When less invasive methods fail to provide diagnoses in patients with pulmonary disease, a lung biopsy may be required. Concern for childhood interstitial lung disease, atypical infection (especially in an immunocompromised host), and evaluation of a mass/malformation are the most common indications for biopsy. CT-guided needle biopsy performed by an interventional radiologist is an option if limited histology is needed and the lesion is amenable to percutaneous approach (e.g., fungal nodules). Either a thoracoscopic procedure or a thoracotomy is preferred if thorough histologic evaluation is desired. Thoracotomy allows the surgeon to inspect and palpate the lung, which aids in choosing the best site for biopsy, but it is more invasive than thoracoscopy. In most cases, infants and children tolerate lung biopsy well.
Any child in respiratory distress should be treated with supplemental O2 to maintain normal O2 saturation levels. For long-term administration of O2, a nasal cannula is the most widely used device, as it enables patients to eat and speak unhindered by the O2 delivery system. Though nasal cannula is the easiest way to provide supplemental O2, the actual fraction of inspired oxygen (FIO2) delivered to the patient can be quite variable and affected by the child’s size and respiratory pattern. Humidified high flow nasal cannula (HFNC) allows the provider to more comfortably deliver higher flow rates while controlling the FIO2 and is now widely used in neonates as an alternative to noninvasive positive pressure. Supplemental O2 may also be delivered by a variety of face-mask systems ranging from a simple face mask, which can provide 30% to 40% O2, to a nonrebreather mask with reservoir that can provide nearly 100% O2.
The concentration of administered O2 should be high enough to relieve hypoxemia. The acceptable O2 saturation depends on the patient and clinical situation. Generally, supplemental O2 should be administered to achieve a goal saturation level above 90%. Normal oxygen saturation is greater than 95%. It is unnecessary to achieve 100% saturation, especially if this requires potentially toxic levels of inspired O2 for extended periods of time.
Inspired O2 concentrations less than 40% are usually safe for long-term use. Patients requiring supplemental O2 should be monitored with pulse oximetry, either intermittently or continuously, or with arterial blood gas measurements of Po2 to allow titration to the lowest possible O2 concentration.
Delivering therapeutic agents to the lower respiratory tract can be accomplished by inhalation of aerosol forms of the agents via dry powder inhaler (DPI), metered dose inhaler (MDI), or nebulizer. All of these devices are designed to generate relatively small particles that can bypass the filtering action of the upper airway and deposit in the lower airways. Many factors influence drug deposition, including patient technique, device used, age of the child, and breathing pattern. Nebulizers should be used with a face mask (infants) or mouthpiece (children and teens) to minimize loss of drug to ambient air. Plastic holding chambers (spacers) are available for all ages and should always be used with MDIs. Dry powder inhalers require a single rapid deep inhalation for optimal drug delivery, which is difficult for children under 6 years of age. MDIs and nebulizers are equally effective in delivering medications only if the technique is correct, so it is important to review this frequently and carefully with families.