Case of the Month #22 - intra-abdominal hypertension

The decision to treat IAH should be taken after considering a combination of – (a) the overall pressure and (b) it’s impact that pressure is having on the patient. Based on this, management of IAH should involve three key questions:

1. Is an intervention required?
   • The decision to intervene in a case of IAH will be guided by the degree of resultant organ dysfunction. Patients with higher pressures but improving organ function may not require intervention initially, and especially so if these interventions carry risks themselves (for example, sedation requiring intubation or decompressive laparotomy). However, if IAP is elevated or rising and impacting organ function, intervention will be required.
2. How urgent is the intervention?
   • The urgency of the intervention will be determined by the IAP, the rate of pressure increase and its effects on organ function. Slowly rising pressures allow time for more delayed interventions, while precipitous rises in pressure with organ dysfunction will require urgent intervention – this can rapidly become life threatening should ACS develop. Stepwise management should be instituted, although immediate decompression may be indicated in the event of refractory cardiovascular or respiratory failure³.
3. What is the most appropriate intervention?
   • The best intervention will be determined by the cause. A multi-modal approach may be favourable to a single intervention in isolation. IAP should be measured every four-six hours³ and excessive fluid administration³ should be avoided.  IAP should be targeted to <15 mmHg¹. Management strategies can be divided into:
     • Intra-luminal volume reduction – Evacuation of gut contents, through the use of prokinetics & enemas. Although nasogastric tubes and rectal tubes may be beneficial, these will only decompress the most proximal and distal aspects of the gastrointestinal tracts.
     • Extra-luminal volume reduction – May be amenable to percutaneous drainage as a temporising measure while other treatments take effect.
     • Abdominal wall compliance improvement – Depends on the cause – Prone patients can be supinated if clinical condition allows, while burn patients with IAH may be amenable to escharotomy to reduce the abdominal constriction. Sedation and muscle relaxation may be required to reduce muscular tone in the abdomen and thus increase compliance.
     • Optimise fluid therapy and organ perfusion – Goal directed fluid therapy and monitoring¹ to target an APP >60 mmHg².
     • Decompressive laparotomy – A definitive treatment for ACS³, which has considerable morbidity so should be reserved for cases of treatment failure. When performed, it may result in an extensive reperfusion syndrome. Close monitoring of IAPs should occur post-operatively to monitor for recurrence of ACS.