The primary task of the lungs is respiration. Respiration is the exchange of gases between an organism and its environment with the utilization of O2 and production of CO2. The most important physiological measure is the compliance of the intact respiratory system. The movement of O2 and CO2 in and out of the capillaries both in the lungs and in the peripheral tissues depends on gas diffusion. Positive pressure ventilation results in most of the ventilation being directed into the upper rather than the lower lung. The blood flow gradient due to gravity favors the dependent lung during one-lung ventilation (OLV). If the non-dependent lung is not ventilated any blood flow to it becomes shunt flow. This results in a larger alveolar-to-arterial oxygen tension difference with a lower PaO2 for a given oxygen concentration under identical circumstances, when compared to two-lung ventilation in the same position.

Safe and successful treatment of the morbidly obese patient requires a level of organizational commitment, protocols, expertise and staff training. Patients with morbid obesity should be identified by the surgeons and referred to the anesthetists at an earlier stage for pre-operative assessment. Morbidly obese patients have a greater risk of pulmonary hypertension due to obstructive sleep apnea and CO2 retention. Obesity is strongly correlated with obstructive sleep apnea syndrome (OSA). Large double lumen tubes (DLT) is used to minimize airway resistance in morbidly obese patients undergoing one-lung ventilation (OLV). Direct airway measurement is an accurate way of selecting a DLT rather than tube selection based solely on patient gender, height and weight. Morbidly obese patients have a higher proportion of adipose tissue and lower proportions of tissue water and lean body mass. These can cause differing patterns of drug distributions.

The institution of one-lung ventilation (OLV) can be problematic in approximately 20% of any case mix. A significant number will prove difficult at the lung separator insertion stage. The usual conditions of difficult intubation pertain, as well as some specific to the thoracic discipline and the pathologies encountered and exacerbated by the structure and bulk of some lung separators. The use of OLV and the adoption of the lateral decubitus position results in specific physiological changes, such as the shifts in west zones from vertical to horizontal, which are best countered by positive pressure ventilation. The open pneumothorax, weight of mediastinum, abdominal contents on adoption of the lateral decubitus position and the surgeon at work compress the dependent lung; and, all must be opposed through the narrow conduit of, often, the single lumen of a double lumen endobronchial tube (DLT).

This chapter deals with anesthesia for surgery to major intrathoracic structures excluding the heart and great vessels in neonates, infants and children. It focuses on thorough pre-operative assessment, intra-operative management including techniques for one-lung ventilation (OLV) and post-operative care including analgesia as well as a brief discussion of several conditions which present specifically in the pediatric patient population. Each phase of the anesthetic management of the pediatric thoracic patient should be carefully planned in advance and anesthetic nursing staff should be fully briefed. Two-lung ventilation is usually a perfectly acceptable and a simpler technique for many surgical procedures. To help reduce the chance of damaging the lung, apnea can be maintained while the thoracic cavity is entered. Providing satisfactory peri-operative management of the pediatric thoracic patient requires the highest standards of pre-operative assessment, technical expertise and communication between team members, but is both challenging and rewarding.