The distinction between solubilitypc and partial pressure

1
The distinction between solubility(pc) and
partial pressure
A blood gas partition coefficient of 2.4 means
that for every molecule in the gas
phase(alveolus) it takes 2.4 molecules in the
blood to exert the alveolar pressure in this
case 1 of atmosphere or 7.6 mm hg.
2
Significant physical properties
3
(No Transcript)
4
(No Transcript)
5
Possible sites of action of inhalational agents
in the CNS

• Membrane lipids
• Synapses
• Increased GABA
• Decreased glutamate
• Protein ionophores through membranes

• Postsynaptic action (enhancement of n/m block by
  inhalationals)
• Decreased intracellular calcium
• Increased brain cAMP
• Endogenous opiates
• Nitric oxide

6
Minimum Alveolar Concentration

• MAC
• Expressed as percent atmospheric pressure
• Prevents movement
• 50
• Standard surgical incision

7
MAC varies with age
8
MAC varies with temperature
9
Further notes on MAC

• 1.5 to 2.5 MAC needed when an inhalational agent
  is sole anesthetic.
• MAC-BARR dose required to suppress hemodynamic
  responses.(1.45 MAC halo)
• Narcotics and N2O lower MAC
• Atracurium raises MAC

10
(No Transcript)
11
Uptake and distribution

• Agent concentration
• Ventilation
• Uptake---lungs(B/G pc)
• Distribution to tissues
• Tissue uptake
• Venous partial pressure
• Flow(cardiac output)

12
Anesthetic uptake in tissue groups
Maximum anesthetic effect
13
The second gas effect
14
Diffusion hypoxia
15
(No Transcript)
16
N2O and loculated air space
17
Effect of ventilation
Increased ventilation speeds up induction of all
anesthetics more so with soluble agents
18
Effect of cardiac output
Low cardiac output speeds up induction with
soluble agents like ether
19
Effect of inhalationals on the heart
contractility
Frank-Starling curve Negative
inotropic Halothane is most
neg-inotrop, next is enflurane, next isosevodes
End diastolic vol
20
(No Transcript)
21
Left ventricular-arterial coupling
Matching negative inotropism with afterload
reduction
Mechanical efficiency of halothane is reduced
more than iso, sevo and des where matching is
good at 1 MAC
22
(No Transcript)
23
(No Transcript)
24
Longer time for diastolic relaxation
25
Cardioprotection with inhalational anesthetics
Managed care-fast track-switch from opioids to
inhalationals-better outcomes
26
Cardioprotection
Volatile anesthetics prime mitochondrial KATP
channels
27
Halothane protects the heart during ischemic
injury
28
Airways resistance
29
ventilation
CO2
Inhalational anesthetics depress respiration
30
Halothane depresses chemoreceptor sensitivity to
hypoxia