The Neurological and Hemodynamics Safety of an Airway Clearance Technique in Patients with Acute Brain Injury: An Analysis of Intracranial Pressure Pulse Morphology Using a Non-Invasive Sensor

Abstract

Patients with acute brain injury (ACI) often require mechanical ventilation (MV) and are subject to pulmonary complications, thus justifying the use of Airway Clearance Techniques (ACTs), but their effects on intracranial pressure (ICP) are unknown. This study investigates the neurological and hemodynamics safety of an ACT called ventilator hyperinflation (VHI) in patients with ACI. This was a randomized clinical equivalence trial, which included patients aged ≥ 18 years with a clinical diagnosis of hemorrhagic stroke, with symptom onset within 48 h. The participants were randomly allocated to the Experimental Group (EG, n = 15), which underwent VHI followed by tracheal aspiration (TA), and the Control Group (CG, n = 15), which underwent TA only. Neurological safety was verified by analyzing the morphology of the ICP wave through the non-invasive B4C sensor, which detects bone deformation of the skull, resulting in a P2/P1 ratio and TTP, and hemodynamics through a multi-parameter monitor. Evaluations were recorded during five instances: T1 (baseline/pre-VHI), T2 (post-VHI and before TA), T3 (post-TA), T4 and T5 (monitoring 10 and 20 min after T3). The comparison between groups showed that there was no effect of the technique on the neurological variables with a mean P2/P1 ratio [F (4,112) = 1.871; p = 0.120; np2 = 0.063] and TTP [F (4,112) = 2.252; p = 0.068; np2 = 0.074], and for hemodynamics, heart rate [F (4,112) = 1.920; p = 0.112; np2 = 0.064] and mean arterial pressure [F(2.73, 76.57) = 0.799; p = 0.488; np2 = 0.028]. Our results showed that VHI did not pose a neurological or hemodynamics risk in neurocritical patients after ACI.

Keywords: ICP wave morphology; intracranial compliance; intracranial pressure; mechanical ventilation; mucociliary clearance; non-invasive intracranial pressure monitor; ventilator hyperinflation.

Figure 1

Flowchart of recruitment, interventions and assessments of participants. EG: Experimental Group; CG: Control Group; RASS: Richmond Agitation–Sedation Scale; EVD: External Ventricular Shunt; PFI: Peak Inspiratory Flow; PEF: Peak Expiratory Flow; PEEP: Positive End-Expiratory Pressure; FIO₂: Fraction of Inspired Oxygen; SpO₂: peripheral oxygen saturation; VT: Tidal Volume; F: Flow; RR: Respiratory Rate; IT: Inspiratory Time.

Figure 2

Schematic drawing of the experimental design. T1 to T5 represent evaluation moments. EG: Experimental Group; HMVM: Hyperinflation Mechanical Ventilation Maneuver; CG: Control Group; TA: tracheal aspiration; DD: Dorsal Decubitus.

Figure 3

ICP curve obtained by the B4C sensor in a report. P2/P1 ratio: the ratio between the amplitudes of peaks P2 and P1; TTP: time to peak, defined as the time, from the start of the pulse, at which the ICP waveform reaches its highest peak. The shaded line represents the confidence interval of the 1 min monitoring. HR: heart rate.

Figure 4

Values of VTE (A), ETCO₂ (B), DP (C) and Cst (D) achieved in the EG during VHI. Values expressed as means and CIs. Cst: Static Compliance; VTE: Expired Tidal Volume; DP: driving pressure. * Statistical difference (p < 0.001)—t-test for paired samples.

Figure 5

Mean values and confidence intervals for the P2/P1 ratio (A) and time to peak (TTP) (B) across five monitoring moments, categorized by groups. A two-way ANOVA was performed to evaluate differences among groups and moments and no statistical difference was found.

Figure 6

Mean values and confidence intervals for the heart rate (HR) (A), mean arterial pressure (MAP) (B) and peripheral oxygen saturation (SPO₂) (C), measured at five monitoring times, categorized by groups. A two-way ANOVA was conducted to compare differences between groups and moments. Statistical differences between groups were found at T2 and T5 (Tukey’s post hoc p < 0.001).