Optimization of the diameter of a radial irradiation device for photodynamic therapy in the esophagus.

BACKGROUND AND STUDY AIMS: Photodynamic therapy (PDT) is a local therapeutic technique based on the photosensitization of lesions using a dye prior to light-induced tissue destruction. PDT of intraepithelial neoplasia in Barrett's esophagus, or of early squamous-cell carcinoma of the esophagus, requires light application devices that allow homogeneous and well-defined illumination of the tissue surface. Such devices must be large enough to induce complete unfolding of the esophagus in spite of esophageal motility and elasticity. The aim of this study was therefore to determine the optimal diameter of a cylindrical illumination device for PDT in this organ. PATIENTS AND METHODS: The study included nine patients (aged 49-72 years) who underwent panendoscopy. Flexible transparent hollow tubes with diameters ranging from 13 to 19 mm were successively introduced into the esophagus, and the esophageal wall was viewed from the inside through the tube using a flexible small-diameter endoscope. The number of folds was counted. Observations of the upper, middle, and lower thirds of the esophagus were recorded. The radial location of the folds was also recorded, and defined as follows: anterior wall (up), posterior wall (down), side walls (right, left). RESULTS: No significant difference in the number of folds between the lower and middle parts of the esophagus was noticed. However, the upper third had significantly fewer folds (about 30 %) than the other two parts. For diameters above 17 mm, this difference was less dramatic. The number of such folds was shown to decrease with the increasing diameter of the device. CONCLUSIONS: It appears that 18 mm or more is the optimal diameter for a fixed-geometry cylindrical photodynamic therapy irradiating device for the patient category considered in this study. It was also observed that most folds were located on the side walls of the esophagus.

Concept analysis: abuse of ageing caregivers by elderly care recipients.

PURPOSE: The purpose of this article is to clarify the concept of abuse within the context of ageing women who are at risk for or experiencing physical or emotional injury inflicted by elderly family members for whom they provide care. BACKGROUND: The study of abuse of ageing individuals in family caregiving situations has traditionally focused on abuse of the dependent care receiver. However, evidence supports the health risks related to abuse of ageing caregivers as well. Women, usually spouses, daughters, or daughters-in-law, most frequently assume the caregiver role. METHODS: A modification of the strategies for concept analysis proposed by Walker and Avant (1995) is used to clarify the concept of caregiver abuse. Searches of the professional literature reveal that caregiver abuse is rarely addressed; therefore, the broader concept of elder abuse is reviewed and then placed within the general context of family caregiving. Audiotapes of the first session of a community based intervention research study entitled Intervention for the Abuse of Ageing Caregivers (Phillips et al., NIH Grant No. R01 DA-AG11155-01, 1996), in which ageing women caregivers described abusive caregiving situations, were analysed qualitatively using the principles of concept analysis. The audiotapes serve as a second source of data for the concept analysis process. FINDINGS: Antecedents, defining characteristics, and consequences of abuse of ageing caregivers were identified through the process of concept analysis. Model, contrary, and borderline cases are presented to illustrate the findings. CONCLUSIONS: Findings supported the need for awareness that ageing caregivers can be placed at risk by verbally and physically abusive behaviours of the elders for whom they provide care. Use of the term 'abuse' by health care professionals has potentially negative consequences for identification and intervention in cases of potential or actual caregiver abuse.

Pharmacokinetics and pharmacodynamics of tetra(m-hydroxyphenyl)chlorin in the hamster cheek pouch tumor model: comparison with clinical measurements.

The pharmacokinetics (PK) of the photosensitizer tetra(m-hydroxyphenyl)chlorin (mTHPC) was measured by optical fiber-based light-induced fluorescence spectroscopy (LIFS) in the normal and tumoral cheek pouch mucosa of 29 Golden Syrian hamsters with chemically induced squamous cell carcinoma. Similar measurements were carried out on the normal oral cavity mucosa of five patients up to 30 days after injection. The drug doses were between 0.15 and 0.3 mg per kg of body weight (mg/kg), and the mTHPC fluorescence in the tissue was excited at 420 nm. The PK in both human and hamster exhibited similar behavior although the PK in the hamster mucosa was slightly delayed in comparison with that of its human counterpart. The mTHPC fluorescence signal of the hamster mucosa was smaller than that of the human mucosa by a factor of about 3 for the same injected drug dose. A linear correlation was found between the fluorescence signal and the mTHPC dose in the range from 0.075 to 0.5 mg/kg at times between 8 and 96 h after injection. No significant selectivity in mTHPC fluorescence between the tumoral and normal mucosa of the hamsters was found at any of the applied conditions. The sensitivity of the normal and tumoral hamster cheek pouch mucosa to mTHPC photodynamic therapy as a function of the light dose was determined by light irradiation at 650 nm and 150 mW/cm2, 4 days after the injection of a drug dose of 0.15 mg/kg. These results were compared with irradiations of the normal oral and normal and tumoral bronchial mucosa of 37 patients under the same conditions. The reaction to PDT of both types of human mucosae was considerably stronger than that of the hamster cheek pouch mucosa. The sensitivity to PDT became comparable between hamster and human mucosa when the drug dose for the hamster was increased to 0.5 mg/kg. A significant therapeutic selectivity between the normal and neoplastic hamster cheek pouch was observed. Less selectivity was found following irradiations of normal mucosa and early carcinomas in the human bronchi. The pharmacodynamic behavior of mTHPC was determined by test irradiations of the normal mucosa of hamsters and patients between 6 h and 8 days after injection of 0.5 and 0.15 mg/kg in the hamsters and the patients, respectively. The normal hamster cheek pouch showed a maximum response to irradiation 6 h after injection and then decreased continuously to no observable reaction at 8 days after injection. The reaction of the normal human oral mucosa, however, showed an increasing sensitivity to the applied light between 6 h and 4 days after mTHPC injection and then decreased again at 8 days. The hamster model with the chemically induced early squamous cell cancer in the cheek pouch thus showed some similarity to the early squamous cell cancer of the human oral mucosa considering the PK. However, a quantitative difference in fluorescence signal for identical mTHPC doses as well as a significant difference in pharmacodynamic behavior were also observed. The suitability of this animal model for the optimization of PDT parameters in the clinic is therefore limited. Hence great care must be taken in screening new dyes for PDT of early squamous cell cancer of the upper aerodigestive tract based upon observables in the hamster cheek pouch model.

Photodynamic therapy for 101 early cancers of the upper aerodigestive tract, the esophagus, and the bronchi: a single-institution experience.

Cancer, when detected at an early stage, has a very good probability of being eradicated by surgery or radiotherapy. However, less aggressive treatments also tend to provide high rates of cure without the side effects of radical therapy. We report on the results of our clinical experience with photodynamic therapy (PDT) for the treatment of early carcinomas in the upper aerodigestive tract, the esophagus, and the tracheobronchial tree. Sixty-four patients with 101 squamous cell carcinomas were treated with three different photosensitizers: hematoporphyrin derivative (HPD), Photofrin II, and tetra (m-hydroxyphenyl)chlorin (mTHPC). Seventy-seven (76%) tumors showed a complete rsponse with no recurrence after a mean follow-up period of 27 months. There was no significant difference in terms of cure rates among the three dyes. However, mTHPC has a stronger phototoxicity and induces a shorter skin photosensitization than either of the other photosensitizers. There were eight major complications: three esophagotracheal fistulae after illumination with red light in the esophagus, two esophageal stenoses following 360 degrees circumferential irradiation, and three bronchial stenoses. Illumination with the less penetrating green light and the use of a 180 degrees or 240 degrees windowed cylindrical light distributor render the risk of complications in the esophagus essentially impossible, without reducing the efficacy of the treatment. Therefore, PDT may be considered as a safe and effective treatment for early carcinomas of the upper aerodigestive tract, the esophagus, and the tracheobronchial tree.

Interstitial photodynamic therapy with tetra(m-hydroxyphenyl)chlorin: tumor versus striated muscle damage.

PURPOSE: The present study was initiated to determine the conditions under which a single photodynamic treatment would induce maximal damage to a tumor with no or at least minimal reversible damage to a normal striated muscle. METHODS AND MATERIALS: The technique of interstitial light delivery was used after prior 0.5 mg/kg tetra(m-hydroxyphenyl)chlorin administration in a hamster model. After having estimated the threshold light doses required for minimal muscle damage, the same light doses were applied to squamous cell carcinomas to evaluate the efficiency of interstitial photodynamic therapy. Sixteen and 96 h after the injection, irradiation at 650 nm was performed on the thigh muscle of the left hind leg. The applied light doses ranged between 0.3-15 J and were delivered at an intensity of 44 mW per cm of diffuser length. RESULTS: The threshold of muscle damage was obtained using light doses of 1.5-3 J at two drug-light intervals of 16 and 96 h, respectively. More than 85% of the tumor mass was destroyed when lesions were illuminated using these threshold conditions. In terms of immediate short-term tumor response, this means that for the given irradiation conditions, a relatively low threshold energy of only 1.5 or 3 J, depending on the drug-light interval, is sufficient to induce massive tumor destruction with minimal muscle damage. CONCLUSION: These results have implications for evaluating interstitial PDT for squamous cell cancers in unfavorable localization in the oral cavity or pharynx, such as at the base of the tongue.

In vivo fluence rate effect in photodynamic therapy of early cancers with tetra(m-hydroxyphenyl)chlorin.

Several parameters affect clinical trials in photodynamic therapy and influence the therapeutic outcome. Beside drug dose, light dose, drug-light interval and other variables, the fluence rate is a parameter that can influence the therapeutic results. In this study we have evaluated the fluence rate effect with a second-generation photosensitizer, tetra(m-hydroxyphenyl)chlorin (mTHPC) using a 7,12-dimethylbenz(a)anthracene induced early squamous cell carcinoma of the Syrian hamster cheek pouch as a tumor model. Following injection of 0.5 mg/kg of mTHPC, irradiation tests were performed at two drug-light intervals, 4 and 8 days. Wavelength and light dose were adapted from those applied routinely in clinical trials. Irradiations at 652 nm were carried out with fluences ranging from 8 to 20 J/cm2 delivered at fluence rates of 15 and 150 mW/cm2. Similar tests were also performed at 514 nm with a fluence of 80 J/cm2 delivered at fluence rates ranging from 25 to 125 mW/cm2. At both wavelengths and drug-light intervals for a given fluence, the higher fluence rates resulted in less tissue damage in tumor and healthy mucosae. However, the lower fluence rates yielded slightly less therapeutic selectivity. This study confirms that the fluence rate is of major importance in clinical PDT.

Photodynamic therapy for cancer of the upper aerodigestive tract using tetra(m-hydroxyphenyl)chlorin.

A major step in the development of photodynamic therapy (PDT) is the clinical optimization and evaluation of new photosensitizers (PS). Ideally, new compounds should be more effective and/or induce fewer side effects than the first generation PS such as hematoporphyrin derivative and Photofrin. We report the results of our study of PDT applied in the human upper aerodigestive tract, using tetra(m-hydroxyphenyl)chlorin (mTHPC) as the photosensitizing drug. Twenty-seven patients with early (i.e., in situ or microinvasive) squamous cell carcinomas and 4 patients with T1 or T2 cancers were studied. In most cases, illumination of the tumor was performed 4 days after i.v. injection of 0.15 mg/kg of mTHPC using 652 or 514 nm laser light. Of the 36 early tumors evaluated 30 (83%) showed no recurrence after a mean disease-free follow-up of 15.3 months (3-35 months). Of the T1 and T2 cancers, only one achieved a complete response. Major complications, all following red light illuminations, included 1 bronchial stenosis, 1 esophagotracheal fistula, and 2 probable occult perforations of the esophagus. PDT in the esophagus with green light renders such perforations essentially impossible, without, however, reducing the efficacy of the treatment. Skin photosensitization, never observed later than the first week after injection, was seen in 12 patients. In conclusion, photodynamic therapy with mTHPC is a safe and effective technique for the treatment of early carcinomas of the upper aerodigestive tract. Its efficacy is much lower for more advanced cancers.

Mixed incontinence: a new nursing diagnosis?

Consistent efforts to identify and clinically validate new nursing diagnosis within recognized categories are essential to taxonomy development. Mixed incontinence is a clinical condition resulting in leakage of urine associated with increased intra-abdominal pressure (stress) and inability to delay voiding (urge). The presence of mixed incontinence was clinically validated in two populations (n = 9, n = 40) of community-dwelling women and initial defining characteristics were identified. Research findings from both studies support the addition of a proposed sixth nursing diagnosis, mixed incontinence, to the diagnostic category, alteration in urinary elimination.

Stress incontinence: clinical identification and validation of defining characteristics.

Stress incontinence as a valid nursing diagnosis has remained clinically untested since its approval as a nursing diagnosis in 1986. No defining characteristics of stress incontinence have been clinically identified or validated. The Stress Urge Incontinence Instrument was developed to assist nurses to differentiate between two nursing diagnoses: stress incontinence and urge incontinence. Findings from two clinical studies validate the presence of stress incontinence in a population of community-dwelling older women and provide an initial list of clinically identified and validated defining characteristics present in women with the confirmed medical diagnosis of stress incontinence.

Microteaching: developing tomorrow's teachers.

Microteaching is a technique for developing teaching skills. The authors report a study that assessed graduate students' perspectives of a microteaching experience. Information is provided to help current and potential faculty members to improve their teaching skills through microteaching.

Thirst: a critical care nursing challenge.

Thirst is a symptom commonly experienced by critically ill patients. Critical care nurses have the opportunity to prevent and reduce thirst by recognizing the types of thirst, identifying patients at risk, monitoring physiological parameters, and providing comfort measures.

Home health care--providing a missing link.

1. If nurses are to provide the continuity of care that helps patients at home achieve expected patient outcomes, nurses must diagnose actual and potential health problems and design a plan of care. 2. Before patient outcomes can be identified, nurses must first recognize, assess, and describe the patient's defining characteristics. 3. The study found that nurses use a limited range of nursing diagnoses and incompletely document the care they give. 4. Results of the study indicated that nurses provide continuity of care between the hospital and home; there is also a need for home-based health care to provide support for elderly caregivers whose health is less than good.

Prospective payment and baccalaureate nursing education: projections for the future.

The implementation of a prospective payment system has had a profound effect on health care delivery in the United States. Providing realistic nursing experiences for baccalaureate students has become a challenge in the new arena of increased patient acuity, decreased length of patient stay in acute care settings, and increased use of home care services. The purpose of this study was to describe changes in the health care system and projected changes in baccalaureate nursing education associated with prospective payment. The descriptive survey design used a mail questionnaire to which deans or their designees from 186 National League for Nursing (NLN) accredited baccalaureate nursing programs responded. Outcomes of the study indicated specific health care delivery changes in all geographic areas and all types of institutions. Projected changes in nursing education included curriculum, teaching methods, and clinical learning experiences.

Identification of nursing diagnoses and defining characteristics: two research models.

Nursing diagnoses and their defining characteristics associated with one Diagnosis Related Group (DRG) were identified and validated. The clinical-retrospective model and the nurse validation model were used to identify high-volume nursing diagnoses associated with DRG 366, transurethral prostatectomy, and to validate related defining characteristics. For the clinical-retrospective model, 34 patient records classified as DRG 366 were reviewed, nursing diagnoses and their associated defining characteristics were identified and retrospectively validated. The nurse-validation model was implemented by assessing nine patients within DRG 366 over 22 shifts. Analysis using descriptive statistics demonstrated 80% level of agreement on five most frequently identified nursing diagnoses, but lack of agreement on the associated defining characteristics.

Validation of defining characteristics: clinical design.

In order to formulate accurate nursing diagnoses, neuroscience nurses must determine clinical validity of defining characteristics. Physiologic, psychologic, behavioral or social signs and symptoms may be studied. This article suggests methods to be used in validating defining characteristics including practical and research design considerations.

Validation of defining characteristics: retrospective design.

The American Association of Neuroscience Nurses (AANN) has accepted the concept of nursing diagnosis as one component of a general nursing framework which is designed to direct and evaluate the care of individuals with neuroscience dysfunction. Continuing development of nursing diagnosis as a conceptual basis for neuroscience practice is dependent upon several factors, one of which is research-based identification and validation of defining characteristics associated with nursing diagnoses commonly used in the care of patients with neurologic dysfunction. Defining characteristics are observable signs and symptoms present in the person with the problem. Identification and validation of defining characteristics are essential to the continued development and use of nursing diagnosis in nursing practice. Without clear, specific defining characteristics, neuroscience nurses are unable to effectively assess patients for the signs and symptoms necessary to formulate nursing diagnoses, monitor patient status or evaluate nursing interventions. One way to validate defining characteristics is the use of retrospective design.

Deans of nursing: perceived sources of conflict and conflict-handling modes.

The purpose of this study was to explore the relationship between sources of conflict with nursing faculty and deans' conflict-handling styles. A three-part questionnaire was sent to 257 deans of baccalaureate nursing programs. One hundred sixty-seven deans responded. The findings showed that deans identified two levels of conflict with nursing faculty, and sources of conflict leading to each level. Deans perceived no change in conflict-handling styles in relation to conflict source or perceived effect. In addition, significant relationships were found among conflict-handling modes, conflict sources, and demographic data.