• Direct arterial catheterization: detects surgical cardiac compression, sudden bleeding, serial blood gases during OLV
• Central venous pressure: may not reflect intravascular fluid volume and is no longer considered an accurate guide for fluid responsiveness
• Pulmonary artery catheterization: interpretation may be difficult during OLV, application of PEEP
• TEE: ventricular function, valvular function, motion changes reflecting ischemia
• Arterial blood gases (especially PaCO₂)

OLV = one-lung ventilation; PEEP = positive end-expiratory pressure; TEE = transesophageal echocardiography.