Objective assessment of hoarseness by measuring jitter.

The objective measurement of hoarseness by measuring 'jitter' (the average percentage pitch-period variation between consecutive pitch-cycles) using an inverse filtering technique is described. Twenty-five patients with a variety of causes of hoarseness were studied, together with five individuals who had mild hoarseness induced by histamine challenge and 12 normal individuals. The mean severity of jitter in the patient group (9.8%) was significantly different from the normals. (1.04%) In addition, there was a significant correlation (R2 = 0.53; P < 0.0001) between jitter and subjective assessment of hoarseness. The mean values of jitter with histamine challenge before and after recovery (1.03%, and 1.18%) were significantly different (P < 0.0001) to the mean maximum value during the challenge (2.64%). These data suggest that jitter is an objective and repeatable measurement of hoarseness-even small changes in hoarseness in individual patients. It is likely to prove most effective for monitoring treatment response.

Impact of routine use of intraoperative transesophageal echocardiography during cardiac surgery.

PURPOSE: To determine the relative impact of each category-based TEE indication according to the ASA guidelines. METHODS: In 851 patients undergoing cardiac surgery, TEE clinical indications were classified as category I or II according to the ASA guidelines. Category I indications are patients in which TEE is considered useful and category II are those where TEE is potentially useful but indications are less clear. All TEE examinations were reviewed by two anesthesiologists with advanced training in TEE. For each patient, the clinical impact of TEE in the clinical management was assessed using five criteria: 1) change of medical therapy; 2) change in the surgical procedure; 3) confirmation of a suspected diagnosis; 4) positioning of an intravascular device, and 5) substitute to a pulmonary artery catheter (PAC). RESULTS: TEE had greater utility in category I than in category II indications (15/53 (28%) vs. 110/798 (14%) respectively) (P<0.01). The nature of the clinical impact was as follows: modification of medical therapy in 67/125 (53%), modification of planned surgical intervention in 38/125 (30%), confirmation of a diagnosis in 34/125 (27%). The impact on therapy was higher in complex surgical procedures (39%) than in valvular replacement (19%) (P<0.01) and coronary artery bypass surgery (10%) (P<0.001). CONCLUSIONS: Our findings validate the usefulness of the ASA practice guidelines demonstrating a greater impact of TEE on clinical management for category I indications than for category II. TEE also had a greater clinical impact in complex surgical procedures and in valvular replacement.

Inverse filtering applied to upper airway sounds.

Inverse filtering is a digital signal processing technique which may be applied to speech-like sounds to remove resonances introduced by upper airway cavities to leave a residual signal which is, in principle, spectrally flat and strongly related to the excitation source. The filter parameters, normally computed by a form of linear prediction analysis, are indicative of the frequencies and bandwidths of the resonances. This paper briefly outlines the principle of inverse filtering and describes two applications in the study of upper airway sounds for diagnostic purposes. The first application is concerned with the non-invasive measurement of variations in upper airway dimensions which occur with changes in posture. Results show that differences in the resonance frequencies caused by changes in posture can be measured, these being of the order of about 10% in normals. The measurement of such changes is known to be useful in the assessment of patients with sleep apnoea. The second application concerns the evaluation of vocal tract abnormalities resulting from infection in the larynx. Parameters derived from the residual are believed to be indicative of the existence and severity of a hoarse voice. Results have been obtained which support this theory.

Haemodynamic interaction of high-dose fentanyl and increasing doses of vecuronium in patients undergoing myocardial revascularization.

BACKGROUND: Bradyarrhythmia has been reported with vecuronium when given with high dose narcotics. We hypothesized that if the bradycardic response is dependent on a vagal reaction mediated by narcotics, it should be independent of the vecuronium dose. A dose-related response of vecuronium on heart rate (HR) would be in favour of a chronotropic action of this agent. METHODS: We examined three induction techniques using high doses of fentanyl in which vecuronium was given in increasing doses. In addition, a reference group received a low dose of atracurium. Forty patients scheduled for elective CABG surgery were anaesthetized with fentanyl (50 mu g/kg) given over 5 min, and were randomly assigned to receive either 0.056, 0.14, 0.28 mg/kg of vecuronium or 0.28 mg/kg of atracurium. Haemodynamic measurements were obtained at the following intervals: before induction (time 0), after the administration of fentanyl (at 5 min), and 1, 2 and 5 min after tracheal intubation (at 10, 11 and 15 min). RESULTS: In vecuronium-treated groups, there were significant decreases in HR, mean arterial pressure, and cardiac output (P<0.05). There were no differences between the three vecuronium groups. Although the atracurium-treated group displayed no significant haemodynamic changes, 2 patients of this group developed HR < 40 bpm. CONCLUSIONS: Over the range of vecuronium doses studied, we observed a reduction in HR during induction for CABG surgery with high doses of fentanyl and vecuronium. This effect was not dose dependent and is likely related to a direct effect of a high-dose narcotic technique and/or due to a vagal stimulation regarding the airway procedure.

Acoustic discrimination of velar impairment in children.

Cepstral coefficients calculated out of a linear prediction have been used to discriminate two groups of 19 control children and 12 patients with velar impairment. French vowels /a/, /i/, /u/ had been studied using the cepstral coefficients. Vowels /i/ and /u/ appeared to be efficient to perform the separation on acoustic grounds. A 100% recognition score can be reached when the two vowels are considered together. Modifications of the cepstrums dealing with velar incompetence are also discussed. A way to make an automatic grading of the pathology is finally presented.

[Reduction laryngoplasty by external approach for glottic incompetence. Current role, demonstration of its efficacy by objective analysis of parameters of vocal quality]. / Laryngoplastie réductrice par voie externe pour fuite glottique. Place actuelle, et démonstration de son efficacité par les méthodes d'analyse objective des paramètres de la qualité vocale.

Authors talk about the place of surgical treatments with cervicotomy in abducted vocal cord, about the statistics of the department of Phoniatrics of the Hospital Edouard Herriot in Lyon. These techniques have actually a marginal place. But the analysis of a recent case shows us that endoscopic treatment for vocal fold augmentation with biomaterials such as collagen or teflon can fail. So ENT surgeons have to absolutely know the Guerrier's technique to improve the quality of the voice when injectable biomaterials fail. With the description of this case, we will describe the objective analysis methods of the voice parameters that we use in the department.

Effect of a hydrostatic pleural pressure gradient on mechanical behavior of lung lobes.

Using 133Xe, the vertical distribution of regional volume (Vr) was measured in three regions of excised canine lobes both in air and when completely submerged in saline at 40, 60, 70, and 80% lobar vital capacity (VC). The estimated pleural pressure gradient, derived from values of Vr, distance between regions, and the lobar pressure-volume (PV) curve, underestimated the true gradient by 45%. Conversely, the gradient of Vr was substantially less than predicted. From the mean depth of each region below the waterline, pleural, and hence transpulmonary, pressure (PL) was computed. The values of Vr-PL for each region at 40, 60, and 80% lung volume (VL) were related to the lobar PV curve. Slopes of lines joining initial VL-PL points on the lobar PV curve to corresponding Vr-PL points in submerged lobes represent an effective regional compliance of a lobe undergoing deformation. With one exception this was less than the corresponding homogeneous compliance, indicating a stiffening of the lobe during deformation. Slopes of lines joining Vr-PL points of each region at the three lobar volumes represent effective regional compliance of a deformed lobe undergoing volume change. This was not significantly different from the homogeneous compliance. However, effective compliance can only be an approximate indicator of the forces required for a given volume change due to the inadequacy of PL to represent the unequal stress components induced by lobe deformation.