It’s high time for intra-abdominal hypertension guidelines in pregnancy after more than 100 years of measuring pressures

Sir,

The questions raised by Garg & Tyagi¹ illustrate a fundamental challenge related to the limitations and heterogeneity of published original research on intra-abdominal pressure (IAP) in pregnancy. We sought to coalesce data into clinically meaningful recommendations for the diagnosis and management of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) in pregnancy.² We defined IAH as pre-delivery IAP ≥14 mm Hg or postpartum IAP ≥12 mm Hg. These cutoffs are supported by Tyagi et al³, who performed the only known study of IAP in critically ill obstetric patients. Each patient with IAH was pregnant when diagnosed and had an IAP ≥14 mm Hg. Postpartum, IAP decreased to <12 mm Hg in four patients, but persisted ≥12 mm Hg despite delivery in two women who died. Our definitions would have captured all IAH patients in the Tyagi study, while excluding patients with phys iologic IAP elevations.

Tyagi et al found IAP had no impact on organ function or mortality.³ The median sequential organ failure assessment (SOFA) cardiovascular, renal and hepatic sub-scores were zero. Higher neurologic sub-scores contributed most to organ dysfunction, but these may be susceptible to false calculation (such as when seda tives were used). Therefore, this case mix may not be comparable to previous data obtained in critically ill patients.⁴ Furthermore, it is unclear how many patients required mechanical ventilation for >24 hours, vasopressor/inotrope support or renal replacement therapy, nor were Acute Physiology and Chronic Health (APACHE)-II or APACHE-III scores or Simplified Acute Physiology Score (SAPS)-II or SAPS-III provided. Nevertheless, the authors deserve congratulations for this study in obstetric patients. The data are reassuring in that positive fluid balance was associated with poor outcome. While generalizations are impossible, notable findings include: (1) IAP on intensive care unit (ICU) admission was higher among pregnant than non-pregnant patients (13.3 ± 2.2 vs 8.1 ± 1.5, P < 0.001), and (2) total SOFA score was higher among non-survivors than survivors (11.3 ± 3.7 vs 5.7 ± 3.4, P < 0.001). These findings suggest that pregnant patients with high IAP may indeed have organ dysfunction.

We suggest clinicians consider left uterine displacement effect on IAP while recommending measurements be performed in the supine position. This is consistent both with guidelines from the World Society of the Abdominal Compartment Syndrome (WSACS)⁵ and with the Tyagi study methods.³

Most data on IAP in pregnancy come from patients undergoing elective cesarean delivery under spinal anesthesia. The anesthetic effects cause increased abdominal wall compliance and lower IAP. Despite this, mean IAP values in most studies (Table 1) are similar to those in unanesthetized, critically ill obstetric patients.³ As ICU patients are unlikely to have neuraxial anesthesia, our proposed definitions are appropriately calibrated.

TABLE 1.

Intra-abdominal pressure measurements of obstetric patients

Author	n	Gestation (wk)	Patient position	IAP (mm Hg) mean ± SD	Transducer position	Delivery characteristics	Comments
Pre-delivery measurements
Paramore, 1913	23	6 mo-term	Supine; left side; knee chest; standing	15–44			Rectal manometer
Al-Khan, 2011	100	36–41	Leftward tilt	22 ± 2.9	Not specified	Elective CD	50-mL saline injection
Chun, 2012	20	38–40	Supinel0° leftward tilt	10.8 ± 4.7 8.9 ± 4.9	MAL at iliac crest	Elective CD; spinal	25-mL saline injection
Fuchs, 2013	70	38.1	Supine, end-expiration	14.2a	Pubic symphysis	Elective CD; spinal	25-mL saline injection
Staelens, 2014	23	39.0	Supine, flat, end-expiration	14.0 ± 2.6	MAL at iliac crest	Elective primary or repeat CD	25-mL saline injection
Tyagi, 20173	8	10–39	Supine, end-expiration	13.2 ± 2.2	MAL	Critical, ICU admission-Vaginal delivery in ICU	20-mL saline injection
Marshalov, 2017	117b	38–39	Supine	17.8 ± 3.6	Pubic symphysis	38 SVD, 79 elective CD	20-mL saline injection
Author	n	Hours Postpartum	Patient position	IAP (mmHg) mean ± SD	Transducer position	Delivery Characteristics	Comments
Post-delivery measurements
Abdel-Razeq, 2010	21	1	Supine	6.4 ± 5.2	Pubic symphysis	Elective CD	25-mL saline injection
Fuchsc, 2013	70	2	Supine, end-expiration	10.7a	Pubic symphysis	Elective CD	25-mL saline injection
Staelensc, 2014	23	1	Supine, flat, end-expiration	9.8 ± 3.0	MAL at iliac crest	Elective primary or repeat CD	25-mL saline injection
Tyagi, 20173	93	Variable	Supine, end-expiration	8.1 ± 1.5	MAL	Critical, ICU admission	IAP measured daily
Marshalovc, 2017	117	1	Supine	9.6 ± 0.89	Pubic symphysis	38 SVD, 79 elective CD	20-mL saline injection

Adapted and reproduced with permission from Lozada et al (Management of peripartum intra-abdominal hypertension and abdominal compartment syndrome. Acta Obstet Gynecol Scand 2019 under Open Access CC BY License 4.0).

Complete list of references available in the original publication.

CD, cesarean delivery; IAP, intra-abdominal pressure; MAL, mid-axillary line; SVD, spontaneous vaginal delivery.

^aStandard deviation not reported.

^bControl group data only presented.

^cSame patient cohort as pre-delivery (above).

The request by Garg & Tyagi for more evidence¹ comes more than 100 years after Paramore first measured IAP in pregnant patients. Even with ongoing research, nothing suggests that practice changing data are imminent. Our proposed recommendations are a framework upon which future updates can build. We welcome in sight from others and encourage collaboration to produce consensus guidelines. This would strengthen our recommendations and benefit patients around the world.