Cardiac effects
The normal physiology of breathing means
that negative pressure draws air into the
chest cavity and the lungs. This negative
pressure also helps in the return of blood to
the heart and is important in maintaining
normal circulation. During artificial
ventilation the air is forced into the lungs
creating a positive pressure in the chest
cavity. This reduces the amount of blood
returning to the heart and for this reason
patients who are ventilated can have
problems with adequate circulation.
During mechanical ventilation this change
in blood circulation is compensated for
partly by the body’s own mechanisms
and also by drugs that are given to the
patient, as well as by careful management
l Understand the range of physical
effects on a patient of discontinuing
mechanical ventilation
l A ppreciate how the cardiac and
respiratory systems are affected
by removing a patient from
mechanical ventilation
l Understand how other body systems
are affected by removing a patient
from mechanical ventilation
l G ain a full understanding of the
range of possible psychological
effects on the patient
Learning objectives