II. Cortical Spreading Depression

Intracortical spreading depression following local application of K+Cl-. The signal is spreading in a wave pattern at a speed of 3,5 mm/min over the whole Cortex (Vilagi, Klapka & Luhmann, 2001).

IV. Excitotoxicity

Energy depletion shuts down Glutamate-Portersystems and produces Lactacidosis.

Extracellular Glutamate concentration rises; Acidosis removes the Mg++-lock from the NMDA-Receptor (Ca-channel)

Intracellular Ca++-overload

„Misuse“ of Mitochondria

Further Energy depletion, Cell death

V. Lipid Peroxydation

•Oxygen free radicals [Reactive oxygen species (ROS)] attack the cell membrane and organelles

•Arachidonic acid is oxydized to eicosanoids plus further ROS

•Thromboxane disrupts the blood-brain- barrier, producing vasogenic oedema

•Excess Calcium binds to phosphate, limiting phosphorylation of ADP to ATP

Results of „Dysventilation“

•Hypoxia: Brain damage

•Hyperoxia: Convulsions

•Hypocapnia: Cerebral ischaemia

•Hypercapnia: Brain swelling (venous

congestion resulting in intracranial hypertension)

CO2-Reactivity of cerebral vessels: Effects of paCO2 [ETpCO2] on ICP

Removing / reintegrating soda lime absorbers of the breathing system.

Culprit vs. Victim: Specific

(2)

Brain Lung: Subarachnoid Haemorrhage

(SAH)

SAH Neurogenic Pulmonary Oedema

•Frequency: 25%

•Mechanism: Catecholamine surge

SAH ARDS

• Frequency: 20%

Intensive Care Med (2002) 28:1012-23

How does the Lung damage the

Brain ?

•Pulmonary liberation of Cytokines Brain

•Pneumonia Sepsis Septic Encephalopathy

•Pneumonia Fever Cerebral Hyperthermia Excitotoxicity

•ARDS Pulmonary compliance AWP ICP

•ARDS Permissive Hypercapnia ICP

Brain atrophy and cognitive impairment of ARDS

Sharshar et al. 2007

Intensive Care Med 33 798-806

(Brain lesions in septic shock: a MRI study) Hopkins et al. 2006 Brain Injury 20 263-271

Effects of varying levels of positive end-expiratory pressure on intracranial pressure and cerebral perfusion pressure

McGuire et al. Crit Care Med 1997