Newton D. Fischer

Nasal resistance, skeletal classification, and mouth breathing in orthodontic patients

1. 1. A subjective classification of the breathing pattern of each of fifty-one patients presenting for orthodontic treatment reveals that thirty-one were nasal breathers and twenty were mouth breathers. 2. 2. The skeletal classification by the AB difference method was considered to be reliable in this study. 3. 3. The magnitude of nasal resistance and the subjects skeletal classification were found to be independent of each other. 4. 4. The breathing pattern and the skeletal classification of the subject were also found to be independent of each other. 5. 5. In the thirteen subjects with nasal resistance above 4.5 cm. H2O/liter/second, a deviation of the nasal septum was noted in six, injection of the turbinates in two, and allergic rhinitis in two. Three subjects were considered within normal limits. 6. 6. The incidence of clinically observable mouth breathing was found to be greater among the subjects with a nasal resistance above 4.5 cm. H2O/liter/second (77 per cent) than among those with a nasal resistance below this value (26 per cent).

Comparisons of tracheostomy incisions in a pediatric model.

Tracheostomy in children causes approximately twice the mortality and morbidity as in the adult. The occurrence of complications correlates closely with the severity of the preoperative tracheal disease, the length of time the tracheostomy is needed, and the age of the patient. Morbidity documented in the postoperative period includes tracheal stenosis and collapsible anterior tracheal wall. The increased incidence of these problems in the pediatric patient may be related to the less rigid nature of the younger cartilage or to partial arrest of the normal tracheal growth rate, and may be aggravated by the style of tracheal incision used. Our study utilized weanling male ferrets in an effort to evaluate the possibly different response of growing, less resilient cartilage to different types of tracheal incision. Animals were randomized into three groups based on the type of incision used: inferiorly based trapdoor, vertical slit, or horizontal H. Endoscopic, radiographic, and airflow studies, as well as cross-sectional areas, were compared on all animals surviving tracheal cannulation for eight days and subsequent decannulation for seven days. Recommendations for pediatric tracheal incision are made on the basis of these studies.

Effects of laser, scalpel, and electrosurgical excision on wound contracture and graft "take".

SUMMARY Current literature recommends the use of a carbon dioxide laser for excision of lesions where minimal damage and wound contracture are desirable.5,6 The extent of tissue damage is evaluated as a correlate of percentage of split-thickness skin graft “take” following excision of full-thickness skin with scalpel, electrocutting current, or carbon dioxide laser. The poorest overall percentage “take” is apparent following laser excision, while the highest overall percentage “take” occurs following scalpel excision. Wound contracture, an inherent part of wound healing, is reportedly minimal or clinically inapparent with laser excision.5,6 On the contrary, this experimental evaluation suggests that wound contracture following laser excision is at least as great if not greater than that following other methods of excision when a split-thickness skin graft is applied to the wound bed.

Tracheal reconstruction with pedicled thyroid cartilage.

Limited areas of tracheal stenosis have been repaired with a variety of techniques. More extensive upper tracheal defects present a greater challenge with less predictable success. The following is the description of yet another technique for reconstruction of extensive upper tracheal defects. We report on the use of a muscle‐pedicled thyroid alar graft which carries its own blood supply and perichondrial covering, supplies a large, conveniently shaped graft, requires one operative site and one operative sitting, and has proven advantageous even in the compromised patient.

Ethacrynic Acid Ototoxicity Potentiation by Kanamycin

The ototoxicity of ethacrynic acid and kanamycin in combination has been investigated during acute and chronic conditions of exposure. The effect of the combination of 10 mg/kg of ethacrynic acid and 100 mg/kg of kanamycin during both exposure conditions is manifested by a significantly greater drop in measured potentials than is present in the combination with lower doses of kanamycin (50 mg/kg). This effect is manifested mainly by changes in EP. The action of ethacrynic acid and kanamycin, therefore, appears to affect primarily the metabolism of the stria vascularis. According to our electrophysiological findings during acute conditions, not only simultaneous drug exposure can increase the ototoxic effect, but sequential exposure also seems to create a treatment hazard if ethacrynic acid is given following prior exposure to an ototoxic antibiotic. Therefore, a careful evaluation of the drug history in every patient should be carried out before using ethacrynic acid for treatment.

Variation of Endocochlear Po2 and Cochlear Potentials by Breathing Carbon Dioxide

The effect of carbon dioxide on oxygen tension in the endolymph was determined by the micropolarographic technique. Different concentrations (5% and 10% CO2) and different exposure times (3, 5, and 20 minutes) were investigated. The highest levels of Po2 in the endolymph (101.7, 93.9 and 69.5 mm Hg) were accomplished by respiration of 10% CO2, 90% O2, for 20, 5, and 3 minutes consecutively. The lowest Po2 increase, 50.7 mm Hg was observed after breathing 5% CO2, 90% O2 for 20 minutes. Extreme hypercapnia caused an increase of endocochlear potentials (EP) in all groups. In the second group EP increased from +79.3 to +84.9 and in all groups they had returned to the pretreatment level after CO2 discontinuation. These results support the theory that carbonic anhydrase participates in the generation of EP. At the same time that EP increased, cochlear microphonics declined and opposite after the breathing mixture was discontinued. The results permit the conclusion that high levels of Po2 in endolymph is achievable even with short periods of respiration with high CO2 mixture, and suggest the role of carbonic anhydrase during EP generation.

A correlation of the effects of normoxia, hyperoxia and anoxia on PO2 of endolymph and cochlear potentials.

Change in PO2 in endolymph, endocochlear potentials and cochlear microphonics have been tested in normoxia, hyperoxia and anoxia on 24 guinea pigs. The polarographic method and construction of oxygen-sensitive microelectrodes is described in detail. The normal level of PO2 in endolymph vaires between 20 and 30 mm Hg. One-minute anoxia induced by breathing 100% N2 caused a decline in PO2, EP and CM, but during recovery only PO2 returned with over-correction to the preexposure level. Hyperoxia evoked by breathing 100% oxygen failed to increase the cochlear potentials and the PO2 in the endolymph. This suggests that vasoconstriction most likely occurs proximal to the capillaries bed of the stria vascularis.

Otoscopy and Photography A New Method

A new hand-held otoscope photographic system, convenient and suitable for clinical application, is introduced. This instrument allows clear otoscopic examination in stenotic or tortuous ear canals, and photographs the subject in one procedure. The instrument consists of a rodlens optical system, a fiberoptic light source, a camera, and exchangeable speculum and a strobe light. Color photographs of tympanic membranes and middle ear pathology are presented.

Frontal sinus trephination: A new technique for office procedure

A new office technique for frontal sinus trephination is described. The procedure is simple, expedient, and inexpensive. Our experience with 16 patients suggests that this procedure is reasonably safe and, in addition, avoids the often‐seen complications of supra‐trochlear nerve injury and persistent noticeable scar.

Ototoxicity of tobramycin sulfate.

Fifty‐four healthy guinea pigs were studied histologically for evaluation of Tobramycin sulfate ototoxicity. They were treated with 50, 100, 150 and 200 mg/kg/day under different schedules. Loss of hair cells occurred when dosage of 1,200 mg/kg was reached. Animals receiving 700 mg/kg were without damage to the inner ear. Outer hair cell loss occurred first in the basal turn, spreading upward. Inner hair cell loss began in the apical turn, progressing downward. When a total dose of 1,400 mg/kg was reached by (two) different schedules the higher daily dose produced about twice the hair cell loss; therefore, the ototoxic effect depends on the total dose but even more on the increased blood concentration.