Barbiturates Effects

Some barbiturates effects are explained here. The thiopental sodium causes profound fall in cerebral blood flow (35 to 40%) and thus ICP. Thiopentone also causes profound decrease in CMRO2.

Thiopentone increases Cerebral perfusion pressure (CPP). The barbiturates effects increased the amplitudes of subcortical and early cortical components of somatosensory evoked potentials.

Even full suppression of all spontaneous EEG activity by thiopentone does not suppress the somatosensory evoked responses making it a useful test in comatose patients receiving this treatment.

Incremental doses of thiopentone produce EEG pattern similar to sleep. As the dose increases, the frequency of waves decreases and becomes isoelectric at very high dose.

One of the barbiturates effects is that the Barbiturate-induced depression of cerebral metabolic oxygen requirements when the EEG is iso-electric is about 55%. A continuous infusion of thiopental, 4 mg/kg, produces an isoelectric EEG that is consistent with near maximal decreases in cerebral metabolism.

Barbiturates effects on the  Cardiovascular system

Hypnotic doses may cause a slight fall in BP and a decrease in heart rate as occurs during natural sleep. Toxic doses produce a sustained hypotension as a result of

  1. Direct depression of the myocardium and the vasomotor center,
  2. Hypoxia and
  3. Probably, blockade of sympathetic ganglia.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top