Cannulate, Extubate, Ambulate: The Anesthesiologist's Role in Rapid Deployment of Extracorporeal Support During the COVID-19 Pandemic

To the Editor:

The COVID-19 PANDEMIC generated exponential demand for extracorporeal membrane oxygenation (ECMO) with an expanded array of indications.¹ Our healthcare institution is a high-volume center with an area covering 55 counties and 5 states within the United States.² As the COVID-19 pandemic progressed, we adjusted our approach to extracorporeal support, notably switching from cannulating patients in the intensive care unit to instead using the operating room to maintain higher standards of sterility, communication, and precision with the oversight of an anesthesiologist. The anesthesiologist's role in disaster mitigation became critical in the COVID-19 pandemic triage.

Initial engagement involved communication between our on-call cardiac surgeon and the medical team of an outside medical center. The surgeon and our institution's Director of ECMO discussed ECMO eligibility. The surgeon then discussed the case with the charge cardiac anesthesiologist for further input about candidacy, timing, consent, airway status, ventilatory strategies, vascular access, and hemodynamic status. This anesthesiologist evaluated ongoing surgeries, staffing, and resources while simultaneously triaging upcoming cases to facilitate emergent ECMO cannulation. The transportation team was contacted to facilitate optimal management during helicopter transfer from the outside hospital directly to our operating room. Before transport, patients often required a maximum ventilation strategy, with a fraction of inspired oxygen of 100% and positive end-expiratory pressure ranging from 15-to-20 cmH₂O in the face of failing conventional strategies. The anesthesiologist's thoughtful selection of these factors was essential to prevent ensuing hypoxia, hypercapnia, and acidemia that often precede cardiopulmonary arrest.

The endotracheal tube was clamped during the transfer from the transport gurney to the operating room table. The patient was often maintained on an intensive care unit ventilator throughout the case, and anesthesia was achieved with a propofol infusion that was titrated using bispectral index monitoring. Routinely, we immediately infused 100 mEq of intravenous sodium bicarbonate to acutely temporize acidemia, particularly when hypercapnia during transportation could be anticipated, to reduce the risk of cardiac arrest. Invasive arterial and venous catheters were placed expeditiously. Vasopressor and inotropic medication infusions, calcium chloride, albumin, blood products, and heparin were administered subsequently as necessary in anticipation of initiating ECMO.

Intraoperative cannulation allowed for preferential placement of a right internal jugular vein dual-lumen cannula, a strategy aligned with our “Cannulate, Extubate, Ambulate” approach to patients requiring extracorporeal support.³ The identification of various anatomic anomalies with transesophageal echocardiography and fluoroscopy permitted rapid decision-making about the choice of cannulation. For example, the presence of a Chiari network (Fig 1 , A1 and A2) prompted a change in cannulation strategy from a single-site to a dual-site option. Similarly, a thrombus obstructing the superior vena cava changed the cannulation strategy (Fig 1, B1 and B2). On another occasion, the presence of an atrial septal defect explained the magnitude of hypoxemia that was observed (Fig 1, C1 and C2). Transesophageal echocardiography was used to guide inotropic support to maintain a mean arterial pressure of >65 mmHg. Right ventricular dysfunction identified with transesophageal echocardiography prompted the use of inhaled nitric oxide. The surgeon and anesthesiologist jointly maintained ECMO in the operating room. Once ECMO was initiated, ventilator settings and endotracheal tube size reflected our intent to mitigate barotrauma and permit bronchoscopy. Peak pressures were limited to <30 cmH₂O, and a small endotracheal tube was exchanged to an internal diameter tube size of ≥7.5 mm to allow for bronchoalveolar lavage.

Figure 1.

Examples of cardiac anomalies identified using transesophageal echocardiography before extracorporeal membrane oxygenation cannulation in COVID-19 patients. The midesophageal bicaval view showing a Chiari network in the right atrium (A1) and a midesophageal right ventricular inflow-outflow view also showing the Chiari network in the right atrium (A2). The modified midesophageal 4-chamber view showing a large right atrial thrombus (B1) and a midesophageal bicaval view showing right atrial and superior vena cava thrombi (B2). The modified midesophageal bicaval view showing a large atrial septal defect and prominent Eustachian valve (C1) and a modified midesophageal bicaval view showing a large atrial septal defect with color-flow Doppler displaying left-to-right shunting (C2).

Declaration of Competing Interest

None.