Venous Saturation Research Articles

Ocular blood flow in glaucoma - the Leuven Eye Study.

Elevated intra-ocular pressure (IOP) has been identified as a major risk factor for glaucoma. Additionally, extensive literature depicts a vascular dysfunction to exist in these patients. However, a large ocular blood flow-oriented trial to integrate these findings in the clinical setting is lacking. This study would likely help to identify which of these vascular data can be used as a clinical tool for screening and disease stratification. Prospective, cross-sectional, case-control hospital-based study. Patients with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG), ocular hypertension (OHT), glaucoma suspects and healthy volunteers were recruited. In addition to a comprehensive ophthalmological examination, a vascular-oriented questionnaire was completed and ocular blood flow assessment (colour Doppler imaging of retrobulbar vessels, retinal oximetry, dynamic contour tonometry, optical coherent tomography enhanced-depth imaging of the choroid) were performed. Statistical analysis was based on multiple imputation to account for missingness. A total of 614 subjects (291 males) were recruited between March and December 2013 (POAG: 214, NTG: 192; OHT: 27; glaucoma suspect: 41; healthy controls: 140). Glaucoma groups (NTG and POAG) were age and gender matched with the control group (p>0.05). Glaucoma groups were paired in terms of functional and structural parameters (p>0.08). Mean ocular perfusion pressure was higher in the glaucoma groups than in controls (p<0.001). Glaucoma groups had lower retrobulbar velocities, higher retinal venous saturation and choroidal thickness asymmetries when compared to the healthy group, in line with the current literature. The Leuven Eye Study stands as one of the largest clinical trials on ocular blood flow in glaucoma. The creation of this vast database may help integrate the vascular aspects of glaucoma into the clinical practice of glaucoma.

Evolution of regional oxygen saturation in the peri-operative of thoracic surgery and its relationship with central venous saturation

ObjectiveTo study the relationship between the values of SvcO2 and SrcO2 in lung resection with one lung ventilation (OLV) and changes in these variables and mean arterial pressure (MAP) and arterial oxygen saturation (SpO2) during the perioperative period. Material and methodsProspective, observational study of 25 patients in whom pulmonary resection was performed with OLV. The values of MAP, SpO2, SvO2, and SrcO2 were recorded at 6 different times: (1) baseline; (2) double-lung ventilation before the OLV (VBP1); (3) during OLV; (4) after double-lung ventilation (VBP2); (5) 30min after surgery, and (6) 6h after surgery. ResultsThe SrcO2 showed a significant increase from baseline to starting ventilation (65.72±9.05% vs 70.44±7.24%; p<.01). There were no significant changes in their values at the different intraoperative times. Post-operatively, as in the case of the SvcO2, a significant decrease (p<.001) of its value compared with the previous value was observed. ConclusionsSrcO2 showed a significant increase after induction of anaesthesia and initiation of mechanical ventilation compared to baseline, and a significant decrease at the end of surgery after extubation in the immediate postoperative period. Being a tissue monitoring, non-invasive technique and with continuous values it can alert the clinician of changes in the ratio of oxygen consumption (VO2) to oxygen delivery (DO2) at times of greatest risk, such as OLV, extubation, and the early postoperative period.

Comparison of high glucose concentration blood and crystalloid cardioplegia in paediatric cardiac surgery: a randomized clinical trial.

This study investigates the effects of high glucose content on patients undergoing cold crystalloid versus cold blood cardioplegia in terms of early clinical results, functional myocardial recovery and ischaemia-reperfusion injury in patients undergoing repair of acyanotic cardiac lesions. Patients were randomly assigned to receive either crystalloid (n = 31) or blood cardioplegia (n = 31). Early clinical results were assessed. Changes in left ventricular fractional shortening, arterial blood lactate levels, central venous saturation, cardiac Troponin I release and blood glucose concentration were measured during the first 24 h after ischaemia. There was no significant difference in clinical outcomes and postoperative complication rates between groups. The postoperative changes in left ventricular function, lactate levels, central venous saturation and Troponin I were not significantly different between groups. The use of crystalloid cardioplegia was associated with significant increases in serum glucose compared with blood cardioplegia. A high glucose content blood cardioplegia does not show any advantage compared with crystalloid cardioplegia in terms of clinical outcomes, functional recovery and the degree of ischaemic injury in infants and children undergoing repair of acyanotic heart lesions. High glucose concentration of the cardioplegic solution might potentiate ischaemia-reperfusion injury and diminish the beneficial effects of blood cardioplegia.

Perivascular and Quadrant Nerve Fiber Layer Thickness and Its Relationship with Oxygen Saturation

ABSTRACTPurpose: To study whether there exists a relationship between retinal nerve fiber layer thickness and oxygen saturation and to identify whether perivascular thickness (pRNFL) or quadrant thickness (qRNFL) has a stronger correlation.Methods: Patients without any detectable ocular abnormality on complete ophthalmic evaluation underwent non-invasive photo-spectrometric retinal oximetry on the Oxymap T1 retinal oximeter (Oxymap hf, Reykjavik, Iceland) and spectral-domain optical coherence tomography to determine if the pRNFL (Spectralis, Heidelberg, Germany) and the qRNFL (RtVue, Optovue) correlated with the measured light intensities and the calculated retinal oxygen saturations.Results: 30 eyes of 30 patients (120 arterioles, 120 venules) were included in the study. The mean arteriolar saturations (%) were temporal: 84.5 (95% CI 82.7–86.3) and nasal: 93.5 (95% CI 91.0–95.8); venous saturations were temporal: 54.4 (95% CI 52.9–55.9) and nasal: 59.9 (95% CI 58.3–61.4). The mean pRNFL thickness (µm) around arterioles was temporal: 153.1 (95% CI 146–159) and nasal: 109.4 (95% CI 103–115); around venules it was temporal: 147.4 (95% CI 140–154) and nasal: 101.2 (95% CI 95–107). The oxygen saturations correlated significantly with pRNFL (arteriolar r = −0.514; p < 0.001 and venous r = −0.513; p < 0.001) but did not show a significant correlation with qRNFL values.Conclusion: This relationship between perivascular RNFL could be physiological or artifactual. If physiological, it would explain and form the basis of altered oxygen saturation in a multitude of diseases. If artifactual, it would necessitate the incorporation of a pRNFL correction. However, the results of this study enable us to expect increased saturation in areas of thinner RNFL or vice versa with the current methodology of retinal vessel oximetry as obtained by dual-wavelength photo-spectrometric fundus imaging.

The Impella® Recover mechanical assist device in acute cardiogenic shock: a single-centre experience of 66 patients.

Short-term ventricular assist devices are more frequently used in patients with acute cardiogenic shock. The aim of this study was to evaluate its effect on haemodynamic parameters, as well as the short- and long-term outcome and complication rate associated with the device. All patients treated with the Impella® Recover device at our centre from 2003 to 2014 (n = 66) were included in this study, and follow-up time was 2.9 (±0.4) years. Data were obtained through patient records and the population register. Patient-related factors, preimplantation and early postimplantation haemodynamic and biochemical parameters were analysed. Characteristics of survivors and non-survivors were compared. The device was implanted in 66 patients and 58% (38/66) were alive at 30 days post-implantation. The mean duration of support was 7.4 (±0.8) days. Mean time in the intensive care unit was 24 (±4) days. Following device implantation, patients' cardiac index improved from 2.1 l/min/m(2) (±0.20) to 3.8 l/min/m(2) (±0.20) at Day 7, mixed venous saturation increased from 56% (±2.0) to 68% (±1.2) and diuresis increased from 69 ml/h (±9) at device insertion to 105 ml/h (±19) at Day 7 on support. Central venous pressure, lactate levels and inotropic support decreased on support. No difference between survivors and non-survivors was established. No correlation was established between preimplant parameters and 30-day mortality. The Impella® Recover device improved haemodynamics in patients with acute cardiogenic shock. Still, 30-day mortality remains high and future studies must focus on the optimal timing of placement of the device.

Valor pronóstico de los parámetros gasométricos del dióxido de carbono en pacientes con sepsis. Una revisión bibliográfica

The anaerobic metabolism is the cornerstone in physiopathology of septic shock. Nowadays we have both the central or mixed venous oxigen saturation and lactate levels to monitoring the metabolism in septic patients. Some studies have shown that normalization of systemic hemodynamic and oxygen metabolism variables not prevent progression to multiorgan damage and death.Recently has been proposed the venous-to-arterial carbon dioxide difference (ΔpvaCO2) as an alternative marker of tissue hypoperfusion, like Cardiac Index. High ΔpvaCO2 predicts adverse outcomes. Also has been proposed both, the ratio between the ΔpvaCO2 and arterial-to-venous oxygen content difference (ΔCavO2): ΔpvaCO2/ΔCavO2; and, the ratio between venous-to-arterial carbon dioxide difference (ΔCvaCO2) and ΔCavO2: ΔCvaCO2/ΔCavO2, as markers of anaerobic metabolism. Both of high ratios are related to high levels of lactate and worse prognosis. Therefore in patients with sepsis the combination of markers of resuscitation could be important to improve the outcomes.

Hyperoxia and Functional MRI.

Oxygen plays a fundamental role in functional magnetic resonance imaging (FMRI). Blood oxygenation level-dependent (BOLD) imaging is the foundation stone of all FMRI and is still the essential workhorse of the vast majority of FMRI procedures. Hemoglobin may provide the magnetic properties that allow the technique to work, but it is oxygen that allows the contrast to effectively be switched on or off, and it is oxygen that we are interested in tracking in order to observe the oxygen metabolism changes. In general the changes in venous oxygen saturation are observed in order to infer changes in the correlated mechanisms, which can include changes in cerebral blood flow, metabolism, and the fraction of inspired oxygen. By independently manipulating the fraction of inspired oxygen it is possible to alter the amount of dissolved oxygen in the plasma, the venous saturation, or even the blood flow. The effects that these changes have on the observed MRI signal can be either a help or a hindrance depending on how well the changes induced are understood. The administration of supplemental inspired oxygen is in a unique position to provide a flexible, noninvasive, inexpensive, patient-friendly addition to the MRI toolkit to enable investigations to look beyond statistics and regions of interest, and actually produce calibrated, targeted measurements of blood flow, metabolism or pathology.

Особенности микроциркуляторного кровотока в коже у больных легочной гипертензией разной этиологии

Aim: to evaluate features of the functional state of microvascular bed of the skin in patients with pulmonary arterial hypertension associated to congenital cardiac disease (PAH-CCD) and chronic thromboembolic pulmonary hypertension (CTEPH). Methods. In study included 25 patients (41.6±15.8) with PAH-CCD, 25 patients (48.8±14.2) with CTEPH and 25 healthy volunteers (39.3±10.1 years). All the patients underwent a six-minute walking test (6-MWT), transthoracic echocardiography, thorax organs radiography, right heart catheterization (RHC) and Laser Doppler flowmetry (LDF) with amplitude and frequency wavelet analysis of blood flow oscillations and evaluation of constrictory and dilatatoryskin resistive microvesselsfunctions. Results. In the PAH-CCD in relation to the CTEPH groupaccording to the RHC were noted significantly higher values of systolic pressure in pulmonary artery (93.2 and 77.8 mm Hg respectively) and venous mixted blood saturation(63 and 57% Hg respectively). On this background 6- MWT distance was 356 and 325 m, the Borg dyspnea scale index was on average 3.12 and 3.76 respectively. According to the LDF pulseoximetry PAH-CCD and CTEPH patients had 90.1 and 94.7% respectively. According to the LDF with amplitude and frequency wavelet analysis the PAH-CCD patients had sig-nificantly higher values of the amplitude of myogenic, respiratory and pulse sectionof blood flow modulation, and also increased constrictory activity smooth muscle cells of skin precapillary arterioles in response to the stretching at venous occlusion and decreased dilatatory reserve at post-occlusi-ve reactive hyperemia. According to the LDF the CTEPH patients had elongationof time development of microvessel constriction in response to acti-vation of sympathetic nervous systemin respiratory and cold tests. Conclusion. According to the LDF functional state of skin microvessels in systemic circulation of the CTEPH patients was comparable with control groupexcept for elongation of time development of microvessel reactions for sympathetic vasoconstrictor stimulations. The PAH-CCD patients demonstrated basal tonus decreasing of smooth muscle cells of skin precapillary arterioles in systemic circulation, which can be regarded as a manifestation of autoregulatory response to systemic hypoxia.

High central venous saturation after cardiac surgery is associated with increased organ failure and long-term mortality: an observational cross-sectional study

IntroductionCentral venous saturation (ScvO2) monitoring has been suggested to address the issue of adequate cardiocirculatory function in the context of cardiac surgery. The aim of this study was to determine the impact of low (L) (<60%), normal (N) (60%-80%), and high (H) (>80%) ScvO2 measured on intensive care unit (ICU) admission after cardiac surgery.MethodsWe conducted a retrospective, cross-sectional, observational study at three ICUs of a university hospital department for anaesthesiology and intensive care. Electronic patient records of all adults who underwent cardiac surgery between 2006 and 2013 and available admission measurements of ScvO2 were examined. Patients were allocated to one of three groups according to first ScvO2 measurement after ICU admission: group L (<60%), group N (60%-80%), and group H (>80%). Primary end-points were in-hospital and 3-year follow-up survival.ResultsData from 4,447 patients were included in analysis. Low and high initial measurements of ScvO2 were associated with increased in-hospital mortality (L: 5.6%; N: 3.3%; H: 6.8%), 3-year follow-up mortality (L: 21.6%; N: 19.3%; H: 25.8%), incidence of post-operative haemodialysis (L: 11.5%; N: 7.8%; H: 15.3%), and prolonged hospital length of stay (L: 13 days, 9–22; N: 12 days, 9–19; H: 14 days, 9–21). After adjustment for possible confounding variables, an initial ScvO2 above 80% was associated with adjusted hazard ratios of 2.79 (95% confidence interval (CI) 1.565-4.964, P <0.001) for in-hospital survival and 1.31 (95% CI 1.033-1.672, P = 0.026) for 3-year follow-up survival.ConclusionsPatients with high ScvO2 were particularly affected by unfavourable outcomes. Advanced haemodynamic monitoring may help to identify patients with high ScvO2 who developed extraction dysfunction and to establish treatment algorithms to improve patient outcome in these patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-015-0889-6) contains supplementary material, which is available to authorized users.

The effects of thoracic epidural analgesia on oxygenation and pulmonary shunt fraction during one-lung ventilation: an meta-analysis.

BackgroundThe aim of our study is to compare the effects of thoracic epidural analgesia combined with general anesthesia (GA) vs. general anesthesia on oxygenation and pulmonary shunt fraction during one-lung ventilation (OLV).MethodsLiterature research was firstly conducted for studies related to comparison of epidural anesthesia combined with GA vs. GA with reporting of hemodynamic and oxygenation variables and published from Jan 1990 to Jan 2014 in EMBAS, MEDLINE and Cochrane Central Register of Controlled Trials databases. The studies were reviewed and data were extracted and analyzed using fixed-effect and random-effect models.ResultsThere are 14 trials with 60 separate comparisons enrolling 653 patients for analysis. Regarding systemic hemodynamics, thoracic epidural analgesia decreased the mean arterial pressure and mean pulmonary arterial pressure with weighted mean difference 95 % confidence interval (−6.64 [−9.57 to −3.71] vs. -6.33 [−9.25 to −3.41] and −3.18 [−5.07 to −1.28] vs. -2.05 [−3.35 to −0.75]) respectively at the two measurements time, however, only decreasing heart rate and systemic vascular resistance (−3.28 [−5.98 to −0.67] and −319.99 [−447.05 to −192.94]) over the first 30 min after OLV. For oxygenation variables, thoracic epidural analgesia is associated with significant reduction in partial arterial oxygen pressure, mixed arterial saturation of oxygenation and increased pulmonary venous admixture fraction compared to general anesthesia with weighted mean difference 95 % confidence interval (−16.52 [−21.98 to − 11.05] vs. − 14.23 [−20.81 to − 7.65]), (0.74 [0.33 to 1.15] vs. − 0.63 [−1.23 to −0.04]) and (2.53 [1.35 to 3.72] vs. 2.77 [1.81 to 3.74]) respectively before and after 30 min of one-lung ventilation. A decrease in mixed venous saturation of oxygenation occurred after 30 min of OLV (−2.39 [−3.73 to −0.99]). Besides, a higher mean value of airway pressure was found in the thoracic epidural analgesia with weighted mean difference 95 % confidence interval (1.95 [1.61 to 2.28] vs. 0.87 [0.54 to 1.20]) at the measurements.ConclusionBased on the existing limited data puts forward recommendations for cautious usage of thoracic epidural analgesia in case of underlying risks in lower systemic hemodynamics, decreased partial arterial oxygen pressure but increases pulmonary shunt during one-lung ventilation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12871-015-0142-5) contains supplementary material, which is available to authorized users.

Can venous-to-arterial carbon dioxide differences reflect microcirculatory alterations in patients with septic shock?

PurposeSeptic shock has been associated with microvascular alterations and these in turn with the development of organ dysfunction. Despite advances in video microscopic techniques, evaluation of microcirculation at the bedside is still limited. Venous-to-arterial carbon dioxide difference (Pv-aCO2) may be increased even when venous O2 saturation (SvO2) and cardiac output look normal, which could suggests microvascular derangements. We sought to evaluate whether Pv-aCO2 can reflect the adequacy of microvascular perfusion during the early stages of resuscitation of septic shock.MethodsProspective observational study including 75 patients with septic shock in a 60-bed mixed ICU. Arterial and mixed-venous blood gases and hemodynamic variables were obtained at catheter insertion (T0) and 6 h after (T6). Using a sidestream dark-field device, we simultaneously acquired sublingual microcirculatory images for blinded semiquantitative analysis. Pv-aCO2 was defined as the difference between mixed-venous and arterial CO2 partial pressures.ResultsProgressively lower percentages of small perfused vessels (PPV), lower functional capillary density, and higher heterogeneity of microvascular blood flow were observed at higher Pv-aCO2 values at both T0 and T6. Pv-aCO2 was significantly correlated to PPV (T0: coefficient −5.35, 95 % CI −6.41 to −4.29, p < 0.001; T6: coefficient, −3.49, 95 % CI −4.43 to −2.55, p < 0.001) and changes in Pv-aCO2 between T0 and T6 were significantly related to changes in PPV (R2 = 0.42, p < 0.001). Absolute values and changes in Pv-aCO2 were not related to global hemodynamic variables. Good agreement between venous-to-arterial CO2 and PPV was maintained even after corrections for the Haldane effect.ConclusionsDuring early phases of resuscitation of septic shock, Pv-aCO2 could reflect the adequacy of microvascular blood flow.Electronic supplementary materialThe online version of this article (doi:10.1007/s00134-015-4133-2) contains supplementary material, which is available to authorized users.

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

Adjusting for Risk Associated With Pediatric and Congenital Cardiac Catheterization: A Report From the NCDR IMPACT Registry.

As US health care increasingly focuses on outcomes as a means for quantifying quality, there is a growing demand for risk models that can account for the variability of patients treated at different hospitals so that equitable comparisons between institutions can be made. We sought to apply aspects of prior risk-standardization methodology to begin development of a risk-standardization tool for the National Cardiovascular Data Registry (NCDR) IMPACT (Improving Pediatric and Adult Congenital Treatment) Registry. Using IMPACT, we identified all patients undergoing diagnostic or interventional cardiac catheterization between January 2011 and March 2013. Multivariable hierarchical logistic regression was used to identify patient and procedural characteristics predictive of experiencing a major adverse event after cardiac catheterization. A total of 19,608 cardiac catheterizations were performed between January 2011 and March 2013. Among all cases, a major adverse event occurred in 378 of all cases (1.9%). After multivariable adjustment, 8 variables were identified as critical for risk standardization: patient age, renal insufficiency, single-ventricle physiology, procedure-type risk group, low systemic saturation, low mixed venous saturation, elevated systemic ventricular end-diastolic pressure, and elevated main pulmonary artery pressures. The model had good discrimination (C statistic, 0.70), confirmed by bootstrap validation (validation C statistic, 0.69). Using prior risk-standardization efforts as a foundation, we developed and internally validated a model to predict the occurrence of a major adverse event after cardiac catheterization for congenital heart disease. Future efforts should be directed toward further refinement of the model variables within this large, multicenter data set.

Abstract 19722: Cardiac Output Estimation by Inert Gas Rebreathing is Accurate in Mechanically Ventilated Children With Heart Disease

Introduction: Real time estimates of pulmonary (Qp) and systemic blood flow (Qs) could improve pediatric cardiac care. Current generation inert gas rebreathing (IGR) devices are safe, portable, and easy to use; can estimate Qp and Qs rapidly at the bedside; and can now be adapted for use in intubated patients. We compared IGR and two types of Fick Qp estimates, those using measured (FickM) and assumed (FickA) oxygen consumption (VO2) values, in mechanically ventilated pediatric cardiac patients with no shunt lesion or exclusive right-to-left shunt. Secondarily, we compared measured VO2 with assumed values and values back-calculated from the Fick equation (using measured saturations, hemoglobin and IGR Qp). Methods: In 18 intubated patients in the pediatric catheterization laboratory, the modified ventilator-compatible InnocorTM device was used to measure IGR Qp and breath-by-breath VO2; assumed VO2 was taken from LaFarge tables. Sampled pulmonary arterial and venous saturations were used to calculate FickM and FickA. Bland-Altman agreement and Spearman correlation were assessed for IGR Qp with FickA Qp and FickM Qp. Secondarily, agreement was analyzed between measured VO2, assumed VO2, and VO2 calculated from the Fick equation. Results: Subjects were aged 4-23 years, with a range of cardiac diagnoses. The figure shows Bland-Altman plots for Qp. Compared with FickA, IGR Qp had mean bias -0.9 L/min, 95% limits of agreement (=±1.96 SD) -2.8 to +1.0 L/min, and r=0.75. Compared with FickM, IGR Qp had mean bias -0.2 L/min, 95% limits of agreement -1.3 to +1.0 L/min, and r=0.90. Agreement of assumed and measured VO2 was poor (bias +23%, ±55%); measured VO2 agreed better with Fick calculated VO2 than assumed VO2. Conclusions: IGR Qp estimates agree well with Fick Qp estimates. This agreement improves when VO2 is measured, as assumed VO2 agrees poorly with measured VO2. IGR is an attractive option for bedside monitoring of Qp in intubated children.

Abstract 17405: Phosphodiesterase-based Vasodilation Improves Oxygen Delivery and Clinical Outcomes Following Stage 1 Palliation

Introduction: The use of systemic vasodilators is known to decrease the incidence of postoperative cardiac arrest in infants with hypoplastic left heart syndrome (HLHS) following stage 1 palliation (S1P) with Blalock-Taussig shunt. Their impact on measured oxygen delivery (DO2) are uncharacterized. Methods: In 2013, we implemented a treatment algorithm at our institution to standardize care and lower systemic vascular resistance (SVR) in the postoperative period (A). We measured standard hemodynamic variables in consecutive neonates prior to (n=32) and following (n=24) its implementation. 92% of these infants received a Sano modification. We continuously measured oxygen consumption (E-COVX module™, GE Healthcare) and venous oxyhemoglobin saturation (SvO2, PediaSat, Edwards) for Fick-based calculation of DO2 and SVR in a subset (n=21) of patients. Variables were compared pre and post-implementation using linear mixed effects models. Results: Demographic, anatomic and echocardiographic risk factors were similar between groups, although aortic cross-clamp (ACC) time was significantly shorter following protocol implementation (120.9 vs 91.9 mins, P&lt;0.001). When corrected for ACC time, serum lactate (p&lt;0.001, B) and incidence of postoperative cardiac arrest (P=0.04, C) were lower (B), and SvO2 (P&lt;0.001) was higher following protocol implementation. Systemic cardiac output (β[SE], 0.52 [0.32] L/min/m2; P=0.10) and systemic DO2 (β[SE], 86.7 [55.4] mL/min/m2; P=0.12, D) were higher post-implementation. DO2 was most closely correlated with SVR (r2=0.87), and commonly utilized surrogate variables such as arterial saturation (r2=0.01), SvO2 (r2=0.1), and arterial-venous saturation difference (r2=0.35) correlated poorly. Conclusions: The implementation of a phosphodiesterase-based treatment algorithm decreased SVR, lactate accumulation and the incidence of cardiac arrest in infants with HLHS following S1P with Sano modification.

Abstract 17532: Impact of High Hepatic Wedge Pressure, Portal Hypertension, on Hemodynamics and Liver Function in Patients After the Fontan Operation

Background: Fontan circulation may be, in part, characterized by portal hypertension that can be estimated by hepatic vein wedge pressure (HWP). Purpose: To evaluate associations of HWP in cosecutive 318 Fontan patients (18±7 years old) during catheterization and compared the results with the hemodynamics, liver function and the related plasma biomarkers. HWP significantly correlated positively with inferior vena cava pressure (IVCP), pulmonary artery resistance (Rp), ration of Rp to systemic artery resistance (Rs) (Rp/Rs), and cardiac index and negatively with Rs and arterial and mixed venous oxgen saturations. Of those, high IVCP, low Rp and high Rp/Rs were independently correlated with high HWP (p&lt;0.05 for all). As for the liver function, HWP significantly correlated positively with plasma levels of total bilirubin (TB), hyaluronic acid, and type IV collagen (TyIV) and negatively with plasma levels of albumin and cholinesterase (ChE). Of those, ChE, TB and TyIV were independently correlated with high HWP (p&lt;0.01 for all). High HWP, low ChE, and high TyIV significantly correlated with high plasma nitric oxide products (p&lt;0.01). Conclusion: High HWP associates with a significant reduction of Rp and Rs with preserved cardiac output. This unique Fontan circulation with Rs-dominant reduction may be due to both portal hypertension and overproduction of nitric oxide secondary to liver dysfunction.

Tissue oxygen saturation as an early indicator of delayed lactate clearance after cardiac surgery: a prospective observational study.

BackgroundIn this observational study near infrared spectroscopy (NIRS) was evaluated as a non-invasive monitor of impaired tissue oxygenation (StO2) after cardiac surgery. StO2, cardiac output, mixed venous oxygen saturation and mean arterial pressure were compared with lactate clearance as established measure for sufficient tissue perfusion and oxygen metabolism.MethodsForty patients after cardiac surgery (24 aortocoronary bypass grafting, 5 heart valve, 3 ascending aorta and 8 combined procedures) were monitored until postoperative day 1 with NIRS of the thenar muscle (InSpectra™ StO2-monitor, Hutchinson Technology), a pulmonary-artery catheter and intermittent blood gas analyses for the assessment of lactate clearance.ResultsStO2 was reduced 4 h after surgery (75 ± 6 %), but recovered at day 1 (84 ± 5 %), while lactate concentration remained increased. Using uni- and multivariate regression analysis, minimum StO2 (r = 0.46, p <0.01) and cardiac index (r = 0.40, p <0.05) correlated with lactate clearance at day 1, while minimum mixed venous saturation and mean arterial pressure did not. In a receiver-operating characteristics (ROC) analysis, minimum StO2 (with a threshold of 75 %) predicted a lactate clearance <10 % at day 1 with an area under the ROC-curve of 0.83, a sensitivity of 78 % and a specificity of 88 %. In the subgroup with StO2 <75 %, troponin and creatine kinase MB were significantly increased at day 1.ConclusionsStO2 below 75 % in the first hours after surgery was a better early indicator of persistent impaired lactate clearance at day 1 than cardiac index, mixed venous oxygen saturation or mean arterial pressure.

Improvement in retinal vessel oxygen saturation after vitrectomy

PurposeTo evaluate the effects of vitrectomy on retinal vascular oxygen saturation.MethodsThis was a prospective observational study. 27 eyes of 27 patients who underwent vitrectomy for macular conditions were included. Retinal oximetry was performed using the Oxymap (Oxymap Inc., Reykjavik, Iceland) prior to vitrectomy and 3 months after surgery. The mean retinal arterial and venous oxygen saturation were measured and the arterial‐venous difference (AVD) was calculated as the difference between the arterial and venous saturations.Multivariate linear regression models were constructed to compare oxygen saturation before and after surgery, with adjustments for age, sex, hypertension, hyperlipidemia, diabetes mellitus and indication for surgery.ResultsThe mean age of the subjects was 68.4 ± 8.9 years, 15 (55%) were male and the majority were of Chinese ethnicity (93%). The mean arterial saturation increased significantly after vitrectomy (101.93 ± 8.36% vs 96.16 ± 14.14%, p = 0.01). The mean venous saturation also increased significantly after surgery. (59.76 ± 8.52% vs 50.40 ± 11.72%, p = 0.02). The mean AVD significantly decreased from 45.76 ± 12.18% before surgery to 42.17 ± 10.94% after surgery (p = 0.02).ConclusionsRetinal arterial and venous oxygen saturation are significantly increased after vitrectomy, while the AVD is decreased after vitrectomy. Our results suggest that vitrectomy enhances retinal oxygenation. This may account for the apparent benefit of vitrectomy on conditions with retinal hypoxia such as diabetic retinopathy.

Improvement in retinal vessel oxygen saturation after vitrectomy

PurposeTo evaluate the effects of vitrectomy on retinal vascular oxygen saturation.MethodsThis was a prospective observational study. 27 eyes of 27 patients who underwent vitrectomy for macular conditions were included. Retinal oximetry was performed using the Oxymap (Oxymap Inc., Reykjavik, Iceland) prior to vitrectomy and 3 months after surgery. The mean retinal arterial and venous oxygen saturation were measured and the arterial‐venous difference (AVD) was calculated as the difference between the arterial and venous saturations.Multivariate linear regression models were constructed to compare oxygen saturation before and after surgery, with adjustments for age, sex, hypertension, hyperlipidemia, diabetes mellitus and indication for surgery.ResultsThe mean age of the subjects was 68.4 ± 8.9 years, 15 (55%) were male and the majority were of Chinese ethnicity (93%). The mean arterial saturation increased significantly after vitrectomy (101.93 ± 8.36% vs 96.16 ± 14.14%, p = 0.01). The mean venous saturation also increased significantly after surgery. (59.76 ± 8.52% vs 50.40 ± 11.72%, p = 0.02). The mean AVD significantly decreased from 45.76 ± 12.18% before surgery to 42.17 ± 10.94% after surgery (p = 0.02).ConclusionsRetinal arterial and venous oxygen saturation are significantly increased after vitrectomy, while the AVD is decreased after vitrectomy. Our results suggest that vitrectomy enhances retinal oxygenation. This may account for the apparent benefit of vitrectomy on conditions with retinal hypoxia such as diabetic retinopathy.

Retinal Vessel Oxygen Saturation and its implications in myopia

PurposeTo evaluate retinal vessel oxygen saturation and its relationship with ocular volume and axial length.MethodsWe included 65 healthy individuals (age range: 19–51 years) of varying axial lengths (20.74–28.24 mm). All subjects underwent full ocular examination including intra‐ocular pressure measurements and systemic blood pressure measurements which was followed by auto‐refraction, axial length, anterior chamber, corneal radii and retinal oxygen saturation assessments. In addition, all subjects underwent routine retinal photography which was used to determine their retinal arterial and venular calibres.ResultsRetinal vessel calibres, both arteries and venules were significantly decreasing with increasing axial length (arteries: β = −0.37; p &lt; 0.001 and venules: β = −0.37; p &lt; 0.001). Arterial vessel oxygenation showed a statistical significant relationship with axial length but not posterior volume (axial length: β = −0.88; p = 0.032 and posterior volume: β = 0.73; p = 0.075). Venous vessel saturation and oxygen consumption (A‐V) were independent of ocular length and volume.ConclusionsStructural vascular changes such as vessel narrowing combined with changes in posterior volume and those brought about from vitreous detachment and degeneration could explain oxygenation related glaucomatous changes in highly myopic individuals.