High versus low ultrafiltration rates during experimental peritoneal dialysis in rats: Acute effects on plasma volume and systemic haemodynamics

Introduction: Intradialytic hypotension is a common complication of haemodialysis, but uncommon in peritoneal dialysis (PD). This may be due to lower ultrafiltration rates in PD compared to haemodialysis, allowing for sufficient refilling of the blood plasma compartment from the interstitial volume, but the underlying mechanisms are unknown. Here we assessed plasma volume and hemodynamic alterations during experimental PD with high versus low ultrafiltration rates. Methods: Experiments were conducted in two groups of healthy Sprague-Dawley rats: one group with a high ultrafiltration rate ( N = 7) induced by 8.5% glucose and a low UF group ( N = 6; 1.5% glucose), with an initial assessment of the extracellular fluid volume, followed by 30 min PD with plasma volume measurements at baseline, 5, 10, 15 and 30 min. Mean arterial pressure, central venous pressure and heart rate were continuously monitored during the experiment. Results: No significant changes over time in plasma volume, mean arterial pressure or central venous pressure were detected during the course of the experiments, despite an ultrafiltration (UF) rate of 56 mL/h/kg in the high UF group. In the high UF group, a decrease in extracellular fluid volume of −7 mL (−10.7% (95% confidence interval: −13.8% to −7.6%)) was observed, in line with the average UF volume of 8.0 mL (standard deviation: 0.5 mL). Conclusion: Despite high UF rates, we found that plasma volumes were remarkably preserved in the present experiments, indicating effective refilling of the plasma compartment from interstitial tissues. Further studies should clarify which mechanisms preserve the plasma volume during high UF rates in PD.

Correlation of Inferior Vena Cava diameter and IVC Collapsibility Index with Central Venous Pressure (CVP) in critically ill surgical patients

Introduction: Central Venous Pressure is a valuable parameter in the management of critically ill surgical patients in the ICU. Non-invasive methods to extrapolate the volume status of the patient can aid clinicians in expediting proper treatment. The objective of this study is to find a correlation between Inferior Vena cava (IVC) diameter and collapsibility index (CI) with Central venous pressure (CVP) in critically ill surgical patients. Methods: This cross-sectional study included 60 critically ill patients from September 2020 – 31st February 2021. We recorded the patient's age, sex, heart rate, blood pressure, CVP, volume status, IVC minimum, and maximum diameter. After taking consent and explaining the procedure to the patient, the maximum IVC anteroposterior diameter was noted at the end of inspiration and end of expiration in centimeters. IVC collapsibility index was calculated using the formula ([IVCdmax-IVCdmin]/IVCdmax*100%). Following this, the CVP of the patient was measured. Results: Among the patients evaluated, 32 were females. The mean age of the participants was 44.90 ± 15.76 years. The mean central venous pressure maintained was 11.10 ± 2.11cm H2O with an inferior vena cava collapsibility index of 29.69 ± 8.75. There was a negative correlation between CVP and IVC collapsibility index (%), which was statistically significant (r = -0.701, n = 60, p < 0.01). A strong positive correlation between CVP and maximum IVC diameter (r = 0.712, n = 60, p < 0.01) and minimum IVC diameter (r = 0.796, n = 60, p < 0.01) was found. Conclusion: Inferior Vena Cava diameter and IVC Collapsibility Index can be used as a reliable substitute to central venous pressure to determine the patient's volume status.

P-L03 The efficacy and safety of controlled low central venous pressure for liver resection: a systematic review and meta-analysis

Background Partial hepatectomy is an effective treatment for benign and malignant liver diseases . However, intraoperative bleeding is one of the major factors affecting the outcome of hepatectomy. Currently, the most commonly used method of hepatic blood flow occlusion in clinical practice is Pringle method, but this method has a great impact on liver function and can cause hepatic ischemia-reperfusion injury. .Studies have shown that blood loss volume during hepatectomy is related to central venous pressure (CVP) . Intraoperative control of central venous pressure (LCVP) is increasingly popular in hepatectomy, but its effectiveness and safety remain controversial. Methods The main result of the analysis was to reduce the blood loss and blood infusion. Secondary outcomes included operative time, fluid infusion, urine volume, ALT, TBIL, BUN, CR, postoperative complication rates and length of hospital stay. Statistical analysis was performed using RevMan 5.3 software (Cochrane Collaboration, Oxford, England). The results of all studies were measured by mean ± standard deviation. If there is significant heterogeneity between the results (P &lt; 0.05), a random-effects model is used. A fixed-effect model was used when there was no significant heterogeneity (P &gt; 0.05). Heterogeneity was assessed using the Cochrane χ2 text . Results In total, 10 studies, involving 324 patients undergoing liver resection with controlled low central venous pressure, were identified. Meta-analysis showed that blood loss in the LCVP group was significantly less than that in the control group ( P = 0.0002). blood transfusion in the LCVP group was also significantly less than that in the control group(P = 0.0006). there was no difference between LCVP group and control group in operation time(P = 0.17), fluid infusion( P = 0.46), urinary volume(P = 0.38), ALT( P = 0.23), TBIL(P = 0.86), BUN(P = 0.67), CR(P =0.59), postoperative complication rates( P = 0.01) and hospital stay(P = 0.26). Conclusions Compared with the control, controlled low central venous pressure showed comparable efficacy and safety for the treatment during liver resection.

Is measurement of central venous pressure required to estimate systemic vascular resistance? A retrospective cohort study

Background The clinical range of central venous pressure (CVP) (typically 5 to 15 mmHg) is much less than the range of mean arterial blood pressure (60 to 120 mmHg), suggesting that CVP may have little impact on estimation of systemic vascular resistance (SVR). The accuracy and feasibility of using an arbitrary CVP rather than actual CVP for the estimation of SVR during intraoperative period is not known. Methods Using vital records obtained from patients who underwent neurological and cardiac surgery, the present study retrospectively calculated SVR using fixed values of CVP (0, 5, 10, 15, and 20 mmHg) and randomly changing values of CVP (5 to 15 mmHg) and compared these calculated SVRs with actual SVR, calculated using actual CVP. Differences between actual SVR and SVRs based on fixed and random CVPs were quantified as root mean square error (RMSE) and mean absolute percentage error (MAPE). Bland-Altman analysis and four-quadrant plot analysis were performed. Results A total of 34 patients are included, including 18 who underwent neurosurgery and 16 who underwent cardiac surgery; 501,380 s (139.3 h) of data was analyzed. The SVR derived from a fixed CVP of 10 mmHg (SVRf10) showed the highest accuracy (RMSE: 115 and 104 [dynes/sec/cm− 5] and MAPE: 6.3 and 5.7% in neurological and cardiac surgery, respectively). The 95% limits of agreement between SVRf10 and actual SVR were − 208.5 (95% confidence interval [CI], − 306.3 to − 148.1) and 242.2 (95% CI, 181.8 to 340.0) dynes/sec/cm− 5 in neurosurgery and − 268.1 (95% CI, − 367.5 to − 207.7) and 163.2 (95% CI, 102.9 to 262.6) dynes/sec/cm− 5 in cardiac surgery. All the SVRs derived from the fixed CVPs (regardless of its absolute value) showed excellent trending ability (concordance rate > 0.99). Conclusions SVR can be estimated from a fixed value of CVP without causing significant deviation or a loss of trending ability. However, caution is needed when using point estimates of SVR when the actual CVP is expected to be out of the typical clinical range. Trial registration This study was registered Clinical Research Information Service, a clinical trial registry in South Korea (KCT0006187).

Diagnostic accuracy of internal jugular vein ultrasound in quantification of the central venous pressure for hemodialysis patients

Background Assessment of the central venous pressure (CVP) is an essential hemodynamic parameter for monitoring the dialyzing patients. Our objective of the present study is to investigate the accuracy of CVP measurement by internal jugular vein US in comparison to the direct measurement by the central venous catheters for hemodialysis patients. We included 106 patients; where their CVP was assessed in two different non invasive US methods (CVPni) separately and in combination and the obtained measurements were correlated to the invasive measurements (CVPi) by catheters. Results By method 1, there is a highly significant positive correlation between CVPni and CVPi (ρ < 0.001) and a Pearson correlation coefficient (r = 0.913 n = 93), and by method 2, there is also a highly significant positive correlation between the CVPni and CVPi in both groups (r = 0.832, 95%, n = 106, p < 0.001), 1.935 was the cut-off point for prediction of CVP ≥ 10cmH20. For differentiation between patients with CVP < 10cmH20 and ≥ 10cmH20, the accuracy measures (sensitivity, specificity, PPV, NPV, and overall accuracy) were 100%, 79.31%, 74.47%, 100%, and 87.10% by method 1, and were 91.11%, 85.48%, 82.00%, 92.98%, and 87.85% by method 2, while the combination of both methods had gained 88.57%, 89.66%, 83.78%, 92.86%, and 89.25%, respectively. Conclusion The US offered a reliable and non-invasive tool for monitoring CVP. The present study has a novelty of combining more than one US method and this had reported higher accuracy measures and outperformed the use of a single method.

Gas embolism under standard versus low pneumoperitoneum pressure during laparoscopic liver resection (GASES): study protocol for a randomized controlled trial

Background Gas embolism induced by CO2 pneumoperitoneum is commonly identified as a risk factor for morbidity, especially cardiopulmonary morbidity, after laparoscopic liver resection (LLR) in adults. Increasing pneumoperitoneum pressure (PP) contributes to gas accumulation following laparoscopy. However, few studies have examined the effects of PP in the context of LLR. In LLR, the PP-central venous pressure (CVP) gradient is increased due to hepatic vein rupture, hepatic sinusoid exposure, and low CVP management, which together increase the risk of CO2 embolization. The aim of this study is to primarily determine the role of low PP (10 mmHg) on the incidence of severe gas embolism. Methods Adult participants (n = 140) undergoing elective LLR will be allocated to either a standard (15 mmHg) or low (10 mmHg) PP group. Anesthesia management, postoperative care, and other processes will be performed similarly in both groups. The occurrence of severe gas embolism, which is defined as gas embolism ≥ grade 3 according to the Schmandra microbubble method, will be detected by transesophageal echocardiography (TEE) and recorded as the primary outcome. The subjects will be followed up until discharge and followed up by telephone 1 and 3 months after surgery. Postoperative outcomes, such as the Post-Operative Quality of Recovery Scale, pain severity, and adverse events, will be assessed. Serum cardiac markers and inflammatory factors will also be assessed during the study period. The correlation between intraoperative inferior vena cava-collapsibility index (IVC-CI) under TEE and central venous pressure (CVP) will also be explored. Discussion This study is the first prospective randomized clinical trial to determine the effect of low versus standard PP on gas embolism using TEE during elective LLR. These findings will provide scientific and clinical evidence of the role of PP. Trial status Protocol version: version 1 of 21-08-2020 Trial registration ChiCTR2000036396 (http://www.chictr.org.cn). Registered on 22 August 2020.