Clinical Guidelines (Nursing)

Intra-abdominal Pressure Monitoring

  • Introduction

    Measurement of intra-abdominal pressure is used to identify children at risk of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS).  IAH & ACS are most likely to occur in the setting of major fluid resuscitation, severe gut oedema, intra-peritoneal or retroperitoneal bleeding, or ascites.  Patient groups may include trauma, burns, septic shock, post abdominal surgery.  IAH & ACS can cause significant morbidity and mortality due to reduced venous return and cardiac output, and altered respiratory mechanics. This results in end organ dysfunction; renal failure, impaired hepatic blood flow, respiratory failure, poor splanchnic perfusion and increased intracranial pressure are potential problems. Early recognition and treatment of IAH & ACS has been shown to significantly improve morbidity and mortality.

    Aim

    The aim of this guideline is to outline the management principles related to intra-abdominal pressure monitoring  within the Paediatric Intensive Care Unit at the Royal Children's Hospital.

    Definition of Terms

    Bladder Pressure: reflects the intra-abdominal pressure and is measured via the indwelling urinary catheter. It is expressed in mmHg.

    Intra-abdominal Pressure (IAP): is the pressure within the abdominal cavity. Normal IAP in a well child is 0 mmHg and in a child on positive pressure ventilation is 1 - 8 mmHg.

    Intra-abdominal hypertension (IAH): is defined as an IAP greater than 12mmHg.

    Abdominal compartment syndrome (ACS): is defined as an IAP >20mmHg and the onset of new organ failure.

    Abdominal perfusion pressure (APP): APP = Mean Arterial Pressure (MAP) - IAP. In adults keeping this > 50-60mmHg significantly improves morbidity & mortality. The appropriate APP for children is unknown, but will be less than the adult level due to a lower MAP.

    Risk factors

    • Diminished abdominal wall compliance
      • Major trauma & burns; acute respiratory failure; abdominal surgery
    • Increased intra-luminal contents
      • Gastropareisis; ileus; pseudo obstruction
    • Increased abdominal contents
      • Ascites/liver dysfunction; Haemoperitioneum/pneumoperitoneum;
    • Capillary leak/fluid resuscitation
      • Acidosis (pH<7.2); hypotension; hypothermia(<33); massive fluid resuscitation; poly transfusion; coagulopathy; sepsis, major trauma & burns.

    Management

    • IAP is usually measured indirectly via the patient's bladder.  The changes in intravesical pressure demonstrate an accurate reflection of intra-abdominal pressure (IAP). 
    • Patients with two or more risk factors for IAH should have a baseline IAP performed and if elevated should have continued serial measurements.
    • IAP is measured 4 hourly or more frequently if IAP >12mmHg or the patient is hypotensive, has decreased urine output or a tense abdomen.
    • An increased IAP reading should be rechecked to ensure there is not a technical problem e.g. a blocked catheter.(7)
    • If IAP > 12mmHg then medical management of IAH should be instituted in a timely manner to prevent further morbidity and mortality. Renal impairment can occur with IAP as low as 10-15mmHg. Management will not be discussed in detail in this document but involves improving systemic perfusion, measures to reduce IAP, and in refractory cases early abdominal decompression. Excessive fluid administration should be avoided as it is strongly associated with ACS. The patient will need close clinical monitoring of organ function

    Procedure for Intrabdominal Pressure monitoring

    Equipment required

    • Foley© urine catheter of appropriate size
    • Urine bag for drainage of urine
    • 2 x 3 way tap
    • Connector (leur lock to catheter tip)
    • Pressure transducer and tubing
    • 50ml leur lock syringe
    • 10ml or 30ml leur lock syringe
    • Sterile 0.9% sodium chloride
    • Clamp

    Preparation of monitoring equipment

    1. Perform hand hygiene.
    2. Using an aseptic non-touch technique, prime the transducer set and monitoring lines with 0.9% sodium chloride only.
    3. The tubing must be free of kinks and air bubbles.
    4. Connect catheter to the drainage bag with connector and 3 way taps. (see photo below).
    5. Attach transducer to 3 way tap.
    6. All connections should be securely luer locked.
    7. All transducer monitoring lines should be clearly labeled.
    8. Urine flow into the drainage bag should be uninterrupted except during IAP measurement.
    9. Refer to invasive haemodynamic monitoring guideline for more information.

    intra_abdominal_pressure_pic

    Measurement of Intra-abdominal pressure

    1. Patient should be placed in the supine position for measurement.
      • If this is not clinically feasible it is important to recognise that elevation of the head of the bed will result in a higher IAP.
      • Ensure all subsequent readings are taken in the same position.
      • At end of measurement return all patients to head up/reverse trendelburg position to reduce risk of VAP
    2. Adjust the height of the transducers so that the top of the 3 way tap (atmospheric port) is level with the mid-axillary line at the iliac crest and zero the transducer. 
    3. Clamp the drainage tube to the urine bag
    4. Fill the bladder with 1ml/kg (maximum 25mls) of 0.9% sodium chloride using the syringe.  The volume of fluid in the bladder should be constant for each measurement.
    5. Close the stopcock of the syringe and allow 30-60seconds for equilibrium to occur. Obtain the mean pressure reading upon end expiration (this minimises the effects of pulmonary pressures).
    6. The abdominal blood flow should produce fluctuations in the waveform. Air in the system or kinking of the monitoring lines may dampen the waveform.  Refer to invasive haemodynamic monitoring guideline for more information on waveforms

    Discontinuing monitoring

    • Monitoring of IAP can cease when IAP is < 12 mmHg for several hours and the patient is clinically improving. The patient should continue to receive close clinical observation for deterioration
    • The transducer/monitoring attachments can be disconnected and removed prior to the removal of the patient's urinary catheter.
      • Perform hand hygiene & don gloves
      • Use a clean non-touch technique.
      • Detach the transducer at the 3 way tap.
      • Re-attach the urinary catheter to the drainage bag
      • Discard the transducer in the appropriate waste, remove gloves & wash hands.

    Special Considerations

    • 0.9% Sodium Chloride  should only be used to fill the patient's bladder when undertaking an intra abdominal pressure measurement.
    • The tubing must be free of kinks and air bubbles.
    • All transducer monitoring lines should be clearly labeled
    • Transducer sets  should be changed every 72 hours.
    • All connections should be securely luer locked.
    • All interventions must be carried out using an aseptic technique

    Complications

    Infection of the bladder is a complication of this procedure. Symptoms vary depending on the age of the child but include:

    • Fever
    • Vomiting
    • General malaise
    • Frequency
    • Local pain
    • Dysuria

    Urine culture and sensitivity is the gold standard for diagnosis if an infection is suspected.

    Documentation

    • Document the order for Intra-abdominal pressure monitoring, including frequency on the PICU medical orders MR765/A
    • Document the IAP and APP on the patient's observation chart (MR 100)

    Links

    References

    • Cheatham M, Malbrain M, Kirkpatric A, Sugrue M, Parr M et al (2007). Results from the international conference of experts on intr-aabdominal hypertension and abdominal compartment syndrome. II Recommendations. Intensive Care Medicine. 33:951-962.
    • Davis P, Koottayi S, Taylor A, Butt W. (2005) Comparison of indirect methods of measuring intra-abdominal pressure in children. Intensive Care Medicine. 31:471-475
    • Ejike J, Bahjri K, Mathur M. (2008). What is the normal intra-abdominal pressure in critically ill children and how should we measure it? Critical Care Medicine. 36(7):2157-2162
    • Ejike J, Kadry J, Bahjri K, Mathur M. (2010). Semi recumbent position and body mass percentiles: effects on intra-abdominal pressure measurements in critically ill children.
    • Gallagher JJ (2000) Ask the Experts  Critical Care Nurse, 20, 1 p:87.
    • Iberti TJ, Lieber CE, Benjamin E. (1989) Determination on intra-abdominal pressure using a transurethral bladder catheter: clinical validation of the technique.  Anesthesiology, 70 (1): 47-50
    • LCP Rao, CR Chaudhry, LCS Kumar ( 2006) Abdominal Compartment Pressure Monitoring - a simple techniques. MJAFI,Vol. 62, No. 3.
    • Moore A, Hargest R, Martin M, Delicata R.J, (2004) Intra-abdominal hypertension and the abdominal compartment syndrome.  British Journal of Surgery, 91: 1102-10
    • Ravishankar N, Hunter J (2005) Measurement of Intra-abdominal hypertension in intensive care units in the United Kingdom. British Journal of Anaesthesia Volume 94, Number 6 Pp. 763-766.
    • Sugrue M, Intra-abdominal pressure: time for clinical practice guidelines?.  Intensive Care Med 28: 389-91.
    • Balough Z, Jones B, Amours S, Parr M and Sugrue M Continuous intra-abdominal pressure measurement technique.  The American Journal of Surgery Volume 188(6):679-684

    Evidence Table

    Please remember to read the disclaimer. 

    The development of this clinical guideline was coordinated by Janine Evans, Rosella - PICU. Approved by the Clinical Effectiveness Committee. Authorised by Bernadette Twomey, Executive Director Nursing Services. This updated version published March 2012 (originally published 2007).