The Role of Femoral Venous Pressure and Femoral Venous Oxygen Saturation in the Setting Of Intra-Abdominal Hypertension: A Pig Model

The development, feasibility and credibility of intra-abdominal pressure measurement techniques: A scoping review

AIM

To provide a comprehensive overview on emerging direct and alternative methods for intra-abdominal pressure (IAP) measurement techniques.

METHODS

This was a scoping review study following Arksey and Malley's framework. The PubMed, EMBASE, Web of Science, EBSCO, Scopus and ProQuest databases were searched, and we only considered studies published from 2000 as we have extended the data from two previous reviews. Original studies that reported on the development, feasibility and credibility of IAP measurement techniques were included.

RESULTS

Forty-two of 9954 screened articles were included. IAP measurement techniques include three major categories: direct, indirect and less invasive measurement techniques. Agreement analyses were performed in most studies, and some explored the safety, time expenditure and reproducibility of IAP measurement techniques.

CONCLUSIONS

Clinical data assessing the validation of new IAP measurement techniques or the reliability of established measurement techniques remain lacking. Considering the cost and invasiveness, direct measurement is not recommended as a routine method for IAP measurement and should be preserved for critically ill patients where standard techniques are contraindicated or could be inaccurate. The measurement accuracy, reliability and sensitivity of the transrectal and transfemoral vein methods remain insufficient and cannot be recommended as surrogate IAP measures. Transvesical measurement is the most widely used method, which is the potentially most easy applicable technique and can be used as a reliable method for continuous and intermittent IAP measurement. Wireless transvaginal method facilitates the quantitative IAP measurement during exercise and activity, which laying the foundations for monitoring IAP outside of the clinic environment, but the accuracy of this technique in measuring absolute IAP cannot be determined at present. Less invasive technology will become a new trend to measure IAP and has substantial potential to replace traditional IAP measurement technologies, but further validation and standardization are still needed. Medical professionals should choose appropriate measurement tools based on the advantages and disadvantages of each IAP technique in combination with assessing specific clinical situations.

Hands off Trans-Femoral Venous Intra-Abdominal Pressure Estimates in Children: Results of a Sobering Single-Center Study

BACKGROUND

For a long time, trans-femoral venous pressure (FVP) measurement was considered a simple alternative for estimating intra-abdominal pressure (IAP). Since intravesical [IVP] and intragastric [IGP] pressure measurements are sometimes contraindicated for anatomical and pathophysiological reasons, FVP raised hopes, especially among pediatricians. Pediatric FVP validation studies have never been published; recent results from adult studies cast doubt on their interchangeability. Therefore, we compared for the first time the measurement agreement between FVP and IVP and IGP in children.

MATERIAL AND METHODS

We prospectively compared FVP with IVP and IGP, according to the Abdominal Compartment Society validation criteria. Additionally, we analyzed the agreement as a function of IAP or right heart valve regurgitation and pulmonary hypertension.

RESULTS

In a real-life PICU study design, n = 39 children were included (median age 4.8 y, LOS-PICU 23 days, PRISM III score 11). In n = 660 FVP-IGP measurement pairs, the median IAP was 7 (range 1 to 23) mmHg; in n = 459 FVP-IVP measurement pairs, the median IAP was 6 (range 1to 16) mmHg. The measurement agreement was extremely low with both established methods (FVP-IGP: r2 0.13, mean bias -0.8 ± 4.4 mmHg, limits of agreement (LOA) -9.6/+8.0, percentage error (PE) 55%; FVP-IVP: r2 0.14, bias +0.5 ± 4.2 mmHg, limit of agreement (LOA) -7.9/+8.9, percentage error (PE) 51%). No effect of the a priori defined influencing factors on the measurement agreement could be demonstrated.

CONCLUSIONS

In a study cohort with a high proportion of critically ill children suffering from IAH, FVP did not agree reliably with either IVP or IGP. Its clinical use in critically ill children must therefore be strongly discouraged.

Evaluation of the effects of medial saphenous venous pressures as an indirect method of measurement of intra-abdominal pressures in the horse

OBJECTIVE

To evaluate the effect of changes in intra-abdominal pressure (IAP) on medial saphenous venous pressure (MSVP) and hemodynamics in normal horses.

DESIGN

Experimental, in-vivo study.

SETTING

University Teaching Hospital.

ANIMALS

Convenience sample of 7 mixed breed horses; 5 geldings, and 2 mares.

INTERVENTIONS

Pneumoperitoneum was induced in horses under standing sedation with carbon dioxide gas using a laparoscopic insufflator for a total of 60 minutes to simulate clinical elevation in IAP. Pressure was increased stepwise to 20 mm Hg over 30 minutes, and maintained at that pressure for 30 minutes to evaluate the effect of sustained intra-abdominal hypertension. The MSVP and vital parameters were recorded, along with direct arterial blood pressure from the transverse facial artery.

MEASUREMENTS AND MAIN RESULTS

As IAP increased, MSVP increased in a stepwise manner, in concert with changes in IAP. The consistency in measurement between MSVP and IAP was high (intraclass correlation coefficient = 0.92; P < 0.001) and repeated measures correlation was excellent (r = 0.98; P < 0.001). Heart rate was unchanged over the course of the experiment (P = 0.09), however, respiratory rate increased with increasing IAP (P < 0.001). Arterial blood pressure also increased with insufflation (P < 0.001), with a significant difference at an IAP of 15 mm Hg (P = 0.04).

CONCLUSIONS

This report provides preliminary data demonstrating a strong correlation between equine MSVP and changes in IAP, similar to that observed in other species. Further investigations are needed to evaluate this relationship, and to confirm these results in clinical patients.

Positive end-expiratory pressure adjusted for intra-abdominal pressure - A pilot study

PURPOSE

Intra-abdominal hypertension (IAH) is associated with impaired respiratory function. Animal data suggest that positive end-expiratory pressure (PEEP) levels adjusted to intra-abdominal pressure (IAP) levels may counteract IAH-induced respiratory dysfunction. In this pilot study, our aim was to assess whether PEEP adjusted for IAP can be applied safely in patients with IAH.

MATERIALS AND METHODS

We included patients on mechanical ventilation and with IAH. Patients were excluded with severe cardiovascular dysfunction or severe hypoxemia or if the patient was in imminent danger of dying. Following a recruitment manoeuvre, the following PEEP levels were randomly applied: PEEP of 5cmH₂O (baseline), PEEP=50% of IAP, and PEEP=100% of IAP. After a 30min equilibration period we measured arterial blood gases and cardio-respiratory parameters.

RESULTS

Fifteen patients were enrolled. Six (41%) patients did not tolerate PEEP=100% IAP due to hypoxemia, hypotension or endotracheal cuff leak. PaO₂/FiO₂ ratios were 234 (68), 271 (99), and 329 (107) respectively. The differences were significant (p=0.009) only between baseline and PEEP=100% IAP.

CONCLUSIONS

PEEP=100% of IAP was not well-tolerated and only marginally improved oxygenation in ventilated patients with IAH.

Can Femoral Venous Pressure be Used as an Estimate for Standard Vesical Intra-Abdominal Pressure Measurement?

Intra-abdominal hypertension (IAH) is highly prevalent in critically ill patients admitted to the intensive care unit and is associated with an increased morbidity and mortality. The present study investigated whether femoral venous pressure (EVP) can be used as a surrogate parameter for intra-abdominal pressure (IAP) measured via the bladder in IAH grade II (IAP <20 mmHg) or grade III (IAP ≥20 mmHg). This was a single-centre prospective study carried out in a tertiary adult intensive care unit. IAP was measured via the bladder with a urinary catheter with simultaneous recording of the FVP via a femoral central line. If the IAP was <20 mmHg external weight to a maximum of 10 kg was applied to the abdomen with subsequent measurements of IAP and FVP. Eleven patients were enrolled into the study. IAH (IAP >12 mmHg) was identified in five patients (42%) and abdominal compartment syndrome (ACS, IAP >20 mmHg with new onset organ failure) in two (18%) with all-cause study mortality of 18%. The mean Acute Physiology and Chronic Health Evaluation (APACHE) II score was 21 ± 5, Simplified Acute Physiology (SAPS 2) score 49 ± 8, and Sequential Organ Failure Assessment (SOFA) score 9 ± 3. At baseline the bias between IAP and FVP was 3.2 with a precision of 3.63 mmHg (limits of agreement [LA] −4.1, 10.4). At 5 kg and 10 kg, the bias was 2.5 with a precision of 3.92 mmHg (LA-5.4, 10.3) and 2.26 mmHg (LA-2.1, 7.0) respectively. A receiver operating characteristic analysis for FVP to predict IAH showed an area under the curve of 0.87 (95% confidence interval 0.74–0.94, P=0.0001). FVP cannot be recommended as a surrogate measure for IAP even at IAP values above 20 mmHg. However, an elevated FVP was a good predictor of IAH.

Use of femoral vein catheters for the assessment of perfusion parameters

The use of central venous oxygen saturation (SvcO₂) and arterial lactate in the diagnosis of severe tissue hypoperfusion is well established, and the optimization of these parameters is currently under investigation, particularly in patients with severe sepsis/septic shock. However, the only place for deep venous puncture or the first choice for puncture is often the femoral vein. Although venous saturation obtained from blood sampling from this catheter, instead of SvcO₂, has already been used in the diagnosis of severe tissue hypoperfusion, little is known about the accuracy of the results. The venous lactate in place of arterial puncture has also been used to guide therapeutic decisions. We conducted this literature review to seek evidence on the correlation and concordance of parameters obtained by collecting femoral venous blood gases in relation to SvcO₂ and arterial lactate. Few studies in the literature have evaluated the use of femoral venous oxygen saturation (SvfO₂) or venous lactate. The results obtained thus far demonstrate no adequate agreement between SvfO₂ and SvcO₂, which limits the clinical use of SvfO₂. However, the apparent strong correlation between arterial and peripheral and central venous lactate values suggests that venous lactate obtained from the femoral vein could eventually be used instead of arterial lactate, although there is insufficient evidence on which to base this procedure at this time.

Acute elevation of intra-abdominal pressure contributes to extravascular shift of fluid and proteins in an experimental porcine model

BACKGROUND

Intra-abdominal hypertension and abdominal compartment syndrome contribute significantly to increased morbidity and mortality in critically ill patients. This study describes pathophysiologic effects of the acutely elevated intra-abdominal pressure on microvascular fluid exchange and microcirculation. The resulting changes could contribute to development of organ dysfunction or failure.

METHODS

16 pigs were randomly allocated to a control-group (C-group) or an interventional group (P-group). After 60 min of stabilization, intra-abdominal pressure of the P-group animals was elevated to 15 mmHg by Helium insufflation and after 120 min to a level of 30 mmHg for two more hours. The C-group animals were observed without insufflation of gas. Laboratory and hemodynamic parameters, plasma volume, plasma colloid osmotic pressure, total tissue water content, tissue perfusion, markers of inflammation and cerebral energy metabolism were measured and net fluid balance and fluid extravasation rates calculated. Analysis of variance for repeated measurements with post-tests were used to evaluate the results with respect to differences within or between the groups.

RESULTS

In the C-group hematocrit, net fluid balance, plasma volume and the fluid extravasation rate remained essentially unchanged throughout the study as opposed to the increase in hematocrit (P < 0.001), fluid extravasation rate (P < 0.05) and decrease in plasma volume (P < 0.001) of the P-group. Hemodynamic parameters remained stable or were slightly elevated in the C-group while the P-group demonstrated an increase in femoral venous pressure (P < 0.001), right atrial pressure (P < 0.001), pulmonary capillary wedge pressure (P < 0.01) and mean pulmonary arterial pressure (P < 0.001). The protein mass decreased in both study groups but was significantly lower in the P-group as compared with the C-group, after 240 min of intervention. The increased intra-abdominal pressure was associated with elevated intracranial pressure and reduced tissue perfusion of the pancreas and the gastric- and intestinal mucosa.

CONCLUSION

Elevation of intra-abdominal pressure has an immediate impact on microvascular fluid extravasation leading to plasma volume contraction, reduced cardiac output and deranged perfusion of abdominal organs.

A new model for the study of secondary intra-abdominal hypertension in rats

BACKGROUND

To build a new and appropriate model of secondary intra-abdominal hypertension (IAH) in rats.

METHODS

A total of 32 female Sprague-Dawley rats were randomized into four groups. Group I: the rats were hemorrhaged to a mean arterial pressure (MAP) of 40 mm Hg for 1 h and portal hypertension was induced by partial ligation of the portal vein 1 h later; Group II: after inducing portal hypertension, hemorrhagic shock of MAP of 40 mm Hg was induced and maintained for 1 h; Group III: after inducing portal hypertension, hemorrhagic shock of MAP of 40 mm Hg was induced and maintained for 2 h; Group IV: after inducing portal hypertension, hemorrhagic shock of MAP of 40 mm Hg was induced and maintained for 2 h, and a specially designed abdominal restraint device was used. After these procedures, respectively, the collected blood was reinfused and lactated Ringer solution was continuously infused until the secondary IAH model was established.

RESULTS

No models were built in Groups I, II, and III. One rat died in Group IV after portal vein ligation, and all the remaining rats successfully developed IAH; the success rate was 87.5%. During the resuscitation period, the average time was 5.26 ± 0.59 h and the average total infusion volume was 665.5 ± 86.04 mL/kg.

CONCLUSION

A rat model of secondary IAH was successfully established by resuscitation after a combination of inducing portal hypertension, hemorrhaging to a MAP of 40 mm Hg for 2 h, and using an abdominal restraint device. All these criteria mimic key etiological factors for the development of secondary IAH.

Femoral venous oxygen saturation is no surrogate for central venous oxygen saturation

OBJECTIVE

The purpose of our study was to determine if central venous oxygen saturation and femoral venous oxygen saturation can be used interchangeably during surgery and in critically ill patients.

DESIGN

Prospective observational controlled study.

SETTING

Nonacademic university-affiliated teaching hospital in The Netherlands.

PATIENTS

One hundred cardiac outpatients, 30 high-risk surgical patients, and 30 critically ill patients.

INTERVENTIONS

None.

METHODS AND MAIN RESULTS

We concurrently determined femoral venous oxygen saturation and central venous oxygen saturation in a group of 100 stable cardiac patients, which served as control group. Furthermore, we determined simultaneously femoral venous oxygen saturation and central venous oxygen saturation in 30 surgical patients and in 30 critically ill patients and evaluated changes over time. Correlation and agreement of femoral venous oxygen saturation and central venous oxygen saturation were assessed, including the difference between femoral venous oxygen saturation and central venous oxygen saturation.Despite significant correlation between obtained values of femoral venous oxygen saturation and central venous oxygen saturation (rs = 0.55; p < .001), the limits of agreement were wide in the control group (mean bias 2.7% ± 7.9%; 95% limits of agreement -12.9% to 18.2%). In both the surgical and critically ill patients, limits of agreement (mean bias of -1.9% ± 9.3%; 95% limits of agreement -20.0% to 16.3%, and mean bias of 4.6% ± 14.3%; 95% limits of agreement -23.5% to 32.6%, respectively) were wide. Results for changes of femoral venous oxygen saturation and central venous oxygen saturation were similar. During initial treatment of critically ill patients, the difference between femoral venous oxygen saturation and central venous oxygen saturation including its range of variation diminished.

CONCLUSION

There is lack of agreement between femoral venous oxygen saturation and central venous oxygen saturation in both stable and unstable medical conditions. Thus, femoral venous oxygen saturation should not be used as surrogate for central venous oxygen saturation.

Does femoral venous pressure measurement correlate well with intrabladder pressure measurement? A multicenter observational trial

PURPOSE

To investigate if femoral venous pressure (FVP) measurement can be used as a surrogate measure for intra-abdominal pressure (IAP) via the bladder.

METHODS

This was a prospective, multicenter observational study. IAP and FVP were simultaneously measured in 149 patients. The effect of BMI on IAP was investigated.

RESULTS

The incidences of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) were 58 and 7% respectively. The mean APACHE II score was 22 ± 10, SAPS 2 score 42 ± 20, and SOFA score 9 ± 4. The mean IAP was 11.2 ± 4.5 mmHg versus 12.7 ± 4.7 mmHg for FVP. The bias and precision for all measurements were -1.5 and 3.6 mmHg respectively with the lower and upper limits of agreement being -8.6 and 5.7. When IAP was above 20 mmHg, the bias between IAP and FVP was 0.7 with a precision of 2.0 mmHg (lower and upper limits of agreement -3 and 4.6 respectively). Excluding those with ACS, according to the receiver operating curve analysis FVP = 11.5 mmHg predicted IAH with a sensitivity and specificity of 84.8 and 67.0% (AUC of 0.83 (95% CI 0.81-0.86) with P < 0.001). FVP = 14.5 mmHg predicted IAP above 20 mmHg with a sensitivity of 91.3% and specificity of 68.1% (AUC 0.85 (95% CI 0.79-0.91), P < 0.001). Finally, at study entry, the mean IAP in patients with a BMI less then 30 kg/m(2) was 10.6 ± 4.0 mmHg versus 13.8 ± 3.8 mmHg in patients with a BMI ≥ 30 kg/m(2) (P < 0.001).

CONCLUSIONS

FVP cannot be used as a surrogate measure of IAP unless IAP is above 20 mmHg.