The effect of carbon dioxide on oxygen dioxide 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.

Action Potentials↗

PubMedDate not supplied

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 rod-lens 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.

Ear Canal↗

PubMedDate not supplied

Frequency dependence of effective nasal resistance.

Forced random noise techniques were used to characterize the effective resistance of the nasal passages in normal subjects and subjects who were candidates for surgical correction of nasal obstruction. The slope of the effective resistance curve was characterized by the average resistances over 3 to 5 Hz and 13 to 15 Hz. Subjects with nasal obstruction had effective nasal resistance curves which were more frequency-dependent than those of normal subjects (p less than 0.05). A mathematical model consisting of two series resistance-inertance elements in parallel was used to simulate the nasal passages. With this model we were able to generate effective resistance curves similar to those measured in both normal and obstructed subjects. The forced random noise technique may be a convenient, noninvasive technique for studying the fluid mechanical properties of airflow in the nasal passages and the effects of pharmacological and surgical interventions on nasal resistance.

Acoustics↗

PubMedDate not supplied

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.

Animals↗

PubMedDate not supplied

The changes in the endolymphatic oxygen concentration and cochlear potentials after short anoxia, hyperoxia, and hypercapnia.

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Animals↗

PubMedDate not supplied

The bookend nasal septal splint.

A malleable nasal septal splint is presented. Its purpose is to hold the septum in the midline, and to depress the floor of the inlet over the premaxillary wings. Blunting of the nasal valves is avoided. This appliance can be both firmly seated and well tolerated, since its pedestals can be curved up laterally within the lateral crura. Additional splints can be threaded onto the first one to reach high posterior synechiae. A useful modification is provided to support nasal bones when nasal packing must be avoided.

Humans↗

PubMedDate not supplied

Teflon injection of vocal cords under general anesthesia: a new method.

Use of general anesthesia permits the injection of Teflon paste into immobile vocal cords in an accurate and predictable manner, with the help of a special endotracheal tube and jetted O2 or O2/n2O mixture. The authors position a nonfunctioning vocal cord so that when the functioning cord is fully adducted , the two cords are in perfect approximation for phonation. This has allowed marked improvement in effective expulsive postoperative coughing and vocalization. Debris is blown away from the operating side and not into the patient's trachea. If excessive injection of Teflon is avoided, an uneventful postoperative course can be expected.

Anesthesia, Endotracheal↗

PubMedDate not supplied

Toxicity of ethacrynic acid in different blood PO2.

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Animals↗