INTRODUCTION:Repaired congenital heart defects can complicate hemodynamic management of septic shock.
CASE PRESENTATION:26-year-old obese female admitted after exploratory laparotomy for tuboovarian abscess at another facility. Postoperative course was complicated by shock and respiratory failure. On admission the blood pressure was 100/50 millimeters of mercury (mmHg) on norepinephrine, heart rate 110 beats per minute, respiration 22 breaths per minute, temperature 38.6 degree centigrade, oxygen saturation 94 percent(%). Central venous pressure (CVP) was 35 centimeter of water. Assist control volume regulated mechanical ventilation initiated at the rate of 22 breaths per minute, tidal volume 500 liters per minute, positive end expiratory pressure (PEEP) of 8 centimeter of water, fraction of inspired oxygen 0.5. On physical examination, midline surgical scar was noted on the sternum with distant heart sounds and diminished breath sounds at the bases. Mixed venous oxygen saturation (MvO2) was 64%, lactate was 2.4 millimoles per liter, hemoglobin 10 grams per deciliter, blood urea nitrogen 26 milligram per deciliter, creatinine 2.4 milligram per deciliter and normal cosyntropin stimulation test. Chest radiograph revealed large cardiac silhouette, bilateral infiltrates (figure 1). Patient was treated for septic shock and dobutamine drip was initiated per sepsis protocol. Upon further questioning of family members, remote Fontan procedure was brought to attention. Volume resuscitation was initiated. Transesophageal echocardiogram revealed surgically corrected pulmonary atresia with intact ventricular septum, extremely large right atrium with sluggish flow, patent conduit from right atrium to left pulmonary artery with a small volume contracted left ventricle (figure 2). Receiving 46 liters of normal saline, patient was weaned off vasopressor support. She was ultimately transferred to a rehabilitation facility.
DISCUSSIONS:This patient’s pulmonary atresia was corrected using the Fontan operation. The right ventricle was bypassed and the right atrium was connected directly to the pulmonary arteries. In Fontan physiology, systemic venous blood is directed passively into the pulmonary circulation. Oxygenated blood then drains into a common atrium and thence into the single ventricle that perfuses the systemic circulation. The difference between central venous pressure and systemic ventricular end-diastolic pressure is the primary force promoting pulmonary blood flow and cardiac output. Efficacy of Fontan circulation depends upon the systemic venous pressure and volume, pulmonary vascular resistance, atrioventricular valve function, cardiac rhythm, and function of the systemic ventricle. Perturbation of any of these factors can compromise systemic cardiac output as seen in this patient. Volume resuscitation was the key to the management of this patient due to the preload dependece of the Fontan circulation. CVP was not a reliable indicator of intravascular status. Pulmonary hypertension led to overestimation of CVP. The sepsis protocol mandated the use of dobutamine initially when the CVP was “at goal” and the MvO2 was low. To our knowledge, only one case report was found citing the use of dobutamine in Fontan circulation. Just as positive pressure ventilation can decrease venous return, pulmonary blood flow is increased as the pleural pressure becomes negative during spontaneous inspiration. High tidal volume and PEEP may result in paradoxical deterioration by limiting pulmonary blood flow. The amount of PEEP applied was carefully monitored to optimized oxygenation while limiting reduction in preload. Early tracheostomy was performed to allow trials off positive pressure ventilation in order to evaluate tolerance of increasing venous return.
CONCLUSION:This case reminds us that more people with repaired congenital heart defects are surviving into adulthood. In the setting of critical illness this may lead to significant challenges when utilizing current treatment algorithms.
DISCLOSURE:Soophia Khan, No Financial Disclosure Information; No Product/Research Disclosure Information