resection. Deep safety margins were clear in 19 of 21 resected specimens (2 patients, unfit for operations, had submucosal invasion of squamous cell carcinoma and adenocarcinoma, respectively). Lateral margins were not clear by definition in 7 circumferential Barrett's esophagi, but were clear in 4 incomplete Barrett's esophagi and 10 early squamous cell carcinomas. CONCLUSIONS: Large EMRs of 12 cm(2) can safely be performed at the submucosal level in the esophagus. Although feasible in one session, circumferential EMR in humans is not yet advisable because of the risk of stricture formation during the healing phase. The rate of complications of this series of 21 EMRs in humans is acceptable.

Assessment of a sheep animal model to optimise photodynamic therapy in the oesophagus.

BACKGROUND AND OBJECTIVES: Precursor lesions of oesophagus adenocarcinoma constitute a clinical dilemma. Photodynamic therapy (PDT) is an effective treatment for this indication, but it is difficult to optimise without an appropriate animal model. For this reason, we assessed the sheep model for PDT in the oesophagus with the photosensitiser meta-(tetra-hydroxyphenyl) chlorin (mTHPC). MATERIALS AND METHODS: Twelve sheep underwent intravenous mTHPC injection, blood sampling and fluorescence measurements. mTHPC's pharmacokinetics was measured in vivo and in plasma by fluorescence spectroscopy. Biopsies of sheep oesophagus were compared to corresponding human tissue, and the mTHPC's biodistribution was studied under fluorescence microscopy. Finally, the sheep oesophageal mucosa was irradiated, 4 days after mTHPC's injection. RESULTS: Histologically, the sheep and human oesophagus were closely comparable, with the exception of additional fatty tissue in the sheep oesophagus. mTHPC's pharmacokinetics in sheep and human plasmas were similar, with a maximum of concentration in the sheep 10 hours after i.v. injection. mTHPC's pharmacokinetics in vivo reached its maximum after 30-50 hours, then decreased to background levels, as in humans under similar conditions. Two days after injection, mTHPC was mainly distributed in the lamina propria, followed by a penetration into the epithelium. The sheep and human tissue sensitivity to mTHPC PDT was similar. CONCLUSION: In conclusion, this model showed many similarities with humans as to mTHPC's plasma and tissue pharmacokinetics, and for tissue PDT response, making it suitable to optimise oesophagus PDT.

In vivo time-resolved spectroscopy of the human bronchial early cancer autofluorescence.

Time-resolved measurements of tissue autofluorescence (AF) excited at 405 nm were carried out with an optical-fiber-based spectrometer in the bronchi of 11 patients. The objectives consisted of assessing the lifetime as a new tumor/normal (T/N) tissue contrast parameter and trying to explain the origin of the contrasts observed when using AF-based cancer detection imaging systems. No significant change in the AF lifetimes was found. AF bronchoscopy performed in parallel with an imaging device revealed both intensity and spectral contrasts. Our results suggest that the spectral contrast might be due to an enhanced blood concentration just below the epithelial layers of the lesion. The intensity contrast probably results from the thickening of the epithelium in the lesions. The absence of T/N lifetime contrast indicates that the quenching is not at the origin of the fluorescence intensity and spectral contrasts. These lifetimes (6.9 ns, 2.0 ns, and 0.2 ns) were consistent for all the examined sites. The fact that these lifetimes are the same for different emission domains ranging between 430 and 680 nm indicates that there is probably only one dominant fluorophore involved. The measured lifetimes suggest that this fluorophore is elastin.

Improvement of the specificity of cancer detection by autofluorescence imaging in the tracheo-bronchial tree using backscattered violet light.

BACKGROUND: Autofluorescence bronchoscopy (AFB) is a highly sensitive tool for the detection of early bronchial cancers. However, its specificity remains limited due to primarily false positive results induced by hyperplasia, metaplasia and inflammation. We have investigated the potential of blue-violet backscattered light to eliminate false positive results during AFB in a clinical pilot study. METHODS: The diagnostic autofluorescence endoscopy (DAFE) system was equipped with a variable band pass filter in the imaging detection path. The backscattering properties of normal and abnormal bronchial mucosae were assessed by computing the contrast between the two tissue types for blue-violet wavelengths ranging between 410 and 490 nm in 12 patients undergoing routine DAFE examination. In a second study including 6 patients we used a variable long pass (LP) filter to determine the spectral design of the emission filter dedicated to the detection of this blue-violet light with the DAFE system. RESULTS: (Pre-)neoplastic mucosa showed a clear wavelength dependence of the backscattering properties of blue-violet light while the reflectivity of normal, metaplastic and hyperplastic autofluorescence positive mucosa was wavelength independent. CONCLUSIONS: Our results showed that the detection of blue-violet light has the potential to reduce the number of false positive results in AFB. In addition we determined the spectral design of the emission filter dedicated to the detection of this blue-violet light with the DAFE system.

Extended endoscopic mucosal resection in the esophagus and hypopharynx: a new rigid device.

We present a new device allowing for the diagnosis and treatment of extended superficial lesions of the esophagus and hypopharynx such as early squamous cell carcinoma, intestinal metaplasia with high grade intraepithelial neoplasia or early adenocarcinoma arising in Barrett's esophagus. A new modified rigid esophagoscope (Karl Storz GmbH, Germany) has been designed. A large mucosal area is sucked against a transparent and perforated hemi-cylindrical window. Mucosal resection is performed by an electrical wire loop at a constant depth of 1 +/- 0.1 mm. The resected surface varies from 4 to 12 cm(2). Circumferential resection consists of two opposite individual hemi-circumferential resections. We performed three series of animal trials: hemicircumferential mucosectomies; circumferential resections of variable (2 to 6 cm) length and long-segment mucosectomies with follow-up. Hemi- and circumferential resections could be done in one or two specimens only which allowed precise histological studies. This facilitated easy orientation and analysis of the surgical margins. The deep resection margin was precisely located at the submucosal level, a prerequisite for a safe resection of superficial cancers of the esophagus and hypopharynx.

Evaluation of the photosensitizer Tookad for photodynamic therapy on the Syrian golden hamster cheek pouch model: light dose, drug dose and drug-light interval effects.

We have evaluated the efficacy of the new photosensitizer (PS) Tookad in photodynamic therapy (PDT) in vivo. This PS is a palladium-bacteriopheophorbide presenting absorption peaks at 762 and 538 nm. The light dose, drug dose and drug injection-light irradiation interval (DLI), ranging between 100 and 300 J/cm2, 1 and 5 mg/kg and from 10 to 240 min, respectively, were varied, and the response to PDT was analyzed by staging the macroscopic response and by the histological examination of the sections of the irradiated cheek pouch. The level of PDT response, macroscopically and histologically, shows a strong dependence on the DLI, light dose and drug dose at the applied conditions in the normal hamster cheek pouch. A decay of the tissular response with increasing DLI is observed corresponding to a time of half-maximum response ranging from 10 to 120 min, depending on drug dose and light dose. The tissues affected at the lowest doses are predominantly the vascularized diffuse connective tissue situated between the inner and outer striated muscle (SM) layers as well as these muscle layers themselves. The highest response at the shortest DLI and the absence of a measurable response at DLI longer than 240 min at 300 J/cm2 and drug dose of 5 mg/kg are characteristics of a predominantly vascular effect of this PS. This observation suggests that Tookad could be effective in PDT of vascularized lesions or pathologies associated with the proliferation of neovessels.

Mucosal ablation with photodynamic therapy in the esophagus: optimization of light dosimetry in the sheep model.

BACKGROUND: Photodynamic therapy is an attractive technique for mucosal ablation in patients with superficial squamous cell carcinoma of the esophagus, or high-grade dysplasia or early stage adenocarcinoma arising in Barrett's esophagus. Although illumination with green light is assumed to be safe, choice of the light has been empirical in clinical studies; light dose is often reduced to avoid potential complications. The present study assessed the safety of green and blue lights during photodynamic therapy in the esophagus by progressively administrating increasing doses in an attempt to standardize the dose and determine a safe upper limit. This would considerably simplify photodynamic therapy and improve therapeutic results. METHODS: The sheep model was chosen because of similarities with humans regarding the thickness and histologic structure of the esophagus. Irradiation with a 180 degrees windowed cylindrical light distributor was performed in 19 sheep 4 days after injection of 0.15 mg/kg of tetra(m-hydroxyphenyl) chlorin. Light doses ranged from 10 to 500 J/cm(2) at 514 nm (argon ion laser) and from 5 to 250 J/cm(2) at 413 nm (krypton laser). RESULTS: Follow-up endoscopies revealed a tissue response with a fibrinous area at almost all light doses, whereas application of extremely high light doses tended to induce circumferential necrosis with subsequent stenosis. Three months after irradiation with green light, histologic examination of the resected specimens revealed transmural scarring at doses higher than 100 J/cm(2). After illumination with blue light, partial or more extensive fibrosis of the muscular layer was observed only at light doses of 175 to 250 J/cm(2). CONCLUSIONS: Application of high doses of green light after sensitization with tetra(m-hydroxyphenyl) chlorin led to severe complications in the esophagus of the sheep that are highly likely to occur in humans as well. Blue light causes significantly less damage than green light and may, therefore, be considered as an alternative for photodynamic therapy of early stage superficial esophageal cancer.

In vivo autofluorescence imaging of early cancers in the human tracheobronchial tree with a spectrally optimized system.

The changes in the autofluorescence characteristics of the bronchial tissue is of crucial interest as a cancer diagnostic tool. Evidence exists that this native fluorescence or autofluorescence of bronchial tissues changes when they turn dysplastic and to carcinoma in situ. There is good agreement that the lesions display a decrease of autofluorescence in the green region of the spectrum under illumination with violet-light, and a relative increase in the red region of the spectrum is often reported. Imaging devices rely on this principle to detect early cancerous lesions in the bronchi. Based on a spectroscopic study, an industrial imaging prototype is developed to detect early cancerous lesions in collaboration with the firm Richard Wolf Endoskope GmbH, Germany. A preliminary clinical trial involving 20 patients with this spectrally optimized system shows that the autofluorescence can help to detect most lesions that would otherwise have remained invisible to an experienced endoscopist under white light illumination. A systematic off line analysis of the autofluorescence images pointed out that real-time decisional functions can be defined to reduce the number of false positive results. Using this method, a positive predictive value (PPV) of 75% is reached using autofluorescence only. Moreover, a PPV of 100% is obtained, when combining the white light (WL) mode and the autofluorescence (AF) mode, at the applied conditions. Furthermore, the sensitivity is estimated to be twice higher in the AF mode than in WL mode.

[Treatment of tracheo-bronchial cancers by photodynamic therapy]. / Traitement des cancers trachéo-bronchiques par photothérapie dynamique.

Cancer of the tracheo-bronchial tree has a dismal prognosis when discovered at an advanced stage. Significant improvement in survival rates can be obtained, however, if the tumors are detected at an early stage. In these cases, an effective and minimally invasive local treatment, such as photodynamic therapy, may be taken into account as a useful alternative to surgery. This paper describes the general aspects, the indications and the benefits of this new promising technique.