Ultrasound Measurement of IVC Diameter and Collapsibility Index in Correlation with Central Venous Pressure in Critically Ill Patient

Introduction

Critically diseased cases are prone to life-threatening complications needing emergency care and admission to the Intensive Care Unit (ICU). They might demonstrate particular decompensations. Numerous critically events found in the general population like heart failure or severe sepsis. Clinical management of all these needs a specific method for critically diseased cases ⁽¹⁾.

A variety of methods are utilized for this objective, involving CVP measurement, physical examination, biochemical markers, pulmonary artery catheters, evaluating the vascular pedicle width, sonographic evaluation of IVC diameter, as well as numerous catheter devices ⁽²⁾.

Assessing central venous pressure (CVP) with the insertion of a CVC is the standard; nevertheless, it is invasive, time-consuming, and needs personnel who have received training. Moreover, it isn't practical in following-hospital settings or urgent resuscitation scenarios, and it involves complications and own risks. Numerous non-invasive techniques for measuring central venous pressure utilizing portable ultrasound as an alternative to invasive CVP measurement were suggested ⁽³⁾.

The difficulty related to CVP insertion consists of subcutaneous hematoma, failure to region the catheter, catheter malposition, arterial puncture, a systolic cardiac arrest, pneumo-thorax, hemothorax, and catheter-associated infection ⁽⁴⁾.

The variables of the IVC, like caval index, diameter, or collapsibility, act as indirect measures of central venous pressure for estimating the volume status of critically diseased cases and have been extensively researched, with varying and confli-cting outcomes ⁽⁵⁾.

The estimation of the inferior vena cava diameter and its alterations with respiratory cycle by US has been utilized to evaluate the volume status of a case, and it can be utilized as a substitute to CVC. It is a dynamic measurement of volume status, as it shows the volume alterations that occur with expiration and inspiration ⁽⁶⁾.

Bedside US is easily accessible in intensive care setups.  It is economical, safe, as well as non-invasive. US of the inferior vena cava is an instrument giving a noninvasive and quick method for gauging  preload and requirement for The resuscitation of fluids ⁽⁷⁾.

This investigation aimed to assess US measurement of collapsibility index and IVC diameter in association with CVP in critically diseased cases.

Patients and methods

This prospective observational research invo-lved 80 adult ICU cases with a CVC inserted for clinical central venous pressure follow-up

Inclusion criteria: Adult cases aged over 18 years who were hemodynamically stable; patients were required to be able to lie in a supine position and have a normal body mass index (BMI). Additionally, all included patients had a central venous catheter (CVC) already inserted via the internal jugular or subclavian vein for clinically indicated central venous pressure (CVP) monitoring.

Exclusion criteria: excluded patients with femoral catheters, bilateral CVC, or a history of radiotherapy to the chest or neck; those had active or earlier upper extremity deep venous thrombosis; or those who had received vasoactive medications (vasoconstrictors or diuretics) within 2 hours prior to the study to attain hemodynamic stability. Patients with clinically significant mitral or tricuspid regurgitation, recent chest or abdominal incisions (such as post-laparotomy), or elevated intra-abdominal or intrathoracic pressure were also excluded. Additionally, cases have been excluded if they were under 18 years of age, pregnant, chronically ventilated, undergoing chronic hemodialysis, or had known cardiac or liver disease.

Methods:

Data Collection

Upon ICU admission, demographic data including age and sex were recorded. Clinical diagnoses were documented, which included conditions such as sepsis, diabetic ketoacidosis, pneumonia, and heart failure.

Hemodynamic and Ultrasonographic

Assessment

Central Venous Pressure (CVP): CVP has been measured through a CVC inserted into the subclavian or internal jugular vein and connected to a calibrated pressure transducer. CVP readings were taken with the case in a supine position and at end-expiration. Depended on CVP values, cases have been categorized into three groups:

Group I: CVP < 7 cmH₂O

Group II: CVP 7–12 cmH₂O

Group III: CVP > 12 cmH₂O

Ultrasound Measurement of IVC: Bedside ultrasonography was performed using a curvilinear transducer (2–5 MHz) in the subxiphoid longitudinal view. The IVC diameter has been calculated two to three centimeters caudal to the hepatic vein-IVC junction.

IVC Maximum Diameter (IVCmax): Assessed at end-expiration.

IVC Minimum Diameter (IVCmin): Assessed at end-inspiration.

IVC Collapsibility Index (IVC-CI): Assessed utilizing the formula:

Other Parameters: Heart rate (HR) and Mean arterial pressure (ABP) have been recorded at the time of CVP and IVC measurement.

Statistical Analysis

Information has been examined utilizing SPSS software. Quantitative variables have been represented as mean ± standard deviation or median (range) as suitable. Variances between CVP-based groups have been analyzed utilizing ANOVA or Kruskal-Wallis tests, while correlations were assessed using Pearson or Spearman coefficients. A p-value below 0.05 has been deemed statistically significant.

Results

The mean of patients age was 51.2 years (±14.5), varying from 20 to 75 years. The gender distribution has been fairly balanced, with 47.5 percent men and 52.5 percent woman participants. Clinically, sepsis was the most common diagnosis, influencing 30% of cases, followed by heart failure (27.5%), while other conditions had lesser percentage such as diabetic ketoacidosis (22.5%) and pneumonia (20%). (table 1)

Discussion

CVP is a frequently utilized variables for evaluating volume status in critically diseases cases.  This variable is usually assessed with a CVC inserted through the internal jugular veins or subclavian ⁽⁸⁾. The IVC is a thin-walled compliant vessel that adjusts to the body’s volume status via altering its diameter according to total volume of fluids found in the body ⁽⁹⁾.

Our results showed that the mean of age of 51.2 years (±14.5), varying from 20 to 75 years. The sex distribution has been fairly balanced, with 47.5 percent male and 52.5 percent woman participants. Clinically, sepsis was the most common diagnosis, influencing 30% of cases, followed by heart failure (27.5%), while other conditions had lesser percentage such as diabetic ketoacidosis (22.5%) and pneumonia (20%).

Consistent with our findings, Maghraby et al., ⁽⁴⁾ sought to evaluate volume status using the IVC collapsibility index (CI) and diameter in intensive care unit cases and its association with central venous pressure. The research enrolled a total of 100 cases admitted to the medical ICU. Of them, 53 (53.0%) were females and 47 (47.0%) were men with a mean age of 50.55 ± 14.87 years. Regarding clinical diagnosis, sepsis was the most common diagnosis, influencing 35% of cases, followed by diabetic ketoacidosis (22.0%) and pneumonia (18%). Other conditions such as heart failure (10%), hepatic encephalopathy (7%), autoimmune diseases (5%), and upper gastrointestinal bleeding (3%) were less frequent.

In the study done by Badry et al., ⁽¹⁰⁾, who aimed to know the effect of fluid administration on the diameters of the IVC and common carotid artery in the prediction of volume status in critically diseased cases. They found that the mean age was 43.3±13.1 years, 52% were males, and 47.3% were females. Clinically, sepsis was the most prevalent cause, influencing 60% of cases.

Furthermore, Ilyas et al., ⁽¹¹⁾ aimed to evaluate the relation between IVC-CI, IVC diameters, and central venous pressure to evaluate the volume status in critically diseased cases. They found that the mean age of the patients was 50.4±19.3 years; there were 68% male and 32% female participants.

Our results showed that the mean arterial blood pressure (ABP) averaged 80.2 mmHg (±11.99), with a range from 60 to 120 mmHg, and the heart rate (HR) was elevated on average at 104.1 beats per minute (±22.5), ranging from 75 to 140, consistent with a stressed or compen-satory state. Central venous pressure (CVP) values showed a median of 8 cmH₂O (range 2–22), with nearly half of the patients (46.25%) classified in Group I (CVP < 7), 38.75% in Group II (CVP 7–12), and 15% in Group III (CVP > 12). The mean maximum inferior vena cava diameter was 16.56±4.56 mm, and the mean minimum diameter was 9.48±5.82 mm.

In alignment with our results, Maghraby et al., ⁽⁴⁾ found that the mean arterial blood pressure (ABP) was 80.16 ± 12.91, with a range from 60 to 120 mmHg, and the mean heart rate (HR) was 103.51 ± 22.70 beats per minute, ranging from 75 to 140, consistent with a stressed or compensatory state. The central venous pressure (CVP) of the studied group ranged from 2 to 22, with a median of 8, with nearly half of the patients (46.0%) classified in Group I (CVP < 7), 39% in Group II (CVP 7–12), and 15.0% in Group III (CVP > 12). The mean maximum diameter of the IVC was 3.03 ± 0.52, and the mean minimum diameter was 2.30 ± 0.51, reflecting variable intravascular volume status. The mean IVC-CI was 23.67 ± 11.71, ranging from 6.5% to 48.7%.

In cross-sectional research, Ilyas et al., ⁽¹¹⁾ observed that the mean arterial pressure was 82.6 ± 21.1 millimeters of mercury and the mean heart rate was 95.2 ± 21.1 beats per minute. The mean CVP was 10.38 ± 4.14 cmH2O, accompanied by an IVC-CI of 30.68 ± 10.93. Among the cases, twenty-six percent exhibited a central venous pressure of less than eight cmH2O, forty-eight percent had a CVP ranging from eight to twelve cmH2O, and twenty-six percent presented with a CVP above twelve cmH2O. The mean minimum diameter of the IVC was 1.17 ± 0.27 centimeters, whereas the maximum diameter was 1.75 ± 0.27 centimeters.

Our outcomes illustrated that a statistically insignificant distinction has been found between the examined groups with regard to IVC Diameter Max, while a statistically significant variance has been observed among the examined groups with regard to Mean ABP, heart rate, IVC Diameter Min, and IVC-CI.

In accordance with our outcomes, Badry et al., ⁽¹⁰⁾ observed that a statistically significant variance has been found among the examined groups (CVP>8 and CVP<8) regarding IVC Diameter Min and IVC-CI (P<0.001).

In addition, Ilyas et al., ⁽¹¹⁾ reported that a statistically significant variance has been observed among the examined groups regarding the mean heart rate, IVC Diameter Min, and IVC-CI (P < 0.001).

As well, in alignment with our results, Singh et al, ⁽⁷⁾ who aimed to notice an association between collapsibility index and inferior vena cava diameter with central venous pressure in critically diseased cases. They observed that there was statistically significant variance among the examined groups with regard to heart rate and IVC Diameter Min.

In the research performed by Maghraby et al., ⁽⁴⁾ they revealed that IVC min and IVC max decreased in group I (hypovolemic patients, CVP < 7) compared with group II (euvolemic patients, CVP 7-12) and group III (hypervolemic patients, CVP < 12). However, IVC-CI showed a substantial improvement in hypovolemic patients compared with patients with normal volume status and hypervolemic patients.

Unlike our results, Ilyas et al., ⁽¹¹⁾ observed that there was a statistically insignificant distinction among the examined groups with regard to mean arterial pressure (P=0.625), while there was a statistically significant distinction among the examined groups with regard to IVC diameter max.

Also, in contrast with our results, Singh et al., ⁽⁷⁾ reported that there was a statistically insigni-ficant variance among the examined groups with regard to IVC-CI (P=0.08), whereas a statistically significant alteration has been found between the examined groups with regard to IVC diameter max.

Our results illustrated that there was a significant positive association among CVP

and mean ABP, between CVP and IVC Max, and between IVC Min and CVP, while there was a significant negative relation among CVP and HR and between inferior vena cava collapsibility index and CVP.

In accordance with our results, Maghraby et al., ⁽⁴⁾ found that the mean CVP was significantly associated with IVC diameter at expiration (IVC max), IVC diameter at inspiration (IVC min), and mean ABP (r = 0.234, 0.800, and 0.914, respectively), whereas there was an inverse significant relation with IVC-CI and HR (r = -0.803 and -0.789, respectively).

Also, in agreement with our results, Badry et al., ⁽¹⁰⁾ observed that there was a positive association between CVP and IVC max and IVC min diameters (r = 0.895 and 0.890, respectively), whereas there was a negative association among IVC-CI and CVP (r equal -0.347).

As well, in line with our results, Ilyas et al.,, ⁽¹¹⁾ revealed that there was a strong positive association among maximum IVC diameter and CVP (r equal 0.371, p-value under 0.0005) and minimum IVC diameter (r equal 0.572, p-value under 0.0005), whereas a strong negative linear correlation has been found among the inferior vena cava collapsibility index and the CVP, that was statistically significant (r equal -0.827, p-value under 0.0005).

Moreover, in agreement with our results, Mahrous et al., ⁽¹²⁾ who observed a highly statistically significant negative correlation among CVP and IVC-CI (P<0.001).

Furthermore, in alignment with our results, Singh et al., ⁽⁷⁾ illustrated that there was a positive correlation between the CVP and the maximum diameter of IVC and the minimum diameter of IVC, while there was a negative linear association among the CVP and the IVC-CI.

In the study conducted by Dodhy ⁽¹³⁾, the association between sonographic assessment of IVC diameter and its collapsibility index and CVP was identified. A significant association has been observed between IVC measures (IVC collapsibility index and the diameters) and CVP (p-value under 0.001).