The Role of Routine Measurement of Intra-abdominal Pressure in Preventing Abdominal Compartment Syndrome.

INTRODUCTION: Abdomen, a closed compartment, is prone to raised intra-abdominal pressure (IAP) in the postoperative period. After a critical value of ≥ 15 cm of water, IAP produces abdominal compartment syndrome (ACS). ACS leads to reduced venous return, reduced cardiac output, and domino effect of organ dysfunction, leading to death. Hence, it is the need of hour to monitor IAP to pick up intra-abdominal hypertension (IAH) and ACS. This routine facilitates early institution of treatment measures. AIMS AND
OBJECTIVES: To study IAP in abdominal operations in neonates, infants, and older children and to promote concept of routine measurement of IAP as standard care.
MATERIALS AND METHODS: Intravesical route was used to measure IAP in this prospective observational study. Seventy-nine pediatric abdominal surgeries met with criteria of availability of complete data for analysis and formed the cohort of the study. All major, infective, traumatic, tumor-related abdominal surgeries were included in the study. Outcome, C-reactive protein (CRP), procalcitonin, platelet counts, Simplified Sequential Organ Failure Assessment Score, and Acute Physiology and Chronic Health Evaluation II (APACHE II) score were the parameters analyzed. The World Society of ACS grading was adopted in the study with subdivision of normal into low-normal and high-normal subgroups.
RESULTS: Extended Mantel-Haenszel Chi-square statistical tool when applied for linear relationship showed a linear relationship with outcome (P < 0.05), CRP (P < 0.05), procalcitonin (P < 0.05), Simplified Sequential organ failure Assessment Score, and APACHE II. Platelet counts (P > 0.05) were not significantly correlated. Decision for laparotomy was delayed in cases of ACS.
CONCLUSION: Routine measure of IAP facilitates early recognition of IAH. This facilitates therapeutic measures to be initiated to reduce IAP. Early decision to decompress by laparotomy/laparostomy saves lives. Hence, routine IAP measurement should be a part of standard care in pediatric abdominal surgery.

INTRODUCTION

Abdomen is a closed compartment. Rise in intra-abdominal pressure (IAP) reduces perfusion of intra-abdominal organs directly and indirectly. Raised IAP, after a critical level, also compresses inferior vena cava reducing cardiac output and thereby affecting perfusion of organs, leading to abdominal compartment syndrome (ACS), multiorgan dysfunction, and death.

Conventionally abdominal distension in the postoperative period was attributed to paralytic ileus. First, a few reports of intra-abdominal hypertension (IAH) were conceived by Gross and Kidd et al. in diaphragmatic hernia and after closure of gastroschisis.[12]

Measurement of IAP, therefore, becomes essential in all situations where a rise in IAP is likely. This facilitates identification of IAH early enough to act and to take steps to prevent progression to ACS.[34]

Aims and objectives

To study IAP in abdominal surgeries in neonates, infants, and older children

To promote routine measurement of IAP as a part of standard care of pediatric abdominal surgeries.

MATERIAL AND METHODS

This was a prospective, observational cohort study in 79 cases of pediatric abdominal operations between 2007 and 2014. Various conditions for which abdominal surgeries/exploratory laparotomy were done included peritonitis (n = 19), intestinal obstruction (n = 12), neuroblastoma (n = 6), liver resection (n = 8), blunt injury abdomen (n = 4), Hirschsprung's disease associated enterocolitis (n = 7), pull-through for Hirschsprung's disease and anorectal malformations (n = 13), urinary ascites (n = 5), biliary peritonitis (n = 4), and spontaneous bacterial peritonitis (n = 1). Cases with incomplete data were excluded.

Technique of measuring intra-abdominal pressure

Intravesical route was used to measure IAP in the present study. Care was taken with regard to the following:

Emptying bladder

Filling with 25 ml of normal saline (1–2 ml/kg in neonates)[5]

Flattening the headend

Zero-point selection at greater trochanter

Measured every six hourly (more often pressure is > 20 cm of water).

The endpoint of stopping measurement of IAP was that if the IAP trends were not changing or decreasing, frequency of measurement is reduced.

The parameters studied

Outcome

C-reactive protein (CRP)

Procalcitonin

Platelet counts

Simplified Sequential Organ Failure Assessment Score (SSOFA) and Acute Physiology and Chronic Health Evaluation II (APACHE II).

Sequential Organ Failure Assessment (SOFA) has been modified into simplified SOFA as one point for each organ.

Intra-abdominal pressure grading adopted in the present study

IAP grading was adopted by the World Society of ACS (WSACS).[6] WSACS IAH is graded as follows:

Grade I, IAP 12–15 cm of water (IAH)

Grade II, IAP 16–20 cm of water (IAH)

Grade III, IAP 21–25 cm of water (ACS)

Grade IV, IAP >25 cm of water (ACS).

In the present study, normal has been subdivided into low-normal and high-normal (8–12 cm of water) subgroups.

Institutional Internal Ethics Committee clearance was obtained.

Statistical tool used

A blinded statistical analysis was performed using Epi Info version 6.04.

RESULTS

Distribution of IAP grade showed that 22.5% of neonates had high-normal IAP (8–12 cm of water) [Table 1]. ACS was seen in 17.5% of neonates, 11.3% of infants, and 23.9% of older children.

Table 1

Intra-abdominal pressure grade distribution across age

IAP versus outcome [Table 2] revealed higher the IAP grade, higher was the mortality. Extended Mantel–Haenszel Chi-square for linear trend showed a P < 0.05, indicating that higher grades were associated with higher mortality.

Table 2

Intra-abdominal pressure grade verses outcome

IAP trends when compared with CRP as a surrogate marker of stress revealed a significant linear trend with rising grades of IAP, with a P < 0.05 as shown in Table 3.

Table 3

Intra-abdominal pressure grade verses C-reactive protein

IAP when compared with trends of procalcitonin [Table 4] also showed again a linear trend of increase in procalcitonin levels with increase in IAP, with a P < 0.05.

Table 4

Intra-abdominal pressure grade verses procalcitonin

IAP was also correlated with platelet count [Table 5], but it did not show linear relationship (P > 0.05), which was not significant.

Table 5

Intra-abdominal pressure grade verses platelet count

When IAP was compared with organ scoring systems, i.e., SSOFA and APACHE II, scores were higher with rising IAP with sensitivity of 75% each [Table 6].

Table 6

Acute Physiology and Chronic Health Evaluation II and Simplified Sequential Organ Failure Assessment scoring system accuracy as against intra-abdominal pressure grading

DISCUSSION

IAH has been shown to influence mortality morbidity in pediatric abdominal surgeries. The ignorance of recognizing IAP and IAH was well described by Akhobadze et al.[7] DeCou et al. presented ACS in three cases.[8]

Abdomen is a closed compartment and raised IAP contributes to ACS. This rise in IAP after a critical point affects perfusion. Abdominal perfusion pressure (APP) is equal to mean arterial pressure minus IAP. Higher the IAP less is the perfusion. Ideal APP is 70 mmHg. Anything <60 mmHg affects perfusion significantly. The normal IAP in children is around 7 cm of water. The normal IAP in present study ranged from 7 to 12cm of water. When analysis was done for pressure less than 7 and 8-12 cm of water (upper normal limit of IAP), upper normal was associated with increased morbidity and mortality. The authors therefore subdivided normal into low-normal and high-normal. IAP has been graded by WSACS. Authors have adopted WSACS with a simple modification of subdividing normal into high-normal and low-normal.

Although abdomen has been recognized as a compartment from time immemorial, abdominal pressure was not considered important till recently.[910] Raised IAP [Figure 1] progressively compromises cardiac output by influencing both preload and postload. Reduced cardiac output decreases perfusion of all organs, leading to global hypoxic endothelial stress. This leads to activation of innate immunity which in turn activates adaptive immunity, leading to surge in inappropriate levels of anti-inflammatory cytokines, leading to multiorgan dysfunction syndrome (MODS) and death.

Figure 1

The algorithmic sequence of consequences of raised intra-abdominal pressure leading to abdominal compartment syndrome and death

Abdomen compartment syndrome as shown in Figure 1 leads to cascade of MODS. IAH leads to ACS as shown by multiple authors.[11] Ejike et al. described the understanding of ACS across pediatric surgical population.[1213] The present series also showed a linear trend with outcome and stress markers.

Various techniques have been used to measure IAP. They include intra-gastric route, intravesical route, and intra-peritoneal route.[141516] Intravesical route was used in the present study.

Correlation of IAP with stress markers was not addressed in literature. The present study used outcome, CRP, procalcitonin, organ scoring systems, such as SSOFA[17] and APACHE II,[18] as surrogate markers of stress.[1718] This has shown a definite linear trend with expression of CRP, expression of procalcitonin, and worsening scores in SSOFA and APACHE II.

When IAP grades were correlated with outcome, higher grades of IAP were associated with significantly higher mortality (P < 0.05). IAP grades, when correlated with surrogate markers of stress such as CRP and procalcitonin showed a significant linear trend (P < 0.05). Platelet count did not show any significant correlation with IAP grade. IAP grades were also compared with organ scoring systems such as SSOFA and APACHE II; both showed a sensitivity of 75%.

IAH needs to be recognized before it progresses to ACS. ACS when detected needs to be aggressively addressed by medical and early surgical procedures.[1920] Medical measures include nasogastric decompression, decompression of colon by flatus tube and enemata, and diuretics for ascites. The authors also have used neostigmine as a tool to facilitate decompression of colon instantaneously (neostigmine use article under preparation for publication). Surgical procedures such as percutaneous catheter decompression[2122] and decompression laparostomy should be done as early as possible.[2324]

There has been resistance from both pediatrician and pediatric surgeons for a second laparostomy and this resulted in delayed decisions for laparostomy. Decompression laparostomy was not vastly supported by pediatrician and treating unit. It was performed in four children with ACS after an unpleasant protracted debate. Three out of four babies survived. This shows that early decompression laparostomy needs to be encouraged.

Limitations

The study needs to be done in larger numbers and needs to be increased and results need to be validated across multiple centers.

CONCLUSION

IAP measurements need to be routine standard case, following abdominal surgery in infants and children. Routine measurement of IAP facilitates early detection IAH. ACS needs to be aggressively treated with early decision for decompression laparostomy.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.