The health care provider orders positive end expiratory pressure (PEEP) to be added to the settings of a mechanically ventilated patient. Which is the most important information for the nurse to obtain when monitoring for the effectiveness of this intervention?

Choice D rationale Positive end expiratory pressure (PEEP) increases intrathoracic pressure to keep alveoli open and improve oxygenation. However, this increased pressure can compress the heart and great vessels, leading to decreased venous return and a subsequent drop in cardiac output. Monitoring arterial blood pressure is the most important safety assessment because excessive PEEP can cause significant hypotension. While oxygenation is the goal, the nurse must ensure the patient's hemodynamics are not compromised by the intervention. Choice A rationale Oxygen saturation is used to monitor the effectiveness of PEEP in improving gas exchange, as PEEP helps recruit collapsed alveoli. While improving saturation is a goal, it is not the most critical monitoring parameter for complications. A patient could have a rising oxygen saturation while their blood pressure is plummeting due to the mechanical effects of high intrathoracic pressure on the heart. Therefore, hemodynamic stability takes precedence when adjusting and monitoring PEEP levels in ventilated patients. Choice B rationale Tidal volume is the amount of air delivered with each breath. While PEEP affects the functional residual capacity, it is not the primary measure for its immediate systemic impact or effectiveness. The ventilator settings usually control the tidal volume directly in volume controlled modes. Monitoring tidal volume is important for lung protection and preventing barotrauma, but it does not provide immediate feedback on the systemic hemodynamic consequences of the positive pressure being applied to the chest. Choice C rationale Respiratory rate is typically set by the ventilator or influenced by the patient's underlying condition and sedation level. While PEEP might improve the ease of breathing by increasing lung compliance, the respiratory rate is not a specific or sensitive indicator of the effectiveness or the safety of PEEP. Changes in rate are more often related to pain, anxiety, or changes in metabolic demand rather than the direct physiological response to the recruitment of alveoli.