Normative postpartum intraabdominal pressure: potential implications in the diagnosis of abdominal compartment syndrome

Maternal posture-physiology interactions in human pregnancy: a narrative review

There are several well-known medical conditions in which posture and gravity interact with natural history, including pregnancy. In this review, we provide a comprehensive overview of interactions between maternal posture and maternal physiology and pathophysiology at rest during pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 644 studies from 1991 through 2021, inclusive, that met our inclusion criteria. We present a narrative review of the resulting literature and highlight discrepancies, research gaps, and potential clinical implications. We organize the results by organ system and, commencing with the neurological system, proceed in our synthesis generally in the craniocaudal direction, concluding with the skin. The circulatory system warranted our greatest and closest consideration-literature concerning the dynamic interplay between physiology (heart rate, stroke volume, cardiac output, blood pressure, and systemic vascular resistance), pathophysiology (e.g., hypertension in pregnancy), and postural changes provide an intricate and fascinating example of the importance of the subject of this review. Other organ systems discussed include respiratory, renal, genitourinary, gastrointestinal, abdominal, and endocrine. In addition to summarizing the existing literature on maternal posture-physiology interactions, we also point out gaps and opportunities for further research and clinical developments in this area. Overall, our review provides both insight into and relevance of maternal posture-physiology interactions vis à vis healthcare's mission to improve health and wellness during pregnancy and beyond.

Effects of intra-abdominal hypertension on maternal-fetal outcomes in term pregnant women: A systematic review

OBJECTIVE

To carry out a systematic review to assess the effects of intra-abdominal hypertension on maternal-fetal outcomes.

METHODS

The search was carried out between 28th June to 4th July 2022 on the Biblioteca Virtual em Saúde, Pubmed, Embase, Web of Science, and Cochrane databases. The study was registered in PROSPERO (CRD42020206526). The systematic review was performed according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. To assess the methodological quality and control the risk of bias, New Castle was used.

RESULTS

A total of 6203 articles were found. Of these, 5 met the selection criteria for a full reading. The selected studies included a total of 271 pregnant women, of which 242 underwent elective cesarean section and measurement of intra-abdominal pressure via a bladder catheter. In both pregnant women groups, the lowest intra-abdominal pressure values were found in the supine position with left lateral tilt. Prepartum values in normotensive women with singleton pregnancy (7.3±1.3 to 14.1 ± 1 mmHg) were lower than in gestational hypertensive disorders (12.0±3.3 to 18.3±2.6 mmHg). In postpartum, the values decreased in both groups but were even lower in normotensive women (3.7±0.8 to 9.9 ± 2.6 mmHg vs 8.5 ± 3.6 to 13.6 ± 3.3 mmHg). The same was true for twin pregnancies. The Sequential Organ Failure Assessment index ranged from 0.6 (0.5) to 0.9 (0.7) in both groups of pregnant women. The placental malondialdehyde levels were statistically (p < 0.05) higher in pregnant women with pre-eclampsia (2.52±1.05) than normotensive (1.42±0.54).

CONCLUSIONS

Prepartum intra-abdominal pressure values in normotensive women were close or equal to intra-abdominal hypertension and compatible with gestational hypertensive disorders even in the postpartum period. IAP values were consistently lower in supine position with lateral tilt in both groups. Significant correlations were found between prematurity, low birth weight, pregnant women with hypertensive disorders, and increased intra-abdominal pressure. However, there was no significant association of dysfunction in any system in the relationship between intra-abdominal pressure and Sequential Organ Failure Assessment. Despite the higher malondialdehyde values in pregnant women with pre-eclampsia, the findings were inconclusive. Given the observed data on maternal and fetal outcomes, it would be recommended that intra-abdominal pressure measurements be standardized and used as a diagnostic tool during pregnancy.

TRIAL REGISTRATION

PROSPERO registration: October 9th, 2020, CRD42020206526.

Intraabdominal pressure and its relation with organ dysfunction in patients scheduled for elective cesarean section: Effect of supine vs left lateral tilt position

INTRODUCTION

Intraabdominal pressure (IAP) is related to clinical outcome of patients. It is measured as intravesical pressure through a Foley catheter in the supine position. During pregnancy, there are data showing elevated IAP and also a suggestion that it may be a false increase due to pressure on the urinary bladder by the gravid uterus in the supine position. Additionally, it is not known whether the elevated IAP during pregnancy is merely a physiological change or is associated with impairment of organ functions. We thus aimed to establish a normal value of IAP in supine (IAP_supine ) as well as 10° left lateral (IAP_lateral-tilt ) positions, and their association with organ functions as well as certain maternal risk characteristics.

MATERIAL AND METHODS

This prospective cross-sectional cohort study included 100 consenting parturients with term gestation posted for elective cesarean section under single-shot subarachnoid block. IAP was measured via an indwelling Foley catheter with a transducer connected to it, as per the recommended technique. Organ dysfunction was defined as Sequential Organ Failure Assessment (SOFA) subscore ≥1 for the particular system.

TRIAL REGISTRATION

ctri.gov.in (CTRI/2017/11/010527).

RESULTS

The IAP_supine was significantly higher than IAP_lateral-tilt (13.8 ± 2.4 vs 12 ± 2.3 mm Hg) (P < .001). The incidence of intraabdominal hypertension as per conventional definition, that is, IAP ≥12 mm Hg, was also higher in the supine position (77% vs 55%) (P < .001). None of the patients had dysfunction of the cardiovascular, renal or central nervous system. The incidence of respiratory, hepatic and hematologic dysfunction was 2%, 15% and 32%, respectively. Receiver operating characteristic analysis showed insignificant association of IAP_supine and IAP_lateral-tilt with various organ dysfunctions (P > .05). There was a significant correlation of intraabdominal hypertension when considering IAP_supine or IAP_lateral-tilt , with obesity (P = .004 and .000, respectively), as well as preeclampsia (P = .006 and .000, respectively).

CONCLUSIONS

In nonlaboring patients undergoing elective cesarean section, IAP is significantly higher in the supine vs 10° left lateral position. In neither position is IAP significantly associated with organ dysfunction. Thus, the usual recommendation of a supine position for measuring IAP to diagnose intraabdominal hypertension, formulated consequent to its pathological effects on organ functions, may not be applicable to pregnant patients and needs urgent validation studies.

Intraabdominal pressure in non-laboring preeclamptic vs normotensive patients undergoing cesarean section: A prospective observational study

INTRODUCTION

It is hypothesized that increased intraabdominal pressure (IAP) may be a cause of preeclampsia. There is, however, a paucity of clinical data regarding IAP in preeclamptics. We evaluated and compared the IAP and its effects on organ functions, in normotensive and preeclamptic patients.

MATERIAL AND METHODS

Previously healthy non-laboring patients with a singleton pregnancy scheduled for elective cesarean section under subarachnoid block were enrolled (preeclamptic and normotensive; n = 29 each). IAP was measured using an indwelling Foley catheter, and compared in both cohorts at four predefined time points: just before subarachnoid block, immediately after the onset of sensory block to T₆ dermatomal level, just after surgery, and 2 hours later. In addition, the presence of organ dysfunction for respiratory, cardiovascular, renal, hepatic, hematopoietic and central nervous systems were evaluated for association with IAP.

RESULTS

Although age, body mass index, gravidity, parity, serum bilirubin, serum creatinine, PaO₂ /FiO₂ ratio and Glasgow coma score of the preeclamptic and normotensive patients were similar, the mean blood pressure was significantly higher (P < 0.001), the period of gestation less (P = 0.003) and the platelet count lower (P = 0.020) in the former. The IAP was significantly higher in the preeclamptic group at all four time points: respectively, 15.1 (1.0) vs 14.2 (0.9) mm Hg (P = 0.002); 14.9 (0.9) vs 14.1 (1.0) mm Hg (P = 0.002), 10.4 (1.0) vs 9.5 (1.3) mm Hg (P = 0.008) and 10.2 (0.8) vs 9.2 (1.2) mm Hg (P = 0.001). There was no correlation between the IAP and various organ dysfunctions.

CONCLUSIONS

Preeclampsia is associated with a significantly higher IAP in patients undergoing a cesarean section. The clinical relevance of this finding needs further investigation.

Management of peripartum intra-abdominal hypertension and abdominal compartment syndrome

Normal pregnancy leads to a state of chronically increased intra-abdominal pressure. Obstetric and non-obstetric conditions may increase intra-abdominal pressure further, causing intra-abdominal hypertension and abdominal compartment syndrome, which leads to maternal organ dysfunction and a compromised fetal state. Limited medical literature exists to guide treatment of pregnant women with these conditions. In this state-of-the-art review, we propose a diagnostic and treatment algorithm for the management of peripartum intra-abdominal hypertension and abdominal compartment syndrome, informed by newly available studies.

The influence of Body Roundness Index on sensorial block level of spinal anaesthesia for elective caesarean section: an observational study

In this prospective trial, we investigate the effectiveness of maternal Body Roundness Index in predicting the spread of spinal anaesthesia and vasopressor requirement in parturients receiving spinal anaesthesia during the elective caesarean section. We prospectively enrolled 175 parturients. Spinal anaesthesia performed with 10 mg 0.5% hyperbaric bupivacaine at the L3-L4 intervertebral space and the optimal cut-off points of the BRI evaluated as 6.59 by receiver operating characteristic analysis calculating area under the curve. Parturients were divided into two groups with BRI <6.59 and BRI ≥6.59 for analyses. Multivariate logistic regression analysis was used to test for a relationship between variables and maximum sensory block level and vasopressor requirement. BRI was found as an independent risk factor associated with maximum sensory block level (OR = 1.378, 95% CI: 1.125-1.687, p = 0.002). Hypotension and bradycardia events after spinal anaesthesia was not associated with BRI and other variables. The present study indicates that BRI was a practical tool to predict spinal drug distribution in term parturients undergoing caesarean delivery.Impact statementWhat is already known on this subject? Spinal anaesthesia is a commonly used anaesthetic technique for the caesarean section. However, the spinal drug distribution is highly unpredictable. Anthropometric variables may predict the intrathecal drug distribution in parturients. Body Roundness Index (BRI) captures body circumference regarding height to predict body fat percentage, consider the shape of the human body as an ellipse. An ellipsoid body shape might affect the spread of spinal anaesthesia.What do the results of this study add? Our results show that the BRI was as an independent risk factor associated with maximum sensory block level in term parturients undergoing caesarean delivery.What are the implications of these findings for future clinical practice and/or further research? A future study would present the possibility to design a formula for the exact amount of local anaesthetic to be used in spinal anaesthesia with the aid of maternal BRI.

Relationship Between Body Mass Index and Spread of Spinal Anesthsia in Pregnant Women: A Randomized Controlled Trial

BACKGROUND The effect of body mass index (BMI) on the spread of spinal anesthesia is not completely clear. The aim of this study was to determine the dose requirements of ropivacaine and the incidence of hypotension in pregnant women with different BMIs during cesarean delivery. MATERIAL AND METHODS In this double-blind study, 405 women undergoing elective cesarean delivery were allocated to group S (BMI <25), group M (25 ≤BMI <30), or group L (BMI ≥30). Women in each group were further assigned to receive 7, 8, 9, 10, 11, 12, 13, 14, or 15 mg of spinal ropivacaine. RESULTS The ED50 and ED95 values of ropivacaine were 9.487 mg and 13.239 mg in Group S, 9.984 mg and 13.737 mg in Group M, and 9.067 mg and 12.819 mg in Group L. There were no significant differences among the 3 groups (p=0.915). Group L had a higher incidence of hypotension and a greater change in MAP after spinal anesthesia compared to the other 2 groups, and also required more doses of ephedrine than the other 2 groups when a dose of 15 mg ropivacaine was used. The incidence of hypotension had a positive correlation with the dose of ropivacaine (OR=1.453, p<0.001) and gestational age (OR=1.894, p<0.001). CONCLUSIONS Spinal ropivacaine dose requirements were similar in the normal BMI range. However, higher doses of spinal ropivacaine were associated with an increased incidence and severity of hypotension in obese patients compared with that in non-obese patients.

Intra-abdominal pressure and intra-abdominal hypertension in critically ill obstetric patients: a prospective cohort study

BACKGROUND

Critically ill obstetric patients may have risk factors for intra-abdominal hypertension. This study evaluated the intra-abdominal pressure and its effect on organ function and the epidemiology of intra-abdominal hypertension.

METHODS

Obstetric patients admitted to an Intensive Care Unit, with an anticipated stay greater than 24hours, were included. Intra-abdominal pressure was measured daily via a Foley catheter, based on intravesical pressure.

RESULTS

One-hundred-and-one patients were enrolled. The intra-abdominal pressure was 5-7mmHg in 34%; 7-12mmHg in 60%; and ≥12mmHg (intra-abdominal hypertension) in 6%. All six patients with intra-abdominal hypertension were pregnant at the time of admission. The intra-abdominal pressure in four patients normalized to <12mmHg following delivery, but in the remaining two it persisted ≥12mmHg and both these patients died. Correlation between intra-abdominal pressure and organ dysfunction was weak (r=0.211). Statistical comparison between patients with and without intra-abdominal hypertension for risk factors, daily intra-abdominal pressures, and Sequential Organ Failure Assessment score could not be done due to the disproportionately small number of patients with intra-abdominal hypertension as opposed to those without (6 versus 95). Intra-abdominal pressure did not significantly differ between survivors and non-survivors (8.5±1.1 vs 7.9±1.7mmHg, P=0.079).

CONCLUSIONS

The incidence of intra-abdominal hypertension in critically ill obstetric patients was lower than previously defined for mixed Intensive Care Unit populations, with an association with the pregnant state. Normalization of intra-abdominal pressure after delivery was associated with better survival. There was no correlation between intra-abdominal pressure and organ function or mortality.

Delayed postpartum abdominal bleeding caused by a spontaneous ruptured branch of the internal iliac artery and successfully treated by arterial embolisation

A 34-year-old gravida 2 para 1 had an uneventful second pregnancy and successful vaginal birth after caesarean section. She was readmitted on the third day postpartum with severe abdominal pain coinciding with lactation. On admission, her vital signs were stable and was expectantly managed. After an unexpected drop in haemoglobin level, a CT scan was ordered, showing a haemoperitoneum. Laparoscopy was performed and 2.5L of blood was evacuated from the peritoneal cavity, no source of the bleeding could be identified. At the intensive care unit the patient's vital signs deteriorated and her haemoglobin level dropped to 2.2 mmol/L. The patient was stabilised and instead of a laparotomy to locate the bleeding, an arterial CT and angiography were performed. This revealed the presence of a blush from a pseudoaneurysm rising from a branch of the internal iliac artery. The artery was successfully occluded by embolisation.

Pre-eclampsia renamed and reframed: Intra-abdominal hypertension in pregnancy

This hypothesis proposes pre-eclampsia is caused by intra-abdominal hypertension in pregnancy. Sustained or increasing intra-abdominal pressure ⩾12mmHg causes impaired venous return to the heart, systemic vascular resistance, ischemia reperfusion injury, intestinal permeability, translocation of lipopolysaccharide endotoxin to the liver, cytotoxic immune response, systemic inflammatory response, pressure transmission to thoracic and intra-cranial compartments, and multi-organ dysfunction. This hypothesis is predicated on Pascal's law, evidence founded in the intra-abdominal hypertension literature, and the adapted equation ΔIAP-P=ΔIAVF/Cab, where ΔIAP-P=change in intra-abdominal pressure in pregnancy, ΔIAVF=change in intra-abdominal vector force (volume and force direction) and Cab=abdominal compliance. Factors causing increased intra-abdominal pressure in pregnancy include: progressive uterine expansion, obstetrical factors that increase intra-uterine volume excessively or acutely, maternal anthropometric measurements that affect intra-abdominal pressure thresholds, maternal postures that increase abdominal force direction, abdominal compliance that is decreased, diminished with advancing gestation, or has reached maximum expansion, habitation at high altitude, and rapid drops in barometric pressure. We postulate that the threshold for lipopolysaccharide translocation depends on the magnitude of intra-abdominal pressure, the intestinal microbiome complex, and the degree of intestinal permeability. We advance that delivery cures pre-eclampsia through the mechanism of abdominal decompression.

Intra-abdominal pressure measurements in term pregnancy and postpartum: an observational study

Objective

To determine intra-abdominal pressure (IAP) and to evaluate the reproducibility of IAP-measurements using the Foley Manometer Low Volume (FMLV) in term uncomplicated pregnancies before and after caesarean section (CS), relative to two different reference points and to non-pregnant values.

Design

Observational cohort study.

Setting

Secondary level referral center for feto-maternal medicine.

Population

Term uncomplicated pregnant women as the case-group and non-pregnant patients undergoing a laparoscopic assisted vaginal hysterectomy (LAVH) as control group.

Methods

IAP was measured in 23 term pregnant patients, before and after CS and in 27 women immediately after and 1 day after LAVH. The midaxillary line was used as zero-reference (IAP_MAL) in all patients and in 13 CS and 13 LAVH patients, the symphysis pubis (IAP_SP) was evaluated as additional zero-reference. Intraobserver correlation (ICC) was calculated for each zero-reference. Paired student's t-tests were performed to compare IAP values and Pearson's correlation was used to assess correlations between IAP and gestational variables.

Main outcome measures

ICC before and after surgery, IAP before and after CS, IAP after CS and LAVH.

Results

The ICC for IAP_MAL before CS was lower than after (0.71 versus 0.87). Both mean IAP_MAL and IAP_SP were significantly higher before CS than after: 14.0±2.6 mmHg versus 9.8±3.0 mmHg (p<0.0001) and 8.2±2.5 mmHg versus 3.5±1.9 mmHg (p = 0.010), respectively. After CS, IAP was not different from values measured in the LAVH-group.

Conclusion

IAP-measurements using FMLV is reproducible in pregnant women. Before CS, IAP is increased in the range of intra-abdominal hypertension for non-pregnant individuals. IAP significantly decreases to normal values after delivery.

Are standard intra-abdominal pressure values different during pregnancy?

Background

Measurement of intra-abdominal pressure (IAP) is an important parameter in the surveillance of intensive care unit patients. Standard values of IAP during pregnancy have not been well defined. The aim of this study was to assess IAP values in pregnant women before and after cesarean delivery.

Methods

This prospective study, carried out from January to December 2011 in a French tertiary care centre, included women with an uneventful pregnancy undergoing elective cesarean delivery at term. IAP was measured through a Foley catheter inserted in the bladder under spinal anaesthesia before cesarean delivery, and every 30 minutes during the first two hours in the immediate postoperative period.

Results

The study included 70 women. Mean IAP before cesarean delivery was 14.2 mmHg (95%CI: 6.3–23). This value was significantly higher than in the postoperative period: 11.5 mmHg (95%CI: 5–19.7) for the first measurement (p = 0.002). IAP did not significantly change during the following two postoperative hours (p = 0.2). Obese patients (n = 25) had a preoperative IAP value significantly higher than non-obese patients: 15.7 vs. 12.4; p = 0.02.

Conclusion

In term pregnancies, IAP values are significantly higher before delivery than in the post-partum period, where IAP values remain elevated for at least two hours at the level of postoperative classical abdominal surgery. The knowledge of these physiological changes in IAP values may help prevent organ dysfunction/failure when abdominal compartment syndrome occurs after cesarean delivery.

Intra-abdominal pressure, intra-abdominal hypertension, and pregnancy: a review

The last several decades have seen many advances in the recognition and prevention of the abdominal compartment syndrome (ACS) and its precursor, intra-abdominal hypertension (IAH). There has also been a relative explosion of knowledge in the critical care, trauma, and surgical populations, and the inception of a society dedicated to its understanding, the World Society of the Abdominal Compartment Syndrome (WSACS). However, there has been almost no recognition or appreciation of the potential presence, influence, and management of intra-abdominal pressure (IAP), IAH, and ACS in pregnancy. This review highlights the importance and relevance of IAP in the critically ill parturient, the current lack of normative IAP values in pregnancy today, along with a review of the potential relationship between IAH and maternal diseases such as preeclampsia-eclampsia and its potential impact on fetal development. Finally, current IAP measurement guidelines are questioned, as they do not take into account the gravid uterus and its mechanical impact on intra-vesicular pressure.

Measurement of intra-abdominal pressure in term pregnancy: a pilot study

BACKGROUND

This study was conducted to assess the feasibility of measuring intra-abdominal pressure in term parturients under spinal anesthesia.

METHODS

Intra-abdominal pressure was measured in 20 term parturients after spinal anesthesia for elective caesarean section. Pressure was measured in the supine and 10° left lateral tilt positions with a constant reference point throughout.

RESULTS

Intra-abdominal pressure measurement was feasible and safe to perform. Pressure was significantly lower in the left lateral tilt position than supine (10.9 mmHg ± 4.67 vs. 8.9 mmHg ± 4.87, P=0.0004). The range of intra-abdominal pressure in pregnancy was wide, from 2 to 20 mmHg, with >25% of patients resting with pressures above 12 mmHg in both positions.

CONCLUSIONS

Under spinal anesthesia, intra-abdominal pressure in >25% of healthy term parturients was > 12 mmHg, which has conventionally been defined as intra-abdominal hypertension. The intra-abdominal pressure in term pregnancy should be performed in the left lateral tilt position to avoid falsely elevated pressure measurements.

Cutting-edge advances in the medical management of obstetrical hemorrhage

Hemorrhagic shock is the most common form of shock encountered in obstetric practice. Interventions that may limit transfusion requirements include normovolemic hemodilution, use of recombinant activated factor VII, selective embolization of pelvic vessels by interventional radiology, and the use of the cell saver intraoperatively. Current understanding of the mechanisms of acute coagulopathy calls into question the current transfusion guidelines, leading to a tendency to apply massive transfusion protocols based on hemostatic resuscitation despite lack of prospective data.

Hypothesis: preeclampsia is a venous disease secondary to an increased intra-abdominal pressure

It is hypothesized that in some women an excessively high intra-abdominal pressure (IAP) compresses the inferior vena cava, uterine veins, portal vein, hepatic veins, splenic vein and renal veins which lead to a decreased flow in these vascular beds, producing lower extremity edema, fetal-placental ischemia, a glomerulopathy with proteinuria and hypertension, hepatic ischemia and thrombocytopenia, increased uric acid, and hemolysis/elevated liver enzymes/low platelet known as the HELLP syndrome. There can be variability in the expression of these components. Placental-fetal ischemia could lead to expression of soluble fms-like tyrosine kinase1 (sFLT) and endoglin which have been shown to cause additional diffuse endovascular damage. A further increase in IAP pushes the diaphragm cephalad, increasing intrathoracic pressure leading to upper extremity edema, decreased internal jugular venous flow, cerebral vascular engorgement, raised intracranial pressure, and if unresolved, seizures. Placental/fetal ischemia and hepatic ischemic necrosis may lead to diffuse inflammation and a septic inflammatory response syndrome (SIRS) which may become a vicious cycle, perpetuating the ischemia. It is further hypothesized that application of an externally applied negative abdominal pressure device will lower IAP and possibly reverse the pathophysiology of preeclampsia. As the abnormal placental proteins develop weeks before clinical preeclampsia, early application of external negative abdominal pressure may prevent development of the syndrome.