|LETTER TO EDITOR
|Year : 2019 | Volume
| Issue : 2 | Page : 271-273
Pulmonary arterio venous malformations - What the anesthesiologist must know
BK Lakshmi, Supriya Dsouza, Adarsh Kulkarni, Jyoti Kamble, Madhu Garasia
Department of Anaesthesiology, Seth GS Medical College and KEM Hospital, Mumbai, Maharashtra, India
|Date of Web Publication||25-Jun-2019|
Department of Anaesthesiology, Seth GS Medical College and KEM Hospital, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Lakshmi B K, Dsouza S, Kulkarni A, Kamble J, Garasia M. Pulmonary arterio venous malformations - What the anesthesiologist must know. J Anaesthesiol Clin Pharmacol 2019;35:271-3
|How to cite this URL:|
Lakshmi B K, Dsouza S, Kulkarni A, Kamble J, Garasia M. Pulmonary arterio venous malformations - What the anesthesiologist must know. J Anaesthesiol Clin Pharmacol [serial online] 2019 [cited 2020 Jun 4];35:271-3. Available from: http://www.joacp.org/text.asp?2019/35/2/271/261281
A 11-year-old male child diagnosed to have pulmonary arteriovenous malformations (PAVM) 6 years back, treated with embolization and coiling twice in the past presented with exertional dyspnea and cyanosis since 2 months. Chest x-ray showed increased bronchovascular markings and coils [Figure 1]. Computed tomography pulmonary angiography revealed bilateral arteriovenous malformations in the right middle and lower lobes, and the left upper and lower lobes. 2D Echo and USG abdomen were unremarkable. Hemoglobin was 19.3 g%, PCV was 62.5% which settled to 16.4 g%, and 54.9% after two exchange transfusions. ABG in sitting position on room air revealed a pO2 of 25.2 mmHg and SaO2 of 40.4% and a pO2 of 35 mmHg and SaO2 of 66% in the supine position. pCO2 was normal in both ABGs. The treatment plan was repeat embolization under general anesthesia.
|Figure 1: Digital Subtraction Angiography image showing coils in the pulmonary vasculature|
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After adequate hydration and antibiotic prophylaxis, the child was preoxygenated with 100% oxygen and anesthesia was induced with Inj. Midazolam 0.03 mg/kg iv, Inj. Fentanyl 2 μg/kg iv, Inj. Propofol 2 mg/kg iv, and Inj. Vecuronium 0.1 mg/kg iv, intubated with 6-mm cuffed endotracheal tube and anesthesia was maintained with 50%–50% oxygen–air mixture and propofol infusion at 50–100 μg/kg/min. Extreme care was taken to keep the intravenous line free of air bubbles. The intraoperative oxygen saturation varied between 56% and 62% and improved to 77% after embolization. Neuromuscular blockade was reversed and trachea extubated uneventfully. Immediate post-operative ABG taken in supine position showed a pO2 of 36 mmHg and a SaO2 of 70%. SPO2 was 65% in sitting position and 75% in supine position. In post-operative period, there was a reduction of Hb (11.9 g%) and PCV (39.1%).
PAVMs are abnormal pulmonary arteries and pulmonary veins communicating directly without interposition of a capillary bed. About 80%-90% of patients with PAVMs eventually may present with hereditary hemorrhagic telangiectasia (HHT), whereas others are sporadic. Due to the PAVMs typically being located in the lower lobes, postural changes in the degree of shunt in the supine position characteristically show an improvement in oxygenation (as measured by pulse oximetry or arterial gas sampling) over those in the sitting position. Risks include rupture presenting with massive hemoptysis and/or hemothorax, significant right to left shunt resulting in hypoxemia, heart failure, and the potential passage of emboli across the shunt into the systemic circulation causing complications, such as stroke and cerebral or systemic abscesses.
PAVM poses quite a challenge to the anesthesiologist. Adequate hydration and exchange transfusion is needed if overt polycythemia is present as in our case, to maintain fluidity of blood and prevent sludging. Preoperative optimization of fluid status also helps maintain blood pressure. Great care should be exercised to avoid injecting even a minuscule air bubble with intravenous medications. Drug syringes, stopcocks, and all other air-trapping components of intravenous tubings should be cleared before use as capillary filter is lost in these patients. Antibiotic prophylaxis is essential as paradoxical shunting of emboli from the venous to the arterial circulation occurs leading to unfiltered blood returning to the heart causing septic embolism especially brain abscesses. Positive pressure ventilation may exacerbate shunting in PAVM and worsen hypoxemia; hence, spontaneous ventilation or breathing must be maintained or restored as soon as possible. PAVM causes a right to left shunt and may result in hypoxemia or mimic symptoms of airway obstruction. Oxygenated arterial blood bypasses the microcirculation where gas exchange occurs resulting in hypoxemia. Rise in blood pressure can be detrimental, so maintaining it within 20% of baseline is important especially during induction and emergence. Blunting of the pressor response and intraoperative propofol infusion can help maintain the blood pressure. However, since patients with AV malformations have a right to left shunt and decrease in systemic vascular resistance (SVR), anesthesia-induced drop in SVR is a concern. An unpredictable response to induced hypotension is seen due to the absence of tone in the AV malformation and so is the response to vasopressors. Intraoperatively rise in airway pressures is to be avoided to prevent rupture of AV malformations and increase in shunt and hypoxia; hence, the use of lower tidal volumes is prudent. Total intravenous anesthesia seems appropriate to avoid the inhibition of hypoxic pulmonary vasoconstriction and worsening of shunting by inhalational anesthetics.
Reassurance that the anesthesia provider is familiar with this rare condition and anesthesia considerations to prevent adverse outcomes will engage the trust and confidence of the patient in his/her anesthesiologist and help ease anxieties. A basic knowledge of the challenges presented by this syndrome is the first step in providing a safe and effective anesthetic technique.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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