H. Riechelmann

Respiratory epithelium exposed to sulfur dioxide--functional and ultrastructural alterations.

The value of morphological investigations of airway mucosa should be compared to a functional method when estimating the toxicity of airborne pollutants. In 34 guinea pig tracheas, mucociliary activity was measured using a modified light beam reflex method before and following exposure to sulfur dioxide for 30 minutes in concentrations ranging between 7.5 and 37.5 mg/m3. Exposure to air served as a control. Simultaneously, specimens were taken for light and electron microscopy. Mucociliary activity decreased from 8.4 ± 2.9 Hz (control exposure) to 4.0 ± 2.9 Hz following exposure to 7.5 mg/m3, to 3.4 ± 2.7 Hz at 15 mg/m3 sulfur dioxide, to 1.8 ± 2.2 Hz at 22.5 mg/m3 sulfur dioxide, to 1.5 ± 1.8 Hz at 30 mg/m3 sulfur dioxide, and to 2.0 ± 1.2 Hz at 37.5 mg/m3 sulfur dioxide, respectively (P<.01).

Autonomic regulation of nasal vessels during changes in body position

The effects of postural changes on nasal airflow and nasal capillary blood flow were investigated in 15 healthy volunteers. Measurements were performed following nasal application of saline solution (control), the alpha-1 receptor antagonist prazosin, the alpha-2 receptor antagonist yohimbine, and after application of both prazosin and yohimbine. Nasal airflow in the control experiments did not significantly differ in the upright (362 ± 166 ml/s), dorsally recumbent (350 ± 167 ml/s) and 70° head down position (311 ± 167 ml/s). Following application of prazosin, nasal airflow was reduced to 223 ± 121 ml/s in the upright position. Prazosin treatment significantly reduced nasal airflow to 177 ± 111 ml/s when subjects were placed in dorsally recumbent positions and to 117 ± 104 ml/s in 70° head down positions (P < 0.001). Following application of yohimbine, nasal airflow remained stable when subjects were turned from upright (348 ± 165 ml/s) to supine position (352 ± 186m1/s), whereas it was reduced to 199 ± 137 ml/s in the head-down position. Application of both prazosin and yohimbine significantly increased nasal capillary blood flow in laser Doppler flowmetry measurements (P < 0.05). Changes in body position with or without application of the active drugs did not alter nasal capillary blood flow. These findings suggest that nasal congestion due to increased filling pressure in nasal capacitance vessels following postural changes is mainly prevented by alpha-1 adrenergic mechanisms.

Objective measures of nasal function

Numerous techniques to objectively measure nasal function are available to the rhinologic surgeon. Rhinomanometry, acoustic rhinometry, laser Doppler flowmetry, saccharin transport time, determination of ciliary beat frequency, and olfactory and trigeminal event-related potentials are all techniques in current use. Rhinomanometry is the standard clinical tool used to indicate those patients complaining of nasal obstruction who are likely to benefit from septal and turbinate surgery. Acoustic rhinometry permits the precise localization of nasal stenoses and is the best predictor of a patients postoperative satisfaction. It is, in addition, more sensitive than rhinomanometry in recording changes of mucosal swelling. Laser Doppler flowmetry, a technique to determine mucosal blood flow, is mainly used to study nasal pathophysiology and mucosal reactions to drug effects. The measuring of saccharin transport time has been found to be an easy and sufficiently reliable test of mucociliary transport. The evaluation of ciliary beat frequency adds further information and helps to distinguish between primary and secondary ciliary dyskinesia. Analysis of nasal secretions helps the rhinologist to understand the pathophysiology of the inflamed airway. Additionally, it opens the door to the development of new therapeutic modalities as our knowledge grows. Olfactory and trigeminal event-related potentials and event-related magnetic fields are newer techniques in use to objectively evaluate olfactory nerve capabilities.

An experimental model for the exposure of human ciliated cells to sulfur dioxide at different concentrations

Mucociliary transport is an important nonimmunological defense mechanism of the respiratory tract. The aim of this study was to investigate the effect of sulfur dioxide (S02) at different concentrations on ciliary beat frequency (CBF). Ciliated cells were obtained from 12 volunteers by nose brush. CBF was quantified using video-interference microscopy. The cells were placed on a polycarbonate membrane in contact with the surface of a reservoir filled with RPMI 1640 (bicarbonate buffered) or Ringers (electrolyte) solution, allowing the cells to be supplied by capillarity. In an exposure chamber the cells were exposed for 30 min to SO2 2.5–12.5 ppm at 37°C and 100% air humidity. SO2 induced a dose-dependent decrease in CBF of the cells cultured in Ringers solution. SO2 at 2.5 ppm caused a 42.8 % decrease and at 12.5 ppm a 96.5% decrease (8.1 ± 0.24 versus 0.28 ± 0.20 Hz). CBF of cells cultured in RPMI 1640 was reduced only moderately after 12.5 ppm SO2 exposure (7.9 ± 0.26 versus 6.70 ± 0.30 Hz). In Ringers solution a decrease in pH was observed after 30 min of S02 exposure to 12.5 ppm to a minimum value of 3.6. By contrast, the pH of RPMI 1640 remained constant at 7.5 under identical conditions. After adding RPMI 1640 to Ringers solution, CBF increased in parallel to the pH to control values (5.0 ppm: 4.64 ± 0.45 to 8.51 ± 0.60 Hz). These data suggest that the highly water-soluble SO2 reversibly eliminates CBF in correlation with a decrease in pH.

Eosinophil cationic protein in nasal secretions and blood serum in grass-pollen allergic rhinitis

Concentration of the Eosinophil Cationic Protein (ECP) measured in different body fluids has been demonstrated to be a good marker of eosinophilic inflammation. In allergic asthma, ECP levels in both broncho-alveolar-lavage (BAL) fluid and serum can be used to monitor disease activity. In allergic rhinitis, the value of ECP determinations in serum and nasal secretions was not directly compared, so far. In the present study, ECP levels in blood serum (Se) and nasal secretions (NS) of grass pollen allergic and healthy individuals under pollen exposure were analyzed. Forty-three grass-pollen allergic subjects and 19 healthy volunteers were included. Grass-pollen counts were measured using Burkhard traps and a symptom scoring performed. In the allergic subjects, the mean ECP concentration in nasal secretions was 789 ± 515 ng/mL compared with 12.1 ± 7.4 ng/mL in serum; in the healthy volunteers it was 29.6 ± 15.4 ng/mL in NS compared to 9.4 ± 6.9 ng/mL in Se. ECP concentration in NS was significantly higher in allergic than in healthy subjects (P < 0.001) and in both significantly higher than in Se (P < 0.01). ECP concentration in Se did not differ significantly in patients and healthy volunteers (P > 0.05). In the allergic subjects, ECP concentration in NS but not in Se was closely correlated to symptom score and pollen exposure. We conclude that ECP levels in NS are a better marker of eosinophilic inflammation in allergic rhinitis than ECP serum levels.

Effect of sulfur dioxide on mucociliary activity and ciliary beat frequency in guinea pig trachea

SummaryThe effects of 30 min exposure to sulfur dioxide on mucociliary activity (MCA) and ciliary beat frequency (CBF) were studied in 31 guinea pig tracheas. MCA was measured by recording the light reflected from ciliated mucous membranes using an infrared bar code reader. CBF of single ciliated cells obtained by brushing was measured with phase-contrast microscopy. Each tracheal sample was exposed to SO2 at concentrations ranging from 2.5 to 12.5 ppm, or to air for control purposes. MCA and CBF were measured before and immediately after gas exposure. A reduction in mean MCA of 63% (P = 0.0007) and statistically insignificant changes in CBF (P > 0.05) were recorded at concentrations of 2.5 PPM SO2. Higher SO2 concentrations caused a further impairment of MCA as well as a dose-dependent decrease in CBF (P = 0.002). A concentration of 12.5 PPM SO2 induced a decrease from baseline values of approximately 80% in mean MCA and of roughly 70% in mean CBE This study demonstrates a dose-dependent SO2-induced decrease in MCA of guinea pig tracheas. The decrease in MCA was associated with an impairment of CBF only at SO2 concentrations higher than 5.0 ppm.

Diltiazem for prevention of acoustical trauma during otologic surgery

100 patients were tested in a prospective, randomized, double-blinded study to assess the perioperative efficacy of a calcium channel blocker (diltiazem) in preventing acoustical trauma during otologic surgery. The patients were randomly divided into a therapy group (diltiazem) and a control group (placebo). Bone conduction hearing thresholds were examined preoperatively and again 1 day and 3 months postoperatively. Frequency-dependent changes in postoperative bone conduction and the number of patients with various degrees of postoperative hearing loss in both groups were statistically analyzed. The results indicated only a small postoperative hearing loss after ear surgery in both groups. There was a tendency for better results in the therapy group, but this was not statistically significant. Despite favorable results in animal trials utilizing different types of noise and the prophylactic application of diltiazem, further studies in humans are needed to determine the role of calcium antagonist drugs in the prophylaxis or treatment of acoustical trauma.

The influence of Ca2+ antagonists on the ciliary activity of the guinea pig trachea.

SummaryThe ciliary activity of the guinea pig tracheal respiratory epithelium was measured using a photoelectric device. Fourteen animals were administered 75 mg diltiazem/kg body weight 2 days, 1 day and 4 h prior to the investigation. Thirteen animals served as controls. In the pretreated group, the mean ciliary stroke frequency (13.4 ± 3.0 Hz) was significantly lower (P = 0.02) than in the control group (16.6 ± 3.7 Hz). The application of aerosolized 0.3 mmol/l nifedipine solution on the tracheal preparations of the control animals also significantly reduced the stroke frequency (P = 0.02). The ciliary activity never dropped beyond a frequency of about 8 Hz. The most probable interpretation of these results is a modulating effect of Ca2+ antagonists on ciliary activity by blocking voltage-gated calcium channels.

Measurement of pharyngeal pressure in patients using nasal CPAP

In patients with obstructive sleep apnea syndrome (OSAS), nasal continuous positive airway pressure (nCPAP) prevents pharyngeal collapse by applying positive pressure transnasally. Currently there are not objective criteria to determine whether surgical improvement of nasal resistance is necessary in patients undergoing nCPAP treatment. In 16 patients with documented OSAS, inspiratory and expiratory pressures in the pharynx were measured during nCPAP with pressures ranging from 5 to 20 mbar. Identical studies were performed in 12 patients with severe nasal obstruction without OSAS and in eight normal patients. The results of each group were compared to the nasal resistance as measured by acoustic rhinometry. The pharyngeal pressures under nCPAP were found to be independent of nasal resistance and of the minimal cross-sectional area of the nose. Additionally, nCPAP was effective in individuals with severe nasal obstruction. Nasal obstruction has no influence on nasal pressure when using nCPAP. Perhaps other factors, such as collapsing of the pharynx or tone of the pharyngeal muscles, play a role in determining the nasal pressure of the nCPAP.

CARTILAGE PALISADE TYMPANOPLASTY

Recurrent tympanic membrane perforations are usually caused by underlying conditions such as an adhesive process with a poorly aerated middle ear space, a thermal perforation, infection, or technical error at the time of graft placement. Despite surgical treatment these reperforations pose a significant otologic problem that may lead to the development of chronic otitis media and cholesteatoma. The purpose of this study is to detail the use of a new cartilage palisade tympanoplasty technique that has yielded a 100% tympanic membrane closure rate without recurrent perforations in 52 operated ears over a 2-year period. The acoustic properties of the rebuilt tympanic membrane were analyzed for types I, II, and III tympanoplasty and revealed a significant improvement in the postoperative air bone gap.