A critical reviewed of the article: Effect of endotracheal suctioning on cerebral oxygenation in traumatic brain-injured patients.
Reviewed for the Pennsylvania Society of Respiratory Care
by Desmond Allen, PhD, RCP
Effect of endotracheal suctioning on cerebral oxygenation in traumatic brain-injured patients. Mary E. Kerr, RN, PhD, FAAN; Barbara B, Weber, RN, MS; Susan M. Sereika, PhD; Joseph Darby, MD; Donald W. Marion, MD; Patricia A. Orndoff, RN, MEd. Crit Care Med 1999; 27 (12): 2776-2781.
The routine intervention of endotracheal suctioning (ETS) may negatively effect the cerebrovascular status by increasing the intracranial pressure (ICP). Decreased cerebral oxygenation, secondary to conditions such as an increased ICP, is known to cause brain damage in trauma patients with severe head injuries.
Does ETS influence cerebral oxygenation in patients with traumatic brain injury?
Method & Sample:
This cohort study took place in a ten-bed Level-1 trauma intensive care unit. 24 patients with acute head injury are enrolled. However, 5 had missing data, leaving a sample size of 19 patients. 14 males and 5 females. Each was ≥16 years (mean age of 29), had a Glasgow Coma Scale score £8 (mean 3.5), had external ventricular drain, arterial lines, and was intubated and mechanically ventilated. Patients considered brain dead or having an invalid ICP waveform were excluded from the study.
All data was collected using a standardized suctioning protocol of monitoring baseline physiologic data for 5 minutes with patients in a supine position with head flat, the administration of 4 ventilator breaths at 135% of Vt with 100% Fi02, the initial application of suction for 10 seconds at 16 L/min, 4 ventilator breaths repeated, a second suction application, 4 ventilator breaths repeated, followed by a minute-by-minute post-protocol monitoring for a maximum of 10 minutes.
In general, there were considerable changes in each cerebrovascular and oxygenation indices. Specifically, the ICP presented significant changes from baseline through the phases of suctioning. The mean baseline of 23.5 mm Hg elevated to a mean 24.5 mm Hg during the third cycle of 4 ventilated breaths. This returned to below baseline within 1 minute. The mean arterial pressure (MAP) also displayed significant phase specific changes ranging from a baseline of 100.7 mm Hg to a peak of 122.8 mm Hg during the second suctioning. Post-protocol values were similar to baseline and even decreasing after the third hyperinflation. Cerebral perfusion pressure (CPP) changes were similar to those of the MAP. However, in general cerebral oxygenation was adequately maintained during ETS in those patients with only transient elevations of ICP. Sustained elevations in ICP >20 mm Hg remain a concern and are associated with poor outcome.
Transient elevations in ICP and MAP associated with ETS preceded by pre-oxygenation do not appear to impair cerebral oxygenation.
Problems With the Study:
The Value of the Study:
Until this study, there was little evidence concerning the direct effect of transient increases in ICP and MAP on cerebral oxygenation during ETS. By contributing further understanding
of cerebrovascular dynamics during ETS, and by documenting the resultant benign transient increase in the ICP and MAP, this study assures the clinician a safe parameter within which suctioning can be applied without risk of further injury.
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