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Department of Pediatric Anesthesia Children’s Hospital of New Jersey Newark Beth Israel Medical Center Newark, NJ 07112
I read with interest the efforts of Hammer et al. (1) to provide guidelines for the performance of single-lung ventilation (SLV) in children. I have developed the following practices while providing SLV, with a high degree of success in the most uncomplicated manner possible, for video-assisted thoracoscopic surgery (VATS) in children under the age of 12.
Most children under the age of 12 years can be cared for by using regular cuffed endotracheal tubes that are 1.5 to 2 mm inner diameter (ID) smaller than indicated by the commonly used formula: (age + 16)/4. For example, a cuffed tube with an ID of 4 or 4.5 would be used for an 8-yr-old. This has allowed the cuff of the tube to easily enter the mainstem bronchus in every instance. I use 3-mm ID cuffed tubes in children less than 12 mo.
I have needed no special efforts to achieve selective intubation of the right mainstem bronchus. I have consistently been able to achieve selective left mainstem intubation by using a firm stylet bent to closely resemble the stylet provided with left-sided double-lumen tubes.
The use of a cuff in the mainstem bronchus is essential in VATS to prevent reexpansion of the collapsed operative lung by flow of gas across the carina from the ventilated lung when suction is applied in the surgical field.
Satisfactory collapse of the operative lung is encouraged by the early inflation of the cuff in the mainstem bronchus of the ventilated lung. Early assumption of the lateral decubitus position maximizes the effect of gravity on facilitating this collapse. Hypoxemia is also prevented by a more favorable distribution of pulmonary blood flow between the two lungs.
The endotracheal tube must be secured in position as displacement out of the mainstem bronchus is a constant concern during positioning of the patient, and it is essential to confirm adequate separation of the lungs by auscultation, and if necessary, by fiberoptic bronchoscopy.
References
Department of Anesthesia Stanford University School of Medicine Stanford, CA 94305-5115
We appreciate Dr. Patankar’s interest in our article (1). We acknowledged the use of a cuffed, single-lumen endotracheal tube (ETT) advanced into a mainstem bronchus for single-lung ventilation (SLV) in children. As we noted, this is the simplest method available for SLV. The problems with this technique are 1) suction cannot be applied to the operative lung; 2) hypoxemia may result from obstruction of the upper lobe bronchus by the cuff of the ETT, especially when the short right mainstem bronchus is intubated; and 3) oxygen and continuous positive airway pressure cannot be administered to the operative lung should the patient become hypoxemic.
Hypoxemia is especially common in infants because of their increased O2 consumption and is exacerbated in the lateral decubitus position. In this age group, Dr. Patankar’s statement that "hypoxemia is also prevented by a more favorable distribution of pulmonary blood flow between the two lungs in the lateral decubitus position" is inaccurate. In adults, ventilation and perfusion are better matched during SLV in the lateral decubitus position. In infants, however, the reverse is true, so that oxygenation is worse during SLV in the lateral decubitus versus supine position (2). Several factors account for this discrepancy between adults and infants. Infants (and young children) have a soft, easily compressible rib cage that cannot fully support the underlying lung. Therefore, functional residual capacity is closer to residual volume, making airway closure likely to occur in the dependent lung even during tidal breathing. In addition, the patient’s small size results in a reduced hydrostatic pressure gradient between the nondependent and dependent lungs. Consequently, the favorable increase in perfusion to the dependent, ventilated lung in adults is reduced in infants and young children. For these reasons, infants and young children are at an increased risk of significant oxygen desaturation during surgery in the lateral decubitus position. Therefore, we favor the use of an end-hole bronchial blocker during SLV in young children, through which oxygen and continuous positive airway pressure may be administered to prevent or treat hypoxemia.
References
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