Quest for the holy grail: Assessment of echo-derived dynamic parameters as predictors of fluid responsiveness in patients with acute aneurysmal subarachnoid hemorrhage

Background: Acute aneurysmal subarachnoid hemorrhage (aSAH) is a potentially devastating event often presenting with a plethora of hemodynamic fluctuations requiring meticulous fluid management. The aim of this study was to assess the utility of newer dynamic predictors of fluid responsiveness such as Delta down (DD), superior vena cava collapsibility index (SVCCI), and aortic velocity time integral variability (VTIAoV) in patients with SAH undergoing neurosurgery. Materials and Methods: Fifteen individuals with SAH undergoing surgery for intracranial aneurysmal clipping were enrolled in this prospective study. Postinduction, vitals, anesthetic parameters, and the study variables were recorded as the baseline. Following this, patients received a fluid bolus of 10 ml/kg of colloid over 20 min, and measurements were repeated postfluid loading. Continuous variables were expressed as mean ± standard deviation and compared using Student's t-test, with a P < 0.05 considered statistically significant. The predictive ability of variables for fluid responsiveness was determined using Pearson's coefficient analysis (r). Results: There were 12 volume responders and 3 nonresponders (NR). DD >5 mm Hg was efficient in differentiating the responders from NR (P < 0.05) with a sensitivity and specificity of 90% and 85%, respectively, with a good predictive ability to identify fluid responders and NR; r = 0.716. SVCCI of >38% was 100% sensitive and 95% specific in detecting the volume status and in differentiating the responders from NR (P < 0.05) and is an excellent predictor of fluid responsive status; r = 0.906. VTIAoV >20% too proved to be a good predictor of fluid responsiveness, with a sensitivity and specificity of 100% and 90%, respectively, with a predictive power; r = 0.732. Conclusion: Our study showed that 80% of patients presenting with aSAH for intracranial aneurysm clipping were fluid responders with normal hemodynamic parameters such as heart rate and blood pressure. Among the variables, SVCCI >38% appears to be an excellent predictor followed by VTIAoV >20% and DD >5 mmHg in assessing the fluid status in this population.

Entropy score, patent ductus arteriosus (PDA), and cardiopulmonary bypass (CPB): Ligation of PDA on CPB can compromise cerebral blood flow.

A patent ductus arteriosus (PDA) is often present in patients undergoing correction of congenital heart disease. It is well appreciated that during cardiopulmonary bypass (CPB), a PDA steals arterial inflow into pulmonary circulation, and may lead to systemic hypoperfusion, excessive pulmonary blood flow (PBF) and distention of the left heart. Therefore, PDA is preferably ligated before initiation of CPB. We describe acute decreases of arterial blood pressure and entropy score with the initiation of CPB and immediate increase in entropy score following the PDA ligation in a child undergoing intracardiac repair of ventricular septal defect and right ventricular infundibular stenosis. The observation strongly indicates that a PDA steals arterial inflow into pulmonary circulation and if the PDA is dissected and ligated on CPB or its ligation on CPB is delayed the cerebral perfusion is potentially compromised.

Pericardial tamponade after left posterolateral thoracotomy for left upper lobectomy for pulmonary aspergilloma.

Pericardial tamponade limits diastolic filling of the heart; therefore, a high venous pressure is required to fill the ventricle. In presence of cardiac tamponade, therapeutic agents and manoeuvres that results in venodilation or vasodilation can severely compromise diastolic filling of the heart and might result in rapid cardiac decompensation. Equalization of central venous pressure and pulmonary artery diastolic pressure or equalization of pressures in all four chambers during diastole confirms cardiac tamponade. Transthoracic echocardiography can detect the site of tamponade and assist in pericardiocentesis. We describe acute pericardial tamponade in a young man who underwent left posterolateral thoracotomy for left upper lobectomy. Intraoperatively, mobilization of the left upper lobe was frequently associated with hypotension. Postoperatively, the patient suffered two more episodes of hypotension. The episodes of hypotension were attributed to surgical manipulation and epidural blockade. Hemodynamics normalized after discontinuing epidural infusion, volume resuscitation and lobectomy. On third postoperative day, the patient developed cardiovascular collapse; arterial blood pressure and central venous pressure were 70/50 and 12 mmHg. Investigations showed haziness of left lung, and severe respiratory acidosis. On opening of the left thoracotomy wound, pericardial tamponade was diagnosed. A pericardial window was created and tamponade was released with that the hemodynamics normalized. Episodes of unexplained hypotension after left upper lobectomy suggest a cardiac etiology and acute pericardial tamponade is a possibility which should be released immediately otherwise it can result in fatal outcome.

Superior vena cava syndrome after pulsatile bidirectional Glenn shunt procedure: perioperative implications.

Bidirectional superior cavopulmonary shunt (bidirectional Glenn shunt) is generally performed in many congenital cardiac anomalies where complete two ventricle circulations cannot be easily achieved. The advantages of BDG shunt are achieved by partially separating the pulmonary and systemic venous circuits, and include reduced ventricular preload and long-term preservation of myocardium. The benefits of additional pulsatile pulmonary blood flow include the potential growth of pulmonary arteries, possible improvement in arterial oxygen saturation, and possible prevention of development of pulmonary arteriovenous malformations. However, increase in the systemic venous pressure after BDG with additional pulsatile blood flow is known. We describe the peri-operative implications of severe flow reversal in the superior vena cava after pulsatile BDG shunt construction in a child who presented for surgical interruption of the main pulmonary artery.