To the Editor:
The carefully crafted study “Auscultation versus Point-of-care Ultrasound to Determine Endotracheal versus Bronchial Intubation”1 was performed with great care to blind the observers. The ultrasound technique is described in detail, but the auscultation technique is unmentioned. Because the authors report that the “screens of the anesthesia machine and general monitor were partially covered to conceal the peak and mean airway pressure readings, capnography waveform, and the pulse oximetry (SpO2) values,” we may deduce that auscultation was performed during mechanical ventilation, presumably using current recommendations of tidal volumes of 5 to 7 ml/kg and positive end-expiratory pressure. The proper technique for auscultating for endotracheal tube placement requires placement of the stethoscope in the axilla and rapidly inflating the lungs with a larger than normal tidal volume to maximize breath sounds. Failure to utilize such a technique places auscultation at a distinct disadvantage in the comparison. An appropriate comparison for an ultrasound examination might be performing it with the gain minimized or the display turned to minimal intensity. Is it scientifically rigorous to compare two devices when the technique applied to one seriously hinders its application?
In the accompanying editorial, Isono et al.2 have supported their argument that the stethoscope is obsolete with a table claiming that there is “no” “cost per use” for point-of-care ultrasonography. A quick check of the internet for the LOGIQ E device utilized in this study suggests retail prices of $25 to $30,000 with replacement probes costing a few thousand dollars each. Amortizing this cost over some reasonable number of anesthetic uses is clearly going to result in a real cost per use, perhaps half the $50 they quote for fiberscopy. Just as the editorial suggests that sensitivity and specificity can be improved by a variety of enhancements in technique, so can auscultation be augmented by other physical diagnostic maneuvers, including the assessment of the cuff position by ballottement of the suprasternal notch to improve its performance.
In our enthusiasm to embrace new technology, it is easy to accept unfair comparisons as demonstration of superiority. In response to the editorial’s titular question, the well-trained clinician needs to use all of his senses, including common sense, to provide optimal care for his patients.
The author declares no competing interests.