Peripheral measurements of venous oxygen saturation and lactate as a less invasive alternative for hemodynamic monitoring

Midline Catheters as an Alternative for Central Venous Catheters in Venous Oxygen Saturation Monitoring: A Single Center Experience

BACKGROUND

Central venous oxygen saturation (ScvO2) obtained from a central venous catheter (CVC) is often used to approximate oxygen delivery in critically ill patients. Despite their importance in administering medications and monitoring oxygen delivery, the use of CVCs can be associated with significant complications. Midline catheters are inserted via a peripheral vein above the antecubital fossa and provide a safe alternative to CVCs. This study aimed to determine the equivalence of ScvO2 and midline catheter oxygen saturation (SmO2) in critically ill patients.

METHODS

This was a single-center observational study of critically ill adult patients who had concurrently placed CVCs (internal jugular and subclavian) and midline catheters as part of standard ICU care. Venous oxygen saturation and lactate levels were measured from both catheters using the Abbott point-of-care i-STAT analyzer. Demographic and ICU admission data were collected. Continuous variables were compared using the paired t-test. Pearson's correlation was used to evaluate the linear correlation between ScvO2 and SmO2. The systematic error (bias) was calculated using Bland-Altman analysis. Receiver operating characteristic curves were constructed to evaluate the sensitivities and specificities for different values of SmO2 to predict ScvO2.

RESULTS

Forty-eight patients (n = 48) were enrolled in the study. The mean ScvO2 and SmO2 were 65.5% +/- 11.2% and 62.7% +/- 17.6% respectively (p = 0.1197). In the Bland-Altman analysis, the mean bias between ScvO2 and SmO2 was 2.8% +/- 12.3% with 95% limits of agreement of -21.3% to 26.9%. More than 60% of the ScvO2 and SmO2 values diverged by ≥ 5%.

CONCLUSIONS

The difference between the mean SmO2 and ScvO2 was not statistically significant and the mean bias between SmO2 and ScvO2 is low. Despite this, the substantially large standard deviation and limits of agreement preclude the use of SmO2 as a direct surrogate of ScvO2.

Non-invasively Measured Venous Oxygen Saturation as Early Marker of Impaired Oxygen Delivery in Preterm Neonates

INTRODUCTION

Adequate oxygen supply for preterm neonates may be defined through non-invasive measurement of venous oxygen saturation (SvO₂) and fractional oxygen extraction using near-infrared spectroscopy (NIRS). We investigated whether there was a difference in peripheral muscle SvO₂ (pSvO₂) and peripheral fractional oxygen extraction (pFOE) in preterm neonates with early inflammation/infection compared to healthy subjects during the first 72 h after birth.

MATERIALS AND METHODS

We retrospectively analyzed secondary outcome parameters of prospective observational studies, including preterm neonates at risk of infection in whom peripheral NIRS measurements were performed in combination with venous occlusions. Early neonatal inflammation/infection was diagnosed by clinical signs and laboratory parameters. Peripheral muscle tissue oxygenation index (pTOI) was measured using either NIRO 300 or NIRO 200-NX (both Hamamatsu Photonics, Japan) on the patients' lower legs. Using 20-s venous occlusions, pSvO₂ and pFOE were calculated incorporating simultaneous measurements of arterial oxygen saturation (SpO₂).

RESULTS

We analyzed measurements from 226 preterm neonates (median gestational age 33.9 weeks), 64 (28.3%) of whom were diagnosed with early neonatal inflammation/infection. During the first 24 h after birth, pSvO₂ (66.9% [62.6-69.2] vs. 69.4% [64.6-72.0]; p = 0.04) and pTOI (68.6% [65.3-71.9] vs. 71.7% [67.3-75.1]; p = 0.02) were lower in those neonates with inflammation/infection, while there was no such difference for measurements between 24-48 and 48-72 h.

DISCUSSION

NIRS measurement of pSvO₂ and pFOE is feasible and may be utilized for early detection of impaired peripheral oxygen delivery. As pTOI was also significantly lower, this parameter may serve as substitute for diminished regional oxygen supply.

Venous-arterial oxygen saturation and serum lactate in the postoperative period of cardiac surgery

INTRODUCTION

Oxygen saturation and lactate are markers of tissue hypoxia; they are obtained from central venous and mixed venous sample of the pulmonary artery. The simultaneous behavior of these parameters in the postoperative period of cardiac surgery is unknown.

OBJECTIVE

To characterize the lactate and oxygen saturation of the venous-arterial circuit of the postoperative patient from cardiac surgery.

METHODS

Design: Analytical cross-sectional. In consecutive patients after cardiac surgery, serum lactate and oxygen saturation of the venous-arterial circuit were obtained. The variables were reported with median (25.75 percentiles). They were analyzed with Kruskal-Wallis ANOVA and respective adjustment, Spearman correlation, the descriptive Bland-Altman statistic and intraclass correlation coefficient (95% confidence interval). A p < 0.05 was considered significant.

RESULTS

244 blood samples from 61 patients were studied. Women 30 (49%). (Oxygen saturation) [lactate] were: arterial 98 (95.3, 99.4%) and 1.7 (1.1, 2.1); peripheral venous 85 (75.4, 94%) and [1.9 (1.35, 2.3)]; central venous 68.8 (58.74, 70.2%) and 1.8 (1.3, 2.3); mixed central venous 66.8 (61.2, 73.1%) and 1.8 (1.3, 2.2), p < 0.05. The best intraclass correlation coefficient for oxygen saturation were from central vein to mixed central vein 0.856 (0.760,0.914); and lactate: 0.954 (0.923, 0.972).

CONCLUSIONS

The oxygen saturation differs in the venous-arterial circuit unlike lactate where they are similar. The best values of the intraclass correlation coefficient for lactate and oxygen saturation were those obtained in central vein and mixed central vein.

Effects of upper limb ischemia-reperfusion on regional oxidative stress during aortic surgery with moderate hypothermia

INTRODUCTION

This study aims to evaluate the effect of acute, iatrogenic right arm ischemia and reperfusion (I/R) due to right axillary cannulation on regional oxidative stress using tissue perfusion markers such as central venous oxygen saturation, lactate, the difference between central venous and arterial CO₂ pressure, near-infrared spectroscopy (NIRS) measurements, and biomarkers like sialic acid, malondialdehyde, advanced oxidative protein products in aortic surgery with moderate hypothermia.

METHODS

Adult patients undergoing ascending aorta repair with antegrade cerebral perfusion via the axillary artery participated. Blood samples were collected from the internal jugular vein, right arm cubital vein, and left arm cubital vein, and analysis was performed at intraoperative time points.

RESULTS

Right-arm venous oxygen saturation levels are significantly lower than left arm and central venous, as expected in iatrogenic ischemia. Right arm lactate levels are significantly higher. Somatic right arm NIRS values are significantly lower than somatic left arm. There are no significant differences for biomarkers throughout the time points.

CONCLUSIONS

We have concluded that well-known markers reflect the results of ischemia-reperfusion more rapidly, and are more valuable than novel biomarkers. NIRS is a promising monitor in terms of providing information about tissue oxygenation. Oxidative stress biomarkers do not change quickly enough to give useful information in a short enough period of time; moreover, their costs are high and laboratory studies take time. Although axillary cannulation is controlled limb ischemia, the local effects of I/R did not completely normalize at the end of the surgery, and this regional I/R did not affect the global body organism.