Background: The basic requirements for monitoring anesthetized patients during
surgery are assessing cardiac and respiratory function. Esophageal stethoscopes
have been developed for this purpose, but these devices may not provide clear heart
and lung sound due to existence of various noises in operating rooms. In addition,
the stethoscope is not applicable for continues monitoring, and it is unsuitable for
observing inaccessible patients in some conditions such as during CT scan.
Objective: A wireless electronic esophageal stethoscope is designed for continues
auscultation of heart and lung sounds in anesthetized patients. The system
consists of a transmitter and a receiver. The former acquires, amplifies and transmits
the acquired sound signals to the latter via a frequency modulation transmitter. The
receiver demodulates, amplifies, and delivers the received signal to a headphone to
be heard by anesthesiologist.
Results: The usability and effectiveness of the designed system was qualitatively
evaluated by 5 anesthesiologists in Namazi Hospital and Shahid Chamran Hospital,
Shiraz, Iran on 30 patients in several operating rooms in different conditions; e.g.,
when electro surgery instruments are working. Fortunately, the experts on average
ranked good quality for the heard heart and lung sounds and very good on the user
friendly being of the instrument.
Conclusion: Evaluation results demonstrate that the developed system is capable
of capturing and transmitting heart and lung sounds successfully. Therefore, it can be
used to continuously monitor anesthetized patients’ cardiac and respiratory function.
Since via the instrument wireless auscultation is possible, it could be suitable for
observing inaccessible patients in several conditions such as during CT scan