● Decreased pulmonary compliance. Increased peak inspiratory pressure and plateau pressure
● Decreased O2 saturation. Decrease in PaO2 over 20 minutes while hypoxic pulmonary vasoconstriction (HPV) decreases blood flow to nonventilated lung during this time.
● Shunt: During single lung ventilation, perfusion to the unventilated lung is still present. This leads to an intrapulmonary shunt and can precipitate hypoxemia. Protective mechanisms like hypoxic pulmonary vasoconstriction can help counteract the shunt, but only to a certain extent. Hypoxic pulmonary vasoconstriction can also exacerbate pulmonary hypertension. It can also slow the rise of FA/FI and can delay induction. More pronounced in less soluble inhaled anesthetics.
● Atelectasis: The nonventilated lung remains atelectatic, even after resuming ventilation until proper recruitment is performed. In the ventilated lung, an FiO2 of 1.0 may be required during one-lung ventilation to maintain adequate SpO2. This can promote atelectasis in the ventilated lung and can be mitigated with frequent recruitment maneuvers. Atelectasis can also be minimized by increasing positive end-expiratory pressure (PEEP).
● Lung Injury: The ventilated lung is at increased risk for volutrauma and barotrauma due to increased tidal volumes and increased airway pressures required to maintain adequate ventilation and oxygenation. Trauma to the ventilated lung is lessened by using lung protective ventilation strategies including tidal volumes of 3-5 ml/kg ideal body weight.
- Mehrotra M, Jain A. Single Lung Ventilation. [Updated 2019 Mar 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan Link
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