Pulmonary Hypertension Crises

Acute pulmonary Hypertensive Crises.Welcome to PICU Doc On Call, A Podcast Dedicated to Current and Aspiring Intensivists.I'm Pradip Kamat and I'm Rahul Damania. We are coming to you from Children's Healthcare of Atlanta - Emory University School of Medicine.Welcome to our Episode a 7 month old boy ex-26 week premature infant with acute hypoxemia, bradycardia episodes, poor perfusionHere's the case:A 7 month old ex-26 week male was transferred from the outside hospital to our PICU for tracheostomy evaluation. Patient was intubated on second day of life. He had a prolonged course, on inhaled Nitric Oxide for first 2-3 months of life in the setting of severe pulmonary hypertension, requiring HFOV for a prolonged period of time. Failed extubation attempts multiple times. Received steroid burst x2. BPD settings trialed (lower rate, longer iTime, high PEEP, larger TV) without improvement. At time of transfer he was in PRVC mode on the ventilator — TV ~10ml/kg, 50%, PEEP 8, rate 28 (Peak pressures 27-32). Patient received albuterol Q4 for bronchospasm/wheezing and pulmicort BID. Patient was deeply sedated with morphine and midazolam. Interstitial lung disease panel was negative. ECHO showed: systolic septal flattening, moderate RV hypertrophy with normal systolic functioning. Patient was not on any PH medications at transfer. Patient is also on furosemide, hydrochlorothiazide and spironolactone.Patient has completed a course of antibiotics for klebsiella tracheitis from a ETT CX a week prior to admission to our picu. Patient tolerated feeds via an NJ tube.The team continues to evaluate his case as the Patient continues to have episodes of acute desaturation, tachycardia, cool extremities and poor perfusion.To summarize key elements from this case, we have a 7month old who is ex-26 week premiePatient has BPD and is on high vent settings and failing extubationAbnormal echocardiogram with flat septum and hypertrophied Right ventricleEpisodes of cold shock-tachycardia, poor perfusion, and cool extremitiesHypoxiaAll of which bring up a concern for acute pulmonary hypertensive crisisRahul Let's transition into some history and physical exam components of this case?What are key history features in this infants who presents with an acute pulmonary hypertensive crisisPrematurityBPDRemember BPD is defined by a requirement of oxygen supplementation either at 28 days postnatal age or 36 weeks postmenstrual age.Are there some red-flag symptoms or physical exam components which you could highlight?Presence of cold shock: tachycardia, cool extremities and poor perfusionHypoxiaCardiac exam will reveal a bounding right ventricle, prominent loud single S2Although not obvious in this patient: some patients can have a palpable liver, cardiac gallop, peripheral edema and jugular venous distentionS2 heart sound represents the closure of the PV very close to AV — In pulmonary hypertension this PE sign is seen with equal right and left ventricular pressures.To continue with our case, the patient's labs were consistent with:Respiratory acidosis (PCO2 > 100)CMP, CBC are normalBNP < 100, serum lactate normalEchocardiography findings in these patients can show tricuspid regurgitation. We can estimate right ventricular systolic pressure on echo and, by extension, systolic PAP (sPAP), by using tricuspid regurgitant (TR) jet velocity in combination with other echocardiographic findings. Using the modified bernoulli principle 4 x TR jet velocity squared, we can estimate the sPAP. If sPAP >2/3 systemic sBP with severe flattening or posterior bowing of the interventricular septum the patient can be diagnosed with severe pHTN.Pradip, what if the patient had a PDA on echo — what would you see?Rahul, when you see Predominantly right-to-left shunting across the PDA suggests suprasystemic sPAP. And as a result these patients can be hypoxemicOk, to summarize, we have:A 7-month ex-26 week premie infant old with shock with signs of poor perfusion +bounding right ventricle and loud single second heart sound, which brings us to the concern for acute pulmonary hypertensive crises.Let's start with a short multiple choice question:The best treatment for an acute pulmonary hypertension crises in an six month old ex-26 week with premie without congenital heart disease who is mechanically ventilated secondary to RSV bronchiolitis isA) SildenafilB) HypoventilationC) MilrinoneD) Sedation and paralysisRahul the correct answer is D sedation and paralysis. Although not a choice the I would recommend giving 100% O2 which is a potent vasodilator preferably with bag-mask hyperventilation (which causes alkalemia and causes pulmonary vasculature vasodilatation). Of the choices given in the above question none will be helpful in an acute PH crises although they are frequently used to treat PH in children. Milrinone is a PDE-3 inhibitor (increases cAMP) where as sildenafil is a PDE-5 inhibitor (increases cGMP). Hypoventilation will increase PCO2 which is a potent stimulus for PH crises. If available nitric oxide could be used.To summarize, acute pHtn you have to think about the pulmonary vasculature — which is responsive to changes in 02, pH, and Co2.As you think about our case, what would be your differential?Cold shock (although the in patients without PH-the cardiac exam will not reveal a loud single S2 or hyperdynamic right ventricle"Tet spell"-cyanotic spells typically seen in infants with congenital heart disease with a VSD such as tetralogy of fallot. deoxygenated blood is shunted across fro the right to the left across the VSD due to increased PVR. Cardiac exam may reveal reduced intensity or no murmur (as the murmur due to right ventricular outflow tract obstruction is proportional to the blood flow to the pulmonary circuit).We should also be vigilant of obstruction/Kinking of ETT in a patient resulting in hypoxia, bradycardia and cardiac arrest- which may look like a PH crisesRemember due to inc RV afterload you are going to have impairment of forward flow thus clinically presenting with hypoxemia and signs of poor perfusionIf you had to work up this patient with what would be your diagnostic approach?Really you don't need any investigation during an acute crises especially in a patient with h/o PHTN, h/o chronic lung disease, BPD or an infant with known cyanotic heart disease. Once patient is stable- consider chest radiograph (to check ETT tube position), blood gas for adequacy of ventilation. If patient is febrile then a CBC with differential + blood culture should be considered. An EKG may show RAH, RVH, ECHO may reveal findings...