The Impact of Different Sedation Regimens on Hemodynamics in Patients Undergoing Mechanical Ventilation With Shock

Critically ill patients requiring mechanical ventilation in the ICU frequently present with concurrent shock. The hemodynamic effects of sedative agents may further exacerbate circulatory instability. Studies indicate that 34% of ICU patients require simultaneous mechanical ventilation and vasoactive agent support. Among ARDS patients, over 60% develop shock, with approximately 65% necessitating vasopressor administration.

Common sedatives like propofol and dexmedetomidine, despite being first-line choices, exhibit significant hemodynamic side effects:

• **Propofol** induces hypotension (incidence: 20%) through vasodilation, sympathetic suppression, and bradycardia.
• **Dexmedetomidine** causes hypotension and bradycardia at low doses, while triggering vasoconstriction via peripheral α-2 receptor activation at high doses-both scenarios reduce cardiac output.

Additional factors affecting hemodynamic stability include sedation depth, duration, and daily awakening protocols. Deep sedation may mask dynamic assessment of fluid responsiveness, delaying shock resuscitation. Conversely, daily awakening-though reducing ventilation duration-may increase circulatory fluctuations through stress responses. These complex interactions necessitate balancing sedation efficacy and circulatory stability in shock patients, yet standardized protocols for this population remain lacking.

Inclusion criteria

• Age ≥ 18 years;
• Receiving invasive mechanical ventilation, with endotracheal intubation -performed <12 hours before enrollment;
• Patient requiring sedative and analgesic medications;
• Hemodynamic instability: Hypotension (systolic blood pressure <90 mmHg or mean arterial pressure <65 mmHg) occurring within 6 hours before intubation to 6 hours after intubation, requiring continuous vasoactive medication therapy for >1 hour.

Exclusion criteria

• Pregnant or breastfeeding patients;
• Patients with confirmed or suspected acute primary brain pathology (e.g., traumatic brain injury, intracranial hemorrhage, stroke, hypoxic brain injury);
• Patients with confirmed or suspected spinal cord injury or other pathologies likely to cause permanent or prolonged weakness;
• Patients with known allergy to the analgesic, sedative, or vasoactive medications used in the study protocol;
• Patients receiving palliative care or with an expected survival of ≤48 hours; Patients previously enrolled in this study.