Oxygen and blood in Brain-Brain Protection Part 1

Brain is metabolically very active and its oxygen consumption is about 3.5 - 4.0 ml/100 gm/min.

Electrical activity of neurons (transient depolarization and repolarization with their attendant ionic shifts) consumes about 50% of the total energy production of neurons.

Thus, energy consumption can be reduced significantly by agents that can render the EEG isoelectric (e.g., barbiturates).

The remaining 50% is used to maintain basal cellular homeostasis.Although this portion of the total energy consumption is not amenable to reduction by anesthetic agents, hypothermia can reduce it substantially.

The normal CBF in humans is about 50 ml/100 gm/min.

The response of the brain to ischemia has been well characterized.

When CBF reaches about 20 ml/100 gm/min, EEG isoelectricity occurs.

At a flow of about 15 ml/100 gm/min, evoked responses can no longer be obtained. Although neurons do not immediately die at this flow rate, death will eventually occur if flow is not restored.

Below a flow of 10 ml/100 gm/min, ATP levels decline rapidly (within 5 minutes) and the neuron is

unable to maintain ionic homeostasis. At this point, the neuron undergoes depolarization (anoxic depolarization). By activating several biochemical cascades in a haphazard manner, calcium ultimately leads to neuronal death.

Comments

power injectable peripherally inserted central catheters

Clinical experience with power injectable peripherally inserted central catheters in intensive care patients Introduction In intensive care units (ICU), peripherally inserted central catheters (PICC) may be an alternative option to standard central venous catheters, particularly in patients with coagulation disorders or at high risk for infection. Some limits of PICCs (such as low flow rates) may be overcome by the use of power-injectable catheters . Method We have retrospectively reviewed all the power injectable PICCs inserted in adult and pediatric patients in the ICU during a 12-month period, focusing on the rate of complications at insertion and during maintenance. Results We have collected 89 power injectable PICCs (in adults and in children), both multiple and single lumen. All insertions were successful. There were no major complications at insertion and no episodes of catheter-related blood stream infection. Non-infective complications ...

Falling from Height...The Prognostic factors

Falls from Height is Knwon to cause major morbidities and mortalities. There are several prognostic factors for survival that have been identified: Height Age Type of surface Body part that touches the ground first Two other factors are important, but do not have a significant effect on mortality: Circumstances of the fall (suicide, accident, escape) Initial impact with an object before impacting the ground Height . Overall, about half of victims die at the scene, and a total of 70% die before they reach the hospital . The median height leading to death is about 49 feet, or about 4 to 5 storeys. 100% of victims die after falling 85 feet, or about 8 storeys. Age . Mortality increases with age due to pre-existing medical conditions and decreased physiologic reserve. Type of surface . The type of surface struck (i.e. grass, water, construction debris) can also have an effect on secondary injuries and survival. Mortality after striking a hard surface is nearly doubl...

Things to Avoid in Anesthesia for Pregnant with Pulmonary hypertension

Anesthesia for Pregnant woman with Pulmonary Hypertension is a real challenge for anesthesiologist. It is very crucial to remember the pathophysiology of pulmonary hypertension in pregnant women and to avoid some practices that will worsen the cardiac status. 1-Avoid single shot spinal anesthesia. Some authorities consider pulmonary hypertension as absolute contraindication for single shot spinal anesthesia specially in patients with NYHA III ,IV. Spinal anesthesia causes major hemodynamic instability(decrease SVR, decrease VR, decrease in CO) The preferred neuroaxial techniques are (epidural anesthesia and CSE with minimal spinal dose) 2-Avoid PAC. Pulmonary Artery catheters insertion may lead to pulmonary artery rupture or thrombosis. TEE is better cardiac monitor/Arteial line is mandatory. 3-Avoid Nitrous oxide in gas mixture.N2O increase the PVR 4-If MV to be started, avoid High TV and PEEP 5-Avoid Oxytocin Boluses, or rapid administration of Pitocin. Oxytocin causes ...

sedationstation

Search This Blog