Skip to main content

Planet-friendly low flow anesthesia!!!


What and why of low flow anesthesia...





Flow rates can be categorized into:
Metabolic flow: 250 ml/mn
Minimal flow: 250-500 ml/mn
Low flow: 500-1000 ml/mn
Medium flow: 1-2 L/mn
High flow: 2-4 L/mn
Super-high flow >4 L/mn

Advantages of low flow anesthesia:
-Anesthetic gases delivered using high FGF are usually dry and cold. Reducing FGF makes gases recirculating in the circle system more humid and warmer. This has A significant influence on the function and the integrity of the ciliated epithelium of the respiratory tract, prevent airway and bronchial drying during ETT use. It also helps maintain body heat and prevent postoperative shivering.
-Several studies prove that the use of low and minimal flow anesthesia techniques can dramatically reduce the (annual) costs of volatile anesthetics. Typically, the reduction of FGF from 3 L/min to 1 L/min results in savings of about 50% of the total consumption of any volatile agent. Reduced FGF releases a lower amount of anesthetic agents into the environment, resulting in less pollution. All gases delivered from the anesthesia machines are lost to the atmosphere. Halothane, Enflurane, Isoflurane contain chlorine. They are believed to have significant Ozone (O3) depletion potential.
-Relatively stable hemodynamic conditions during the process of surgery with closed-circuit anesthesia.
-Low expense.

Disadvantages of low flow anesthesia:
-Accidental hypoxia
-Hypercapnia
-Inadequate depth of anesthesia (Difficulty in changing the inspired anesthetic concentration rapidly due to the limited dial settings).
-Accumulation of potentially toxic trace gases
*Carbon monoxide accumulation: CO production comes from the contact of anesthetics with dry soda lime and gradual accumulation is due to difficult elimination under low flow. However, this is of no risk to the patient
*Accumulation of compound A: Compound A is derived from the contact of sevoflurane with soda lime. However, the highest value lies within the range determined to cause histological renal tubular damage in rats.
*Accumulation of methane
*Accumulation of acetone



Labels

Labels:

Comments

Post a Comment

Popular posts from this blog

Driving Pressure in ARDS: A new concept!

Driving Pressure and Survival in the Acute Respiratory Distress Syndrome Marcelo B.P. Amato, M.D., Maureen O. Meade, M.D., Arthur S. Slutsky, M.D., Laurent Brochard, M.D., Eduardo L.V. Costa, M.D., David A. Schoenfeld, Ph.D., Thomas E. Stewart, M.D., Matthias Briel, M.D., Daniel Talmor, M.D., M.P.H., Alain Mercat, M.D., Jean-Christophe M. Richard, M.D., Carlos R.R. Carvalho, M.D., and Roy G. Brower, M.D. N Engl J Med 2015; 372:747-755 February 19, 2015 DOI: 10.1056/NEJMsa1410639 BACKGROUND Mechanical-ventilation strategies that use lower end-inspiratory (plateau) airway pressures, lower tidal volumes (V T ), and higher positive end-expiratory pressures (PEEPs) can improve survival in patients with the acute respiratory distress syndrome (ARDS), but the relative importance of each of these components is uncertain. Because respiratory-system compliance (C RS ) is strongly related to the volume of aerated remaining functional lung during disease (termed functional lung size)...
5 comments
Read more

Anaphylaxis updates part 2- Empty Ventricle Syndrome

Patients with anaphylaxis should not suddenly sit, stand, or be placed in the upright position. Instead, they should be placed on the back with their lower extremities elevated or, if they are experiencing respiratory distress or vomiting, they should be placed in a position of comfort with their lower extremities elevated. This accomplishes 2 therapeutic goals: 1) preservation of fluid in the circulation (the central vascular compartment), an important step in managing distributive shock; and 2) prevention of the empty vena cava/empty ventricle syndrome, which can occur within seconds when patients with anaphylaxis suddenly assume or are placed in an upright position. Patients with this syndrome are at high risk for sudden death. They are unlikely to respond to epinephrine regardless of route of administration, because it does not reach the heart and therefore cannot be circulated throughout the body
Post a Comment
Read more

Epidural catheter tests...not only the test dose

Siphon test The catheter is held upright and a fluid level sought. If the catheter is then elevated, the fluid level should fall (see inset) as the fluid siphons in to the epidural space, which is usually under negative pressure compared with atmospheric. If the fluid column continues to rise, this may suggest subarachnoid placement. The siphon test can be reassuring, but is not mandatory. Aspiration  This should be considered mandatory. The Luer connector is attached to the catheter and a syringe is used to apply negative pressure. Free and continued aspiration of clear fluid can indicate subarachnoid placement of the catheter. However, if saline has been used for loss of resistance, it is not unusual for a small amount of this to be aspirated. If there is doubt, the aspirated fluid can be tested for glucose (cerebrospinal fluid will generally test positive) or mixed with thiopentone (cerebrospinal fluid forms a precipitate). If blood is freely and continuously aspirated, this sug...
Post a Comment
Read more