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What's New in ACS Surgery
Pulmonary Insufficiency

from ACS Surgery: Principles & Practice
Posted 08/04/2003

Robert H. Bartlett, MD, FACS, Preston B. Rich, MD
Tell Patients to Shape Up Before Elective Operations

Describes the preoperative testing of pulmonary function, preoperative
and postoperative measures to prevent pulmonary insufficiency, and
intraoperative measures to prevent pulmonary complications; also
described is the clinical presentation of postoperative pulmonary
insufficiency, the treatment of postoperative pulmonary insufficiency
caused by atelectasis or edema, and progression to pneumonia or ARDS.

If a patient is scheduled for an elective operation, as much time as
is necessary should be spent measuring lung function, correcting
abnormalities where present, and changing conditions that may
predispose to pulmonary complications. This is particularly true in
patients with preexisting cardiopulmonary disease. Patients should be
advised to train for a major operation as they would for an athletic
event. The respiratory muscles should be exercised and specific
breathing maneuvers learned.

Postoperative Changes in Lung Function

After any major operation, changes occur in lung function. These
changes occur in all patients but are not detected on routine
examination. Aside from shallow tidal ventilation and some decreased
breath sounds at the lung bases, the patient shows no signs of
respiratory abnormality. On direct measurement, lung volumes are
decreased (particularly residual volume, expiratory reserve volume,
functional reserve capacity, and vital capacity). Compliance is
decreased because of the decrease in functional residual capacity
(FRC). The work of breathing is increased for the same reason: more
pressure is required to inhale a given volume into the decreased lung
air space. Further evidence that alveoli are not being ventilated is
absolute or relative arterial hypoxemia, which occurs with the patient
breathing room air or 100% oxygen, indicating that nonventilated
alveoli are being perfused (transpulmonary shunting). These changes in
lung function are present immediately after an operation and progress
slowly over 1 to 2 days. Lung function then returns to normal in most
patients


Robert H. Bartlett, MD, FACS, University of Michigan Medical School,
Preston B. Rich, MD, University of North Carolina School of Medicine

ACS Surgery 2003. © 2003 WebMD Inc.
All rights reserved.

http://www.medscape.com/viewarticle/459359?mpid=17081