Background: Endotracheal suctioning (ES) provokes a cumulative hemodynamic response by activation of sympathetic and parasympathetic circuits in the central nervous system. In this proof-of-concept study, we aimed to analyze hemodynamic changes during ES in ventilated subarachnoid hemorrhage (SAH) patients and investigated whether the associated hemodynamic changes relate to the time to arousal and functional outcome.
Methods: For the current observational study, 191 SAH patients admitted to the neurological intensive care unit of a tertiary hospital requiring mechanical ventilation were included. One thousand eighty ES episodes during the first 72 h of admission were analyzed. Baseline median heart rate (HR) and mean arterial pressure (MAP) were compared to peak HR and MAP during ES based on 5-min averaged data (ΔHR and ΔMAP). Multivariable analysis to assess associations between ΔHR and ΔMAP and time to arousal (time to Richmond Agitation Sedation Scale ≥ 0, RASS) and poor functional outcome (modified Rankin Scale Score > 2, mRS) was performed using generalized estimating equations.
Results: Patients were 59 (IQR, 50-70) years old and presented with a median admission H&H grade of 4 (IQR, 3-5). In-hospital mortality was 22% (25% at 3 months) and median time to arousal was 13 (IQR, 4-21) days. HR increased by 2.3 ± 7.1 beats per minute (bpm) from 75.1 ± 14.8 bpm at baseline. MAP increased by 3.2 ± 7.8 mmHg from baseline 80.9 ± 9.8 mmHg. In multivariable analysis, ΔHR (p < 0.001) was significantly lower in patients who regained consciousness at a later time point and a lower ΔHR was associated with poor functional 3-month outcome independent of RASS (adjOR = 0.95; 95% CI = 0.93-0.98) or midazolam dose (adjOR = 0.96; 95% CI = 0.94-0.98). ΔMAP was neither associated with the time to regain consciousness (p = 0.087) nor with functional outcome (p = 0.263).
Conclusion: Augmentation in heart rate may quantify the hemodynamic response during endotracheal suctioning in brain-injured patients. The value as a biomarker to early discriminate the time to arousal and functional outcome in acutely brain-injured patients needs prospective confirmation.
Keywords: Autonomic testing; Brainstem integrity; Critical care; Endotracheal suctioning; Subarachnoid hemorrhage.