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Introduction to Intra Abdominal Hypertension
Intra-abdominal hypertension (IAH) is a condition characterized by a sustained or repeated pathological elevation in intra-abdominal pressure (IAP) generally equal to or above 12 mmHg. IAH affects 19-45% of patients admitted to the intensive care unit and is associated with organ dysfunction and failure. Early identification and monitoring of IAH plays a key role in management and improving outcomes for critically ill patients. Several devices exist which allow clinicians to accurately measure IAP.
Direct Methods for Measuring IAP
The gold standard method for direct measurement of IAP is via bladder pressure measurement using a foley catheter connected to a pressure transducer and monitor. With the patient lying supine, the foley catheter is clamped and saline instilled into the bladder until the patient feels a desire to void. The transducer is then zeroed at the mid-axillary line and the bladder pressure reading reflects IAP. Direct bladder pressure offers many advantages including repeatability of measurements, no risk of pneumoperitoneum, and correlation with indirect methods. However, it requires placement of a foley catheter which increases risk of infection.
Alternatives to direct bladder pressure measurement include placing an extraperitoneal (pre-peritoneal or pre-vesical) pressure transducer during surgery or by percutaneous technique. This avoids the need for a foley catheter but requires an invasive procedure. Direct measurement via gastro-intestinal tract tubes and drains have also been explored but offer limited clinical application.
Indirect Methods for Assessing IAP
Several indirect methods have been developed that rely on transduction of abdominal wall pressure rather than direct IAP measurement. These include insufflation/capnopressure, ultrasonography, and abdominal perfusion pressure.
Capnoperitoneum involves insufflation of carbon dioxide into the abdominal cavity via a Verres needle until the patient reports abdominal fullness or tenderness. The pressure required to achieve this degree of abdominal distension indirectly reflects IAP. However, capnoperitoneum carries the potential risks of gas embolism, hypercarbia, and respiratory compromise.
Abdominal ultrasound provides a rapid, non-invasive method for estimating elevated IAP by measuring the maximum diameter of the inferior vena cava (IVC). An IVC diameter less than 2 cm correlated with normal Intra Abdominal Pressure while larger diameters reflect elevated IAP. However, accuracy depends on operator skill and abdominal wall thickness/ascites can limit visibility of the IVC.
Abdominal perfusion pressure, calculated as mean arterial pressure minus IAP, provides an important clinical parameter as adequate organ perfusion pressure is critical. This indirect method requires concurrent measurement of arterial blood pressure for calculation.
Commercially Available IAP Measurement Devices
Several commercially available devices aid in accurate, standardized IAP measurement in clinical practice:
– FoleyMAK Pressure Monitoring System (Holtech Medical): Consists of a foley catheter, pressure transducer and monitor. Considered the gold standard for direct IAP monitoring.
– AbViser IAP (ConvaTec): Single-use device inserted through the foley catheter allowing non-invasive IAP readings displayed on the portable monitor. No fluids required.
– IAP-O-MAT (Hicare): Modular system providing direct or indirect IAP via urine output-independent intrabladder or extrabladder balloon transducers.
– Abdo-Pressure (Artech): Disposable transducer placed in the bladder or extraperitoneally, connected to the Artech monitor for continuous IAP monitoring.
– Grip IAP (Biomedica): Portable device utilizing proprietary technology to indirectly measure IAP through the abdominal wall.
– SoloSure (Noble): Indwelling foley catheter with integrated pressure port for continuous direct monitoring of IAP via any standard pressure line and monitor.
These advanced devices automate the process, standardize measurements and reduce human error, providing vital IAP data to guide clinical management of critically ill patients with IAH/ACS. Multicenter trials continue to validate additional novel devices.
Conclusion
Intra-abdominal hypertension is an under-recognized clinical condition that significantly impacts outcomes of critically ill patients. Accurate, reliable intra-abdominal pressure measurement allows early identification and risk stratification allowing timely therapeutic intervention. While direct bladder pressure remains the gold standard, recent technological advances have produced sophisticated commercial devices facilitating standardized monitoring of IAP either directly or indirectly in clinical practice. This overview discussed current guidelines and various measurement methodologies that clinicians can utilize for improved management of patients with IAH/ACS.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile
