An intubated patient with no known history of congestive heart failure is in the ICU.The patient is comatose and currently receiving mechanical ventilation via volume-controlled continuous mandatory ventilation (VC-CMV),set rate 12 bpm,set tidal volume (V_T)400 mL,positive-end-expiratory pressure (PEEP)18 cm H₂O,fractional inspired oxygen (FIO₂)0.35,and the patient is not assisting.Hemodynamic measurements show the following: central venous pressure (CVP)5 mm Hg,pulmonary artery pressure (PAP)33/20 mm Hg,and pulmonary artery occlusion pressure (PAOP)16 mm Hg.Arterial blood gas (ABG)results are: pH 7.43,arterial partial pressure of carbon dioxide (P_aCO₂)38 mm Hg,arterial partial pressure of oxygen (P_aO₂)90 mm Hg.The physician asks for recommendations to improve this patient's hemodynamics.The most appropriate recommendation for this patient is which of the following?

Question

Quizplus · Accepted Answer

The patient's central venous pressure (CVP)is within normal limits.The pulmonary artery pressure (PAP)and pulmonary artery occlusion pressure (PAOP)are both elevated.These hemodynamic results are consistent with left ventricular failure.However,when looking at the ventilator settings it should be noted that the set positive-end-expiratory pressure (PEEP)is > 15 cm H₂O.This setting will prolong changes in lung zones and produce erroneously elevated pressure readings by squeezing the pulmonary vessels and overinflating the lungs.Changing the mode to pressure support ventilation (PSV)or synchronized intermittent mandatory ventilation (SIMV)will lower the mean inspiratory pressures and minimize the hemodynamic effects of positive intrathoracic pressure.However,this patient is comatose so PSV is not an option (choice "A")and changing to volume-controlled synchronized intermittent mandatory ventilation (VC-SIMV)with the same PEEP level (choice "C")will have little effect on the hemodynamics.Pressure ventilation (choice "D")will have about the same effect on the patient's hemodynamic values as the current settings.Decreasing the PEEP incrementally and checking the hemodynamic measurements can be used to optimize the PEEP level for this patient.

An Intubated Patient with No Known History of Congestive Heart