Effect of different interfaces on FiO_2 and CO_2 rebreathing during noninvasive positive pressure ventilation / 中国实用内科杂志

OBJECTIVE: To investigate the effect of different interfaces on FiO_2 and CO_2 rebreathing(ViCO_2) during noninvasive positive pressure ventilation. METHODS: The Active Servo Lung respiratory simulation system was used to simulate a hypercapnia COPD patient received NPPV through injection of CO_2 gas from the place closest to the outlet of simulated lung to maintain end-tidal carbon dioxide partial pressure at 80 mmHg,and oxygen delivery during NPPV was simulated by means of injection of 5 L/min oxygen through the hole of interface. FiO_2 and ViCO_2 were integral calculated through the synchronous collect real-time pressure, flow rate, oxygen concentration and CO_2 concentration. The effect of different type and models of interfaces on FiO_2 and ViCO_2 were compared, and the bivariate correlation analysis was applied to investigate the correlation of FiO_2 and ViCO_2. RESULTS: The inner volume, leak volume and leak position of different interfaces were different. The FiO_2 of the oral-nasal mask and nasal mask were significantly different(P<0.05), which were(39.81±9.06)% and(43.91±6.33)%,respectively. The FiO_2 of the different models of interfaces was significantly different(P<0.05), the FiO_2 of the No.4 oral-nasal mask was the lowest(28.29±0.08)%, and the FiO_2 of the No. 10 oral-nasal mask was the highest(53.83±0.63)%. The ViCO_2 of the oral-nasal mask and nasal mask wasn't significantly different(P=0.19), which was(15.26±1.27)mL and(14.79±2.21)mL, respectively. The ViCO_2 of the different models of interfaces was significantly different(P<0.05), the FiO_2 of the No.8 nasal mask was the lowest(12.48±0.29%), and the ViCO_2 of the No. 10 nasal mask was the highest(18.38±0.31)%. There was a significant correlation between FiO_2 and ViCO_2(r=0.41, P<0.05), and the general linear equation was Y=14.51+1.82 X(R~2=0.168). CONCLUSION: Different interfaces have significant effects on FiO_2 and ViCO_2 during NPPV,and FiO_2 and ViCO_2 are positively correlated.

A comparitive study on correlation between partial CO_2 rebreathing and thermodilution for cardiac output monitoring by animal experiment / 重庆医科大学学报

0.05).Regression analysis revealed an R value of 0.89 and the regression equation was as follows:CORB=0.78COTD+0.25;After manipulating inotropic drugs there was also a good agreement between RBco and Tdco,the correlation coefficient was 0.81,while the regression equation was CORB=0.91COTD+0.61.Conclusion:There is a high correlation between RBco and TDco measurement.Partial CO2 rebreathing measurement provids a new noninvasive circulation monitoring method for critical patients.

Hemodynamic Changes using Partial CO2 Rebreathing Method and Esophageal Doppler Monitor during Bilateral Total Knee Replacement Arthroplasty / 대한마취과학회지

BACKGROUND: We studied hemodynamic changes using a noninvasive partial CO2 rebreathing cardiac output method (NICO) and esophageal Doppler monitor (EDM), and metabolic changes in elderly patients undergoing bilateral total knee replacement arthroplasty (BTKA). METHODS: Twenty patients undergoing BTKA were studied. Hemodynamic and metabolic parameters were measured before tourniquet inflation (TI), 0, 3, 6, 9, 15, 30, 45 min after TI, and 0, 3, 6, 9, 15, 30 min after tourniquet deflation (TD) and skin suture. Stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) were measured using NICO and EDM. RESULTS: Mean blood pressure (MBP), central venous pressure (CVP), and SVR had significant increases in TI, and decreases in TD compared with value measured before TI (baseline value). Especially, MBP had higher decrease in the second tourniquet compared with first tourniquet, SV and CO were decreased in TI, and increased in TD compared with baseline value, HR had significant increases in the TD of second tourniquet. pH and lactate were shown significantly lower values at the second tourniquet compared with the first tourniquet (P < 0.05). The bias and precision derived from CO between EDM and NICO was 0.27 +/- 0.41 L/min, and CO by NICO was smaller than that by EDM. The correlation coefficient between NICO and EDM was calculated to be 0.43. CONCLUSIONS: MBP, SV, CO, pH and lactate were shown to be higher in the second tourniquet in BTKA. NICO showed lower CO compared with EDM after TD in patients undergoing BTKA, but statistically insignificant at most measurement.

Correlations between Mean Arterial Blood Pressure, Cardiac Index, and Systemic Vascular Resistance Index in Laparoscopically-assisted Vaginal Hysterectomy (LAVH) / 대한마취과학회지

BACKGROUND: The purpose of this study was to evaluate the correlations between mean blood pressure (MBP), cardiac index (CI), and systemic vascular resistance index (SVRI) in patients undergoing laparoscopically-assisted vaginal hysterectomy (LAVH). METHODS: The authors enrolled 47-female patients prior to a LAVH. Hemodynamic parameters were measured before anesthetic induction, just after tracheal intubation, before skin incision, and 2, 5, 10, 20, and 30 min after pneumoperitoneum with CO2 by noninvasive cardiac output measurement using the partial carbon dioxide rebreathing method. RESULTS: CI was significantly reduced 2 and 5 min after pneumoperitoneum (2.6 +/- 0.7 L/min/m2, and 2.5 +/- 0.7 L/min/m2, respectively), and then returned to the pre-skin incision level. SVRI increased significantly after pneumoperitoneum and was then restored to that measured pre-skin incision at 20 min after pneumoperitoneum. MBP before anesthetic induction was found to be correlated with CI at 20 and 30 min after pneumoperitoneum (R = 0.37, P = 0.022, R = 0.37, P = 0.036, respectively). A moderate correlation was observed between MBP before anesthetic induction and SVRI at 2, 5, 10, 20, and 30 min after pneumoperitoneum (R = 0.39 0.60, P < 0.05). CONCLUSIONS: MBP before anesthetic induction correlated with CI at 20, and 30 min after pneumoperitoneum and with SVRI at 2, 5, 10, 20, and 30 min after pneumoperitoneum. Howerer, reduced CI at 2, 5, and 10 min after pneumoperitoneum was not correlated with MBP before anesthetic induction.

Effects of a Crystalloid Preload on Hemodynamics after Pneumoperitoneum in Laparoscopically-Assisted Vaginal Hysterectomy (LAVH) / 대한마취과학회지

BACKGROUND: Pneumoperitoneum and head-down tilt during a laparoscopic hysterectomy causes significant alterations in the hemodynamics including decreased cardiac output. The aim of this study was to evaluate the effects of a crystalloid preload on the hemodynamics after a hysterectomy (LAVH). METHODS: The patients were randomized to receive either no crystalloid fluid preload (control group: 29 women) or 10 ml/kg of a crystalloid fluid preload over 10 min (preloading group: 30 women) before the pneumoperitoneum. The hemodynamic parameters were measured before inducing anesthesia, immediately after the tracheal intubation, before the skin incision, and 2, 5, 10, 20, and 30 min after the pneumoperitoneum with CO2 with noninvasive cardiac output measurements using the partial CO2 rebreathing method. RESULTS: The cardiac index (CI) was reduced 2 and 5 min after the pneumoperitoneum, and then returned to normal. There were no significant differences in the CI after the pneumoperitoneum between the two groups (P<0.05). CONCLUSIONS: The administration of a 10 ml/kg crystalloid preload did not attenuate the decrease in the CI after pneumoperitoneum.

Reliability of Noninvasive Measurement of Cardiac Output Using Partial CO2 Rebreathing: A Comparison with Thermodilution Method / 대한마취과학회지

BACKGROUND: A noninvasive method for estimating cardiac output was tested in dogs. The technique is based on a differential CO2 Fick equation applied during normal ventilation and 50 seconds of partial rebreathing using additional dead space. We compared the cardiac output measured by the CO2 rebreathing method vs. the thermodilution technique. METHODS: Seven mongrel-dogs (24.6 +/- 0.4 kg) were studied, anesthesia was induced and maintained with a pentobarbital 25 mg/kg IV bolus injection followed by an infusion of 5 mg/kg/h. Mechanical ventilation was accomplished with a Servo 900C ventilator with FiO2 0.6 to maintain normocarbia. A fiberoptic pulmonary artery catheter was introduced via an external jugular vein for continuous monitoring of the cardiac output by the thermodilution method. Also cardiac output was measured by using partial CO2 rebreathing method. A continuous infusion of 0.5% bupivacaine was started at 0.5 mg/kg/min via the venous infusion port of the pulmonary catheter. Bupivacaine was infused continuously until mean arterial pressure decreased to 60 mmHg or less for at least 5 seconds. RESULTS: The total measured cardiac outputs (n = 72) were distributed over the range of 1.03-7.72 L/min by thermodilution method and 1.6-7.3 L/min by CO2 rebreathing. The correlation coefficients between both cardiac outputs was 0.6, the mean difference was 0.27 +/- 0.81 L/min. CONCLUSIONS: The cardiac output measured by CO2 rebreathing method was well correlated with cardiac output by thermodilution method.

Noninvasive Cardiovascular and Respiratory System Monitoring in Laparoscopic Cholesystectomy / 대한마취과학회지

BACKGROUND: The deleterious cardiopulmonary side effects immediately after positioning in reverse Trendelenburg and CO2 intra-abdominal insufflation during a laparoscopic cholecystectomy are well tolerated in healthy patients but can lead to serious morbidity and mortality in patients with a limited cardiopulmonary reserve. Using a continuous and non-invasive cardiac output monitor based on partial CO2 rebreathing method, we investigated the immediate cardiopulmonary changes caused by positioning in reverse Trendelenburg and CO2 intra-abdominal insufflation during a laparoscopic cholecystectomy, and assessed the applicability of the partial CO2 rebreathing method for the measurement of cardiac output in a laparoscopic cholecystectomy. METHODS: The investigation was carried out on 11 patients undergoing a laparoscopic cholesystectomy. The control values of cardiac index (CI), cardiac output (CO), mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), systemic vascular resistance (SVR), dynamic compliance (Cdyn), airway resistance (Raw), peak inspiratory pressure (PIP) and end tidal CO2 partial pressure (PETCO2) were measured in the supine position after induction with target-controlled infusion of propofol (5 microgram/ ml). Five minutes after positioning in reverse Trendelenburg and CO2 insufflation, the same cardiopulmonay variables were measured and compared with the control values. RESULTS: CI, CO and CVP were reduced 33.3%, 31.9% and 29.0%, respectively (P < 0.05). MAP and SVR were increased 39.8% and 154.1%, respectively (P < 0.05). Cdyn was reduced 38.0% (P < 0.05). Raw and PIP were increased 22.8%, and 34.8%, respectively (P < 0.05), whereas HR and PETCO2 remained unchanged. CONCLUSIONS: The non-invasive cardiopulmonary monitor using partial CO2 rebreathing method, could be used with ease and safety in a laparoscopic cholecystectomy.