VENTILATORY AND RESPIRATORY CHANGES DURING LAPAROSCOPY
Intraperitoneal insufflation of carbon dioxide (CO2
),
the currently routine technique to create pneumoperitoneum for laparoscopy, results
in ventilatory and respiratory changes and can cause four principal respiratory complications:
CO2
subcutaneous emphysema, pneumothorax, endobronchial intubation, and
gas embolism.[4]
Ventilatory Changes
Pneumoperitoneum decreases thoracopulmonary compliance. Compliance
is reduced by 30% to 50% in healthy,[5]
[6]
[7]
[8]
[9]
[10]
obese,[11]
[12]
[13]
and American
Society of Anesthesiologists (ASA) class III or IV patients, but the shape of the
pressure-volume loop does not change ( Fig.
57-1
). After the pneumoperitoneum is created and kept constant, compliance
is not affected by subsequent patient tilting[14]
or by increasing
Figure 57-1
Change in total respiratory compliance during pneumoperitoneum
for laparoscopic cholecystectomy. The intra-abdominal pressure was 14 mm Hg, and
the head-up tilt was 10 degrees. The airway pressure (Paw) versus volume (V) curves
and data were obtained from the screen of a Datex Ultima monitoring device. Curves
are generated for before insufflation (A) and 30 minutes after insufflation (B).
Values are given for tidal volume (TV, in mL); peak airway pressure (Ppeak, in cm
H2
O); plateau airway pressure (Pplat, in cm H2
O); total respiratory
compliance (C, in mL/cm H2
O); and end-tidal carbon dioxide tension (PETCO2
,
in mm Hg).
the minute ventilation required to avoid intraoperative hypercapnia. Reduction in
functional residual capacity due to elevation of the diaphragm[15]
and changes in the distribution of pulmonary ventilation and perfusion from increased
airway pressure can be expected. However, increasing IAP to 14 mm Hg with the patient
in a 10- to 20-degree head-up or head-down position does not significantly modify
physiologic dead space or shunt in patients without cardiovascular problems.[16]
[17]
[18]
