Intraabdominal Pressure as a Prognostic Marker in Patients scheduled for Cesarean Section: A Prospective Cohort

1. There is limited data evaluating role of intraabdominal pressure (IAP), especially after delivery of fetus, for determining outcome of pregnant patients. This is despite IAPs to be increased to the range conventionally defined for IAH i.e. ≥ 12 mmHg in previous evidence.
2. No studies estimating or evaluating abdominal compliance in these patients (pregnant) with IAP. Measuring abdominal compliance/its relationship with IAP in parturients may help in triage of these patients for postoperative care and type of interventions required in postoperative period.

**Aim:**To evaluate the normalization of IAP to <12 mmHg as well as change in IAP after fetal delivery following cesarean section, as prognostic markers for predicting in-hospital mortality, need of admission to ICU, and length of stay therein.

Also, the intraabdominal volume and abdominal compliance in these patients will be estimated, and then assessed for correlation with the IAP.

Inclusion Criteria:

All pregnant patients with period of gestation of >32 weeks and posted for cesarean section including those with complicated pregnancies will be enrolled. The usual complications of pregnancy likely to be encountered will include preeclampsia, maternal haemorrhage, gestational diabetes, multiple gestation or previous cesarean section.

Exclusion Criteria:

Those in labour, with pre-existing organ dysfunction or failure not related to pregnancy, or any contraindication to intravesical pressure measurement such as bladder surgery, haematuria, neurogenic bladder etc. will be excluded from the study.

**Methodology:**IAP measurement technique

Foley bladder catheter will be inserted under all aseptic precautions if not already in situ. The bladder catheterisation is an essential requirement for cesarean section as well.

The IAP will be measured using the recommended intravesical technique via the indwelling Foley catheter with a manometer connected to the it. The manometer will be zeroed at the level of mid-axillary line, at the iliac crest for all IAP measurements. The pressure will be measured after injecting 25 ml of saline into bladder, at end-expiration, without any active abdominal contractions. For checking that the pressure signal is correctly transduced, gentle compressions of the abdomen and respiration will be seen to cause oscillations in the manometer saline column. The observed height of column in the manometer will be expressed as cmH2O pressure and converted to mmHg.

The IAP will be measured (a) just prior to administration of spinal block/general anesthesia (IAPantepartum); and then (b) after completion of surgery (but prior to reversing muscle relaxation in patients administered general anesthesia) (IAPpostpartum).

The IAPwill be measured with patient in supine position.

Intraabdominal Volume and Abdominal Compliance estimation

We will estimate the intraabdominal volume by calculating the AVI (in litres). AVI is calculated by a previously validated formula: The AVI will be calculated at the time of measurement of IAPantepartumas well as IAPpostpartumby measuring the waist and hip circumference in at these times. Compliance will be calculated as change in AVI/change in IAP at antepartum and postpartum times.

Anesthetic management

The anaesthetic management, whether neuraxial block or general anesthesia, will be standardized as per routine practice.

Sample Size:

Taking into consideration the mortality of 100% associated with lack of normalization of postpartum IAP in a previous study, to detect a 20% decrease 27 patients with and without failure of postpartum IAP normalization will be required. Since only 33% patients had evidence of failure of IAP normalization in the previous data,to get 27 such subjects, total of 81 would have to be enrolled. Thus enrollement will continue till 27 patients each with and without normalization of IAP or a minimum of 81 patients overall are enrolled (depending on time constraints of the thesis).

Statistical Analysis:

Statistical tests will be applied using the SPSS software. A P-value < 0.05 will be considered significant. The correlation between incidence of normalization of postpartum IAP/∆IAP and outcome measures; or intraabdominal volume/compliance with IAP, will be analysed using correlation test or Receiver Operating Characteristic (ROC) analysis with corresponding area under the curve as appropriate. Correlation of hypotension with IAP will also be assessed using ROC analysis. Qualitative data will be represented as percentage and quantitative data will be reported as mean Â±SD for normally distribution data, or median [IQR] for non-normally distributed data.