What effects can CO2 pneumoperitoneum have?
chemical and pressure
pulmonary, renal, and CV alterations
need to monitor cardiac rhythm, pulse ox, ETCO2, HR, BP, and UOP (esp in first 15-20min)
why is CO2 preferred?
- Rapidly absorbed
- Diffusion coefficient is 20x that of 02
- Soluble in blood, easily carried to alveoli for elimination
- Easily eliminated
- Suppresses combustion
- Readily available
- Relatively expensive
what chemical effects are seen in lap?
- Increase arterial CO2 and ETCO2
- Drop in serum pH
- Drop fastest in first 20 minutes, then slowly rises and reaches steady state in next hour
- Higher risk if severe cardiopulmonary disease
Need ETCO2 monitoring
what happens when the diaphragm is pushed cephalad?
-> reduced FRC, increased airway pressure, reduced pulm compliance, and reduced diaphragmatic excursion
___ insufflation rate/pressure is a/w less post op abd and shoulder pain
lower
ways to prevent drops in CO2
Checklist of intraop actions: desufflate, check insufflator settings and function, check for adequate relaxation, check intravascular volume status, look for other causes of hypotension
what’s the most common cardiac arrhythmia?
sinus tach
what may PVCs be secondary to?
effects of CO2 pneumoperitoneum
what causes bradycardia?
vaguely mediated, associated with pressure effects of pneumoperitoneium
if they’re symptomatic, stop insufflation and allow gas to escape
what might IVC resistance lead to?
Reduced lower extremity venous flow rate 2/2 pressure effects of pneumoperitoneum
Venous flow rates drop 26-39%
Risk for VT, but risk < 0.5% in most laparoscopic surgery
Stratify patient risk for prevention strategy
what is common in lap surgery with kidney function?
**intraop oliguria
- decreased filtration
- release of renin and SDH caused sodium and free water absorption (increased intraabdominal pressure decreases renal blood flow)
post oliguria usually resolves in a few hours
signs of gas embolus
Less than 1% of cases
Sudden cardiovascular collapse -> hypotension, tachycardia, JVD, millwheel murmur
STOP Insufflation, evacuate pneumoperitoneum, position LL decubitus position, Trendelenburg position (to prevent embolus from entering RVOT), place CVC and aspirate/break up embolus in R atrium
what are three alternatives to CO2?
- NO
Benefits: Less acid base disturbance, increased ability to tolerate pneumoperitoneum without GETA, less post op pain
Risks: Fire hazard, supports combustion (hydrogen or methane in case of bowel perforation) - Air
- Helium and argon
Benefits: eliminate complications of hypercarbia and acidosis
Risks: Decreased solubility, increased risk of gas embolism; more expensive and insufflators not readily available
