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Proper Probe Positioning for Infants with Compromised Ventilation from Transesophageal Echocardiography

Stayer, Stephen A. MD; Bent, Sabrina T. MD; Andropoulos, Dean A. MD

doi: 10.1097/00000539-200104000-00062
Letters To The Editor: Letters & Announcements
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Department of Anesthesia, Baylor College of Medicine and Texas Children’s Hospital, Houston, TX

To the Editor:

Transesophageal echocardiography (TEE) has become an invaluable tool in pediatric patients undergoing surgery for congenital heart disease. We observed two infants who had compromised ventilation from TEE and describe placing the TEE probe in the hypopharynx when not in use to obtain useful data without significant airway compromise.

Case 1. A 27-day old, 3.5-kg infant was scheduled to undergo an arterial switch procedure and aortic arch advancement. Volume control ventilation was used with a preset tidal volume of 60 mL that generated a peak pressure (PIP) of 26 cm H2O, positive end-expiratory pressure of 3 cm H2O, respiratory rate of 30 breaths/min, and Fio2 0.21. The exhaled tidal volume, as measured by the anesthesia machine, was 54 mL and ETco2 was 31 mm Hg. A pediatric biplane TEE probe with external dimensions 9 × 8 mm (Acuson V705B; Acuson Mountain View, CA) was inserted into the esophagus. A gradual rise in ETco2 to 42 mm Hg was noted with a decrease in exhaled tidal volume to 40 mL and rise in PIP to 30 cm H2O. Increasing the preset tidal volume to 80 mL improved ventilation. After completion of the TEE examination, the probe was withdrawn to the hypopharynx, the original ventilator settings resumed, and ventilation returned to baseline. At the completion of the surgical repair, the TEE probe easily advanced from the hypopharynx into the esophagus. A PIP of 38 cm H2O was again generated to develop adequate chest excursion. After safely weaning from CPB, the TEE probe was removed, with a return to baseline lung compliance noted.

Case 2. A 3-mo-old, 2.24-kg infant was scheduled for mitral valvuloplasty. Pressure control ventilation was initiated with PIP 22 cm H2O, positive end-expiratory pressure 4 cm H2O, respiratory rate 30 breaths/min, Fio2 0.45, and this pressure generated an exhaled tidal volume of 52 mL. During the initial TEE study, we noted an increase in ETco2 from 33 to 38 mm Hg and a decrease in the exhaled tidal volume to 40 mL. Increasing the PIP to 28 cm H2O improved ventilation. After the initial TEE study, the probe was withdrawn to the hypopharynx (Fig. 1) and in this position the ventilation improved, allowing return to the baseline ventilator settings. The TEE probe was easily reinserted into the esophagus after the repair, and a PIP of 30 cm H2O was needed to maintain adequate chest excursion, with exhaled tidal volumes of 50 mL. The surgeon noted that the left lung did not deflate between respiratory cycles. After probe removal, left lung excursion improved and the ventilator settings could be returned to the same as in the pre-CPB period.

Figure 1

Figure 1

Airway obstruction is reported to occur in 1%–2% of all pediatric patients undergoing TEE, and infants are at the greatest risk (1). Ventilation should be carefully monitored during TEE probe insertion to detect partial or complete airway obstruction. The manufacturer does not recommend the use of this probe in infants <3 kg, although we have used this probe for infants weighing between 2 and 3 kg without problems (2).

Some authors recommend that the TEE probe be removed immediately if airway compromise is suspected (3). We report two infants who experienced partial airway obstruction with the insertion of the TEE probe. We were able to maintain normal ventilation with increased airway pressure during the echocardiographic examination, and positioned the TEE probe in the patients’ hypopharynx when the probe was not in use. This positioning allows easy reinsertion into the esophagus, and limits partial airway compression to the times when the TEE probe is in use. However, a probe positioned in the patient’s hypopharynx can inadvertently be removed from the mouth, and probe insertion can cause pharyngeal or esophageal trauma. Therefore, we continue to recommend advancing the probe into the stomach for all patients who do not have evidence of airway or hemodynamic compromise.

Stephen A. Stayer, MD

Sabrina T. Bent, MD

Dean A. Andropoulos, MD

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References

1. Stevenson JG. Incidence of complications in pediatric transesophageal echocardiography: experience in 1650 cases. J Am Soc Echocardiogr 1999; 12: 527–32.
2. Andropoulos DB, Ayres NA, Stayer SA, et al. The effect of transesophageal echocardiography on ventilation in small infants undergoing cardiac surgery. Anesth Analg 2000; 90: 47–9.
3. Cheitlin M, Alpert J, Armstrong W, et al. ACC/AHA guidelines for the clinical application of echocardiography: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Clinical Application of Echocardiography). Circulation 1997; 95: 1686–744.
© 2001 International Anesthesia Research Society