Correlation of peripheral venous pressure and central venous pressure in surgical patients

Association Between the Liver Fibrosis Markers and Scores, and Hemodynamic Congestion Assessed by Peripheral Venous Pressure in Patients With Acute Heart Failure

Background Peripheral venous pressure (PVP) has been shown to be a reliable surrogate for right atrial pressure in assessing congestion in patients with heart failure (HF). Liver fibrosis markers and scores can be useful in assessing organ injury in patients with acute HF. This study aimed to investigate the association of liver fibrosis markers and scores with PVP in patients with acute HF. Methods and Results The 7S domain of the collagen type IV N-terminal propeptide (P4NP 7S), aspartate aminotransferase-to-platelet ratio index, fibrosis-4, and nonalcoholic fatty liver disease fibrosis score were determined along with PVP measurements before discharge in 229 patients with acute HF. The strongest correlation with PVP was found for P4NP 7S (Pearson r=0.40). Patients with high P4NP 7S levels (≥median [6.2 ng/mL]) had an increased risk of cardiovascular death or HF hospitalization (adjusted hazard ratio [HR], 1.80 [95% CI, 1.09-3.04], P=0.02). The concomitant high PVP (≥mean [8 mm Hg])/high P4NP 7S group, in contrast to the high PVP/low P4NP 7S or low PVP/high P4NP 7S group, had a significant risk relative to the low PVP/low P4NP 7S group for cardiovascular death or HF hospitalization (adjusted HR, 2.63 [95% CI, 1.43-5.05], P=0.002). A sustained elevation in PVP for 1 month postdischarge was associated with a persistent increase in P4NP 7S. Conclusions The study demonstrated the relationship between the liver fibrosis marker P4NP 7S and congestion. PVP and P4NP 7S could be useful for assessing congestion-related organ injury and predicting prognosis in patients with acute HF.

Ultrasound-guided venous pressure measurement

Current standard technique for venous pressure measurement is still invasive, requiring insertion of a catheter. Additionally, clinical estimation of central venous pressure (CVP) has proven unreliable compared to invasive methods. Meanwhile, different non-invasive ultrasound guided modalities may provide a valid alternative to invasive venous pressure measurement. Particularly promising is a novel compression ultrasound (CUS) which combines ultrasound properties with a tissue pressure manometer enabling even further future applications. This review provides an overview using ultrasound guided non-invasive venous pressure measurement (UGPni) in clinical trials so far and focuses on three objectives: (1) To summarize the main methods using UGPni for central venous pressure measurement (2) To outline the key findings of previous clinical trials for UGPni regarding CVP measurement with primary focus on novel compression ultrasound of a forearm vein (3) To point out limitations and possible future clinical implications of these ultrasound modalities UGPni represents an easy-to-perform and safe alternative to invasive "gold standard" diagnostic tools for measuring central venous pressure. After a brief introduction, non-specialist personnel using a portable ultrasound device can apply this method in a feasible way. Of all mentioned methods in this review CUS is the method of choice underscoring its ability to assess a patient's CVP categories correctly. Furthermore, detection of non-invasive central venous pressure in the emergency room represents an independent predictor for cardiac rehospitalization in patients with decompensated heart failure, thus helping in risk stratification as well as being an additive tool in general hemodynamic management of critically ill patients. This review concludes a significant role for ultrasound guided non-invasive venous pressure measurement suitable for a wide range of everyday clinical practice. However, further studies are warranted to proof a causal relationship in this regard.

A Novel Non-Invasive Device for the Assessment of Central Venous Pressure in Hospital, Office and Home

Background

Venous congestion can be quantified by central venous pressure (CVP) and its monitoring is crucial to understand and follow the hemodynamic status of patients with cardio-respiratory diseases. The standard technique for CVP measurement is invasive, requiring the insertion of a catheter into a jugular vein, with potential complications. On the other hand, the current non-invasive methods, mainly based on ultrasounds, remain operator-dependent and are unsuitable for use in the home environment. In this paper, we will introduce a novel, non-invasive device for the hospital, office and home assessment of CVP.

Methods

After describing the measurement concept, we will report a preliminary experimental study enrolling 5 voluntary healthy subjects to evaluate the VenCoM measurements’ repeatability, and the system’s capability in measuring small elicited venous pressure variations (2 mmHg), as well as an induced venous hypertension within a pathological range (12÷20 mmHg).

Results

The experimental measurements showed a repeatability of ±1mmHg. The VenCoM device was able to reliably detect the elicited venous pressure variations and the simulated congestive status.

Discussion and Conclusion

The proposed non-invasive VenCoM device is able to provide a fast and repeatable CVP estimate, having a wide spectrum of potential clinical applications, including the monitoring of venous congestion in heart failure patients and in subjects with renal and hepatic dysfunction, as well as pulmonary hypertension (PH) that can be extended to pneumonia COVID-19 patients even after recovery. The device needs to be tested further on a large sample size of both healthy and pathological subjects, to systematically validate its reliability and impact in clinical setting.

Relation of Peripheral Venous Pressure to Central Venous Pressure in Patients With Heart Failure, Heart Transplant, and Left Ventricular Assist Device

Peripheral venous pressure (PVP) monitoring is a noninvasive method to assess volume status. We investigated the correlation between PVP and central venous pressure (CVP) in heart failure (HF), heart transplant (HTx), and left ventricular assist device (LVAD) patients undergoing right heart catheterization (RHC). A prospective, cross-sectional study examining PVP in 100 patients from October 2018 to January 2020 was conducted. The analysis included patients undergoing RHC admitted for HF, post-HTx monitoring, or LVAD hemodynamic testing. Sixty percent of patients had HF, 30% were HTx patients, and 10% were LVAD patients. The mean PVP was 9.4 ± 5.3 mm Hg, and the mean CVP was 9.2 ± 5.8 mm Hg. The PVP and CVP were found to be highly correlated (r = 0.93, p < 0.00001). High correlation was also noted when broken down by HF (r = 0.93, p < 0.00001), HTx (r = 0.93, p < 0.00001), and LVAD groups (r = 0.94, p < 0.00005). In conclusion, there is a high degree of correlation between PVP and CVP in HF, HTx, and LVAD patients. PVP measurements can be used as a rapid, reliable, noninvasive estimate of volume status in these patient populations.

Respiratory changes in biometry of suprarenal inferior vena cava in patients with varicose veins of lower extremities

AIM

This study examines respiratory biometry of inferior vena cava in patients with varicose veins of lower extremities.

MATERIAL AND METHODS

We performed retrospective analysis of clinical and ultrasound data of 67 patients with primary varicose veins.

RESULTS

The largest expiratory (mean 16.2 mm, p-value 0.09) and inspiratory (mean 8.2 mm, p-value 0.02) inferior vena cava diameters were in C3 Clinical Etiological Anatomical Pathophysiological clinical class; the smallest expiratory diameters (mean 13.1 mm, p-value 0.5) were in C6 class; the smallest inspiratory diameters (mean 4.6 mm, intercept) were in C2 class. C2 class was associated with highest inferior vena cava collapsibility index (mean 68.2%, intercept); C6 class was associated with lowest collapsibility index (mean 48.3%, p-value 0.04).Recurrent varices in comparison with previously untreated were associated with smaller inspiratory diameters of inferior vena cava (mean 4.4 mm, p-value 0.005), smaller expiratory diameters (mean 13.4 mm, p-value 0.06) and higher collapsibility index (mean 68.5%, p-value 0.005). Patients with recurrent and bilateral varicose veins had identical respiratory biometry of inferior vena cava.Older age was associated with smaller inferior vena cava diameters (p-value <0.01).

CONCLUSION

Clinical presentation of varicose veins is associated with different respiratory biometry of suprarenal inferior vena cava. C6 clinical class in comparison with C2 clinical class is associated with lower central venous compliance possible due to the narrowing of inferior vena cava. Smaller inferior vena cava diameters and higher collapsibility index in recurrent subgroup in comparison with previously untreated can be a sign of the significantly altered pressure gradient between the systemic capillaries and the right heart and impaired peripheral venous return. Narrowing of inferior vena cava with age can be a sign of more profound changes in systemic venous return with age in patients with varicose veins in comparison to those without chronic venous disease.

Peripheral venous pressure accurately predicts central venous pressure in the adult Fontan circulation

BACKGROUND

Patients with the Fontan circulation lack a subpulmonary ventricular pump and thus the main driver for pulmonary blood flow is a high central venous pressure. Peripheral venous pressure (PVP) measurement has been shown to be a reproducible and fairly accurate surrogate for central venous pressure (CVP), but not specifically for the adult Fontan circulation. This study aims to determine the relationship of PVP to CVP in adult Fontan patients.

METHODS

All adult patients (≥18 yo) with a Fontan circulation undergoing cardiac catheterization were included. Both CVP and PVP were measured during the catheterization. The relationship between the peripheral venous and central venous pressures was assessed using simple linear regression and the Bland-Altman plot analysis for differences.

RESULTS

Thirty-eight adult Fontan patients (mean age 30.7 ± 8.5, range 18-52 years) undergoing 43 cardiac catheterizations were analyzed. The mean CVP was 17.3 +/- 4.7 mmHg. The mean PVP was 18.4 +/- 5 mmHg. CVP and PVP were highly correlated, with an R² value of 0.83 (p < 0.001). The CVP can be estimated with PVP measurements using the formula CVP = (0.86 * PVP) + 1.3. A Bland-Altman plot for PVP and CVP demonstrated that the PVP overestimated CVP by a mean of 1.2 mmHg, with a 95% limit of agreement of -5.2 mmHg to 2.8 mmHg.

CONCLUSIONS

In adult Fontan patients, measuring PVP is a reliable, less-invasive, and accurate method of estimating the CVP during cardiac catheterization procedures. These findings may enable outpatient monitoring of Fontan hemodynamics.

Physiology and clinical utility of the peripheral venous waveform

The peripheral venous system serves as a volume reservoir due to its high compliance and can yield information on intravascular volume status. Peripheral venous waveforms can be captured by direct transduction through a peripheral catheter, non-invasive piezoelectric transduction, or gleaned from other waveforms such as the plethysmograph. Older analysis techniques relied upon pressure waveforms such as peripheral venous pressure and central venous pressure as a means of evaluating fluid responsiveness. Newer peripheral venous waveform analysis techniques exist in both the time and frequency domains, and have been applied to various clinical scenarios including hypovolemia (i.e. hemorrhage, dehydration) and volume overload.

Antistasis Retrograde Flow Vascular Catheter: A Novel Solution to Thrombogenicity: A Computational Fluid Dynamics Study

BACKGROUND

Catheter-related thrombosis (CRT) is a serious complication of vascular catheters. Retrograde catheter insertion has been shown to decrease pericatheter hemostasis and thrombosis, but it is technically challenging. The current in silico trial is an analytical approach to evaluating different approaches to designing retrograde flow into a vascular catheter.

METHODS

The novel catheter design aims to provide antistasis retrograde flow (ASRF) of fluid through multiple backward-directed side openings, with a self-closing terminal opening to facilitate standard insertion. Four different models of the catheter were evaluated by computational fluid dynamic studies, with retrograde-angled openings of 15°, 30°, 45°, and 60° to the long axis of the catheter.

RESULTS

ASRF successfully reduced the areas of fluid stagnation in models with 15° and 30° openings. Models with 45° and 60° did not significantly reduce stagnation. ASRF is reversed by the main bloodstream after a few millimeters. The novel catheter design achieved a slightly higher saline flow rate compared with the standard catheter (89.75, 91.72, 94.13, and 94.26 mL/min for 15°, 30°, 45°, and 60° designs, respectively, versus 86.93 mL/min for the standard catheter).

CONCLUSIONS

The novel ASRF vascular catheter reduces pericatheter fluid stasis and has the potential to reduce CRT. Further in vitro and in vivo trials are warranted to validate these findings and evaluate clinical efficacy.

A new approach to complicated and noisy physiological waveforms analysis: peripheral venous pressure waveform as an example

We introduce a recently developed nonlinear-type time-frequency analysis tool, synchrosqueezing transform (SST), to quantify complicated and noisy physiological waveform that has time-varying amplitude and frequency. We apply it to analyze a peripheral venous pressure (PVP) signal recorded during a seven hours aortic valve replacement procedure. In addition to showing the captured dynamics, we also quantify how accurately we can estimate the instantaneous heart rate from the PVP signal.

Peripheral i.v. analysis (PIVA) of venous waveforms for volume assessment in patients undergoing haemodialysis

Background

The assessment of intravascular volume status remains a challenge for clinicians. Peripheral i.v. analysis (PIVA) is a method for analysing the peripheral venous waveform that has been used to monitor volume status. We present a proof-of-concept study for evaluating the efficacy of PIVA in detecting changes in fluid volume.

Methods

We enrolled 37 hospitalized patients undergoing haemodialysis (HD) as a controlled model for intravascular volume loss. Respiratory rate (F0) and pulse rate (F1) frequencies were measured. PIVA signal was obtained by fast Fourier analysis of the venous waveform followed by weighing the magnitude of the amplitude of the pulse rate frequency. PIVA was compared with peripheral venous pressure and standard monitoring of vital signs.

Results

Regression analysis showed a linear correlation between volume loss and change in the PIVA signal (R2=0.77). Receiver operator curves demonstrated that the PIVA signal showed an area under the curve of 0.89 for detection of 20 ml kg-1 change in volume. There was no correlation between volume loss and peripheral venous pressure, blood pressure or pulse rate. PIVA-derived pulse rate and respiratory rate were consistent with similar numbers derived from the bio-impedance and electrical signals from the electrocardiogram.

Conclusions

PIVA is a minimally invasive, novel modality for detecting changes in fluid volume status, respiratory rate and pulse rate in spontaneously breathing patients with peripheral i.v. cannulas.

The Influence of Flushing Epidural Catheters before use on Detection of Intravenous Placement: An in Vitro and in Vivo Study

Undetected intravenous placement of epidural catheters is rare but potentially fatal and no perfect identification method exists. Epidural catheters may be flushed before insertion to identify faulty epidural catheters, or to prime the system with local anaesthetic. We hypothesised that flushing epidural catheters before insertion may delay the detection of intravenous placement. We investigated our theory using both in vitro and in vivo models. The in vitro component examined flowrates in flushed and unflushed epidural catheters, using conditions designed to mimic epidural venous pressure. The in vivo component examined the flow within flushed and unflushed epidural catheters inserted into the forearm veins of 20 anaesthetised patients, using a randomised crossover design. The endpoint utilised for both components was the time taken for frank blood to reach the 20 cm mark on the epidural catheter. Blood flow to the 20 cm mark on the epidural catheter was significantly faster in the unflushed catheters than the flushed catheters, both in vitro and in vivo (in vitro, unflushed median = 18.6 s (range: 18.0 to 20.5 s), flushed 37.6 s (32.6 to 91.2 s), P=0.0009; in vivo, unflushed 9.2 seconds (range 5.0 to 35.3 s), flushed 19.2 s (10.6 to 47.4 s), P=0.003 in vivo). Flushed catheters also demonstrated a greater variability in the range of flowrates. Flushing epidural catheters before insertion may delay the detection of intravenous placement.

Diastolic Function and Peripheral Venous Pressure as Indices for Fluid Responsiveness in Cardiac Surgical Patients

OBJECTIVE

Identifying fluid responsiveness is critical to optimizing perfusion while preventing fluid overload. An experimental study of hypovolemic shock resuscitation showed the importance of ventricular compliance and peripheral venous pressure (PVP) on fluid responsiveness. The authors tested the hypothesis that reduced ventricular compliance measured using transesophageal echocardiography results in decreased fluid responsiveness after a fluid bolus.

DESIGN

Prospective observational study.

SETTING

Two-center, university hospital study.

PARTICIPANTS

The study comprised 29 patients undergoing elective coronary revascularization.

INTERVENTION

Albumin 5%, 7 mL/kg, was infused over 10 minutes to characterize fluid responders (>15% increase in stroke volume) from nonresponders.

MEASUREMENTS AND MAIN RESULTS

Invasive hemodynamics and the ratio of mitral inflow velocity (E-wave)/annular relaxation (e'), or E/e' ratio, were measured using transesophageal echocardiography to assess left ventricular (LV) compliance at baseline and after albumin infusion. Fifteen patients were classified as responders and 14 as nonresponders. The E/e' ratio in responders was 7.4 ± 1.9 at baseline and 7.1 ± 1.8 after bolus. In contrast, E/e' was significantly higher in nonresponders at baseline (10.7 ± 4.6; p = 0.04) and further increased after bolus (12.6 ± 5.5; p = 0.002). PVP was significantly greater in the nonresponders at baseline (14 ± 4 mmHg v 11 ± 3 mmHg; p = 0.02) and increased in both groups after albumin infusion. Fluid responsiveness was tested using the area under the receiver operating characteristic curve and was 0.74 for the E/e' ratio (95% confidence interval 0.55-0.93; p = 0.029) and 0.72 for the PVP (95% confidence interval 0.52-0.92; p = 0.058).

CONCLUSION

Fluid responders had normal LV compliance and lower PVP at baseline. In contrast, nonresponders had reduced LV compliance, which worsened after fluid bolus. E/e,' more than PVP, may be a useful clinical index to predict fluid responsiveness.

Peripheral Venous Pressure Measurements in Patients With Acute Decompensated Heart Failure (PVP-HF)

BACKGROUND

Accurate assessment of volume status is essential in diagnosis and guidance of decongestive therapy in patients with acute heart failure. We sought to compare peripheral venous pressure (PVP) with central venous pressure (CVP), as well as other invasive hemodynamic measurements, in patients hospitalized with an acute heart failure syndrome.

METHODS AND RESULTS

PVP-HF (Peripheral Venous Pressure Measurements in Patients With Acute Decompensated Heart Failure) was a single-center prospective study, which enrolled patients admitted with acute heart failure, regardless of ejection fraction or disease pathogenesis. PVP and intracardiac pressures were obtained by transducing a peripheral intravenous and pulmonary artery catheter, respectively, after zeroing at the phlebostatic axis. Data were compared using Pearson's correlation coefficient and Bland-Altman plots. A total of 30 patients (median age 64 years, 73% male, 30% ischemic pathogenesis) were enrolled. Mean ejection fraction was 31%, and 60% had moderate or greater right ventricular dysfunction. Median PVP was 9.5 (6-17) mm Hg, CVP was 8.5 (6-18) mm Hg, and pulmonary capillary wedge pressure was 18 (14-21) mm Hg. PVP and CVP were found to be highly correlated (r=0.947), while PVP and pulmonary capillary wedge pressure were found to be moderately correlated (r=0.565). The mean difference between PVP and CVP was 0.4 mm Hg and between PVP and pulmonary capillary wedge pressure was 7.5 mm Hg.

CONCLUSIONS

In patients with acute heart failure syndromes, a simple assessment of PVP demonstrates a high correlation with CVP. These findings suggest that PVP may be useful in the standard bedside clinical assessment of volume status in these patients to help guide decongestive therapy.

Peripheral Venous Pressure as an Indicator of Preload Responsiveness During Volume Resuscitation from Hemorrhage

BACKGROUND

Fluid resuscitation of hypovolemia presumes that peripheral venous pressure (PVP) increases more than right atrial pressure (RAP), so the net pressure gradient for venous return (PVP-RAP) rises. However, the heart and peripheral venous system function under different compliances that could affect their respective pressures during fluid infusion. In a porcine model of hemorrhage resuscitation, we examined whether RAP increases more than PVP, thereby reducing the venous return pressure gradient and blood flow.

METHODS

Anesthetized pigs (n = 8) were bled to a mean arterial blood pressure of 40 mm Hg and resuscitated with stored blood and albumin for pulmonary artery occlusion pressures (PAOPs) of 5, 10, 15, and 20 mm Hg. Venous pressures, inferior vena cava blood flow (ultrasonic flowprobe), and left ventricular diastolic compliance (Doppler echocardiography) were measured. Stroke volume variability was calculated.

RESULTS

With volume resuscitation, the slope of RAP exceeded PVP (P ≤ 0.0001) when PAOP is 10 to 20 mm Hg, causing the pressure gradient for venous return to progressively decrease. Inferior vena cava blood flow did not further increase after PAOP > 10 mm Hg. The E/e' ratio increased (P = 0.001) during resuscitation indicating reduced diastolic compliance. A significant curvilinear relationship was found between PVP and stroke volume variability (R = 0.62; P < 0.001), where fluid responders had PVP < 15 mm Hg.

CONCLUSIONS

Fluid resuscitation above a PAOP 10 mm Hg reduces myocardial compliance and reduces the venous return pressure gradient. The hemodynamic response to fluid resuscitation becomes limited by diastolic properties of the heart. PVP measurement during hemorrhage resuscitation may predict fluid responsiveness and nonresponsiveness.

Comparison between noninvasive measurement of central venous pressure using near infrared spectroscopy with an invasive central venous pressure monitoring in cardiac surgical Intensive Care Unit

Introduction:

Central venous pressure (CVP) measurement is essential in the management of certain clinical situations, including cardiac failure, volume overload and sepsis. CVP measurement requires catheterization of the central vein which is invasive and may lead to complications. The aim of this study was to evaluate the accuracy of measurement of CVP using a new noninvasive method based on near infrared spectroscopy (NIRS) in a group of cardiac surgical Intensive Care Unit (ICU) patients.

Methodology:

Thirty patients in cardiac surgical ICU were enrolled in the study who had an in situ central venous catheter (CVC). Sixty measurements were recorded in 1 h for each patient. A total of 1800 values were compared between noninvasive CVP (CVPn) obtained from Mespere VENUS 2000 CVP system and invasive CVP (CVPi) obtained from CVC.

Results:

Strong positive correlation was found between CVPi and CVPn (R = 0.9272, P < 0.0001). Linear regression equation - CVPi = 0.5404 + 0.8875 × CVPn (r² = 0.86, P < 0.001), Bland–Altman bias plots showed mean difference ± standard deviation and limits of agreement: −0.31 ± 1.36 and − 2.99 to + 2.37 (CVPi–CVPn).

Conclusion:

Noninvasive assessment of the CVP based on NIRS yields readings consistently close to those measured invasively. CVPn may be a clinically useful substitute for CVPi measurements with an advantage of being simple and continuous. It is a promising tool for early management of acute state wherein knowledge of CVP is helpful.

Analysis of central venous pressure (CVP) signals using mathematical methods

Central venous pressure (CVP) is an important clinical parameter for physicians but only the absolute CVP value is typically monitored in the intensive care unit (ICU). In this study, we propose a novel mathematical method to present and analyze CVP signals. A total of 44 suitable samples were chosen from a total of 65 collected in an ICU. Pre-processing of the samples included rate reduction and digital filtering. The statistical features of time and frequency domain, wavelet, and empirical mode decomposition of these signals were extracted. We found no significant difference among the CVP signals regarding sex, smoking, coronary disease, and respiration mode of the samples.

Correlation between central venous pressure and peripheral venous pressure with passive leg raise in patients on mechanical ventilation

Background:

Central venous pressure (CVP) assesses the volume status of patients. However, this technique is not without complications. We, therefore, measured peripheral venous pressure (PVP) to see whether it can replace CVP.

Aims:

To evaluate the correlation and agreement between CVP and PVP after passive leg raise (PLR) in critically ill patients on mechanical ventilation.

Setting and Design:

Prospective observational study in Intensive Care Unit.

Methods:

Fifty critically ill patients on mechanical ventilation were included in the study. CVP and PVP measurements were taken using a water column manometer. Measurements were taken in the supine position and subsequently after a PLR of 45°.

Statistical Analysis:

Pearson's correlation and Bland–Altman's analysis.

Results:

This study showed a fair correlation between CVP and PVP after a PLR of 45° (correlation coefficient, r = 0.479; P = 0.0004) when the CVP was <10 cmH₂O. However, the correlation was good when the CVP was >10 cmH₂O. Bland–Altman analysis showed 95% limits of agreement to be −2.912–9.472.

Conclusion:

PVP can replace CVP for guiding fluid therapy in critically ill patients.

Peripheral venous pressure as a reliable predictor for monitoring central venous pressure in patients with burns

Background:

Optimizing cardiovascular function to ensure adequate tissue oxygen delivery is a key objective in the care of critically ill patients with burns. Hemodynamic monitoring may be necessary to optimize resuscitation in serious burn patients with reasonable safety. Invasive central venous pressure (CVP) monitoring has become the corner stone of hemodynamic monitoring in patients with burns but is associated with inherent risks and technical difficulties. Previous studies on perioperative patients have shown that measurement of peripheral venous pressure (PVP) is a less invasive and cost-effective procedure and can reliably predict CVP.

Objective:

The aim of the present prospective clinical study was to determine whether a reliable association exists between changes in CVP and PVP over a long period in patients admitted to the Burns Intensive Care Unit (BICU).

Subjects and Methods:

The CVP and PVP were measured simultaneously hourly in 30 burns patients in the BICU up to 10 consecutive hours. The predictability of CVP by monitoring PVP was tested by applying the linear regression formula and also using the Bland–Altman plots of repeated measures to evaluate the agreement between CVP and PVP.

Results:

The regression formula revealed a reliable and significant association between CVP and PVP. The overall mean difference between CVP and PVP was 1.628 ± 0.84 mmHg (P < 0.001). The Bland–Altman diagram also showed a perfect agreement between the two pressures throughout the 10 h period.

Conclusion:

Peripheral venous pressure measured from a peripheral intravenous catheter in burns patients is a reliable estimation of CVP, and its changes have good concordance with CVP over a long period of time.

Paradoxical muscle sympathetic reflex activation in human heart failure

BACKGROUND

Muscle sympathetic activation in heart failure with reduced ejection fraction (HFrEF) has been attributed, on the basis of multiunit recordings, to attenuated inhibitory feedback from stretch-sensitive cardiopulmonary mechanoreceptors. However, such preparations integrate 2 populations of single units exhibiting directionally opposite firing when atrial pressure is perturbed. We tested the hypothesis that the proportion of single units firing paradoxically when filling pressure increases is augmented in HFrEF.

METHODS AND RESULTS

Muscle sympathetic nerve activity and estimated central venous pressure were recorded during nonhypotensive lower body negative pressure (LBNP; -10 mm Hg) and nonhypertensive positive pressure (LBPP; +10 mm Hg) in 11 treated HFrEF (left ventricular ejection fraction 25 ± 6% [mean ± standard deviation]) patients and 14 similarly aged controls. Single-unit muscle sympathetic nerve activity discharge was termed either anticipated, if firing frequency exhibited classic negative-feedback responses, or paradoxical. LBNP and LBPP had no heart rate, stroke volume, or blood pressure effects (P>0.05). Estimated central venous pressure decreased with LBNP (P<0.05), increased with LBPP (P<0.05), and was consistently higher in HFrEF (P<0.05). During LBNP, the ratio of single units with anticipated and paradoxical discharge was similar in HFrEF (18:7) and controls (27:5), whereas LBPP elicited paradoxical reflex excitation in a greater proportion of HFrEF single units (7:18 versus 24:6; P=0.0001). Consequently, LBPP increased mean single-unit firing frequency (P<0.05) and did not inhibit multiunit muscle sympathetic nerve activity of HFrEF subjects (P<0.05 versus controls). Firing of 12/18 HFrEF (but no control) single units increased during both LBPP and LBNP.

CONCLUSION

These findings provide the first evidence in human HFrEF for an augmented excitatory cardiopulmonary-muscle sympathetic nerve activity reflex response to increased preload, incorporating 2 distinct single-unit populations with differing firing properties.

Hemodynamic effect and safety of intermittent sequential pneumatic compression leg sleeves in patients with congestive heart failure

BACKGROUND

Pneumatic leg sleeves are widely used after prolonged operations for prevention of venous stasis. In healthy volunteers they increase cardiac function. We evaluated the hemodynamic effects and safety of intermittent sequential pneumatic compression (ISPC) leg sleeves in patients with chronic congestive heart failure (CHF).

METHODS AND RESULTS

We studied 19 patients with systolic left ventricular dysfunction and CHF. ISPC leg sleeves, each with 10 air cells, were operated by a computerized compressor, exerting 2 cycles/min. Hemodynamic and echocardiographic parameters were measured before, during, and after ISPC activation. The baseline mean left ventricular ejection fraction was 29 ± 9.2%, median 32%, range 10%-40%. Cardiac output (from 4.26 to 4.83 L/min; P = .008) and stroke volume (from 56.1 to 63.5 mL; P = .029) increased significantly after ISPC activation, without a reciprocal increase in heart rate, and declined after sleeve deactivation. Systemic vascular resistance (SVR) decreased significantly (from 1,520 to 1,216 dyne-s/cm5; P = .0005), and remained lower than the baseline level throughout the study. There was no detrimental effect on diastolic function and no adverse clinical events, despite increased pulmonary venous return.

CONCLUSIONS

ISPC leg sleeves in patients with chronic CHF do not exacerbate symptoms and transiently improve cardiac output through an increase in stroke volume and a reduction in SVR.

A novel technique to predict pulmonary capillary wedge pressure utilizing central venous pressure and tissue Doppler tricuspid/mitral annular velocities

Assessing left ventricular (LV) filling pressure (pulmonary capillary wedge pressure, PCWP) is an important aspect in the care of patients with heart failure (HF). Physicians rely on right ventricular (RV) filling pressures such as central venous pressure (CVP) to predict PCWP, assuming concordance between CVP and PCWP. However, the use of this method is limited because discordance between CVP and PCWP is observed. We hypothesized that PCWP can be reliably predicted by CVP corrected by the relationship between RV and LV function, provided by the ratio of tissue Doppler peak systolic velocity of tricuspid annulus (S(T)) to that of mitral annulus (S(M)) (corrected CVP:CVP·S(T)/S(M)). In 16 anesthetized closed-chest dogs, S T and S M were measured by transthoracic tissue Doppler echocardiography. PCWP was varied over a wide range (1.8-40.0 mmHg) under normal condition and various types of acute and chronic HF. A significantly stronger linear correlation was observed between CVP·S(T)/S(M) and PCWP (R2 = 0.78) than between CVP and PCWP (R2 = 0.22) (P < 0.01). Receiver-operating characteristic (ROC) analysis indicated that CVP·S(T)/S(M) >10.5 mmHg predicted PCWP >18 mmHg with 85% sensitivity and 88% specificity. Area under ROC curve for CVP·S T/S M to predict PCWP >18 mmHg was 0.93, which was significantly larger than that for CVP (0.66) (P < 0.01). Peripheral venous pressure (PVP) corrected by S T/S M (PVP·S(T)/S(M) also predicted PCWP reasonably well, suggesting that PVP·S(T)/S (M) may be a minimally invasive alternative to CVP·S(T)/S(M) In conclusion, our technique is potentially useful for the reliable prediction of PCWP in HF patients.

Microneurographic evidence in healthy middle-aged humans for a sympathoexcitatory reflex activated by atrial pressure

Atrial mechanoreceptors, stimulated by increased pressure or volume, elicit in healthy humans a net sympathoinhibitory response. The co-existence of an atrial reflex eliciting muscle sympathoexcitation has been postulated but undetected by conventional multi-unit muscle sympathetic nerve activity (MSNA). We hypothesized that in response to a selective increase in atrial pressure, single-unit MSNA would reveal a subpopulation of efferent sympathetic neurons with firing patterns opposite to the integrated multi-unit MSNA envelope. Multi- and single-unit MSNA recordings were acquired in eight healthy middle-aged subjects (age, 57 ± 8 years; body mass index, 25 ± 2 kg/m2) submitted to selective decreases or increases in atrial pressure by nonhypotensive lower body negative pressure (LBNP; −10 mmHg) or nonhypertensive lower body positive pressure (LBPP; +10 mmHg), respectively. Single-unit MSNA firing responses were classified as anticipated if spike frequency and incidence increased with LBNP or decreased with LBPP and paradoxical if they decreased with LBNP or increased with LBPP. LBNP decreased (3.2 ± 2.8 to 1.4 ± 3.1 mmHg, P < 0.01) and LBPP increased (3.3 ± 2.7 to 4.9 ± 2.8 mmHg, P < 0.01) estimated central venous pressure without affecting stroke volume, systemic pressure, or resistance. Multi-unit MSNA increased with LBNP (31 ± 17 to 38 ± 19 bursts/min, P < 0.01) and diminished with LBPP (33 ± 15 to 28 ± 15 bursts/min, P < 0.01). Of 21 single-units identified, 76% exhibited firing responses to both LBNP and LBPP concordant with multi-unit MSNA, whereas 24% demonstrated discordant or paradoxical responses. The detection of two subpopulations of single-units within the multi-unit MSNA recording, exhibiting opposite firing characteristics, establishes the first evidence in humans for the existence of an excitatory cardiac-muscle sympathetic reflex activated by increasing atrial pressure.

Alternative methods to central venous pressure for assessing volume status in critically ill patients

INTRODUCTION

Early goal-directed therapy increases survival in persons with sepsis but requires placement of a central line. We evaluate alternative methods to measuring central venous pressure (CVP) to assess volume status, including peripheral venous pressure (PVP) and stroke volume variation (SVV), which may facilitate nurse-driven resuscitation protocols.

METHODS

Patients were enrolled in the emergency department or ICU of an academic medical center. Measurements of CVP, PVP, SVV, shoulder and elbow position, and dichotomous variables Awake, Movement, and Vented were measured and recorded 7 times during a 1-hour period. Regression analysis was used to predict CVP from PVP and/or SVV, shoulder/elbow position, and dichotomous variables.

RESULTS

Twenty patients were enrolled, of which 20 had PVP measurements and 11 also had SVV measurements. Multiple regression analysis demonstrated significant predictive relationships for CVP using PVP (CVP = 6.7701 + 0.2312 × PVP - 0.1288 × Shoulder + 12.127 × Movement - 4.4805 × Neck line), SVV (CVP = 14.578 - 0.3951 × SVV + 18.113 × Movement), and SVV and PVP (CVP = 4.2997 - 1.1675 × SVV + 0.3866 × PVP + 18.246 × Awake + 0.1467 × Shoulder = 0.4525 × Elbow + 15.472 × Foot line + 10.202 × Arm line).

DISCUSSION

PVP and SVV are moderately good predictors of CVP. Combining PVP and SVV and adding variables related to body position, movement, ventilation, and sleep/wake state further improves the predictive value of the model. The models illustrate the importance of standardizing patient position, minimizing movement, and placing intravenous lines proximally in the upper extremity or neck.

Comparative utility of centrally versus peripherally transduced venous pressure monitoring in the perioperative period in spine surgery patients

STUDY OBJECTIVE

To compare central venous pressure (CVP) with peripheral venous pressure (PVP) monitoring during the intraoperative and postoperative periods in patients undergoing spine surgery.

DESIGN

Prospective observational study.

SETTING

University-affiliated teaching hospital.

PATIENTS

35 ASA physical status 1, 2, and 3 patients.

INTERVENTIONS

A peripheral catheter in the forearm or hand and a central catheter into the internal jugular vein were placed for PVP and CVP monitoring, respectively.

MEASUREMENTS

CVP and PVP values were collected simultaneously and recorded electronically at 5-minute intervals throughout surgery and in the recovery room. The number of attempts for catheter placement, ease of use, maintenance, and interpretation were recorded. Patient comfort, frequency of complications, and cost were analyzed.

MAIN RESULTS

The correlation coefficient between CVP and PVP was 0.650 in the operating room (P < 0.0001) and 0.388 in the recovery room (P < 0.0001). There was no difference between groups in number of attempts to place either catheter, maintenance, and interpretation with respect to PVP and CVP monitoring in the operating room. In the recovery room, the nurses reported a higher level of difficulty in interpretation of PVP than CVP, but no differences were noted in ease of maintenance. There were no complications related to either central or peripheral catheter placement. Patient comfort and cost efficiency were higher with a peripheral than a central catheter.

CONCLUSION

During clinically relevant conditions, there was limited correlation between PVP and CVP in the prone position during surgery and postoperatively in the recovery room.

Comparison of the central venous pressure from internal jugular vein and the pressure measured from the peripherally inserted antecubital central catheter (PICCP) in liver transplantation recipients

Background

Unlike its use during stable conditions, central venous pressure (CVP) monitoring from a peripherally inserted central venous catheter (PICC) has not often been used in surgeries with significant hemodynamic alterations. The aim of this study was to evaluate the feasibility of measuring PICC pressure (PICCP) as an alternative to measuring centrally inserted central catheter pressure (CICCP) in adult liver transplantation (LT) patients.

Methods

We measured PICCP and CICCP simultaneously during each main surgical period in adult LT. Statistical analysis was performed using simple linear regression analysis to observe whether changes in PICCP paralleled by simultaneous changes in CICCP. Correlation analysis and Bland-Altman analysis were used to determine the degree of agreement between the two devices. Differences were considered statistically significant when P values were less than 0.05.

Results

A total of 1342 data pairs were collected from 35 patients. The PICCPs and CICCPs were highly correlated overall (r = 0.970, P < 0.001) as well as at each period measured. The differences among each period were not clinically significant (0.33 mmHg for pre-anhepatic, 0.32 mmHg for anhepatic, -0.15 mmHg for reperfusion, and -0.10 mmHg for neohepatic periods). The overall mean difference was 0.14 mmHg (95% confidence interval: 0.09-0.19) and PICCP tended to give a higher reading by between 0.09 and 0.19 mmHg overall. The limit of agreement was -1.74 to 2.02 overall.

Conclusions

These findings suggest that PICCP can be a reasonable alternative to CICCP in situations of dynamic systemic compliance and preload, as well as under stable hemodynamic conditions.

Peripheral venous pressure as a predictor of central venous pressure in continuous monitoring in children

BACKGROUND

Measurement of central venous pressure (CVP) is a reliable method for evaluating intravascular volume status and cardiac function; however it is an invasive and expensive method that may result in some complications such as arterial puncture, pneumothorax and development of infections. This study was performedto compare CVP measurements between central and peripheral catheters in infant and children with congenital heart disease.

METHODS

The CVP and peripheral venous pressure (PVP) were measured simultaneously in 30 patients within 10 consecutive hours.

RESULTS

The mean difference between CVP and PVP was 1.48±0.98 mmHg. The linear regression equation showed that CVP was 0.374+0.774 PVP (r(2) = 0.725).

CONCLUSION

PVP measured from a peripheral intravenous catheter in infants and children with congenital heart disease is an accurate estimation of CVP and its changes has good concordance with CVP over a long period of time.

Peripheral venous pressure as an alternative to central venous pressure in patients undergoing laparoscopic colorectal surgery

BACKGROUND

Peripheral venous pressure (PVP) is strongly correlated with central venous pressure (CVP) during various surgeries. Laparoscopic surgery in the Trendelenburg position with pneumoperitoneum typically increases CVP. To determine whether PVP convincingly reflects changes in CVP, we evaluated the correlation between PVP and CVP in patients undergoing laparoscopic colorectal surgery.

METHODS

Both CVP and PVP were measured simultaneously at predetermined time intervals during elective laparoscopic colorectal surgery in 42 patients without cardiac disease. The pairs of venous pressure measurements were analysed for correlation, and the Bland-Altman plots of repeated measures were used to evaluate the agreement between CVP and PVP.

RESULTS

A total of 420 data pairs were obtained. The overall mean CVP was 11.3 (sd 4.5) mm Hg, which was significantly lower than the measured PVP of mean 12.1 (4.5) mm Hg (P=0.005). There was a strong positive correlation between overall CVP and PVP (correlation coefficient=0.96, P<0.0001). The mean bias (PVP-CVP) corrected for repeated measurements using random-effects modelling was 0.9 mm Hg [95% confidence interval (CI) 0.54-1.19 mm Hg] with 95% limits of agreement of -1.2 mm Hg (95% CI -1.75 to -0.62 mm Hg) to 2.9 mm Hg (95% CI 2.35-3.48 mm Hg).

CONCLUSIONS

PVP displays a strong correlation and agreement with CVP under the increased intrathoracic pressure of pneumoperitoneum in the Trendelenburg position and may be used as an alternative to CVP in patients without cardiac disease undergoing laparoscopic colorectal surgery.

Noninvasive estimation of central venous pressure in anesthetized dogs by measurement of hepatic venous blood flow velocity and abdominal venous diameter

Determination of central venous pressure (CVP) is relevant to patients with right heart disease, hypovolemia, and following intravenous fluid therapy. We hypothesized that changes in CVP in dogs could be predicted by measurements of hepatic vein diameter, caudal vena cava (CVC) diameter, and hepatic venous flow velocities. Nine healthy American Foxhounds were anesthetized. Following baseline recordings, intravenous fluids were administered to increase CVP. Volume administration created treatment periods with CVP ranges of 5, 10, 15, 20, and 25 mm Hg. Flow velocities in the right medial hepatic vein were recorded using pulsed wave Doppler ultrasound. Hepatic vein, CVC, and aorta diameters were determined with B-mode ultrasound. Variables were compared across the treatment periods by ANOVA for repeated measures. Relationships between CVP, Doppler, and B-mode variables were evaluated using Spearman's rank correlations, multiple linear regression, and repeated measures linear regression. The a-, S- and v-wave velocities were augmented significantly with volume loading. The best part (semipartial) correlation coefficients predicting increasing CVP were identified with v-wave velocity (0.823), S-wave velocity (-0.800), CVC diameter (0.855), and hepatic vein diameter (0.815). Multiple linear regression indicated that CVP in this study could be predicted best by a combination of CVC and hepatic vein diameter and the v-wave velocity (r = 0.928). Ultrasound imaging identified gallbladder and pancreatic edema consistently, likely related to acute volume loading. These findings may be applicable in the assessment of volume status, dogs with right heart disease, and during serial monitoring of dogs receiving fluid or diuretic therapy.

Is external jugular venous pressure a good predictor of volume status in kidney graft recipients?

To ensure appropriate function of the transplanted organ, it is necessary to adequately maintain vascular volume during the kidney transplantation procedure. For this purpose, central venous pressure (CVP) is monitored through a catheter inserted into the superior vena cava (SVC). Central venous cannulation is associated with a risk of serious complications. An objective of this study was to investigate whether there was a correlation between pressures measured in the SVC and in the external jugular vein (EJV). We studied 33 chronically dialyzed patients who had a short catheter placed in the EJV because of difficulties in peripheral vein cannulation in the limbs. In each case, general anesthesia was induced and a central catheter inserted into the SVC. Every 10 minutes venous pressure measurements were obtained simultaneously at both sites. A significant (P < .001) correlation was observed between external jugular vein pressure (EJVP) and CVP. CVP could be described as a function of EJVP by the equation CVP = {0.90299 x EJVP} - 0.8361. The results of this study indicated that monitoring the EJVP allows equally efficient evaluation of vascular volume as the CVP. In our opinion, EJVP is sufficient to evaluate vascular volume during kidney transplantation in patients with difficult vascular access.

Correlation of sonographic measurements of the internal jugular vein with central venous pressure

Determination of volume status is crucial in treating acutely ill patients. This study examined bedside ultrasonography of the internal jugular vein (IJV) to predict central venous pressure (CVP). Ultrasonography was performed on 34 nonventilated patients with monitored CVPs. The IJV was measured during the respiratory cycle and with the patient in different positions. Mean IJV diameter in patients with CVP less than 10 cm H2O was 7.0 mm (95% confidence interval [CI], 5.7-8.3) vs 12.5 mm (95% CI, 11.2-13.8) in patients with CVP of 10 cm H2O and greater. Measurement of end expiratory diameter with the patient supine had the highest correlation coefficient: 0.82 (95% CI). There was strong agreement among ultrasonographers: correlation coefficient, 0.92 (95% CI). This pilot study shows promise that ultrasonography of the IJV can be a noninvasive tool to predict CVP. Measurement of end expiratory diameter in supine patients exhibited a high correlation to CVP.

Measurement of central venous pressure from a peripheral intravenous catheter in the prone position during spinal surgery

INTRODUCTION

A central venous pressure (CVP) measurement is used to assess intravascular status. Although this is usually accomplished by the placement of a central venous catheter (CVC), there are circumstances when placement may be technically difficult or impossible. The current study evaluates the feasibility of measuring CVP from a peripheral intravenous (IV) cannula in the prone position.

METHODS

CVP was simultaneously measured from a central venous catheter (CVC-P) and from a peripheral IV cannula (PVP). The continuity of the peripheral IV cannula with the central venous system was demonstrated by a change in the PVP during a sustained inspiratory effort.

RESULTS

The study cohort included 18 patients. All patients had 2 peripheral IV cannulae, and 10 PVP measurements were taken from each site. In 4 of the 36 cannulae (11%), there was no increase in the PVP in response to a sustained inspiratory effort. For these 4 cannulae, the PVP to CVC-P difference was 13 +/- 4 mm Hg. In the 32 cannulae in which the PVP increased in response to a sustained inspiratory effort, the PVP to CVC-P difference was 2 +/- 1 mm Hg (P < 0.0001), and the difference between the PVP and the CVC-P was <or=5 mm Hg in all of the sample sets. The accuracy of the technique did not vary based on the location of the peripheral cannula, its size, or the actual CVP reading.

CONCLUSION

Provided that the PVP increases to a sustained inspiratory breath, there is a clinically useful correlation between the PVP and the actual CVP in the prone position.

An anesthetic experience during open heart surgery in a patient with Budd-Chiari syndrome combined with superior vena cava syndrome: A case report

Budd-Chiari syndrome (BCS) is a rare disorder that arises from obstruction of the hepatic venous outflow tract. BCS causes various clinical status from liver cirrhosis and other systemic diseases that are usually fatal. BCS is caused by hypercoagulability, e.g, arising from malignancy, oral contraceptives, and deficiency of protein S or C. It is not rare that BCS often shows venous thrombosis, including in superior vena cava. We performed a cardiac anesthesia for a 44 year old male with BCS and total superior vena cava syndrome (SVCS) due to the hereditary protein S and C deficiency. Surgical relief of the hepatic outflow stenosis was performed during deep hypothermic circulatory arrest. The patient was managed successfully without conventional intraoperative hemodynamic monitoring such as central venous catheterization, pulmonary artery catheterization, or transesophageal echocardiography due to underlying SVCS and the risk of varix bleeding. After weaning of cardiopulmonary bypass, mild acidosis and hypoxia improved slowly in an intensive care unit. Hypercoagulability was controlled by warfarin during the first postoperative day.

Hypercapnic vs. hypoxic control of cardiovascular, cardiovagal, and sympathetic function

We compared the integrated cardiovascular and autonomic responses to hypercapnia and hypoxia to test the hypothesis that these stimuli differentially affect muscle sympathetic nerve activity (MSNA) discharge patterns and cardiovagal and sympathetic baroreflex function in a manner related to ventilatory chemoreflex sensitivity. Six males and six females underwent 5 min of hypoxia (end-tidal Po2 = 45 Torr) and 5 min of hypercapnia (end-tidal Pco2 = +8 Torr from baseline), causing similar ventilatory responses. A downward right shift in cardiovagal set point was observed during both conditions, which was strongly related to the change in inspiratory time (Ti) from baseline to hypercapnia (r2 = 0.67, P = 0.007) and hypoxia (r2 = 0.79, P < 0.001). Cardiovagal baroreflex gain was decreased during hypoxia (20.1 +/- 6.9 vs. 8.9 +/- 5.1 ms/mmHg, P < 0.001) but not hypercapnia (26.7 +/- 12.7 vs. 23.0 +/- 9.1 ms/mmHg). Both hypoxia and hypercapnia increased MSNA burst amplitude, whereas hypoxia, but not hypercapnia, also increased in MSNA burst frequency (21 +/- 9 vs. 28 +/- 7 bursts/min, P = 0.03) and total MSNA (4.56 +/- 3.07 vs. 7.37 +/- 3.26 mV/min, P = 0.002). However, neither hypercapnia nor hypoxia affected sympathetic burst probability or baroreflex gain. Hypoxia also caused a greater reduction in total peripheral resistance (P = 0.04), a greater increase in heart rate (P = 0.002), and a trend for a greater cardiac output response (P = 0.06) compared with hypercapnia. Nonetheless, central venous pressure remained unchanged during either condition. These results suggest that hypercapnia and hypoxia exert differential effects on cardiovagal, but not sympathetic, baroreflex gain and set point in a manner not related to ventilatory chemoreflex sensitivity. Furthermore, the data suggest that the individual's respiratory pattern to hypoxia or hypercapnia, as reflected in the inspiratory time, was a strong determinant of cardiovagal baroreflex set- point rather than the total ventilatory chemoreflex gain per se.

Correlation between centrally versus peripherally transduced venous pressure in prone patients undergoing posterior spine surgery

STUDY DESIGN

Prospective clinical observational study.

OBJECTIVE

To evaluate the correlation and agreement between peripherally and centrally transduced venous pressures in prone spine surgery patients.

SUMMARY OF BACKGROUND DATA

In view of a variety of potential complications associated with the placement of central venous lines for the purpose of central venous pressure (CVP) monitoring, a number of authors have suggested that the use of peripherally transduced pressures (PVP) instead may yield similar results. Data confirming the validity of this technique for the purpose of intravascular fluid volume monitoring in prone patients undergoing spine surgery remain scarce.

METHODS

After protocol approval by the internal review board, we enrolled 40 patients who underwent spine surgery in the prone position. CVP and PVP were recorded simultaneously. The data pairs were analyzed for correlation. Bland and Altman plots were created to evaluate the degree of agreement between the 2 modes of venous pressure monitoring.

RESULTS

A total of 1275 data pairs were collected. The mean PVP was 17.55 mm Hg +/- 4.93 mm Hg and the mean CVP 15.52 mm Hg +/- 4.77 mm Hg (P < 0.001), thus yielding a mean difference of 2.04 mm Hg +/- 1.39 mm Hg. PVP and CVP correlated well over a wide range of pressures (r = 0.949, r = 0.920 [P < 0.001]). A high level of agreement was found between both methods of venous pressure measurement.

CONCLUSION

CVP and PVP correlate well under conditions associated with prone spine surgery. With a high level of agreement found in this study, PVP may represent an attractive alternative to CVP monitoring to assess fluid volume trends intraoperatively.

Evaluation of peripheral and central venous pressure in awake dogs and cats

OBJECTIVE

To determine whether peripheral venous pressure (PVP) was correlated with central venous pressure (CVP) when measured by use of different catheter sizes, catheterization sites, and body positions in awake dogs and cats.

ANIMALS

36 dogs and 10 cats.

PROCEDURES

Dogs and cats with functional jugular and peripheral venous catheters were enrolled in the study. Peripheral venous catheters (18 to 24 gauge) were placed in a cephalic, lateral saphenous, or medial saphenous vein. Central venous catheters (5.5 to 8.5 F) were placed in the jugular vein and advanced into the cranial vena cava. Catheters were connected to pressure transducers and a blood pressure monitor capable of displaying 2 simultaneous pressure tracings. For each animal, the mean of 5 paired measurements of PVP and CVP was calculated. The relationship between PVP and CVP when measured by use of different catheter sizes, catheterization sites, and body positions was determined.

RESULTS

Mean +/- SD PVP was 5.7 +/- 5.8 mm Hg higher than CVP in dogs and 6.0 +/- 6.9 mm Hg higher than CVP in cats. However, results of multiple regression analysis did not indicate a significant correlation between PVP and CVP, regardless of catheter size, catheter position, or body position. The relationship was weak in both dogs and cats.

CONCLUSIONS AND CLINICAL RELEVANCE

The PVP was poorly correlated with CVP when different catheter sizes, catheterization sites, and patient positions were evaluated. Peripheral venous pressure should not be used to approximate CVP in awake dogs and cats.

Measurement of central venous pressure from a peripheral intravenous catheter following cardiopulmonary bypass in infants and children with congenital heart disease

The current study evaluates the feasibility and accuracy of measuring central venous pressure from a peripheral intravenous catheter following cardiopulmonary bypass in infants and children. Central venous pressure was simultaneously measured from a right atrial catheter and from a peripheral intravenous cannula. The continuity of the peripheral intravenous cannula with the central venous system was evaluated by noting the change in the pressure during a sustained inspiratory effort and during occlusion of the vessel above (proximal to) the catheter. The cohort for the study included 29 infants and children. In 5 of the 29 patients (17%), there was no increase in the peripheral venous pressure in response to a Valsalva maneuver or occlusion of the extremity proximal to the intravenous site. The difference between peripheral venous pressure and central venous pressure in these patients was 11 +/- 3 mm Hg versus 2 +/- 1 mm Hg in the patients in whom the peripheral venous pressure increased with these maneuvers (P < .0001). No clinically significant variation in the accuracy of the technique was noted based on the actual CVP value, size of the PIV, its location, or the patient's weight. Provided that the peripheral venous pressure increases to a sustained inspiratory breath and occlusion above the intravenous site, there is a clinically useful correlation between the peripheral venous pressure and the central venous pressure following cardiopulmonary bypass in infants and children with congenital heart disease.

Correlation between peripheral and central venous pressures in children with congenital heart disease

Central venous pressure (CVP) measurement is a reliable method for evaluating intravascular volume status and cardiac function, but it is an invasive method that results in some complications such as arterial puncture, pneumothorax, and development of infection. The current study was performed to compare CVP measurements between central and peripheral catheters in infants and children with congenital heart disease referred for right-sided heart catheterization. The CVP and peripheral venous pressure (PVP) in 45 patients were measured simultaneously. The mean difference between CVPs measured from the central and peripheral catheters was 8 +/- 4 cm H(2)O. The linear regression equation showed that CVP = 0.32 PVP + 3.8 (r = 0.67; p < 0.005). There was no difference in CVP measurements depending on the intravenous cannula and chest diameters, arm diameter, arm length, body surface area, patient's age (< or =10 years and >10 years), and type of congenital heart disease (cyanotic or noncyanotic). In conclusion, although CVP measured from a peripheral intravenous catheter in infants and children with congenital heart disease is not as accurate as the measurement in adults, the aforementioned linear regression equation based on measurement of PVP gives a reliable estimate of CVP.

Usefulness of a central venous catheter during hepatic surgery

AIM

Central venous catheter (CVC) is often inserted during liver resection because a low central venous pressure (CVP) reduces blood loss and the procedure may be associated with circulatory impairment. The aim of the study was to evaluate the usefulness of a CVC besides the measurements of CVP, and whether peripheral venous pressure (PVP) measurement could be used reliably in place of CVP.

METHODS

We conducted an observational study during a 16-month period. Number of CVC inserted, expected surgical difficulties, and intraoperative complications which could lead to treatment involving a CVC were prospectively recorded and analysed. Measurements of CVP and PVP were simultaneously obtained at different times during surgery. Bias and limits of agreement with their 95% confidence interval (95% CI) were calculated.

RESULTS

Of the 101 patients included, 28 had expected surgical difficulties. Of the 75 CVCs inserted, only six (8%) were used for another purpose that CVP measurement in patients with expected surgical difficulties. A total of 124 measurements in 23 patients were recorded. Mean CVP was 4.8 +/- 2.9 mmHg and mean PVP was 6.9 +/- 3.1 mmHg (P<0.0001). The bias was -2.1 +/- 1.1 mmHg (95% CI: -2.3 to -1.9). When adjusted by the average bias of -2 mmHg, PVP predicted a CVP</=5 mmHg with a sensitivity and a specificity of 93% and 87%, respectively.

CONCLUSION

Routine insertion of a CVC should be discussed in patients without expected surgical difficulties. Thus, PVP monitoring may suffice to estimate CVP in uncomplicated cases.

Can peripheral venous pressure be an alternative to central venous pressure during right hepatectomy in living donors?

The safety of living donors is a matter of cardinal importance in addition to obtaining optimal liver grafts to be transplanted. Central venous pressure (CVP) is known to have significant correlation with the amount of bleeding during parenchymal transection and many centers have adopted CVP monitoring for right hepatectomy. However, central line cannulation can induce some serious complications. Peripheral venous pressure (PVP) has been suggested as a comparable alternative to CVP. 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 living liver donors. A central venous catheter was placed through the right internal jugular vein and a peripheral venous catheter was inserted at antecubital fossa in the right arm. CVP and PVP were recorded in 15-minute intervals in 50 adult living donors. The paired data were divided into 3 stages: preparenchymal transection, parenchymal transection, and postparenchymal transection. A total of 1,430 simultaneous measurements of CVP and PVP were recorded. Overall, the PVP, CVP, and bias were 7.0+/-2.46, 5.9+/-2.32, and 1.16+/-1.12 mmHg, respectively. A total of 88.9% of all measurements were clinically within acceptable limits of bias (+/-2 mmHg). Regression analysis showed a high correlation coefficient between PVP and CVP (r=0.893; P<0.001) and the limits of agreement were -1.03 to 3.34 overall. In conclusion, frequencies of differences, bias, correlation coefficient, and limits of agreement between PVP and CVP remained relatively constant throughout the operation. Therefore, PVP measurement in the arm can be an alternative to predict CVP and further, obviate central venous catheter-related complications in living liver donors.