Most common gas used for pneumoperitoneum
**Core Concept**
Carbon dioxide (CO2) is a colorless, odorless gas that is commonly used for pneumoperitoneum in laparoscopic surgery due to its low solubility in blood and rapid absorption from the peritoneal cavity, which allows for a quick return to normal physiological conditions post-operatively.
**Why the Correct Answer is Right**
The use of CO2 for pneumoperitoneum is favored because it does not support combustion, is inexpensive, and can be absorbed quickly from the peritoneal cavity, thus reducing post-operative complications. The absorption of CO2 is mediated by the buffering action of bicarbonate ions in the blood, which forms carbonic acid, which is then broken down into water and CO2, which is exhaled by the lungs.
**Why Each Wrong Option is Incorrect**
* **Option A:** Nitrous oxide (N2O) is a potent anesthetic gas and can cause expansion of air-filled spaces in the body, such as the bowel, which can lead to complications during laparoscopic surgery.
* **Option B:** Oxygen (O2) is not used for pneumoperitoneum because it can support combustion and may also cause expansion of air-filled spaces in the body.
* **Option D:** Helium (He) is not used for pneumoperitoneum because it is expensive and does not support combustion, but it also has a low density, which makes it difficult to achieve a stable pneumoperitoneum.
**Clinical Pearl / High-Yield Fact**
It is essential to note that the use of CO2 for pneumoperitoneum requires careful monitoring of end-tidal CO2 levels and ventilation to prevent hypercarbia and respiratory acidosis.
**Correct Answer: C. Carbon dioxide**