The article “Cerebral Metabolism is not Affected by Moderate Hyperventilation in Patients with Traumatic Brain Injury” has been written in cooperation with researchers from Italy, Switzerland, and Australia. They address the impact of moderate short-term Hyperventilation-induced hypocapnia (HV) on patients with traumatic brain injury (TBI) (Brandi et al). Zurich University Hospital provided surgical intensive care units (ICU) from May 2014 till May 2017 to implement the clinical trial.
The study targets patients with a nonpenetrating head injury who are at least 18 years old. The authors use transcranial color-coded duplex sonography (TCCD) to examine the middle cerebral artery (MCA), including peak systolic velocity and end-diastolic velocity (Brandi et al). During the trial professional physicians control elevated intracranial pressure, mean arterial blood pressure, cerebral perfusion pressure arterial oxygen saturation (SaO2), end-tidal CO2 (etCO2), and PbrO2 indicators (Brandi et al). The study protocol implies that all parameters are collected with the help of TCCD during three periods. Altogether there are five TCCD measurements, as demonstrated in Figure 1.
Analysis of data has allowed determining the reduction of the mean flow velocity (CBVF) in MCA and an increase in the pulsatility index. Therefore the authors conclude that moderate short-term HV lowers elevated intracranial pressure (ICP) effectively as it influences CBVF velocity. Furthermore, the study shows the stability of MAP and a heart rate when moderate HV takes place. The application of two additional variables, such as PbrO2, and microdialysis illustrates possible hypoxia of tissues.
The results of the research contribute to the debate over the outcomes of HV for treating patients with TBI. Findings provide supporting evidence to the assumption that moderate HV can reduce ICP and PbrO2. However, the study has limitations related to the small sample size that hinders the generalization of the authors’ conclusions. Thus, identifying sex or age differences in vasoreactivity is not possible. Finally, changes in other brain areas are not explored because the MD and PbrO2 probes depict activities in relatively small zones.
Work cited
Brandi, Giovanni, et al. “Cerebral Metabolism is not Affected by Moderate Hyperventilation in Patients with Traumatic Brain Injury.” Critical Care, vol. 23, no. 45, 2019. Web.