Tonometry as a predictor of inadequate splanchnic perfusion in an intra-abdominal hypertension animal model

Ultrasound-Assisted versus Endoscopic Nasojejunal Tube Placement for Acute Pancreatitis: A Retrospective Feasibility Study

Objective

The optimal technique for nasojejunal tube (NJT) placement in terms of facilitating early enteral nutrition (EN) in patients with acute pancreatitis (AP) is unclear. In this study, we aimed to evaluate the impact of two common techniques on EN implementation and clinical outcomes in a group of AP patients.

Methods

This is a retrospective study. All the data were extracted from an electronic database from August 2015 to October 2017. Patients with a diagnosis of AP requiring NJT placement were retrospectively analyzed. The primary outcome was the successful procedural rate.

Results

A total of 53 eligible patients were enrolled, of whom 30 received an ultrasound-assisted technique and the rest received the endoscopy method (n = 23). There was no difference in success rates of initial placement procedures between the two groups (93.3% and 95.7% in the ultrasound-assisted group and endoscopy group, respectively). The mean amount of EN delivery within the first three days after NJT placement was significantly higher in the ultrasound-assisted group (841.4 kcal (95% CI: 738.8, 944 kcal) vs. 652.5 kcal (95% CI: 562.5, 742.6 kcal), P = 0.018). Moreover, a slight increased postprocedural intra-abdominal pressure (IAP) was observed in patients undergoing endoscopic procedures, but not in the ultrasound-assisted group, especially at 6 hours after NJT placement (0.35 vs. -2.01 from baseline, P < 0.05). For clinical outcomes, we observed no difference between groups.

Conclusion

Compared with endoscopic procedures, ultrasound-assisted NJT placement possesses the acceptable success rates of initial placement procedures.

Relationship between Gastric pH Measurement and Intra-abdominal Pressure in Patients Undergoing Laparoscopic Surgery

Objectives:

Laparoscopic surgery (LS) is a safe and widely used technique. During LS, carbon dioxide insufflation may produce significant hemodynamic and ventilatory consequences, such as elevated intra-abdominal pressure (IAP) and hypercarbia. Splanchnic and cardiovascular blood flow can be affected by the elevated IAP, which can result in ischemia in the splanchnic region prior to hemodynamic changes. Changes in gastric pH may be an early precursor of changes in splanchnic blood circulation. This study investigated the relationship between gastric pH measurement and IAP in patients undergoing LS.

Methods:

This study included 49 patients aged 18–65 years with American Society of Anesthesiologists (ASA) physical status I – III who were undergoing elective laparoscopic cholecystectomy. A gastric pH tonometer probe was applied using an orogastric catheter. Simultaneously, insufflation pressure, cardiac apex beat (CAB), and mean arterial blood pressure (MAP) values were recorded. Indirect IAP was then measured through the bladder. Measurements were performed at baseline; at 15, 30, and 60 minutes after onset of insufflation (AI 15, AI 30, and AI 60, respectively); and at the end of insufflation (EI). Two pH measurements were obtained with a gastric tonometer pH probe, using an automated function of the gastric tonometer to improve measurement reliability.

Results:

IAP was significantly higher than baseline at AI 15, AI 30, AI 60, and EI (p<0.001). The pH₁ and pH₂ levels were significantly lower at AI 15 and AI 30, compared with baseline (p<0.001). There were no significant differences between pH₁ and pH₂ measurements at AI 60 and EI. Compared with baseline, CAB was significantly lower at AI 15, AI 30, AI 60, and EI (p=0.001, p<0.001, p=0.006). There were no statistically significant differences in MAP changes at any time point.

Conclusion:

Elevated IAP caused by CO₂ insufflation during LS led to reductions of pH₁ and pH₂. There was a correlation between gastric pH measurement and IAP. Measurement of gastric pH may be useful to assess blood circulation in the splenic area during LS.

Intestinal histopathological changes in a porcine model of pneumoperitoneum-induced intra-abdominal hypertension

BACKGROUND

Low splanchnic perfusion is an immediate effect of pneumoperitoneum-induced intra-abdominal hypertension (IAH). Anatomical structure results in the intestinal mucosa being the area most sensitive to hypoperfusion. The relationship between intestinal injury and clinical parameters of tissue perfusion [abdominal perfusion pressure (APP), gastric intramucosal pH (pH_i) and lactic acid (Lc)] has not been previously studied. This study aimed to monitorize intestinal pathogenesis through sequential ileal biopsies and to measure APP, pH_i, and Lc levels at different pneumoperitoneum-induced intra-abdominal pressures (20, 30, and 40 mmHg) to evaluate the potential relationships between them.

MATERIALS AND METHODS

Fifty pigs were divided into four groups; a control group (C) and three experimental groups with different pneumoperitoneum-induced levels [20 mmHg (G20), 30 mmHg (G30), and 40 mmHg (G40)], that were maintained for 3 and 5 h. APP, pH_i, and Lc were measured and ileal biopsies taken laparoscopically every 30 min. The mucosal damage was graded using the standardized Park's Score and animals were classified as injured (I+) or uninjured (I-).

RESULTS

Different histopathological lesions were observed in groups G20, G30, and G40 but no damage observed in group C. A 33.3% of animals in G20 and G30 were I+ after 3 h, while 93.3% were injured in G40. After 5 h, histopathological lesions were no longer seen in some animals in G20 and only 10% were I+. Conversely, in G30 I+ pigs increased to 80% while those in G40 remained at 93.3% I+. The I+ animals had significantly lower APP and pH_i than those I-. Lc was the clinical parameter that showed the earliest differences, with significantly higher figures in I+ animals.

CONCLUSIONS

The evolution of intestinal injuries from pneumoperitoneum-induced IAH depends on the degree of IAP. These damages may be associated with decreases in APP and pH_i, and increases in Lc.

Pressure Distribution during Negative Pressure Wound Therapy of Experimental Abdominal Compartment Syndrome in a Porcine Model

(1) Introduction: Negative pressure wound therapy (NPWT) is a frequently applied open abdomen (OA) treatment. There are only a few experimental data supporting this method and describing the optimal settings and pressure distribution in the abdominal cavity during this procedure. The aim of our study was to evaluate pressure values at different points in the abdominal cavity during NPWT in experimental abdominal compartment syndrome (ACS) animal model; (2) Methods: In this study (permission Nr. 13/2014/UDCAW), 27 Hungahib pigs (15.4-20.2 kg) were operated on. ACS was generated by implanting a plastic bag in the abdomen through mini-laparotomy and filled with 2100-3300 mL saline solution (37 °C) to an intraabdominal pressure (IAP) of 30 mmHg. After 3 h, NPWT (Vivano Med^® Abdominal Kit, Paul Hartmann AG, Germany) or a Bogota bag was applied. The NPWT group was divided into -50, -100 and -150 mmHg suction groups. Pressure distribution to the abdominal cavity was monitored at 6 different points of the abdomen via a multichannel pressure monitoring system; (3) Results: The absolute pressure levels were significantly higher above than below the protective layer. The values of the pressure were similar in the midline and laterally. Amongst the bowels, the pressure values changed periodically between 0 and -12 mmHg which might be caused by peristaltic movements; (4) Conclusions: The porcine model of the present study seems to be well applicable for investigating ACS and NPWT. It was possible to provide valuable information for clinicians. The pressure was well distributed by the protective layer to the lateral parts of the abdomen and this phenomenon did not change considerably during the therapy.

Time-course evaluation of intestinal structural disorders in a porcine model of intra-abdominal hypertension by mechanical intestinal obstruction

BACKGROUND

A mechanical intestinal obstruction (MIO) can generate intraabdominal hypertension (IAH) that is life threatening. The intestines are very sensitive to IAH since the low splanchnic perfusion causes intestinal hypoxia, local acidosis and bacterial translocations. This may lead to acute intestinal distress syndrome (AIDS). The identification of intestinal injuries during IAH and its correlation with clinical parameters as the abdominal perfusion pressure (APP), the gastric intramucosal pH (pHi) and lactic acid (Lc) are still unknown. This study aimed to evaluate the sequence of intestinal histopathological findings in an MIO model and to analyze potential relationships with parameters currently used in clinical practice (APP, pHi and Lc).

MATERIAL AND METHODS

Twenty pigs were divided into three groups: a control group (n = 5) and two experimental groups with 20 mmHg (G1, n = 10) and 30 mmHg (G2, n = 5) of IAH by MIO. The pressures were maintained for 3 hours, except in 5 animals in G1 where it was maintained for 5 hours. The APP, pHi and LA were recorded and biopsies of the terminal ileum were taken every 30 minutes in all groups. The intestinal damage was graded according to the Park Score.

RESULTS

Intestinal injuries were found in 42.9% of pigs in the experimental groups. The lesions were independent of the level and duration of IAH. Although APP and pHi were slightly lower in injured animals (I +) of G1 and G2, there were no significant differences among those uninjured (I-). Lc was significantly increased in all I+ pigs from the onset of IAH.

CONCLUSION

The IAH by MIO causes intestinal lesions from the first 30 minutes with concurrent decreases in APP and pHi and increases in Lc. Lc could be the best clinical parameter related to intestinal damages with a clear difference between I + and I- animals.

Mechanical Intestinal Obstruction in a Porcine Model: Effects of Intra-Abdominal Hypertension. A Preliminary Study

Introduction

Mechanical intestinal obstruction is a disorder associated with intra-abdominal hypertension and abdominal compartment syndrome. As the large intestine intraluminal and intra-abdominal pressures are increased, so the patient’s risk for intestinal ischaemia. Previous studies have focused on hypoperfusion and bacterial translocation without considering the concomitant effect of intra-abdominal hypertension. The objective of this study was to design and evaluate a mechanical intestinal obstruction model in pigs similar to the human pathophysiology.

Materials and Methods

Fifteen pigs were divided into three groups: a control group (n = 5) and two groups of 5 pigs with intra-abdominal hypertension induced by mechanical intestinal obstruction. The intra-abdominal pressures of 20 mmHg were maintained for 2 and 5 hours respectively. Hemodynamic, respiratory and gastric intramucosal pH values, as well as blood tests were recorded every 30 min.

Results

Significant differences between the control and mechanical intestinal obstruction groups were noted. The mean arterial pressure, cardiac index, dynamic pulmonary compliance and abdominal perfusion pressure decreased. The systemic vascular resistance index, central venous pressure, pulse pressure variation, airway resistance and lactate increased within 2 hours from starting intra-abdominal hypertension (p<0.05). In addition, we observed increased values for the peak and plateau airway pressures, and low values of gastric intramucosal pH in the mechanical intestinal obstruction groups that were significant after 3 hours.

Conclusion

The mechanical intestinal obstruction model appears to adequately simulate the pathophysiology of intestinal obstruction that occurs in humans. Monitoring abdominal perfusion pressure, dynamic pulmonary compliance, gastric intramucosal pH and lactate values may provide insight in predicting the effects on endorgan function in patients with mechanical intestinal obstruction.

The duration of intra-abdominal hypertension strongly predicts outcomes for the critically ill surgical patients: a prospective observational study

INTRODUCTION

Intra-abdominal hypertension (IAH) is associated with morbidity and mortality in critically ill patients. The present study analyzed the clinical significance of IAH in surgical patients with severe sepsis.

METHODS

This was a prospective study carried out in the surgical intensive care unit (SICU). Intra-abdominal pressure (IAP) was measured three times a day via a urinary catheter filled with 25 mL of saline. IAH was defined as an IAP ≥ 12 mmHg, and the peak IAP was recorded as the IAP for the day. Data were analyzed in terms of IAH development and the IAH duration.

RESULTS

Of the 46 patients enrolled in the study, 42 developed IAH while in the SICU. The development of IAH aggravated the clinical outcomes; such as longer SICU stay, requirement of ventilator support, and delayed initiation of enteral feeding (EF). The IAH duration showed a significant correlation with pulmonary, renal, and cardiovascular function, and enteral feeding. The IAH duration was an independent predictor of 60-day mortality (odds ratio: 1.196; p = 0.014).

CONCLUSIONS

The duration of IAH is a more important prognostic factor than the development of IAH; thus every effort should be made to reduce the IAH duration in critically ill patients.

TRIAL REGISTRATION

NCT01784458.

PiCO2 monitoring of transferred jejunum perfusion using an air tonometry technique after hypopharyngeal cancer surgery

This study aimed to investigate the usefulness of intraluminal PCO2 (PiCO2) monitoring by air tonometry for the assessment of the vascular condition of the transferred jejunum after surgery for hypopharyngeal cancer.PiCO2 in the transplanted jejunum of 24 patients was monitored using air tonometry after radical surgery for hypopharyngeal cancer from 2003 to 2010.All but 1 patient, who removed the catheter before monitoring began, were monitored safely. PiCO2 in the transferred jejunum correlated with arterial PCO2 (PaCO2) that was measured concurrently, and dissociation of PiCO2 from PaCO2 was observed in cases with vascular complication. In those cases without postoperative vascular complication, the PiCO2 value gradually increased for 3 hours but then decreased by 12 hours after surgery. Three patients experienced major vascular complication. All 3 patients had continuous elevation of PiCO2 >100 mm Hg, although vascular flow in 1 patient recovered by removal of a venous thrombosis and reanastomosis of the vein 7.5 hours after surgery. Four other patients who experienced elevation of PiCO2 had their skin suture released for decompression of their neck wound, resulting in a decrease in PiCO2 after treatment.The current results demonstrated that continuous monitoring of PiCO2 by air tonometry accurately reflects the vascular condition of the transferred jejunum, and this method is one of the best options for postoperative monitoring of jejunum blood perfusion.

Gastric tonometry guided therapy in critical care patients: a systematic review and meta-analysis

Introduction

The value of gastric intramucosal pH (pHi) can be calculated from the tonometrically measured partial pressure of carbon dioxide (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {P}_{C{O}_2} $$\end{document}PCO2) in the stomach and the arterial bicarbonate content. Low pHi and increase of the difference between gastric mucosal and arterial \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {P}_{C{O}_2} $$\end{document}PCO2 (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {P}_{C{O}_2} $$\end{document}PCO2 gap) reflect splanchnic hypoperfusion and are good indicators of poor prognosis. Some randomized controlled trials (RCTs) were performed based on the theory that normalizing the low pHi or \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {P}_{C{O}_2} $$\end{document}PCO2 gap could improve the outcomes of critical care patients. However, the conclusions of these RCTs were divergent. Therefore, we performed a systematic review and meta-analysis to assess the effects of this goal directed therapy on patient outcome in Intensive Care Units (ICUs).

Methods

We searched PubMed, EMBASE, the Cochrane Library and ClinicalTrials.gov for randomized controlled trials comparing gastric tonometry guided therapy with control groups. Baseline characteristics of each included RCT were extracted and displayed in a table. We calculated pooled odds ratios (ORs) with 95% confidence intervals (CIs) for dichotomous outcomes. Another measure of effect (risk difference, RD) was used to reassess the effects of gastric tonometry on total mortality. We performed sensitivity analysis for total mortality. Continuous outcomes were presented as standardised mean differences (SMDs) together with 95% CIs.

Results

The gastric tonometry guided therapy significantly reduced total mortality (OR, 0.732; 95% CI, 0.536 to 0.999, P = 0.049; I² = 0%; RD, −0.056; 95% CI, −0.109 to −0.003, P = 0.038; I² = 0%) when compared with control groups. However, after excluding the patients with normal pHi on admission, the beneficial effects of this therapy did not exist (OR, 0.736; 95% CI 0.506 to 1.071, P = 0.109; I² = 0%). ICU length of stay, hospital length of stay and days intubated were not significantly improved by this therapy.

Conclusions

In critical care patients, gastric tonometry guided therapy can reduce total mortality. Patients with normal pHi on admission contributed to the ultimate result of this outcome; it may indicate that these patients may be more sensitive to this therapy.

[Intra-abdominal hypertension: effects on the splanchnic circulation. Preliminary study in a model of ascites]

INTRODUCTION

Intra-abdominal hypertension is defined as a rise in intra-abdominal pressure leading to progressive dysfunction of the abdominal organs.

OBJECTIVE

To evaluate the effects of intra-abdominal hypertension on the splanchnic circulation in a porcine animal model with a view to determining the diagnostic method of choice.

MATERIAL AND METHODS

A total of 10 swine were divided into 2 groups: a control group and a group with an ascites pressure of 20mmHg. Transvesical and transperitoneal intra-abdominal pressures were registered, and the correlation between the measurements obtained was determined. Concentrations of lactic acid, alanine aminotransferase, glucose and gastric mucosal pH were also obtained. We registered the mean arterial and abdominal perfusion pressures, and the correlation of the latter with gastric mucosal pH and lactic acid concentrations. The parameters were registered for a total of 3hours.

RESULTS

We observed a high correlation between transvesical and transperitoneal measurements of intra-abdominal pressure (R(2)=0.98). In the 20mmHg pressure group, lactic acid concentrations increased significantly at 180min (p<0.011). Gastric mucosal pH differed significantly between the 2 groups from the beginning of the study (p=0.004) and significantly decreased from 120min onward. Mean arterial and abdominal perfusion pressures gradually decreased during the trial, with early significant changes in the abdominal perfusion pressure (p=0.001), and a good correlation with the remaining study parameters. There were no significant changes in hepatic indicators.

CONCLUSIONS

We believe the transvesical approach to be the technique of choice to determine intra-abdominal pressure. Abdominal perfusion pressure is a sensitive marker of intra-abdominal hypertension, and gastric mucosal pH is the first parameter to be affected.