Changes of Operative Performance of Pulse Pressure Variation As A Predictor of Fluid Responsiveness in a Swine Model of Endotoxin Shock

Background Several limitations regarding pulse pressure variation (PPV) use have been reported. Our aim was to describe changes in the PPV operative performance as a predictor of fluid responsiveness during the development of a swine endotoxin shock model and to assess hemodynamic variables associated with PPV changes. Methods A swine porcine endotoxin shock model was established (E. Coli 055:B5 endotoxin) in 7 pigs, and 3 pigs were included in the control group. The endotoxin was infused until the mean arterial pressure (MAP) dropped below 50 mmHg (TH0); then, the model animal was reanimated with fluids and vasopressors. We performed fluid challenges every hour for 6 hours. ROC curve analysis was conducted. Additionally, a linear mixed model was performed. Results The area under the curve (AUC) of PPV decreased from 0.95 (0.81–1.00) to 0.60 (0.17–1.00) at TH0. Its cutoff increased from 10.5–22.00% at TH0. PPV showed an inverse relationship with stroke volume, mean systemic filling pressure (MSFP), MAP, and systemic vascular resistance (SVR) (p < 0,001, AIC = 111.85). Conclusions The PPV operative performance as a predictor of fluid responsiveness decreased with the progression of endotoxic shock. This result could be due to the inverse association with MAP and SVR.

SEMI INVASIVE CARDIAC OUTPUT MONITORING IN A CARDIAC PATIENT UNDERGOING TOTAL THYROIDECTOMY USING SMARTPHONE APP CAPSTESIA.

Introduction: Advanced hemodynamic monitoring is need of today especially in patients with limited cardiac reserve. With the advent of smartphones & specially designed applications, hemodynamic monitoring becomes quite easy. Materials & Methods: Patient was pre – medicated with Inj. Fentanyl & inj. Glycopyrrolate, induced with Inj. Etomidate & Inj. Vecuronium and maintained with mixture ofIsourane, Nitrous Oxide & Oxygen. An arterial line was secured in Left Radial Artery. We used the CAPSTESIA app to take picture of the arterial waveform using a smartphone. Demographic data of the patient was fed in the app. App used it's pre- fed algorithm to give the real time Cardiac Output, Pulse Pressure variations, Cardiac Index based upon the arterial waveform. Results: Using the application we were able to monitor the cardiac output of the patient in real time using semi- invasive means. It enabled us to regulate the uid management of the patient and avoid any adverse cardiac events (hypotension). With Pulse Pressure variation also available in real time, we were able to restrict use of vasopressors since the Left Ventricle Ejection Fraction of the patient was 35 % on ECHO. Surgery was conducted without any untoward event. Patient was successfully extubated and sent to PACU. Conclusions:Advanced hemodynamic monitoring is time consuming using manual methods. We found the smartphone app CAPSTESIA pretty useful for semi-invasive hemodynamic monitoring of the Cardiac Output, Pulse Pressure variation, Cardiac Index,etc in real time.

The use of pulse pressure variation for predicting impairment of microcirculatory blood flow

Dynamic parameters of preload have been widely recommended to guide fluid therapy based on the principle of fluid responsiveness and with regard to cardiac output. An equally important aspect is however to also avoid volume-overload. This accounts particularly when capillary leakage is present and volume-overload will promote impairment of microcirculatory blood flow. The aim of this study was to evaluate, whether an impairment of intestinal microcirculation caused by volume-load potentially can be predicted using pulse pressure variation in an experimental model of ischemia/reperfusion injury. The study was designed as a prospective explorative large animal pilot study. The study was performed in 8 anesthetized domestic pigs (German landrace). Ischemia/reperfusion was induced during aortic surgery. 6 h after ischemia/reperfusion-injury measurements were performed during 4 consecutive volume-loading-steps, each consisting of 6 ml kg−1 bodyweight−1. Mean microcirculatory blood flow (mean Flux) of the ileum was measured using direct laser-speckle-contrast-imaging. Receiver operating characteristic analysis was performed to determine the ability of pulse pressure variation to predict a decrease in microcirculation. A reduction of ≥ 10% mean Flux was considered a relevant decrease. After ischemia–reperfusion, volume-loading-steps led to a significant increase of cardiac output as well as mean arterial pressure, while pulse pressure variation and mean Flux were significantly reduced (Pairwise comparison ischemia/reperfusion-injury vs. volume loading step no. 4): cardiac output (l min−1) 1.68 (1.02–2.35) versus 2.84 (2.15–3.53), p = 0.002, mean arterial pressure (mmHg) 29.89 (21.65–38.12) versus 52.34 (43.55–61.14), p < 0.001, pulse pressure variation (%) 24.84 (17.45–32.22) versus 9.59 (1.68–17.49), p = 0.004, mean Flux (p.u.) 414.95 (295.18–534.72) versus 327.21 (206.95–447.48), p = 0.006. Receiver operating characteristic analysis revealed an area under the curve of 0.88 (CI 95% 0.73–1.00; p value < 0.001) for pulse pressure variation for predicting a decrease of microcirculatory blood flow. The results of our study show that pulse pressure variation does have the potential to predict decreases of intestinal microcirculatory blood flow due to volume-load after ischemia/reperfusion-injury. This should encourage further translational research and might help to prevent microcirculatory impairment due to excessive fluid resuscitation and to guide fluid therapy in the future.