Reverse Potts for the Treatment of Severe Idiopathic Pulmonary Hypertension in Children

ABSTRACT Idiopathic pulmonary arterial hypertension is a rare and progressive disease with poor prognosis. Many patients progressively worsen even when using combinations of specific drugs for its treatment. Herein, we present our experience in the management of three children with severe pulmonary arterial hypertension refractory to clinical treatment who underwent Potts surgery in addition to clinical treatment.

Enhanced MR features of central chronic pulmonary artery thromboembolism and the clinical application value / 中华放射学杂志

Objective:To explore the relationship between the imaging features of enhanced MRI in patients with central chronic pulmonary artery thromboembolism (CPTE) and pulmonary vascular resistance (PVR).Methods:Thirty-nine patients with CPTE who had contrast-enhanced MRI examination were retrospectively enrolled this study from January 2018 to December 2020. And 33 patients who received right heart catheterization were divided into two groups based on PVR=1 000 dyn·s·cm -5. The differences of imaging features of CPTE in enhanced MRI between the two groups were compared. The relationship between gender, duration of disease, age, pleural thickening, bilateral bronchial artery dilation, number of the involved vascular segments, number of thrombosis, number of the thrombus-related delayed enhancement of artery wall and PVR was analyzed by binary logistic regression. Results:In 39 patients with central CPTE, the dilated lumen (168, 43.30%) and delayed enhancement of wall (122, 31.52%) were found in most of pulmonary arteries. The rate of the lumen dilatation associated with thrombus was the highest among that of the lumen abnormality (66, 52.80%). There were more thrombi in PVR<1 000 dyn·s·cm -5 group than those in PVR≥1 000 dyn·s·cm -5 group (χ 2=9.55, P=0.002). There was no significant difference in the incidence of wall delayed enhancement associated the thrombus between the two groups (χ 2=0.90, P=0.344). The incidence of bilateral bronchial arterial dilatation in PVR<1 000 dyn·s·cm -5 group was higher than that in PVR≥1 000 dyn·s·cm -5 group ( P=0.019). Logistic regression analysis showed that female, the less number of involved vascular segments and bilateral bronchial artery dilation were correlated with the lower PVR. Conclusions:Enhanced MRI is helpful to accurately evaluate the lumen abnormality of pulmonary artery and wall remodeling in central CPTE, which is of great value for the assessment of patients′ conditions and treatment effect.

Clinical efficacy and safety of Treprostinil in the treatment of children with early decompensation after the Fontan procedure / 中华实用儿科临床杂志

Objective:To investigate the efficacy and safety of Treprostinil in the treatment of children with early decompensation after the Fontan procedure.Methods:A retrospectively analysis was performed on the clinical data of 16 children with early decompensation after the Fontan procedure treated with Treprostinil injection from December 2017 to June 2020 at Fuwai Central China Cardiovascular Hospital.A total of 16 patients were included, including 5 boys (31.2%) and 11 girls (68.8%). The age was (4.6 ±1.2) years, the weight was (16.0±2.1) kg.The changes of central venous pressure (CVP), heart rate (HR), systolic blood pressure (SBP), central venous oxygen saturation (ScvO 2), lactic acid (Lac), oxygenation index and B-type natriuretic peptide (BNP) were recorded at the infusion of Treprostinil and 3 hours, 24 hours, 48 hours and 72 hours after the infusion.The short-term efficacy of Treprostinil was observed[mortality, mechanical ventilation time, and length of intensive care unit (ICU) stay]; paired t-test was used to analyze the above indexes at different time points.The adverse reactions during the administration were also recorded. Results:Of the 16 children, the median mechanical ventilation time was 9 (5, 22) h, and the median ICU stay time was 2 (1, 12)days.After 72 hours of drug administration, CVP, Lac, BNP and HR decreased: CVP decreased from(16±5) mmHg (1 mmHg=0.133 kPa) to (11±2) mmHg ( P<0.001), Lac decreased from(6.8±3.2) mmol/L to (3.2±1.2) mmol/L ( P=0.002), BNP decreased from(980±223) ng/L to (250±120) ng/L( P<0.001), HR decreased from(150±20) times/min to (125±16) times/min( P=0.002); SBP, ScvO 2 and oxygenation index increased: SBP increased from(83±10) mmHg to (98±12) mmHg( P<0.001), ScvO 2 increased from 0.53±0.13 to 0.65±0.11 ( P=0.003), oxygenation index increased from (200±72) mmHg to (298±13) mmHg ( P<0.001), and the differences were statistically significant(all P< 0.05). One case died (6.3%), 2 cases (12.5%) had transient blood pressure drop and 1 case (6.3%) had nausea and vomiting.Besides, no other treatment-related complications were observed. Conclusions:As for children with early decompensation after the Fontan procedure, the intravenous application of Treprostinil can reduce pulmonary artery pressure rapidly, effectively improve circulatory status and oxygenation and ultimately improve the prognosis.

Discussion on heart transplantation indications in patients with end-stage heart failure complicated with reversible pulmonary artery hypertension / 器官移植

Heart transplantation can save the life and improve the quality of life of patients with end-stage heart failure. Nevertheless, it is not suitable for all patients with end-stage heart failure. As a common complication of end-stage heart failure, pulmonary artery hypertension may increase the incidence of right heart failure after heart transplantation, which is associated with the short- and long-term fatality risk in the recipients after heart transplantation. In clinical practice, different transplant centers have different criteria for heart transplantation indications in patients with end-stage heart failure complicated with pulmonary artery hypertension. Accurate preoperative evaluation of surgical indications plays a critical role in determining the success of heart transplantation. In this article, the definition, pathogenesis and effects on heart transplantation, diagnostic methods and reversibility judgment of pulmonary artery hypertension, diagnostic treatment of reversible pulmonary artery hypertension and indications of heart transplantation in patients with end-stage heart failure complicated with reversible pulmonary hypertension were reviewed.

​A Comparative Study of Changes in Left Ventricular Function after Mitral Valve Replacement in Patients with Severe Rheumatic Mitral Regurgitation with and without Mild Mitral Stenosis

Introduction: Presently off- pump CABG has proved itself tobe a safe, cheaper and effective alternative of on- pump CABG.However, it requires manipulation, displacement, positioning& mechanical stabilization of the heart during grafting whichmay cause haemodynamic alteration. Study was done withthe objective of finding out the changes in Central VenousPressure (CVP); Mean Arterial Pressure (MAP); MeanPulmonary Arterial Pressure (MPAP); Right Ventricular EndDiastolic Pressure (RVEDP) & Left Ventricular End DiastolicPressure (LVEDP) while grafting the anterior, lateral &inferior surfaces of heart during off-pump CABG.Material and methods: Over one year time, 50 patients withLVEF ≥40%, undergoing off-pump CABG were monitoredfor the above parameters at various stages of their operation,namely:- 1. During manipulation & shunt introduction,2.During anastomosis without shunt, 3.During anastomosiswith shunt & 4.After anastomosis; while grafting the anterior,lateral & inferior surfaces of heart. These results werecompared with the baseline values of CVP, MAP, MPAP,RVEDP & LVEDP, to look for statistical significance.Results: During manipulation & shunt introduction; CVP(mmHg) significantly increased during Ramus grafting - 12±1.8(p<0.047); and also during OM grafting – 12.6±1.9 (p<0.045),when compared to a baseline value of 9±1.8. The MAP(mmHg) was significantly decreased during manipulation &shunt introduction in Diagonals - 70±5.8 (p<0.046), Ramus- 70±5.8 (p<0.048), OMs - 65±5.8 (p<0.028) & in the Rightterritory - 69±5.9 (p<0.032); as compared with baselineMAP of 76±11.7. During anastomosis without shunt also, theMAP(mmHg) significantly decreased while grafting LAD- 70±3.8 (p<0.048), Diagonals - 68±3.8 (p<0.039), OMs –71.8±4.8 (p<0.039) & Right sided arteries 70.8±4.6 (p<0.039),as compared with baseline MAP values. The MPAP(mmHg)was significantly increased – 18.3±3.7 (p<0.047) as comparedto the baseline value of 16±2.4 during manipulation & shuntintroduction in the OMs.Conclusion: During OPCABG there will be significantalterations in haemodynamics mostly due to mobilizationof the heart, which is necessary to visualise the targetvessels properly & stabilisation of the concerned areawith stabiliser. However, by observing the haemodynamicvariations constantly & by making necessary mechanical &pharmacological adjustments, unnecessary conversion to Onpump technique can be avoided.

Study of Prevalence of Pulmonary Artery Hypertension in Portal Hypertensives Patients in RIMS, Ranchi

Background: The development of pulmonary hypertension i.e.mean pulmonary artery pressure (mPAP) above 25 mmHg withnormal capillary wedge pressure and pulmonary vascularresistance(PVR) above 240 dyn/s/cm−5 in association withelevated pressure in portal circulation is known asportopulmonary hypertension (POPH). Comparing withidiopathic PAH, patients with POPH have a worst survivalprofile, with a 3-year survival of only 38% versus78% foridiopathic PAH. Recent evidence from France shows thatPOPH is the fourth most common form of PAH reported overallin the population-based French National Registry, afteridiopathic PAH and PAH associated with connective tissuediseases and con- genital heart disease. The aim of this studyis to evaluate frequency of POPH in portal hypertensivepatient.Materials and Methods: A cross sectional study of patientadmitted in RIMS, medicine department was performedfulfilling features of portal hypertension with ultrasoundshowing splenomegaly, ascites, portal vein diameter more than13 mm, portal vein velocity less than 15 cm/s and uppergastrointestinal endoscopy showing esophageal varices andpatient with connective tissue disease, congenital heartdisease, left ventricular systolic or diastolic dysfunction,valvular heart disease, lungs disease, sleep related breathingdisorder, chronic hemolytic and myeloproliferative disorderwere excluded. All patient underwent screening withechocardiography for measuring pulmonary artery systolicpressure (PASP) and PASP more than 35 mmHg wereconsidered for POPH which was confirmed with right heartcatheterisation by measuring mean pulmonary artery pressure(mPAP) of more than 25 mmHg.Observation: Among forty-two patient in this study, there werethirty-three male patients and nine female patients. POPH wasseen three female and two male patients with total of five out offorty- two with prevalence of 11.9% out of which 7.1% werefemale and 4.8% were male.Conclusion: Portopulmonary hypertension prevalence is 2–6%. In this study pulmonary hypertension is significantly high inportal hypertensive patient with percentage of 11.9% and moreprevalent in female.

Cómo y cuándo realizar un cateterismo derecho: Su implicancia en el seguimiento de los pacientes

El cateterismo cardíaco derecho representa el principal estudio diagnóstico necesario para confirmar la presencia de hipertensión arterial pulmonar, entendida como enfermedad poco frecuente, discapacitante y de pronóstico variable. Su indicación principal tiene lugar ante todo paciente en el que exista una fuerte sospecha de hipertensión pulmonar, aunque sus usos se extienden más allá, siendo muy útil en la valoración de la respuesta al tratamiento y en el estudio de otras patologías como cardiopatías congénitas y pacientes sometidos a trasplante cardíaco. Para su realización requiere de una técnica sistemática y rigurosa, con el fin de obtener resultados confiables que puedan aplicarse a la práctica diaria. Su valor pronóstico es indiscutible, al aportar parámetros hemodinámicos determinantes para la estratificación de pacientes y la implementación de estrategias terapéuticas dirigidas en función del riesgo. Sin embargo, no está exento de complicaciones, algunas de ellas potencialmente mortales, aunque en términos generales resulta ser un procedimiento seguro con baja tasa de morbi-mortalidad en los principales centros donde se realiza.

Right heart catheterization represents the main diagnostic study necessary to confirm the presence of pulmonary arterial hypertension, understood as a rare, disabling disease with variable prognosis. Its main indication occurs before any patient in whom there is a strong suspicion of pulmonary hypertension, although its uses extend further, being very useful in the assessment of the response to treatment and in the study of other pathologies such as heart disease congenital and patients undergoing cardiac transplantation. To procedure it requires a systematic and rigorous technique, in order to obtain reliable results that can be applied to daily practice. Its prognostic value is indisputable, by providing precise hemodynamic parameters for the stratification of patients and the implementation of therapeutic strategies directed according to risk. However, it is not free of complications, some of them potentially fatal, although in general terms it turns out to be a safe procedure with a low rate of morbidity and mortality in the main centers where it is performed.

O cateterismo cardíaco direito representa o principal estudo diagnóstico necessário para confirmar a presença de hipertensão arterial pulmonar, entendida como uma doença rara e incapacitante com prognóstico variável. A sua principal indicação ocorre em todos os pacientes em que haja uma forte suspeita de hipertensão pulmonar, mas a sua utilização se estendem para além de ser muito útil na avaliação da resposta ao tratamento e o estudo de outras doenças tais como a doença cardíaca congênitos e pacientes submetidos a transplante cardíaco. Para realizá-lo, é necessária uma técnica sistemática e rigorosa, a fim de obter resultados confiáveis que possam ser aplicados na prática diária. Seu valor prognóstico é indiscutível, pois fornece parâmetros hemodinâmicos precisos para a estratificação dos pacientes e a implementação de estratégias terapêuticas direcionadas de acordo com o risco. Entretanto, não é isenta de complicações, algumas delas potencialmente fatais, embora em termos gerais se revele um procedimento seguro, com baixa taxa de morbidade e mortalidade nos principais centros onde é realizada.

Interpretation:recommendations of the 6st World Symposium on Pulmonary Hypertension（Ⅱ）——haemodynamic definitions and updated clinical classification of pulmonary hypertension / 中国实用内科杂志

Pulmonary hypertension(PH)has been defined as mean pulmonary arterial pressure(mPAP）≥25 mmHg at rest,measured by right heart catheterisation. The 6 th WSPH suggested a new pressure level to define an abnormal elevation as the mPAP>20 mmHg and the need for PVR≥3 WU to define the presence of pre-capillary PH. Regarding clinical classification,the main changes were the inclusion in group 1 of a subgroup“pulmonary arterial hypertension(PAH)long-term responders to calcium channel blockers”and a subgroup“PAH with overt features of venous/capillaries involvement“.

Interacciones cardiopulmonares: de la fisiología a la clínica / Cardiopulmonary Interactions: from Physiology to Clinic

Resumen: Las Interacciones Cardiopulmonares (ICP) corresponden al conjunto de interrelaciones entre el sis tema respiratorio y el cardiovascular, durante el ciclo respiratorio y cardíaco. Estas interacciones varían dependiendo de si el paciente se encuentra en ventilación espontánea o mecánica, afectando en distintos grados la precarga y postcarga, tanto del ventrículo derecho e izquierdo. El entender estas interacciones, resulta esencial al momento de manejar pacientes críticamente enfermos, en donde las manipulaciones de la precarga y postcarga, son de especial importancia al momento de optimizar el débito cardíaco y la entrega de oxígeno a los tejidos. En este artículo se presentan los principios fisiológicos que permiten entender las interacciones cardiopulmonares en ventilación espontánea y en ventilación mecánica, aplicadas a situaciones clínicas específicas, lo que nos ayudará a utilizarlas como herramientas en el manejo de los pacientes.

Abstract: Cardiopulmonary Interactions (CPI) refer to the interplay between the respiratory and cardiovascu lar systems during the respiratory and cardiac cycle. These interactions vary depending on whether the patient is in spontaneous or mechanical ventilation and affect the preload and afterload of both ventricles at different levels. Understanding CPI is essential to the management of critically ill pa tients, where preload and afterload manipulations are specialy important to optimize cardiac output and oxygen delivery to the periphery. The present article reviews the physiological principles required to understand CPI in patients both in spontaneous and mechanical ventilation using specific clinical scenarios to facilitate its use as part of day to day clinical practice.

Efficacy of Bosentan in patients after Fontan procedures: a double-blind, randomized controlled trial / 华中科技大学学报（医学）（英德文版）

Fontan surgery is a widely used palliative procedure that significantly improves the survival period of patients with complex congenital heart disease (CHD). However, it does not decrease postoperative complication rate. Previous studies suggested that elevated mean pulmonary artery pressure (mPAP) and vascular resistance lead to decreased exercise tolerance and myocardial dysfunction. Therapy with endothelial receptor antagonists (Bosentan) has been demonstrated to improve the patients' prognosis. A double-blind, randomized controlled trial was performed to explore the efficacy of Bosentan in treating patients who underwent the Fontan procedure. Eligible participants were randomly divided into Bosentan group and control group. Liver function was tested at a local hospital and the results were reported to the phone inspector every month. If the results suggested abnormal liver function, treatment would be adjusted or terminated. All the participants finished the follow-up study, with no patients lost to follow-up. Unblinding after 2-year follow-up, no mortality was observed in either group. However, secondary end-points were found to be significantly different in the comparable groups. The cardiac function and 6-min walking distance in the Bosentan group were significantly superior to those in the control group (P=0.018 and P=0.027). Bosentan could improve New York Heart Association (NYHA) functional status and improve the results of the 6-min walking test (6MWT) in Fontan patients post-surgery, and no other benefits were observed. Furthermore, a primary meta-analysis study systematically reviewed all the similar clinical trails worldwide and concluded an overall NYHA class improvement in Fontan patients who received Bosentan treatments.

Hemodynamic Follow-Up in Adult Patients with Pulmonary Hypertension Associated with Atrial Septal Defect after Partial Closure

PURPOSE: We evaluated the hemodynamic statuses of patients after partial closure of atrial septal defects with fenestration due to pulmonary hypertension. MATERIALS AND METHODS: Seventeen adult patients underwent partial atrial septal defect closure and follow-up cardiac catheterization. We analyzed hemodynamic data and clinical parameters before and after closure. RESULTS: The median age at closure was 29 years old. The baseline Qp/Qs was 1.9+/-0.6. The median interval from the operation to the cardiac catheterization was 27 months. The CT ratio decreased from 0.55+/-0.07 to 0.48+/-0.06 (p<0.05). The mean pulmonary arterial pressure decreased from 50.0+/-11.5 mm Hg to 32.5+/-14.4 mm Hg (p<0.05), and the pulmonary resistance index decreased from 9.2+/-3.6 Wood units*m2 to 6.3+/-3.8 Wood units*m2 (p<0.05). Eleven patients (64.7%) continued to exhibit high pulmonary resistance (over 3.0 Wood units*m2) after closure. These patients had significantly higher pulmonary resistance indices and mean pulmonary arterial pressures based on oxygen testing before the partial closures (p<0.05). However, no significant predictors of post-closure pulmonary hypertension were identified. CONCLUSION: Despite improvement in symptoms and hemodynamics after partial closure of an atrial septal defect, pulmonary hypertension should be monitored carefully.

Stepwise Approach Using Combined Management in Patients with Congenital Heart Disease and Borderline Pulmonary Vascular Disease

BACKGROUND AND OBJECTIVES: Despite remarkable advances in pediatric cardiology, pulmonary arterial hypertension associated with congenital heart disease remains a major problem. In the past decade new vasodilators have been introduced and appear to be effective in reducing pulmonary vascular resistance (PVR). SUBJECTS AND METHODS: From 2000 to 2011, we retrospectively reviewed the records of 22 patients who had congenital septal defects and borderline pulmonary vascular disease (PVD). The PVR in these patients was from 6 to 16 wood units . m2, and/or the systolic pulmonary arterial pressure was more than 2/3 of the systemic arterial pressure. RESULTS: The median age was 16 years (range, 9 months-46 years). The median duration of follow-up was 7.4 years (range, 1.4-11.7 years). According to hemodynamic data and clinical symptoms, the initial management comprised targeted medical therapy in four (18%), complete closure in four (18%), and partial closure in 14 patients (63.6%). In the four patients who had a high PVR and negative vasoreactivity, the PVR decreased and vasoreactivity increased after targeted medical therapy; three of these patients underwent cardiac surgery later. Finally, 11 (50%) received targeted medical therapy and 21 patients (95.4%) underwent cardiac surgery. Complete closure resulted in six patients and partial closure in 17 patients. Mortality was observed in two patients. The other 19 patients (91%) had New York Heart Association functional class I. CONCLUSION: Targeted medical therapy may be effective in reducing PVR in patients with congenital heart disease and borderline PVD. A stepwise approach may help to achieve improved outcomes in these patients.

Nitric oxide and pulmonary hypertension / 대한마취과학회지

Pulmonary hypertension is a serious complication of a number of lung and heart diseases that is characterized by peripheral vascular structural remodeling and loss of vascular tone. Nitric oxide can modulate vascular injury and interrupt elevation of pulmonary vascular resistance selectively; however, it can also produce cytotoxic oxygen radicals and exert cytotoxic and antiplatelet effects. The balance between the protective and adverse effects of nitric oxide is determined by the relative amount of nitric oxide and reactive radicals. Nitric oxide has been shown to be clinically effective in the treatment of congenital heart disease, mitrial valvular disease combined with pulmonary hypertension and in orthotropic cardiac transplantation patients. Additionally, new therapeutic modalities for the treatment of pulmonary hypertension, phosphodiesterase inhibitors, natriuretic peptides and aqueous nitric oxide are also effective for treatment of elevated pulmonary vascular resistance.

Study on the noninvasive estimation of pulmonary vascular resistance by color M-mode echocardiography assisted with computer / 中华超声影像学杂志

Objective To determine the feasibility and accuracy of velocity propagation within main pulmonary artery(VP)from color M-mode Doppler imaging using custom software on a personal computer for noninvasive estimation of PVR.Methods Color M-mode imaging of pulmonary flow was obtained and then transferred to computer,the velocity propagation of pulmonary flow was automatically obtained.Comparative studies among Doppler echocardiography,personal computer and cardiac catheterization for predicting PVR had been done in 20 children with congenital heart disease and 20 normal children.Results Velocity propagations of children with congenital heart disease were significant lower than those of normal children obtained by color Mmode echocardiography[(38.38±18.89)cm/s VS(80.34±15.65)cms,P＜0.01),and correlated well with invasive PVR measurements(r=-0.69,P＜0.01).The correlation and repeatability of VP obtained by the custom software were better than VP obtained by Doppler echocardiography(r=-0.78,P＜0.01).A VP cutoff value obtained by the custom software of 35.910 had a sensitivity of 92.9% and a specificity of 100% to within pulmonary artery obtained by color M-mode echocardiography using custom software on a personal computer.

Aprotinin Attenuates the Elevation of Pulmonary Vascular Resistance After Cardiopulmonary Bypass

Pulmonary vascular resistance (PVR) is generally believed to be elevated after cardiopulmonary bypass (CPB) due to whole body inflammation. Aprotinin has an antiinflammatory action, and it was hypothesized that aprotinin would attenuate the PVR increase induced by CPB. Ten mongrel dogs were placed under moderately hypothermic CPB for 2 hr. The experimental animals were divided into a control group (n=5, group I) and an aprotinin group (n=5, group II). In group II, aprotinin was administered during pre-bypass (50,000 KIU/kg) and post-bypass (10,000 KIU/kg) periods. Additional aprotinin (50,000 KIU/kg) was mixed in CPB priming solution. PVRs at pre-bypass and post-bypass 0, 1, 2, 3 hr were calculated, and lung tissue was obtained after the experiment. Post-bypass PVRs were significantly higher than prebypass levels in all animals (n=10, p<0.001). PVR elevation in group II was less than in group I at 3 hr post-bypass (p=0.0047). Water content of the lung was lower in group II (74+/-9.4%) compared to that of group I (83+/-9.5%), but the difference did not reach significance (p=0.076). Pathological examination showed a near normal lung structure in group II, whereas various inflammatory reactions were observed in group I. We concluded that aprotinin may attenuate CPB-induced PVR elevation through its anti-inflammatory effect.

Change of Pulmonary Artery Hemodynamics and Pulmonary Vascular Resistance in Experimental Pulmonary Embolism / 결핵

BACKGROUND: When we define the pressure of pulmonary vasculature in which a recruitment of blood flow occurs as P1 and the proportion of change in pulmonary artery to that in cardiac output as IR and then we compare PI and IR with pulmonary vascular resistance, we would find some problems in pulmonary vascular resistance. In other words, it is the theory that, IR should be increased mainly in pulmonary embolism in which decreases the cross sectional area of pulmonary vasculature. But there are many contradictory reports resulted from various researches and the fact is known widely that any difference exists between PVR and PI, IR. For this reason, the purpose of this study is to observe how PI and IR change at the time of the outbreak and during treatment of the pulmonary embolism, and to find out the meaning of these new indicators and the difference from the pulmonary vascular resistance used generally when we subdivide the pulmonary vascular resistance into PI and IR. METHOD: After making AV fistula in experimental dog, we controlled cardiac output at the intervals of 15 minute in case of three kinds(all AV fistula are obstructed, only one of fistula is open and all of fistula is open), and after evoking massive pulmonary embolism with radioactive autologous blood clots, we measured the mean pulmonary artery pressure, and calculated PI and IR. We observed the pattern of change in PI and IR, without giving the control group any specific treatment and with injecting intravenously rtPA in the Group 1 and Group 2 at the dose of lmg per kg, for 15 minutes fot the former and 3 hours for the latter. RESULT: 1) Pulmonary vascular resistance showed a change similar to that of pulmonry artery pressure and in all three group, PVR increased significantly, but group 1 and group 2 showed tendency that PVR keeps on decreasing after treatment, and the rate of decrease in group 1 is more rapid than group 2 significantly. 2) Both intersection(PI) and degree(IR) are proved statistically significant, in view of the straight line relationship between cardiac output and pulmonary artery pressure, calculated by minimal regression method. 3) PI changed similarly to pulmonary vascular resistance, while in the IR which is theoretically more similar to PVR, there was no significant difference or change after rtPA infusion. CONCLUSION: In the pulmonary embolism, Both change in IR which means real resistance of pulmonary vasculature and PI which was developed due to secondary vasoconstriction by pulmonary embolism are reflected same time.

Effect of Positive End-expiratory Pressure(PEEP) of Contra-lateral Lung on Redistribution of Pulmonary Blood Flow during One-lung Atelectasis / 대한마취과학회지

The normal response of the pulmonary vasculature to one-lung atelectasis is an increase in pulmonary vascular resistance (PVR). The mechanism of the increase in PVR is thought to be due almost entirely to hypoxic pulmonary vasoconstriction (HPV). Regional HPV results in blood flow diversion from hypoxic regions to normoxic regions. The expected pulmonary shunt is thereby reduced and the arterial oxygen tension increased. PEEP improves the arterial oxygen tension as a result of increasing functional residual capacity (FRC) and decreasing intrapulmonary shunt. The aims of the present studies were to observe blood flow diversion from atelectatic lung to normoxic lung and to prove a sustained redistribution of pulmonary blood flow from ventilated with PEEP to atelectatic regions. This study evaluated the interactions between HPV and PEEP. Eight mongrel dogs were anesthetized with pentobarbital. Left pulmonary blood flow was measured with eletromagnetic flow probes following left lateral thoracotomy. Pulmonary arterial pressures, PCWP, systemic arterial pressures were measured via indwelling catheter. Cardiac output was determined by thermodilution in triplicate. The right lung was ventilated continuosly with 100% O2, while left lung was ventilated with 100 O2 (control phase), and unventilated for 60 min. of atelectasis. PEEP of 5 and 10 cmH2O was ed to the right lung. During two-lung ventilation with 100 oxygen, cardiac output was 2890+/-880 ml/min. (mean SD) and left pulmonary blqod flow was 1100+/-220 ml/min. Left lung atelectasis resulted in a reduction of the percent left blood flow compared with cardiac output from 41+/-10% to 29+/-7% at 15 min and to 22+/-9% at 60 min (p<0.05). The ratio of left pulmonary blood flow to mean pulmonary artery pressure decreased from 51+/-25 ml/min/ mmHg in control to 19+/-7 ml/min/mmHg at 60 min (p<0.05). Left pulmonary vascular resistance increased gradually (p<0.01). Arterial oxgen tension was the lowest at 15 min (165+/-66 mmHg) and increased subsequently (p<0.01). Intrapulmonary shunt was 27+/-6% in, control phase and abruptly increased to 37+/-6% at 15 min after atelectasis and decreased to 34+/-10% at 60 min. When 10 cmH2O PEEP was applied to the right hung during left lung atelectasis, the percent ratio of left pulmonary blood flow to cardiac output was significantly increased from 22+/-9% at 60 min of left lung atelectasis to 34+/-8% (p<0.05). Left pulmonary vascular resistance significantly decreased as compared with 45 and 60,min of left lung atelectasis (p<0.05). Arterial oxygen tension incresed by PEEP of 5 and 10 cmH to 257+/-74 mmHg and 252+/-92 mmHg compared with 164+/-65 mmHg and 177+/-28 mmHg at 15 and 30 min. of left lung atelectasis (p<0.05). The present study demonstrated that the response to acute atelectasis is a regional increase in pulmonary vascular resistance and a sustained diversion of blood flow away from the atelectatic lung. In this study, the application of 10 cmH2O PEEP resulted in a redistribution of pulmonary blood flow from normoxic lung to atelectatic lung and didn't affect arterial oxygenation. We conclude that when employing the technique of one-lung anesthesia, PEEP to improve oxygenstion should be cautiously applied and a search for the maximum oxygenation and a minimum redistribution might be started, in an attempt to find the optimal PEEP.