Cerebral Air Embolism During a Flight

Introduction: We report a case of a 67 year old lady with an acute drop in conscious level whilst on a transatlantic flight. She had a background history of TII DM and recent mild COVID. Past surgical history of a gastric bypass, at which time a CXR had incidentally shown a bulla, with no underlying respiratory symptoms, or history of COPD. Method(s): On arrival in the emergency department, her GCS was 7/15, and she required immediate intubation. Non-contrast CT head showed multiple tiny gas locules in keeping with air emboli. CT Chest, Abdo, Pelvis showed an 88mm bulla within the left lung lingula with a bronchus and many large pulmonary vessels running on its edge. Result(s): It was thought the change in air pressure during the flight caused a communication to open between the bulla and the pulmonary circulation resulting in the release of air emboli. Conclusion(s): She required ITU admission for 8 days. After initial stabilisation she was stepped down to HASU. Neurologically she was dysphagic, dysarthric, quadriplegic and GCS 14 due to confusion. MRI whole spine ruled out spinal cord pathology. Repeat CT head showed air initially present had completely resorbed leaving multifocal, small areas of cortical and subcortical ischaemia in both cerebral hemispheres. MRI head confirmed innumerable small early subacute embolic ischaemic infarcts across multiple vascular distributions.

Gas Pressure From the Endoscope: An Unexplored Contributor to Morbidity and Mortality?

Background It has been shown that the incidence of venous air embolism and venous carbon dioxide (CO2) embolism is high during endoscopic retrograde cholangiopancreatography (ERCP). We examined insufflating gas flow and maximum pressure produced by three types of commonly used endoscopes because we could not readily locate technical data for endoscope gas flow and maximum emitted pressure in the manufacturer's manuals. Methods We tested the Olympus GIF-Q180 used for esophagogastroduodenoscopy, the CF-Q180 used for colonoscopy, and the TJF-Q180 used for ERCP (Olympus America Inc., Center Valley, Pennsylvania). Under three different clinical gas insufflation scenarios, we measured in vitro maximum gas pressure transduced from a closed space created at the endoscope tip in a worst-case scenario analysis. Results We showed that it is readily possible to generate a pressure (>5-30 times normal central venous pressure) in the air space at the tip of all three endoscopes when insufflation is activated and the gas egress is limited. Conclusions These findings shed additional light on in vivo occurrences of gas embolism during gastrointestinal endoscopy. We postulate that in addition to using exclusively CO2 as the insufflating gas, the risk of gas embolism can be further diminished by regulating insufflating gas pressure at the tip of endoscopes.

A Case Report of ECMO Patient with Cerebrovascular Complication Caused by a Broken Dual Lumen Cannula

Introduction: Dual-lumen cannula is used for extracorporeal membrane perfusion (ECMO) to support patients with ARDS due to COVID-19 as a bridge to lung recovery. It tends to be a longer support and there are several factors that can degrade the physical structure of the ECMO cannula and put the cannula at risk for breakage. Case Report: A 63-year-old woman was admitted to the hospital with COVID-19 pneumonia. Two days later, she was intubated and VV-ECMO was initiated due to treatment-resistant acute respiratory failure;a 28Fr CrescentTM dual-lumen cannula (Medtronic, MN) was inserted through the left subclavian vein and connected to a centrifugal oxygen pump with a centrifugal oxygenator. Within six weeks after onset, the patient was unable to be weaned from the ventilator and was transferred to our center with ECMO connected for consideration of lung transplantation. Two days after transfer, the patient developed acute aphasia, altered mental status, disturbed consciousness, and left arm seizures. A suction sound was heard from the left subclavian cannula insertion site and the ECMO bubble detector alarmed, but local inspection, chest X-rays, and CT scans of the brain and chest showed no obvious abnormalities. The patient was reintubated for encephalopathy and subsequently underwent a tracheostomy. The patient regained normal neurological function over the next 7 days. However, the air bubble sensor alarmed and suction sound was heard at the cannulation site again, and air bubbles were seen in the oxygenator. Due to concerns about air entrapment and cannula failure, we changed to a dual-canal VV-ECMO configuration using a right internal cervical and a left femoral cannula. The removed cannula had a 2 cm fracture distal to the skin insertion site. After resumption of ECMO, no new neurological episodes occurred. While awaiting lung transplantation, the patient died due to sepsis and multiple organ failure. An autopsy revealed a possible cause of cerebrovascular disease patent foramen ovale and air embolism to the brain. If a patient has been on ECMO for a long time and the bubble sensor warns of air detection, cannula breakage and impending air embolism should be suspected clinically, even if the defect is not found on examination and is not evident on imaging. If the COVID-19 epidemic continues, increased transport events may increase ECMO cannula breakage.

Retrograde cerebral air embolism in a patient on venovenous ECMO

INTRODUCTION: Retrograde cerebral air embolism (CAE) is rarely described in literature that may be associated with manipulation of central or peripheral venous catheters. During a literature review, there were no described occurrences of CAE in patients on veno-venous (V-V) ECMO. DESCRIPTION: A 42-year-old male with ARDS secondary to COVID-19 pneumonitis was cannulated for V-V ECMO outside our facility and transferred to our cardiovascular intensive care unit. Upon arrival, he was noted to have a right femoral drainage cannula and right internal jugular (RIJ) venous antegrade cannula. On day 10 of his hospital stay he was converted to a RIJ Protek duo cannula and the right femoral drainage cannula was removed. This cannula was repositioned multiple times after placement due to flow issues. Due to poor oxygenator membrane function, it became necessary to exchange the oxygenator on day 25. During the exchange, the patient experienced sudden-onset bradycardia that progressed to several seconds of asystole. He regained spontaneous cardiac activity after a bolus dose of IV glycopyrrolate. Following this, he had several episodes of bradycardia and eventually asystole that resolved after one round of ACLS and IV atropine. The bradycardic episodes continued after this event and were associated with hypertension. On day 25, the patient suffered a decline in neurologic status from a GCS of 11T to 3T. The patient was sent emergently for non-contrast CT head. This scan revealed pneumocephalus with diffuse foci of air emboli in the subarachnoid and intraventricular spaces, the choroid plexus, and dural venous sinuses. After a family discussion, care was withdrawn from the patient on day 27. DISCUSSION: This patient suffered a massive retrograde CAE peri-ECMO circuit oxygenator exchange. It is our understanding that this a novel clinical situation for this phenomenon and not previously described in literature. This emphasizes that manipulation of any vascular cannula may result in the entrainment of air in a retrograde venous fashion into the cerebral vasculature.

Massive Air Embolism Following Necrotizing Pancreatitis and COVID-19 Infection-The Role of Postmortem Computed Tomography.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that caused the COVID-19 pandemic raised important questions about workplace exposures to the virus, including postmortem exposures. The complexity of COVID-19 disease and its numerous unanticipated complications made autopsy even more vital in determining the pathophysiology of the disease. Performing traditional autopsy, however, carries risk of exposure. The following report describes an unusual case in which a patient diagnosed with COVID-19 and necrotizing pancreatitis underwent postmortem computed tomography (PMCT) prior to limited traditional autopsy and was unexpectedly found via PMCT to have large and diffuse venous air emboli and a new peripancreatic hematoma. In this case, not only did PMCT play a crucial role in determining the cause of death but also it allowed for a limited autopsy, thereby reducing the exposure to SARS-CoV-2 and associated risk to the autopsy staff and pathologists.

Safety of transport and retrieval of patients on extracorporeal membrane oxygenation during the peak of COVID-19 pandemic in the State of Qatar

Background: Transport and retrieval of patients on extracorporeal membrane oxygenation (ECMO) support can be hazardous with complications reported for up to 27% of patients1. Transport of COVID-19 patients on ECMO requires appropriate training, resource allocation, meticulous planning, effective communication and co-ordination. Strict adherence to infection control procedures and appropriate use of personal protective equipment is recommended2. The Extracorporeal Life Support Organisation registry reports 43% in-hospital mortality of COVID-19 patients supported on ECMO. This includes in-house and retrieval ECMO cases3. Methods: Between March 1st and September 30th 2020, 32 confirmed COVID-19 positive patients underwent peripheral cannulation followed by transportation to the Medical Intensive Care Unit (MICU) at Hamad General Hospital. Mobile ECMO is complex and time consuming. Following arrival at the bedside and thorough clinical assessment, the ECMO consultantmay decline, recommend optimisation of the care provided, or opt for cannulation and initiation of ECMO. Cannulation can be performed at the bedside or in the operating room. Following stabilisation, the patient is transferred for computed tomography imaging and then transported byambulance to hospital (Figure 1). Finally, another transfer fromhospital entrance to the MICU takes place. All these phases pose risks for errors and complications unless vigilance, teamwork and continuous effective monitoring and co-ordination is observed. Patients were evaluated for age and severity of illness (Table 1). In addition, all major transport-related adverse events were reported and analysed. Major transport events are cardiac arrest, ECMO emergencies (membrane or mechanical failure, air embolism, accidental decannulation, or significant cannula dislodgement), significant arrhythmia, severe bleeding or cardio-respiratory instability, and vehicle breakdown/malfunction. Findings: The majority of our patients were critically ill with high probability of mortality as depicted by SOFA and APACHE2 score. 29 out of 32 patients were male. None of our patients suffered major complications during transportation. Conclusion: This small case series demonstrates transport and retrieval on ECMO for COVID-19 positive patients can be safely undertaken provided appropriate expertise, protocols and resources are used.