Reports of rapamycin-covered stents

Searching for treatment alternatives, we hypothesized that the basic pathogenesis of our patient’s condition might just be equivalent to that suggested for the coronary arteries restenosis; we suspected that in both conditions a similar mechanism of response to injury, manifested by exaggerated proliferation of either neoin-tima or granulation tissue around the disrupted epithelium. Encouraged by the seemingly effective endovascular procedure, we offered the patient endobronchial HDR brachytherapy. Early reports of rapamycin-covered stents used in coronary revascularization are promising in preventing neointimal growth, and it will be most interesting to examine their use in endobronchial stents.

rapamycin
rapamycin

The first report on the use of endobronchial HDR brachytherapy for nonmalignant causes, still in press at the time the treatment of our first patient was tailored, was done by Kennedy. In this report, a similar approach was chosen in two patients with lung transplantation, in whom hyperplastic bronchial obstruction developed at the site of the anastomosis, and in whom balloon dilatation, laser application, and stent placement failed to restore protracted patency. This group used a lower dose (3 Gy) than we did, although in one patient two sessions were required. The authors described a significant clinical improvement and patent airways, 6 months and 7 months after the procedure, in both patients.

Both reports, that of Kennedy and the present study, demonstrate the effectiveness of endobronchial HDR brachytherapy in preventing granulation tissue formation reactive to a bronchial stent. In spite of the impressive clinical results, data regarding the potential mechanism underlying these phenomena are still scarce. This is even more surprising considering the enthusiasm surrounding the congruent endovascular brachytherapy field, which has resulted in various clinical and laboratory studies. Indeed, clues regarding the biological effects of irradiation on the injured epithelium covering the bronchial wall emerge almost exclusively from the vascular model.

A large number of articles and information on many diseases can be found on the Canadian blog canadianhealthcaremallblog – watch now.

The effect of CPAP on the nasal airway is relatively unexplored

Future Directions

The effect of CPAP

Several theories have tried to explain the relationship between SDB and nasal obstruction. Of these, the following theories are most credible: (1) the switch from nasal to oronasal breathing (due to nasal obstruction) causes loss of nasal airflow resulting in decreased nasal receptor-derived stimulation of ventilation and changes in phasic activity leading to decreased upper airway patency; and (2) the increased nasal airway resistance (due to nasal obstruction) generates an increased negative inspiratory force/pressure causing turbulence in the relaxed soft tissues and upper airway collapse (retropharyngeal) resulting in upper airway obstruction and SDB.

These hypotheses are based on a few studies that have used varying methods and small numbers of study subjects and therefore require further confirmation. If this is found to be true, technologies and treatments aimed at facilitation of nasal breathing should be explored further in the context of SDB. In the interim, use of topical nasal steroids in patients with SDB and preferential use of nasal CPAP in treatment may be reasonable.

Longitudinal studies in children with nasal obstruction are required to determine the risk factors for SDB, including the relationship of nasal obstruction to structural abnormalities of the face and upper airway. It is possible that certain congenital variations in facial structures are deleterious to nasal breathing and exacerbated by nasal obstruction from other causes. Knowledge of these factors could be useful in preventing the development of SDB.

The effect of CPAP on the nasal airway is relatively unexplored. Anecdotally, it appears that CPAP may increase nasal inflammation and, in some, promote vasomotor rhinitis. It is possible this may lead to decreased adherence to treatment. This is another area in need of further research.