Aerodynamic characteristics of the Nijdam voice prosthesis in relation to tracheo-esophageal wall thickness

Aerodynamic characteristics of the slit-like trachea-esophagus puncture for voice rehabilitation following total laryngectomy

CONCLUSIONS

The slit-like trachea-esophagus puncture is a reliable procedure to restore the voice in the patient who has undergone a total laryngectomy. The new voice quality could be similar to normal and could meet the patient's daily needs.

OBJECTIVES

We report a new method of tracheoneoesophageal (TE) voice rehabilitation. A slit-like trachea-esophagus puncture was made in the tracheoesophageal wall after the total laryngectomy. No voice prosthesis was used. The purpose of this study was to observe its aerodynamic characteristics.

METHODS

All 60 patients received voice rehabilitation with the slit-like fistula after total laryngectomy. All patients' voices were evaluated as excellent. The aerodynamic characteristics of trachea-esophagus voices were observed.

RESULTS

When a patient attempted to phonate, the upper esophagus was closed. Then, the hypopharyngeal cavity expanded. Just before phonating, the upper esophagus was full of air as a ball. The air flow escaped through the segment of the trachea-esophagus slit and entered the pharyngoesophageal segment (PES). The esophageal meatus opened. It was vibrated together with nearby mucus and mucosa to form the voice. The maximum phonation time of the slit-like fistula voice was not significantly different from the Blom-Singer prosthesis voice. Its sound intensity was similar to the normal voice.

Airflow resistance of heat and moisture exchange filters with and without a tracheostoma valve

Rehabilitation of laryngectomees has been furthered by the introduction of heat and moisture exchange (HME) filters, placed over a tracheostoma or on a tracheostoma valve (TSV). The airflow resistance of HME filters is an important factor with regard to the comfort of the patient. The goal of this study was to determine the airflow resistance (defined as the pressure drop over the device divided by the squared airflow through the device) of 4 commercially available HME filters with and without a TSV. The pressure drop over and the airflow through the devices were measured in vitro. Distinct differences among the devices were found. The mean airflow resistance of the HME filters ranged from 135 to 346 Pa x s2/L2, that of TSVs was between 66 and 297 Pa x s2/L2, and that of the combination was between 263 and 454 Pa x s2/L2. The Stom-Vent 2 HME filter and the Adeva Window TSV with an Adeva filter had the lowest airflow resistance of the devices measured in this study.

Airflow resistance of airflow-regulating devices described by independent coefficients

Rehabilitation after laryngectomy includes more and more the use of airflow-regulating devices such as shunt valves (SVs), tracheostoma valves (TSVs), and heat and moisture exchange (HME) filters. In determining the quality of those devices, airflow resistance is a very important factor. It is currently defined as pressure drop divided by airflow. However, for most applications, this definition does not result in a pressure- and airflow-independent parameter. Therefore, a new set of parameters is defined and applied to pressure-airflow curves of airflow-regulating devices. Pressure drop over TSVs and HME filters appears to have a squared relationship with flow. In SVs, it has a linear relationship. The new set of parameters describes the pressure-airflow relationship properly for all considered devices. In conclusion, theoretical predictions of flow mechanics appear to be valid for SVs, TSVs, and HME filters. Only 2 coefficients are necessary to describe the pressure-flow characteristics of these airflow-regulating devices, independent of pressure drop over and flow through the device.

A prospective study of speech and voice rehabilitation after total laryngectomy with the low-resistance Groningen, Nijdam and Provox voice prostheses

In a prospective study the Groningen, Nijdam, and Provox voice prostheses were evaluated with respect to speech and voice rehabilitation. At approximately 1, 4, and 10 months after operation, patients were submitted to a standardized speaking task to evaluate phonatory skills (phrase length, phonation duration, dynamics on tone, dynamics on sentence, speech rate and availability of sound), speech quality (fluency and overall intelligibility), voice quality and stoma technique (stoma noise). Tracheoesophageal speech rehabilitation proved to be successful in 94-100% of patients, as measured at approximately 10 months after operation. Furthermore, no significant overall differences were found between the three prostheses. There was a significant improvement in time for speech rate and stoma noise. As for the time effects (e.g. improvement in performance over time) no differences between the three prostheses were found.

Analysis of the mechanical behavior of the Nijdam voice prosthesis

The valveless Nijdam prosthesis is a new voice prosthesis for laryngectomized patients using tracheoesophageal speech. An "umbrella-like hat" covers the esophageal side of the tracheoesophageal fistula and is deformed during speech by air pressure. To decrease pressure loss during speech, a good understanding of the mechanical behavior is essential. In the present study, the Finite Element Method (FEM), used in engineering to analyze the mechanical behavior of complex structures, was applied to analyze eight possible improvements of the Nijdam prosthesis. This study found that, during speech, deformation of hat and soft tissue occur. Distinct differences in the hat's deformation of the eight models also were found. It is concluded that complex structures like the Nijdam prosthesis can be analyzed by FEM. An optimal model was found to decrease pressure loss while stresses in the device remain safe.

In vivo aerodynamic characteristics of the Nijdam voice prosthesis

The Nijdam voice prosthesis is an indwelling valveless voice prosthesis for postlaryngectomy voice rehabilitation. The in vitro aerodynamic characteristics are reported to be comparable to that of the low-resistance Groningen voice prosthesis. Owing to the design of the prosthesis the airflow resistance depends on the shaft length of the voice prosthesis in relation to the thickness of the tracheo-oesophageal wall. As tissue characteristics of the patient's oesophageal mucosa could also be of importance, an in vivo study was found necessary. To assess in vivo characteristics the following parameters were recorded in 10 patients: intratracheal pressure, intraoesophageal pressure and airflow during phonation. At an airflow of 0.15 1/sec the transdevice pressure loss varied from 0.5 up to 7 kPa (mean 3.9 kPa). With an artificial increase of the tracheo-oesophageal wall thickness, transdevice pressure losses up to 13 kPa were found. Significant interindividual as well as intraindividual differences were noted. The airflow resistance of the Nijdam voice prosthesis in relation to the thickness of the tracheo-oesophageal wall was compared with the airflow resistance reported for various other voice prostheses. The in vivo aerodynamic characteristics of the Nijdam voice prosthesis found in this study indicate the need to modify the present design in order to improve its airflow resistance and to eliminate the influence of the thickness and tissue characteristics of the tracheo-oesophageal wall.