Mechanical ventilation is a common therapeutic intervention in the intensive care unit (ICU). However, patients undergoing mechanical ventilation often experience agitation, unplanned extubation, patient-ventilator asynchrony, and even neuroendocrine-immune dysregulation, sympathetic overexcitation, and organ dysfunction due to discomfort and pain. Sedation therapy mitigates patient stress, enhances comfort, and ensures the smooth implementation of mechanical ventilation, making it an essential component of treatment for ventilated patients. Nevertheless, sedation may impact peripheral vascular tone, leading to hemodynamic instability and exacerbating inadequate peripheral perfusion.

The precise implementation of sedation therapy to minimize adverse effects remains unclear. This prospective observational study will enroll critically ill patients with shock requiring mechanical ventilation. We will examine the effects of different sedation strategies-including sedation assessment protocols, sedative types, sedation duration, and daily awakening trials-on hemodynamics in this population. The study aims to explore optimized sedation regimens and provide evidence-based guidance for precision sedation therapy in clinical practice.

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.

The cohort will be selected from a tertiary hospital

all collected IPD，all IPD that underlie results in a publication

starting 1 years after publication

The date used and/or analyzed during the current study are available from the investigator on reasonable request