關於 pulmonary artery hypertension ，我們在網路上蒐集到這些相關的討論、資訊與評價

有幾點值得大家思考下

從內文資料分析，小baby有先天性有VSD(ventricular septal defect)，餵奶時面色變紫其實可能有cyanotic heart disease如tetralogy of fallot (TOF)

TOF包括4個元素：VSD、Right ventricular outflow tract obstruction、overriding aorta和right ventricular hypertrophy

在嚴重VSD時情況下，右心室會逐漸變厚，不單止令到肺部血管壓力增加，同時當出現right to left shunt時，便會令小baby的血含氧量變低，因為右心室部分的血液不能經過肺部血管去oxygenate，而是直接shunt去左心室再經大動脈運到身體各處，這叫Eisenmenger syndrome，不過在發達國家如香港，這並不常見。

因為VSD令到更多血液流經肺部和心室，當小baby經過長期的volume overloading便可能會出現心臟衰竭。短期內可以試用藥物控制，但長遠還是要手術修補。
* 小baby可能會同時有右心室厚大(right ventricular hypertrophy)、cyanotic heart disease、肺高血壓(pulmonary hypertension)等問題

當baby出現體重過輕(failure to thrive)、面色變紫(cyanosis)、水腫或呼吸急速困難時，便代表小baby情況其實需要盡快以手術修補VSD或心臟結構異常以改善情況。

以往在初生兒先天性心臟發育不全的患者，有時候會先進行palliative staged surgery，先透過pulmonary artery banding(PAB)減少初期的left to right shunt和過多血液流向肺部(pulmonary over circulation)。不過近年研究發現早期直接primary definitive corrective surgery有更好的效果，但視乎個別情況，如臨床考慮和家屬的想法等，仍有不少病人需要先進行PAB再進行修補手術。

初生兒或兒童外科是非常複雜而且極為專門的專科，本身會去train pediatric surgery的醫生就極少，選擇去做這科的醫生一定都是有熱誠和深愛兒科才會去做，這比成人外科training所需要的成本、心血和時間多很多。

那我們回歸這個併發症：complete heart block

心臟是一個博大精深的器官，一些小小的disruption已經可以影響心臟自動發電心跳的功能。Complete heart block是VSD/TOF repair其中一個罕見的併發症，亦是有文獻documented的。

當然，沒有人會想有併發症，但梅菲定律告訴我們，anything that can happen will happen

不幸地，小baby似乎有complete heart block導致的心跳過低(Bradycardia)的併發症。很多家屬都反射性的想找原因，深信一定有人犯錯才會這樣，其他VSD/TOF repair的baby術後咩事都無，卻只有我的心肝寶貝出事。這種反應是可以理解的，但這是不是代表一定是醫療失誤？還是inadvertent的不幸？這是值得深思的一點

大家都不在手術現場，其實很難評論到底醫生有沒有犯錯、有沒有醫療失誤。目前仍然為口同鼻拗，但如我之前所講，當傳媒大肆報導醫生手術失誤害病人要安裝心臟起博器時，便已經嚴重傷害了醫生的reputation，就算到最後還他清白都好，damage has been done

更加重要的是，如小baby出現complete heart block，是需要治療和安裝永久性心臟起博器以確保心跳速度正常，過久的心跳過慢有導致心臟和器官衰竭的風險。但無奈的是，當家屬不信任醫療團隊時，再正路的醫療意見都不會被接納。

*先天性心臟病非常複雜，同樣是心漏病可以有非常不同的臨床狀況和治療方案。以上為general的分析，並不套用任何病人身上。

社會中有疑問，為什麼先替老弱打疫苗？可以看看邏輯和外面例子。
香港疫苗供應，依賴外來供應，一句到尾，無人敢保證。
社會是我們市民的家，老人家與長期病患者，中了新冠肺炎，死亡率比其他人高，是大家都知道的。
因此，若茂叔只可以偷運幾劑的疫苗，到自己家中，被執法者拘捕之前，一定先替風險高的家人注射。
美國也是先幫老弱、醫護、和部分維持社會運作人員打針。CDC 公佈： https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations.html
還有，在外國，煙民爭取打針，不是離開，也不是「被離開」。

Here’s Chicago’s full list of health conditions that qualify recipients for a COVID-19 vaccination starting March 29:
Cancer (current diagnosis)
Cardiac, cardiovascular, and cerebrovascular disorders (including heart disease, coronary artery disease, and hypertension or high blood pressure)
Chronic Kidney Disease
Chronic respiratory disorders (including cystic fibrosis, moderate to severe asthma, pulmonary fibrosis, and chronic obstructive pulmonary disease/emphysema [COPD])
Diabetes (Type 1 and Type 2)
Disability: physical, developmental, visual, hearing, or mental
Neurologic conditions (including dementia)
Down Syndrome
Immunocompromised state (weakened immune system) including from blood or bone marrow transplant, immune deficiencies, HIV, use of corticosteroids, or use of other immune weakening medicines
Liver disease (including hepatitis)
Pregnancy
Obesity: BMI ≥30 kg/m2
Schizophrenia spectrum disorders
Sickle Cell Disease

ARDS 的血行動力學

Experts’ opinion on management of hemodynamics in ARDS patients: focus on the effects of mechanical ventilation

Acute respiratory distress syndrome (ARDS) is frequently associated with hemodynamic instability which appears as the main factor associated with mortality. Shock is driven by pulmonary hypertension, deleterious effects of mechanical ventilation (MV) on right ventricular (RV) function, and associated-sepsis. Hemodynamic effects of ventilation are due to changes in pleural pressure (Ppl) and changes in transpulmonary pressure (TP). TP affects RV afterload, whereas changes in Ppl affect venous return. Tidal forces and positive end-expiratory pressure (PEEP) increase pulmonary vascular resistance (PVR) in direct proportion to their effects on mean airway pressure (mPaw). The acutely injured lung has a reduced capacity to accommodate flowing blood and increases of blood flow accentuate fluid filtration. The dynamics of vascular pressure may contribute to ventilator-induced injury (VILI). In order to optimize perfusion, improve gas exchange, and minimize VILI risk, monitoring hemodynamics is important.
During passive ventilation pulse pressure variations are a predictor of fluid responsiveness when conditions to ensure its validity are observed, but may also reflect afterload effects of MV. Central venous pressure can be helpful to monitor the response of RV function to treatment. Echocardiography is suitable to visualize the RV and to detect acute cor pulmonale (ACP), which occurs in 20–25 % of cases. Inserting a pulmonary artery catheter may be useful to measure/calculate pulmonary artery pressure, pulmonary and systemic vascular resistance, and cardiac output. These last two indexes may be misleading, however, in cases of West zones 2 or 1 and tricuspid regurgitation associated with RV dilatation. Transpulmonary thermodilution may be useful to evaluate extravascular lung water and the pulmonary vascular permeability index. To ensure adequate intravascular volume is the first goal of hemodynamic support in patients with shock. The benefit and risk balance of fluid expansion has to be carefully evaluated since it may improve systemic perfusion but also may decrease ventilator-free days, increase pulmonary edema, and promote RV failure. ACP can be prevented or treated by applying RV protective MV (low driving pressure, limited hypercapnia, PEEP adapted to lung recruitability) and by prone positioning. In cases of shock that do not respond to intravascular fluid administration, norepinephrine infusion and vasodilators inhalation may improve RV function. Extracorporeal membrane oxygenation (ECMO) has the potential to be the cause of, as well as a remedy for, hemodynamic problems. Continuous thermodilution-based and pulse contour analysis-based cardiac output monitoring are not recommended in patients treated with ECMO, since the results are frequently inaccurate. Extracorporeal CO2 removal, which could have the capability to reduce hypercapnia/acidosis-induced ACP, cannot currently be recommended because of the lack of sufficient data.
http://bit.ly/1Xdb1Kv