This protocol details the use of a set of intra-abdominal pressure monitoring systems with advantages of convenience, continuous monitoring, digital visualization, and long-term IAP recording and data storage in neurocritical patients to detect intra-abdominal hypertension, which is used for correlation analysis to guide treatment and predict prognoses.
Intra-abdominal pressure (IAP) is increasingly being recognized as an indispensable and significant physiological parameter in intensive care units (ICU). IAP has been measured in a variety of ways with the development of many techniques in recent years. The level of intra-abdominal pressure under normal conditions is generally equal to or less than 12 mmHg. Accordingly, abdominal hypertension (IAH) is defined as two consecutive IAP measurements higher than 12 mmHg within 4-6 h. When IAH deteriorates further with IAP higher than 20 mmHg along with organ dysfunction and/or failure, this clinical manifestation can be diagnosed as abdominal compartment syndrome (ACS). IAH and ACS are associated with gastrointestinal ischemia, acute renal failure, and lung injury, leading to severe morbidity and mortality. Elevated IAP and IAH may affect the cerebral venous return and outflow of the cerebrospinal fluid by increasing the intrathoracic pressure (ITP), ultimately leading to increased intracranial pressure (ICP). Therefore, it is essential to monitor IAP in critically ill patients. The reproducibility and accuracy of intra-bladder pressure (IBP) measurements in previous studies need to be further improved, although the indirect measurement of IAP is now a widely used technique. To address these limitations, we recently used a set of IAP monitoring systems with advantages of convenience, continuous monitoring, digital visualization, and long-term IAP recording and data storage in critically ill patients. This IAP monitoring system can detect intra-abdominal hypertension and potentially analyze clinical status in real time. The recorded IAP data and other physiological indicators, such as intracranial pressure, can be further used for correlation analysis to guide treatment and predict a patient's possible prognosis.
The pressure in the abdominal cavity is known as the intra-abdominal pressure (IAP). Accordingly, abdominal hypertension (IAH) is defined as two consecutive IAP measurements higher than 12 mmHg within 4-6 h1. When IAH deteriorates further, with IAP higher than 20 mmHg and organ dysfunction or failure, the clinical manifestation can be diagnosed as abdominal compartment syndrome (ACS). IAH and ACS are associated with gastrointestinal ischemia, acute renal failure, and lung injury, leading to severe morbidity and mortality1,2,3,4. Increased IAP can also lead to diaphragmatic elevation, which increases intrathoracic pressure to reduce pulmonary compliance and increases central venous pressure5,6. Cerebral venous return in the jugular system and outflow of the cerebrospinal fluid may be disturbed by excessive intra-thoracic pressure7,8, leading to intracranial congestion and intracranial hypertension, which can further cause brain dysfunction and affect the prognosis9,10,11,12,13,14. Another theoretical approach is that increased IAP will cause the blood from the sacral venous plexus and vertebral veins to return to the spinal canal, thereby causing intraspinal vein congestion and eventually venous blood flowing into the brain, leading to an increased intracranial pressure8. Currently, IAP is measured by both direct and indirect methods15,16,17,18. The intermittent recording of intra-bladder pressure using an indwelling bladder catheter is the most common and widely accepted method19,20,21,22. This convenient and quick method still relies on the periodical pressure measurements and is usually labor-intensive and time-consuming23.
To solve these difficulties, we have recently adopted a set of IAP monitoring systems with advantages of convenience, continuous monitoring, digital visualization for IAP measurement, and long-term IAP data recording and storage for neurocritical patients. The system is developed for the bladder pressure measurement, and its built-in pressure sensor measures the fluid pressure in the urinary catheter to obtain intra-abdominal pressure. This IAP monitoring system can be used to confirm intra-abdominal hypertension, to analyze the current clinical status, and to predict the possible prognosis of neurosurgical ICU patients. Compared with previous intra-abdominal pressure measurements, this intra-abdominal pressure monitoring system has certain advantages: the system is portable and easy to use; IAP data can be collected and stored in real-time every minute; multiple parameters (i.e., IAP, urinary output, and urinary flow rate) can be measured, recorded, and visualized; and the monitoring is long-term, continuous, and less susceptible to urinary tract infections than previous methods.
Therefore, the purpose of this paper is to present a detailed approach of using digitalized monitoring systems to record IAP for patients with severe traumatic brain injury (TBI) or intracranial hemorrhage (ICH).
This brief article's primary purpose is to introduce continuous monitoring and data storage systems for critical patients in the neurosurgical (ICU). This system can digitally and continuously monitor IAP, thereby providing the possibility of a wider time window of data storage, review, and analysis. The variation of the IAP, especially the IAP increment, always indicates the change of physical status of intra-abdominal organs, such as acute gastrointestinal injury under neurocritical circumstances. Further, the increased IAP may consequently influence intra-thoracal pressure. The affected central venous pressure positively impacts the intracranial status, such as intracranial pressure11,12. The abdominal perfusion pressure evaluation, which is related closely to the cerebral perfusion pressure, provides a convenient method to manage cerebral blood supply if appropriately applied10,13. For the reasons above, detection of intra-abdominal hypertension exhibits the potential to analyze the current clinical status, and, hopefully, predicts the patients' prognosis in the neurosurgical ICU.
Over the last three decades, IAP's concerns have been rediscovered, better articulated and have achieved numerous clinical significance11,24,25. The ideal IAP measurement method was tried over 150 years ago and has since evolved into direct and indirect measurement methods. The former is measured surgically by placing a Veress needle or intraperitoneal catheters in the abdominal cavity and connecting it to pressure transducers26,27,28. The latter measures the pressure in the abdominal organs, including the stomach, bladder, uterus, and rectum29,30,31. Among them, intra-bladder pressure (IBP) is the most accepted IAP measurement method by researchers because it is practical, feasible, and non-invasive features20,21,32. It can be obtained by connecting a catheter to a three-way tube and injecting 25 mL of sterile normal saline into the catheter lumen2. The physician used the above method routinely to measure the intra-abdominal pressure of patients in the neurological ICU. However, a great deal of time and effort is wasted on data with limited timeliness because it cannot be continuously monitored and recorded. The IAP monitoring system resolves the problem of intermittent bladder pressure measurement. However, all parts need to be connected correctly and zeroed correctly according to the above protocol. Otherwise, the incorrectly measured IAP will affect the diagnosis and treatment of the disease state. The IAP monitoring system has been monitored in 8 patients with critical neurological conditions. Although no system failures or errors have been reported, we recommend seeking the assistance of the system maintenance engineer in the event of a problem. Moreover, some minor defects need to be further resolved, such as the 2,000 mL maximum volume of the urine collection bag and one week validity of the pressure transducers.
In brief, the measuring system introduced in the manuscript demonstrates the advantages of accurate data measurement, long-term monitoring, data digitalization, storage, and visualization. Also, the autonomic operation, after properly applied, solves the labor burden in ICU settings. The intra-abdominal pressure monitoring system may become a routine procedure in neurointensive care units in the future, but further clinical evaluation on the relationship of IAP with clinical manifestation is needed.
The authors have nothing to disclose.
We want to thank all the colleagues in the Neurological Intensive Care Unit for their work.
Disposable pressure sensors | Beijing wanshengrenhe keji limited company | 20162070092 | The disposable pressure sensor is used together with the urodynamic monitoring instrument to collect the bladder pressure during and after the treatment of patients with indwelling urethral catheterization. |
Intra-abdominal pressure and urine volume data management software | Beijing wanshengrenhe keji limited company | NA | The data transmitted by urodynamic monitor are received through wireless network, recorded and stored in real time, and the data are exported for researchers to use for analysis. |
Urodynamic monitor | Beijing wanshengrenhe keji limited company | 20162070079 | Urine power monitor is mainly used for patients with indwelling catheter urinary control, dynamic monitoring and urine drainage monitoring urine storage period inside bladder pressure, rectal, urine flow rate (reflecting the urine bladder pressure), urine, and according to the monitoring parameter control micturition, realization of resistance to the flow resistance to overflow the urine of personalized bionics urine drainage, assisted the doctor in clinical diagnosis. |
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