Related Experiment Video
Updated: Oct 12, 2026

Epidural Intracranial Pressure Measurement in Rats Using a Fiber-optic Pressure Transducer
Published on: April 25, 2012
The effects of inverse ratio ventilation on intracranial pressure: a preliminary report
1Department of Anaesthesia, Royal Adelaide Hospital, South Australia.
Objective:
To determine the effects of pressure control inverse ratio ventilation [PC-IRV], as compared with volume controlled normal ratio ventilation [VC], on the intracranial pressure [ICP] of patients with severe head injury.
Design:
A prospective study with unblinded intervention.
Setting:
The Intensive Therapy Unit of a base hospital.
Patients And Participants:
Nine cases of head injury requiring mechanical ventilation and intracranial pressure monitoring were studied.
Interventions:
Patients were twice transferred from VC (1:E ratio 1:2) to PC-IRV (1:E ratio 2:1). Firstly, tidal volume was maintained at an equal value. Secondly, end tidal CO2 was maintained at an equal value. No other changes were made to ventilation, vasopressor therapy or ICP control.
Measurements And Results:
Measurements were taken of ICP, mean arterial pressure (MAP) end tidal CO2 and respiratory parameters. In the first observation, there were significant changes in peak inspiratory pressure (PIP), mean airway pressure (Paw) and intrinsic positive end expiratory pressure (PEEP) but not for ICP, end tidal CO2, MAP and cerebral perfusion pressure (CPP). The correlation between change in ICP and change in end tidal CO2 was r = -0.74. In the second observation there were significant changes in tidal volume, PIP, Paw and intrinsic PEEP but not for ICP, MAP and CPP. The correlation between the change in ICP and the change in Paw was insignificant.
Conclusions:
PC-IRV has a minimal net effect on ICP. Changes in ICP correlate more strongly with changes in CO2 than changes in Paw.
Related Concept Videos
Assessment of Ventilation I: Respiratory Rate
A Ventilation assessment is critical for monitoring a patient's health status. Respiration, one of the most accessible vital signs, provides insights into the function of numerous body systems and can indicate serious health issues, such as brainstem injuries from head trauma.
Critical Guidelines for Assessing Ventilation:
Mechanical Ventilation II: Invasive Ventilation
Negative-Pressure Ventilators
Negative-pressure ventilators create a vacuum around the chest or body to draw air into the lungs, simulating breathing. This method does not require an...
Mechanical Ventilation III: Noninvasive Ventilation
Noninvasive Positive-Pressure Ventilation (NIPPV)
Increased Intracranial Pressure l: Introduction
Increased Intracranial Pressure ll: Pathophysiology

