We do need precordial and esophageal stethoscopes.

Abstract

other than sound transmission? We have all seen the use of small, medium, and large silicone tubing, nasogastric tubing, and intravenous tubing. But do any of us know how each of these affects the transmission of sound? Let us examine the information that can be derived from a precordial or esophageal stethoscope. I maintain that the most that can be gleaned about heart sounds is that they are present and strong, present and weak, or not present. Information such as rate and rhythm is much more accurately acquired from the electrocardiogram. One of my mentors claimed that the adequacy of filling could be determined from listening to the split of the second heart sound [1]. There are no experimental data to support that position, and if the filling pressure is important one should place either a central venous pressure catheter or a pulmonary artery catheter. No one knows the correlation between heart sounds and cardiac output. No laboratory or clinical investigations have examined that question, but all of us have assumed that we can tell i f the cardiac output is depressed by listening to the intensity of the heart sounds. I suggest that by the time the heart sounds become muffled the cardiac output has probably been depressed by more than 50%. Thus, our clinical ability to determine cardiovascular depression by assessing the heart sounds is very limited. A precordial or esophageal stethoscope can only tell us the presence or absence of breath sounds. It can tell nothing about the adequacy of ventilation. The preeordial stethoscope can determine unilateral ventilation only if it is placed on the left chest and the endotracheal tube happens to enter the right main bronchus. Pretracheal and esophageal stethoscopes are useless in indicating whether the endobronchial intubation has taken place. Adequacy of ventilation is much better assessed by using a ventimeter, an end-tidal carbon dioxide analyzer, and a pulse oximeter. In some operations the use of either the precordial or esophageal stethoscope is difficult, if not impossible. These include operations for the repair of tracheoesophageal fistulas, aortic operations, most open-heart operations, and most esophageal operations. Furthermore, the use of either stethoscope during such procedures is usually not very productive. In summary, I think that, although the use of these monitoring devices may have been acceptable in the past, current technology has rendered them obsolete. The precordial and esophageal stethoscope should be relegated to the same position as the ether hook.