ANAESTHESIA IN LAPAROSCOPIC SURGERY
Pathophysiologic changes
( Respiratory system, Cardiovascular system and Hypothermia
)
Respiratory system
Ventilatory changes due to
Pneumoperitoneum,
Co2 is absorbed via portal and systemic veins and excreted via lungs.
Surprisingly the level does not go very high due to impaired absorption
from peritoneum due to haemodynamic changes and acid buffers in the
blood.
Position of the patient
Raised intra abdominal pressure + Trendelenburgs position + Cephalad
shift of carina dislodges the endotracheal tube leading to one lung
anaesthesia and hypoxia.
Reverse Trendelenburg helps respiratory function.
Influence of anaesthesia
Pa Co2 is unaltered in local and regional anaesthesia.
GA has ventilatory depressant effect.
Cardiovascular changes
Has dual problem :
Hypercarbia causes sympathetic stimulation causing tachycardia, increase
in BP and arrythmias
Increased intra abdominal pressure reduces cardiac output upto 50%.
Position of the patient
Head down increases venous return, but arterial pressure does not change
much due to reflex vasodilatation and bradycardia. Head down up to 15
digree in safe.
Head up causes pooling of blood & DVT and Pulmonary embolism. It
is aggravated by lithotomy and pneumoperitoneum.
Effect of raised intra abdominal pressure
Decreases blood flow to all organs, Intestines and Kidneys, leading
to ileus and reduced GFR.
Coronary flow is unaffected.
Hypothermia
Every 50 litres of Co2 decreases the temp by .3 digree C. Warming of
Co2 to 30 digrees is recommended for prolonged laparoscopic surgery.