Waveform and Spectral Characteristics of Perioperative Wheezing

Waveform and Spectral Characteristics of Perioperative Wheezing

With the aid of computerized sound analysis, digital acoustic monitoring could provide a more sensitive, specific, and quantifiable indicator for perioperative respiratory abnormalities including wheezing. It is probable that the digital stethoscope has utility in the detection, monitoring, and resolution following treatment of acoustic changes characteristic of turbulent respiratory gas flow due to wheezing and/or the incomplete resolution of atelectasis following the re-initiation of ventilation in a collapsed lung.

Anesthesiologists still rely on use of a conventional stethoscope to detect abnormal breath sounds during and after surgery - this process is labor intensive, intermittent, relies on human experience and thus is highly subjective. In fact, even for the most basic assessments, e.g. endobronchial intubation, human auscultation is unreliable.1 Digital stethoscopes are able to both amplify and digitize airway sounds and also provide a mechanism to record and analyze them for features undetectable by a human. Several small, pilot studies have shown that acoustic waveforms from the lungs produce characteristic spectral patterns in specific pulmonary pathophysiologic states. At this time, there are no studies that examine the acoustic patterns specific to perioperative wheezing or lung re-expansion. With the aid of computerized sound analysis, digital acoustic monitoring could provide a more sensitive, specific, and quantifiable indicator for perioperative respiratory abnormalities including wheezing. It is probable that the digital stethoscope has utility in the detection and monitoring of acoustic changes characteristic of turbulent respiratory gas flow due to wheezing and/or the incomplete resolution of atelectasis following the re-initiation of ventilation in a collapsed lung. In addition, treatment of perioperative wheezing with an inhaled bronchodilator may lead to resolution of wheezing and this response to treatment may also be monitored using waveform and spectral characteristics of the acoustic patterns from the digital stethoscope.

Inclusion Criteria:

Patients scheduled for either:

1. open thoracic or video-assisted thoracoscopic surgery under general anesthesia requiring one-lung ventilation
2. abdominal surgery with a known history of chronic obstructive pulmonary disease (as documented in the electronic medical record)

Exclusion Criteria:

• Emergency surgery
• surgery requiring the use of transesophageal echocardiography
• refusal of informed consent
• pregnancy
• esophageal surgery
• lung transplantation
• contraindications for placement of esophageal stethoscope including esophageal varices strictures, motility disorders, diverticula or a history of prior esophageal injury or surgery
• age less than 18 years old
• prisoner