The methodical collection of ear surgery data as a basis for quality control.

Data relating to daily clinical practice were collected in an otologic database. Over a period of 3 years, information was gathered about 1,000 ear operations. This led to the following conclusions: the collection of data is difficult; the selection of data and the moment it should be fed into the systems are very important; there is a risk of using too many items and therefore reducing surgeon compliance. On the other hand, too few items result in irrelevant overviews. The collection of ear surgery data makes it easier to understand positive and negative outcomes.

Performance assessment of ossicular chain reconstructions in a University hospital.

It remains to be demonstrated that normal, day-to-day routine surgery is as effective as it would appear from the literature, where the results of very experienced surgeons are presented. The object of this study was to measure our performance for ossicular chain reconstructions. One hundred and thirty-eight total and partial reconstructions performed by 13 different surgeons were evaluated. The population was divided into four different groups based on the presence or absence of the canal wall and stapes suprastructure. The results varied widely. A number of patients benefited greatly, whereas others experienced deterioration in their hearing. The best improvement (median 13 dB) was achieved in the group with an intact canal wall and absent stapes suprastructure. The postoperative air bone gap was better for autologous incus rather than prosthesis in the group where the canal wall and stapes were intact. There were three minor complications. This continuous feedback reports exceptional results (good and bad). The strengths and weaknesses of the department can be determined. This feedback indicates that this procedure is safe and beneficial for the patients in our Institution.

Costs and effects of microsurgery versus radiosurgery in treating acoustic neuroma.

This study analyses costs and effects of treating acoustic neuroma patients by using microsurgery compared to radiosurgery. Radiosurgery is the stereotactic application of radiotherapy and an innovative medical technology. Cost and effect estimates of conventional treatment were based on a retrospective study in the Netherlands. Similar data for a comparable group of patients in Sweden were collected for radiosurgery, as this treatment option is currently not available in the Netherlands. Fifty-three acoustic neuroma patients who had been operated on the University Hospital Rotterdam between November 1990 and February 1995 were included. This group was compared with 92 acoustic neuroma patients treated with radiosurgery (Gamma Knife. Stockholm, Sweden) in the same period. Data on health care use were collected from patient files. To obtain data on production losses and quality of life, a questionnaire was sent by mail in February 1995. This booklet consisted of the Health and Labour-questionnaire (HLQ), the Short Form-36 (SF36) and the EuroQol. The response rate was 92%. Direct costs for microsurgery amounted to Dfl. 20.072,- and for radiosurgery to Dfl. 14.272,-. Indirect costs were respectively Dfl. 16.400,- and Dfl. 1.020,-. General health rating was better for radiosurgery than for microsurgery. On the whole, differences in clinical outcomes between the two patient groups were small. Assuming a reasonable occupancy rate of the expensive radiosurgery equipment, we demonstrated that for the short term treating patients with acoustic neuroma with an extra-meatal tumour diameter of less than 3 centimeters, radiosurgery is more cost-effective than microsurgery.

Maximal expiratory and inspiratory flow-volume curves in bilateral vocal-cord paralysis. Changes after surgical treatment and comparison with glottic resistance characteristics.

The maximal expiratory flow-volume (MEFV) and maximal inspiratory flow-volume (MIFV) curve present maximal attainable flows, plotted against the displaced volume at the mouth during a forced expiratory manoeuvre from total lung capacity (TLC) and a subsequent forced inspiratory manoeuvre from residual volume (RV), respectively. Depending on the glottic resistance characteristics, the usual flow limitation may be absent during forced expiration, drastically influencing the form of MEFV curves. During forced inspiration however, the flow remains effort-dependent. We tested this hypothesis by comparing the form of MEFV and MIFV curves, and the glottic resistance characteristics, before and after an endolaryngeal superolateralization of a vocal cord, in 12 patients with bilateral vocal-cord paralysis. Peak expiratory and inspiratory flows were estimated with the aid of the measured glottic resistance characteristics on the assumption that the maximal alveolar pressures were normal during the manoeuvres. The estimated values agreed well with measured values. The form of the MEFV and MIFV curves was also found to be closely linked to the glottic resistance characteristics. It is concluded that the MEFV and MIFV curves are sensitive indicators of flow limitation in patients with upper-airway obstructions.

Flow limitation in upper-airway obstruction. Theoretical analysis.

During a maximal forced expiration from total lung capacity (TLC) in normal human subjects flow limitation will occur (i.e., the flow will become independent of muscular effort) after the initial part of the expiratory manoeuvre. Flow limitation starts at the flow that causes a pressure drop in the bronchial tree large enough for the generation of a flow-limiting segment. In patients with upper-airway obstruction such as laryngeal obstruction or tracheal stenosis, the upper-airway resistance may keep the flow so low that flow limitation cannot arise. The present theoretical study confirms that glottic resistance does not prevent flow limitation from arising in normal human subjects. On the other hand, the mean glottic resistance characteristics measured for 19 patients with bilateral vocal-cord paralysis were found to be such as to prevent flow limitation. This means that in such patients and also in patients with other types of upper-airway obstruction flow may remain effort-dependent throughout the forced expiratory manoeuvre or in any case during much more of this manoeuvre than normal.

Interpretation of changes in spirographic and flow-volume variables after operative treatment in bilateral vocal cord paralysis.

In 13 patients, who underwent a superolateralization of a vocal cord after bilateral vocal cord paralysis, we studied pre- and postoperatively spirometric dynamic and static lung volumes and variables from maximal expiratory and maximal inspiratory flow-volume (MEFV and MIFV) curves. The effects of surgical treatment on these variables have been established by comparing the statistical significance of the changes post- versus preoperative. A significant increase was found in the vital capacity and a significant decrease in the indices associated with the dynamic variability of the obstruction. The most significant changes were found in peak inspiratory flow and peak expiratory flow, and in the inspiratory defined dynamic estimates, as forced inspiratory volume in 1 second and maximal voluntary ventilation at a frequency of 30 c X min-1. Significant correlations, however, were found to exist only for the changes within the group of flow-volume indices and for those within the group of spirographic variables. This led us to the conclusion that for the diagnosis of this type of upper airway obstruction these measurements are additive, reflecting different aspects of airway mechanics.