intra-abdominal pressure – All Sensors

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities, and you.

Pressure and Laparoscopic Surgery Part 1

Getting room to operate with pressure

Laparoscopic surgery provides an alternative to more extensive open surgical procedures. Its benefits include reduced postoperative pain, reduced scarring and shorter hospital stays. Accessed by incisions through the stomach (abdominal wall), several procedures including appendectomies are routinely performed using laparoscopic surgery. Having adequate space to repair or remove the affected area is achieved by pumping (or insufflating) a gas, usually carbon dioxide (CO₂), into the abdominal (or peritoneal) cavity to create a pneumoperitoneum (abnormal space).

Laparoscopic surgery showing a three-way valve in the gas line (arrow), gas return line (top right) scope (at navel) and operating device.
Source: SemanticsScholar.org

Pressure inside the abdominal compartment, the intra-abdominal pressure (IAP), is normally 0 to 5 mmHg but it can increase to 5 to 7 mmHg during a critical illness. For laparoscopic surgery, carbon dioxide is insufflated into the peritoneal cavity at a rate of 4–6 liter/min to a pressure usually between 12 and 15 mmHg but sometimes the range increases to between 10 to 20 mmHg. To keep this pressure steady, the pneumoperitoneum is maintained by a constant gas flow of 200–400 ml/min.

A high IAP is associated with postoperative problems, so researchers are investigating different techniques to provide alternative lower pressure recommendations for adequate work space instead of using the current, predetermined levels. One study found that the different approaches they tried resulted in an acceptable workspace at 8 mmHg IAP in 61 out of 78 patients.

For other pressures involved in laparoscopic surgery see Pressure and Laparoscopic Surgery Part 2.

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Body Pressures

Common body pressure measurements include blood pressure (80/120-mm (300 mm Hg, max)), respiratory pressure (4 kPa) and intraocular pressure for glaucoma testing (15 mm Hg). However, there are several other pressure measurements made at different body locations, most are made for diagnostic purposes. These include:

intra-bladder pressure (IBP) 12.3 ± 4.5 mmHg depending on body position to about 22 mmHg.
intragastric pressure, (IGP) 15.5 ± 3.5 mmHg vs 18.0 ± 8.7 mmHg
intra-abdominal pressure (IAP) typically less than 12 mmHg
anorectal manometry (ARM) 49 ± 3 mmHg resting to 238 ± 38 mmHg maximum squeeze range
vacuum (negative pressure) for an electric breast pump 0-270 mmHg

Similar to blood pressure and intraocular pressure, higher than normal readings identify potentially dangerous health situations. For example, an IAP equal to or above 12 mmHg is called Intra-abdominal Hypertension (IAH). Also, an IAP above 20 mmHg with evidence of organ dysfunction/failure defines abdominal compartment syndrome (ACS). Both of these higher than normal readings are known to cause significant morbidity and mortality among critically ill patients.

For healthy subjects, anal pressure is highly reproducible on separate days. ARM measurements in resting mode vary from 49 ± 3 to 58 ± 3 mmHg in women and from 49 ± 3 to 66 ± 6 mmHg in men. In contrast, maximum pressures range from 90 ± 9 to 159 ± 45 mm Hg in women and from 218 ± 18 to 238 ± 38 in men.

Oral to anal pressures vary depending on the location of the muscle cross sectional area (MCSA).
Source: Physiology of the Gastrointestinal Tract .

Depending on the location, a significantly lower pressure can be a problem, too. For most people, blood pressure in the foot is similar to the blood pressure in the arm. A pressure drop of as little as 10% can indicate peripheral artery disease (PAD).

Not all pressures are positive measurements or made for diagnostic purposes. For example, an electric breast pump uses a vacuum (negative pressure) as high as 270 mmHg to collect milk for newborns.

For all of these body pressure measurements, highly accurate microelectromechanical systems (MEMS) pressure sensors can provide an essential tool for optimum healthcare.

Comments/Questions?
Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
Email us at [email protected]