Application Of Inferior Vena Cava And Lung Ultrasound In Critical Patients After Cardiac Surgery

Background:Management of fluid balance is the focus of early treatment for critically ill patients.Early clinical decisions directly affect the prognosis.However,as individuals have different requirements for fluid,and no effective capacity assessment methods for blood volume,there are many realistic and troublesome problems about fluid replacement and liquid transfusion,which often lead to frequent rehydration or tissue ischemia and hypoxia injury.Intensivists have tried various methods to assess capacity in several aspects.Specific assessment methods include static indicators such as central venous pressure?CVP?,systolic volume variation?SVV?,and pulse pressure variability?PPV?.However,it is controversy for evaluation of fluid indicators,and the standardized measurement of each indicators is not yet unified.the research of fluid indicators is collecting evidence now.With the development of bedside ultrasound,it has attracted much attention because of its non-invasive,intuitive,convenient and economic advantages.In recent years,based on the purpose of improving treatment on critically ill,intensivists have tried to evaluate the liquid state through some ultrasonic testing indicators.Ultrasound is the only one that can provide information about the circulatory system in terms of both morphological and functional aspects.With its popularity on daily diagnosis,using ultrasound to assess capacity may be development furthermore.As assessing the fluid state for liquid management,the function of vital organs should be considered,which is essential for assessing the tolerance on fluid.By the way,morphological changes in the organs before and after the rehydration are also important indicators for evaluating if the point of“end”is reached.Lung is a respiratory place which is filled with air,and it is also one of the most affected organs by fluid overload.Lung condition is an indispensable part of fluid state assessment.We aimed to study the value of ultrasonic parameters to indicate fluid responsiveness?FR?with the inferior vena cava and lung in critical care medicine,and expand applications of ultrasound in volume management.Part I:Correlation between the collapsibility of inferior vena cava and central venous pressure after cardiac valve replacementObjectives:Patients after cardiac surgery were detected with bedside ultrasound to measure the diameter and retraction rate of the inferior vena cava,and the correlation analysis was performed with the CVP,which is used for volume assessment mostly.To provide a proof for effective rehydration.Methods:1.Subjects:Eighty-four patients after the cardiac surgery operation from April to August 2018 were into group,42 males and 42 females,aged 18-75 years,average?51.66?±13.01)years old.The operation was performed in 39 patients with mitral valve replacement,26 patients with aortic valve replacement,and 19 patients with double valve replacement.Bedside ultrasound was performed for the first time within 48 hours after surgery.Exclusion criteria:hyperthyroidism,coronary atherosclerotic heart disease,moderate to severe pulmonary hypertension,pulmonary heart disease,patent ductus arteriosus,complicated congenital heart disease,and those who is unable to detect inferior vena cava?IVC?.2.Material and measurement:?1?Philips CX50 Color Doppler ultrasound,C5-1 abdominal probe,frequency 1.6³.6MHz,using M-mode ultrasound to measure the maximum and minimum transverse diameters of IVC?IVCmax and IVCmin?,both measured 3 Take and get the average diameter and collapsibility.?2?Pressure transducer?Edward,PX 260?,and use the routine measurement to obtain CVP while performing ultrasound examination.?3?Philips CX50 Color Doppler ultrasound,the S5-1 heart probe,M-mode to measure the left ventricular ejection fraction?LVEF?to perform cardiac function grading.?4?Basic vital signs monitoring indicators including heart rate and systolic and diastolic blood pressure are obtained from the bedside monitor,while obtaining the IVC and CVP,and recording is spontaneous or mechanical ventilation.The patient's gender,age,weight and body mass index were obtained from medical records.Results:1.In this study,84 patients were enrolled,with an average body mass index?23.07±3.74?kg/m²;heart rate?92.69±12.88?bpm;systolic pressure?122.05±16.57?mm Hg,diastolic pressure?66.64±8.39?mm Hg?1 mm Hg=0.133 kPa?.The cardiac function grade:27 in grade 1,21 in grade 2,11 in grade 3,and 17 in absence.There was no significant difference in IVC retraction rate between LVEF at all levels.There was no significant difference in IVC collapsibility between different body mass index?BMI?,body weight,body surface area,heart rate,blood pressure or gender.2.IVCmax,IVCmin,retraction rate of IVC,and CVP is?1.54±0.45?cm??1.19±0.45?cm??24.02±11.52?%??9.46±4.02?cm H₂O?1 cm H₂O=0.1 kPa?.Correlation analysis showed that both IVCmax and IVCmin were positively correlated with CVP?P<0.01?,and IVC retraction rate was negatively correlated with CVP?P<0.01?.The IVCmax,IVCmin and IVC retraction rate in the mechanical ventilation and spontaneous breathing groups were both correlated with CVP well.Conclusions:1.The diameter and collapsibility of IVC are significantly correlated with CVP.Because IVC is a large blood vessel connected to the right atrium directly,and the vessel wall is elastic,it is easy to deform with the change of pressure.Therefore,the change of the IVC transverse diameter can often reflect the right atrial volume and pressure.2.In mechanical ventilation or spontaneous breathing,IVC diameter and collapse rate are correlated with CVP,so ultrasound is able to indicate the fluid capacity.Part II:Application of lung ultrasound in critical patients after cardiac surgeryObjectives:Lung is an important part of liquid assessment.Although the application of pulmonary ultrasound has received attention and has been rapidly promoted recently,lung ultrasound?LUS?has less clinical experience than others.Ultrasound findings in the lungs may change after thoracic surgery,so radiological examination is used to compare the clinical evaluation of pulmonary ultrasound after cardiac surgery.Methods:1.Subjects:89 patients in the intensive care unit after cardiac surgery from May to November 2018 were recruited.There were 47 males and 42 females,aged 18-70 years,mean?52.48±13.29?years old.The operation was performed in 17 cases of mitral valve replacement,17 cases of aortic valve replacement,18 cases of double valve replacement,9cases of coronary artery bypass grafting,and 28 cases of other cardiac surgeries.The ventilation method was 27 cases of mechanical ventilation and 62 cases of spontaneous breathing.Ultrasonic measurement was made within 48 hours after surgery.Exclusion criteria:severe subcutaneous gas that ultrasound cannot penetrate;severe thoracic deformity or right heart;a large area of auxiliary material covering that cannot perform lung.2.Material and detection:?1?Philips CX50 Color Doppler ultrasound,C5-1 abdominal probe,frequency 1.0⁵.0MHz,turning off the harmonics,in supine position,scanning in the mid-axillary line,anterior axillary line,mid-clavicular line and parasternal line,respectively.The right lung was scanned from the second to the fifth intercostal space,whereas the left hemithorax was scanned from the second to the fourth intercostal space,giving a total of 28 sites.Record the number of B-lines.Scores the total number of B-lines on the right and left chest,respectively.Negative when the score is less than 3 at right side or 2 at left side.Otherwise it is positive.?2?Conventional radiograms chest film recently with the ultrasound examination were collected and classified according to the results of pleural effusion,pneumothorax and pneumonia.?3?Philips CX50 Color Doppler ultrasound,L12-3 probe,frequency 4.4⁸.8MHz,in supine position,in the 2-dimensional mode to obtain the short-axis image of the internal jugular vein?IJV?on the left of neck.The maximum and minimum transverse diameter of the IJV?IJVmax and IJVmin?were measured by M-mode in three times,and record the average diameter and calculate the retraction rate of IJV.?4?The IVC diameter and collapsibility,CVP,basic parameters on monitor,ventilation methods and medical records were obtained as before.Results:1.In n 89 patients enrolled in the study,there were no significant differences between LUS and heart rate,systolic and diastolic blood pressure,surgical procedure,ventilation,gender,age,weight or BMI.2.There were 89 patients:2 patients with right pneumothorax only underwent statistical analysis of left side group;8 patients with pleural effusion,4 persons were in the right,2 persons were in the left and 2 patients were bilateral.The volume of pleural fluid was small,and does not affect the image or film.Therefore,a total of 89 patients underwent left lung group analysis and 87 patients did right to analyze the statistical consistency of LUS and chest radiographs.The positive rate of left lung chest radiograph was 46.07%,the positive rate of left LUS was 62.92%,the positive rate of right chest radiograph was48.28%,and the positive rate of right LUS was 50.57%.The Kappa coefficient of left LUS and chest radiograph was 0.185?<0.4?,and the left LUS results were in poor agreement with the chest radiograph.The Kappa coefficient of the right LUS and X-ray was 0.632??0.7?,and the right LUS results were better than the chest radiograph.3.89 patients:B-line total score,IVCmax,IVCmin,retraction rate of IVC,IJVmax,IJVmin,retraction rate of IJV and CVP is?3.44±1.19???1.32±0.43?cm??1.07±0.44?cm??21.02±10.73?%??0.76±0.32?cm??0.63±0.34?cm??58.85±21.07?%??8.43±3.92?cm H₂O?1 cm H₂O=0.1 kPa??There was no statistically significant correlation between pulmonary ultrasound results and inferior vena cava,internal jugular vein and CVP?P>0.05?.Conclusions:1.The positive rate of right lung ultrasound is lower than that of left lung ultrasound,and the diagnosis of right lung ultrasound is in good agreement with chest radiography.This may be due to a slight increase in local fluid leakage in left lung tissue after cardiac surgery,resulting in ultrasound as performance of B-line increased,while the chest radiograph was not recognized.2.Lungs are an important part of the capacity assessment.There is no correlation between the LUS findings and the IVC,IJV and CVP.In the formulation of the liquid program,lung condition should be paid more attention to besides the conventional capacity-related indicators.