Anesthesia Student Survival Guide.pdf - Index of

332 ● AnesthesiA student survivAl Guide
compromise on induction. Blood loss in a patient with gastrointestinal (GI)
bleeding may cause significant hypovolemia. Bleeding in the GI tract also
increases the risk of aspiration.
Loss of different fluids from the GI system is associated with loss of various
electrolytes. For example, loss of stomach secretions either through vomiting or
gastric suction is usually associated with decreased H + and Cl − ions leading to
hypokalemic, hypochloremic metabolic alkalosis. Elective colon surgery with
a bowel prep also can cause electrolyte and fluid imbalance. Consider checking
patient electrolytes and hematocrit prior to major abdominal surgeries.
Finally, a patient’s underlying disease should also be considered for each
procedure. For example, splenectomy for sickle cell disease has different considerations
than splenectomy for Idiopathic Thrombocytopenic Purpura (ITP).
Intraoperative Considerations
laparoscopic surgery
Laparoscopic surgery is frequently performed for esophageal fundoplication,
Heller’s myotomy, cholecystectomy, hernia surgery, bariatric surgery, and some
bowel surgeries. Prior to insufflations, a nasogastric or orogastric tube is placed
to decompress stomach, and a Foley catheter to decompress the bladder.
The respiratory system can be affected in laparoscopic surgery by different
mechanisms. Effects of pneumoperitoneum (insufflation of the peritoneum
by CO 2 ) include intraabdominal pressure increase, systemic CO 2 absorption,
increased end-tidal CO 2 , cephalad displacement and impaired movement of
the diaphragm, decreased FRC and pulmonary compliance, increased PIPs
(peak inspiratory pressures), and ventilatory requirements. Retroperitoneal
dissection of CO 2 may cause a pneumothorax. The effects of Trendelenberg or
reverse-Trendelenberg positions needed during the procedure should also be
considered. Airway pressures including plateau and peak airway pressure may
also change.
Effects on cardiovascular system include increases in systemic vascular
resistance due to increased sympathetic output from CO 2 absorption, and
a neuroendocrine response to pneumoperitoneum. The cardiopulmonary
effects of pneumoperitoneum are proportional to the magnitude of intraabdominal
pressure during laparoscopy with significant changes occurring
at pressures greater than 12 mmHg. Decreased venous return and bradycardia
(due to profound vasovagal reaction) may occur with pneumoperitoneum.
Vascular injection of CO 2 can cause air embolism, hypotension,