Correlation between central venous pressure and peripheral venous pressure in medical intensive care unit patients

Mohamed A I. Hamedh; Abdelaziz A Al Shaari

doi:10.4103/LJMS.LJMS_72_19

ORIGINAL ARTICLE

Year : 2021 | Volume : 5 | Issue : 1 | Page : 21-24

Correlation between central venous pressure and peripheral venous pressure in medical intensive care unit patients

Mohamed A I. Hamedh¹, Abdelaziz A Al Shaari²
¹ Department of Medicine, Faculty of Medicine, University of Benghazi, Benghazi Medical Centre, Benghazi, Libya
² Department of Medicine, Faculty of Medicine, University of Benghazi, Hawari General Hospital, Benghazi, Libya

Date of Submission	27-Dec-2019
Date of Acceptance	01-Dec-2020
Date of Web Publication	10-Apr-2021

Correspondence Address:
Dr. Mohamed A I. Hamedh
Department of Medicine, Faculty of Medicine, University of Benghazi, Benghazi
Libya

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/LJMS.LJMS_72_19

Abstract

Introduction: Central venous pressure (CVP) is a hemodynamic variable commonly used in the intensive care setting to estimate right arterial pressure for evaluation and monitoring a patient's volume status. Risks such as infection, arterial puncture, hematoma, and pneumothorax associated with central venous cannulation can outweigh its benefits. This study was undertaken to determine if peripheral venous pressure (PVP) predicts CVP in medical intensive care unit (ICU) patients. Materials and Methods: This study was conducted on patients admitted to the medical ICU at AlJamhoriya Teaching Hospital in the period from January to September 2009. Sixty-six patients (aged 40–70 years) who were required a central venous line (CVL) were included prospectively in the study. CVP measured through internal jugular vein or subclavian vein by three ways CVL set insertion; and CVL placement was confirmed by chest X-ray. We used the manometers for the measurement of PVP; and 66 paired recordings of CVP and PVP were made. The correlation and Bland-Altman analysis of agreement were performed. Results: The mean (standard deviation [SD]; range) CVP was 11.3778 cmH2O (±5.6; −1.0–27.0); the mean PVP was 15.80 cmH2O (±5.9; 0.0–33.0); offset (bias) of PVP > CVP was 4.42 cmH2O with SD ± 3.62. The correlation of PVP on CVP was r = 0.8059, ( r² = 0.65), P < 0.0001. The 95% confidence intervals for the bias were 3.5352–5.3133 cmH2O. In the Bland-Altman analysis, lower and upper limits of agreement (95% LOA) were 2.7 (4.43–−7.20) and 11.63 (4.4–7.2) cmH₂O. Four out of 66 points were outside the LOA. The dashed zero lies between the LOA. Conclusion: Measurement of PVP from both antecubital area and dorsum of the hand correlated with CVP measurement with acceptable agreement. PVP measurement may be a noninvasive alternative way for estimating CVP.

Keywords: Central venous pressure, medical intensive care unit patients, peripheral venous pressure

How to cite this article:
I. Hamedh MA, Al Shaari AA. Correlation between central venous pressure and peripheral venous pressure in medical intensive care unit patients. Libyan J Med Sci 2021;5:21-4

How to cite this URL:
I. Hamedh MA, Al Shaari AA. Correlation between central venous pressure and peripheral venous pressure in medical intensive care unit patients. Libyan J Med Sci [serial online] 2021 [cited 2023 Mar 30];5:21-4. Available from: https://www.ljmsonline.com/text.asp?2021/5/1/21/313525

Introduction

Central venous pressure (CVP) is a hemodynamic variable commonly used in the operating room and intensive care setting to estimate right atrial pressure to evaluate and monitor a patient's volume status. However, risks such as infection, arterial puncture, hematoma, and pneumothorax associated with central venous cannulation can outweigh its benefits.^[1] Because the peripherally inserted central venous catheter (CVC) can be placed without the acute risks associated with direct catheterization of a CVC into the central vessels, it is an attractive alternative to the conventional CVC, or a centrally inserted central catheter,^[2] thus avoiding possible complications associated with direct central vein catheterization.

The transduction of CVP remains a valuable tool in the clinical practice of intravascular fluid volume management. Conventionally, a CVC introduced through the internal jugular or subclavian vein with the patient in the supine position is used for this purpose. In view of a variety of potential complications associated with the placement of required central venous lines (CVL), including pneumothorax,^[3] line infection,^[4] and vascular damage,^[5] a number of authors have suggested the use of peripherally transduced pressures (PVP) instead, based on the correlation found between CVP and PVP.^{[6],[7],[8],[9]} In addition, there is a patient population in which the surgical site contraindicates catheter placement, or the anatomy of the patients has been altered by surgery or radiation. Under these conditions, inserting a catheter into the jugular or subclavian veins may be difficult, if not impossible and associated with significant risks.^[10] Therefore, there is a trend toward using minimally invasive methods for hemodynamic monitoring to decrease the risk of complications associated with massive invasion.^[11]

The measurement of CVP is very common in clinical practice. The CVP can be obtained with transducers and electronic monitors, with a simple water manometer, and even by simply measuring jugular venous distension on physical examination.^[12] Despite its common use, the physiologic meaning of CVP and its clinical application are frequently misunderstood. This has resulted in many critical analyses of the value of CVP measurements.^[13],[14] Previous studies suggested a correlation of CVP with PVP in different clinical setups. The aim of this study was to determine whether a clinically acceptable agreement or a reliable correlation between CVP and PVP exist; and if CVP can be replaced by PVP in medical intensive care unit (ICU) patients and to determine the degree of agreement between PVP and CVP readings in medical ICU patients.

Materials and Methods

Research design

A prospective comparative research design was utilized in this study.

Setting

Medical ICU, ALJamhoriya Teaching Hospital, Benghazi, Libya.

Patients

This study was conducted on patients admitted to the medical ICU at AlJamhoriya Teaching Hospital in the period between January and September 2009. With ethical approval and informed consent, 66 patients (aged 40–70 years) were prospectively enrolled in the study. They were admitted with different clinical diagnosis and required a CVL. For every patient in the supine position, CVP measured through internal jugular vein or subclavian vein by three ways CVL set insertion; and CVL placement was confirmed by chest X-ray; we used the manometers way for measurement, and PVP measured through peripheral intravenous (IV) lines used IV cannula where inserted at antecubital area and dorsum of the hand; patency of the peripheral IV line was confirmed by the presence of a free-running infusion or by easy injection of 10 ml flush of normal saline with no evidence of pain or swelling at the insertion site; also we used the manometers for the measurement of PVP; and 66 paired recordings of CVP and PVP were made.

Procedure

After explanation of the procedure to the patients and equipment preparation, the catheter was inserted under aseptic techniques as following:

Positioning the patient in the Trendelenburg position with the head turned to the opposite side of insertion for CVC insertion, whereas the patient was positioned in the supine position with the arm extended for peripheral catheter insertion
The insertion site was prepared with povidone-iodine for 30 s for peripheral catheter insertion and for 2 min for CVC insertion and allowed to dry before insertion
Postcatheter insertion, CVC was checked for accurate location by using chest X-ray
CVP and PVP were measured immediately after insertion of both central and peripheral venous catheters.

Technique of pressure measurement

The proximal lumen of the triple lumen CVC was connected to manometers. The central line was flushed with 20 ml of normal saline solution and the manometer was zeroed at the phlebostatic axis, defined as the horizontal line extending from the mid-axillary line and the fourth intercostal space, and the CVP reading was obtained. The manometer was then disconnected from the central line and was connected to the peripheral line through low compliance extension tubing and a three-way stopcock. Continuity of the PVP catheter with the downstream venous system was demonstrated by observing pressure changes in the PVP form during circumferential proximal arm occlusion. The peripheral line was then flushed with 10 ml of normal saline solution to ensure its patency. The patient's upper limb from where PVP was measured was straightened and held out so that the antecubital vein and the manometer were placed at the phlebostatic axis, and the reading of PVP was obtained. Readings were obtained only if the patient was supine and were taken at the end of expiration. The patient's temperature and blood pressure were recorded before each measurement of venous pressure. Comparison between PVP and CVP was then recorded. Flushing was done with normal saline every 12 h to maintain catheters patency. After medication administration and Total Parental Nutrition (for CVC), the catheters were flushed with normal saline. Both catheters were flushed with 10 ml of normal saline solution before each venous pressure measurement to ensure catheter patency and for equilibration and after catheter flushing, the positive pressure was maintained by keeping the thumb on the plunger of the syringe while withdrawing the syringe to prevent blood back flow and clotting in the line. Dressing was changed routinely every 24 h on peripheral catheter site and immediately if the integrity of the dressing was compromised, and dressing was changed routinely every 48 h on central catheter site and immediately if the integrity of the dressing was compromised. The insertion site was visually inspected daily and palpated for tenderness through the intact dressing and assessed for the signs and symptoms of complications. Furthermore, catheter occlusion and the presence of any change in the ability to infuse or withdraw blood or IV fluid or presence of visible clots in the external portion of the catheter were assessed. Care of the catheter site was done using aseptic cleansing of the catheter-skin junction with povidone-iodine solution.

Statistical analysis

Data entry and analyses were performed using the SPSS statistical package version 13 (SPSS, Inc., Chicago, IL, USA). The Bland-Altman analysis of agreement were performed; Graph and Histogram were prepared was used to find association between columns and rows in qualitative data. Correlation between variables was done using Pearson correlation for parametric data. For all above mentioned statistical tests done, P < 0.05 indicates a significant result.

Results

The mean (standard deviation [SD]; range) CVP was 11.3778 cmH₂O (±5.6; −1.0–27.0); the mean PVP was 15.80 cmH2O (±5.9; 0.0–33.0) [Figure 1]; offset of PVP > CVP was 4.42 cmH2O with SD ± 3.62 [Table 1]. The correlation of PVP on CVP was r = 0.8059, ( r² = 0.65), P < 0.0001. The 95% confidence intervals were 3.5352–5.3133 cmH2O. In the Bland-Altman analysis, lower and upper limits of agreement (95% LOA) were-2.7 (4.43–−7.20) and 11.63 (4.4–7.2) cmH2O. Four out of 66 points were outside the LOA. The dashed zero lies between the LOA [Figure 2] and [Figure 3].

Figure 1: This histogram is normally distributed represents the central venous pressure readings (maximum and minimum) with the mean (11.37) and peripheral venous pressure readings (maximum and minimum) with the mean (15.80)

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Table 1: Correlation between CVP and PVP in studied sample

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Figure 2: This graph was drawn to reflect the extent of correlation between venous pressure measured using central cannula and venal pressure measured using peripheral cannula. The blot shows a positive correlation with a calculated r² = 0.65

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Figure 3: Bland-Altman plot of simultaneous peripheral venous pressure–central venous pressure offsets (y-axis) versus means (x-axis); all recordings. Heavy horizontal lines from above down: upper limits of agreement, bias, lower limits of agreement

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Discussion

IV access in the ICU settings is now a routine for the administration of fluids, blood products, drugs, parenteral nutrition, and hemodynamic monitoring. Unfortunately, this puts the critically ill patients at risk for iatrogenic complications such as pneumothorax, hemothorax, and risk of infections, especially blood stream infection which originating from the colonization of the catheter.^[15] The results of our study show there is a high correlation between CVP and PVP. It is not surprising that PVP and CVP are linked, given that the two sites of measurement are part of the same venous continuum.

Several studies have demonstrated that the difference between CVP and PVP varies with the value of CVP. In nine patients undergoing orthotopic liver transplantation, a weaker correlation between PVP and CVP was evident at low CVP.^[16] Another study showed that when CVP increased, the difference between PVP and CVP tended to decrease; when the measured CVP was ≥13 mmHg, the difference between PVP and CVP was <1 mmHg.^[17]

A question raised by our results is whether the measurement of PVP reveals local (peripheral vein), rather than systemic, physiological information. On an empirical level, the correlation between PVP and CVP argues that PVP reflects a systemic phenomenon. At that same empiric level, we chose to study a wide variety of patient and arm positions and catheter sites. We also know from clinical experience that, in the absence of extravasations or obstruction by clotting, IV catheters continue to flow unimpeded into the central circulation throughout surgery.^[18] This implies that fluid continuity is maintained between PVP and CVP sites despite changes in venous geometry that may occur with repositioning, and despite any venous valves that may intervene between the PVP site and the central circulation. Such valves are, by definition, open during steady state venous flow, and should therefore not disrupt fluid continuity between the two sites. Our study confirms that PVP correlates with CVP even under adverse hemodynamic conditions in ICU patients, ( r² = 0.65, P < 0.0001) with acceptable agreement, showed by Bland-Altman diagram. Other patient populations could benefit from PVP hemodynamic assessment when the risk of invasive CVP monitoring as pneumothorax, infection, and arrhythmia may outweigh the benefit. The strong correlation between PVP and CVP suggests an uninterrupted fluid column between the antecubital vein and the superior vena cava.

Finally, it can be seen that in critically ill patients, pressure measured through a catheter inserted into a peripheral vein correlates with CVP and whether changes in one are mirrored by changes in the other. Hence, peripheral venous catheter can be used as a minimally invasive technique to estimate volume status to minimize the complications which arising from using the CVC.

Conclusion

The measurement of PVP from both antecubital area and dorsum of the hand does not interfere with the agreement of CVP with PVP. A significant correlation was found between PVP and CVP with acceptable agreement. It was found that in critically ill patients, pressure measured via a catheter inserted into a peripheral vein correlates with CVP and whether changes in one are mirrored by changes in the other. PVP measurement may be a noninvasive alternative way to estimate volume status of critically ill patients and to minimize the complications which are arising from using and insertion of the CVCs.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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