A previously well 50-year-old physician presented to hospital with fever, lethargy, nausea, and diarrhea. He had returned from Sierra Leone 5 days prior where he had worked in an Ebola treatment facility.

Because of his recent exposure to Ebola virus disease (EVD) and presentation with fevers, he was immediately transferred to the nominated Ebola center in Canada and isolated. A small team of nurses and doctors were assembled to care for him on a rotating shift roster.

On admission he was hypovolemic from vomiting and diarrhea, requiring treatment with intravenous fluids and low-dose norepinephrine. On day 2 of his admission, he was noted to have escalating oxygen requirements and there was a suspicion that he had coexisting pneumonia. He became increasingly delirious, pulling at lines, and removing supplemental oxygen. An arterial blood gas revealed pH 7.47, pCO₂ 29 mm Hg, and pO₂ 55 mm Hg with an inspired oxygen concentration of 0.70 via face mask with oxygen reservoir.

A decision was made to secure the airway prior to further deterioration and to avoid rushing in response to a sudden decline. The assembled team comprised of an experienced anesthesia practitioner to perform the intubation, an intensive care physician to manage the hemodynamics during intubation, and a critical care nurse to assist.

Airway examination revealed a slim build patient (75 kg) with a beard and normal dentition. Reassuring features for an easy direct laryngoscopic intubation included a Mallampati score of II, good mouth opening and thyromental distance of 6 cm, and unrestricted head and neck extension.

What Is EVD?

Ebola virus is a member of the Filoviridae virus family that can cause viral hemorrhagic fever,¹ a severe illness associated with high case fatality rates. The first case of Ebola occurred in 1976 in Equatorial Africa, in two simultaneous outbreaks, one of which was in the Democratic Republic of Congo near the Ebola river after which the disease is named.² Since that time there have been 24 outbreaks.

How Severe Was the 2014 Outbreak?

Since the first cases in the most recent epidemic were notified to the World Health Organization (WHO) on March 21, 2014, this outbreak has caused more cases and more deaths than any previous Ebola epidemic.³ The West African countries of Guinea, Liberia, and Sierra Leone were the hardest hit with almost all cases occurring across these three countries. As of August 2015, there were reported 27,862 cases and 11,281 deaths. Case fatality rates in Guinea, Liberia, and Sierra Leone were 66.6%, 45.05%, and 29.47% respectively⁴—many times higher than the case fatality rates seen in the 2003 severe acute respiratory syndrome (SARS) epidemic which were approximately 7% to 17%.⁵ Outside of Africa, Ebola cases were seen in Spain, Italy, the United Kingdom, and the United States.⁴ Only a single death from Ebola occurred outside of Africa.⁴

How Is EVD Transmitted?

The index case in an Ebola outbreak is transmitted to humans from the natural hosts, which are thought to be fruit bats. Spread within the human population is through direct human–human transmission² via contact with body fluids through mucosal surfaces or skin breaks.^1,2 The Ebola virus has been isolated from blood, sweat, saliva, vomitus, urine, feces, and semen.¹ Humans are infectious from onset of first symptoms for as long as their blood contains virus.²

How Is EVD Diagnosed?

Diagnosis of EVD is based on a history of exposure to EVD within the 2- to 21-day incubation period, clinical features, and laboratory investigations. The real-time polymerase chain reaction (PCR) detects virus in the blood or tissues during the acute phase¹ and can provide diagnosis within hours.⁶

What Is the Differential Diagnosis?

Most returned travelers with febrile illness do not have Ebola and other far more common infections including malaria, typhoid fever, and bacterial or other viral infections should be considered.^3,7 However, during an Ebola epidemic, it is important to have a high index of suspicion for any patients presenting with acute fever plus contact with a clinical case.

What Is the Typical Clinical Picture of a Patient with EVD?

Initial clinical features of EVD are nonspecific and include fever, weakness, myalgia, headache, anorexia, and hiccups. Subsequently, patients often develop nausea, vomiting, and diarrhea.⁸

Despite the fact that Ebola was formerly known as viral hemorrhagic fever, less than half of the confirmed cases of EVD have bleeding and when this occurs it would be late in the clinical course.⁸ Bleeding is secondary to a consumptive coagulopathy and hepatocellular necrosis causing reduced production of coagulation factors.¹ Bleeding includes oozing from puncture sites, bruising, bleeding from gums, melena, hematemesis, conjunctival hemorrhage, epistaxis, hematuria, hemoptysis, and unexplained vaginal bleeding (see Table 32–1).^1,8

Patients with Ebola display intravascular volume depletion and edema—likely related to disruption of the vascular endothelium and capillary leak.¹ In West African centers with laboratory testing facilities, hypoperfusion (evidenced by metabolic lactic acidosis) renal impairment and hypokalemia (secondary to diarrhea) are commonly seen.⁹

What Treatment Is Available?

Phase I and II trials for Ebola vaccines are at early stages of development and production.⁷ A combination of three monoclonal antibodies known as Zmab (Mapp Biopharmaceutical, San Diego, CA) was used as experimental treatment during the recent outbreak.

Since specific treatments are not available, supportive care is the mainstay of treatment. Fluid resuscitation and correction of electrolyte abnormalities are vital supportive measures⁹ and may reduce mortality in this disease.¹ Other treatment components include maintenance of blood pressure with vasopressors if required, oxygen supplementation, pain control, nutritional supports, and treatment of secondary bacterial infections.^3,7

Why Might a Patient with EVD Require Tracheal Intubation?

In contrast to other recent viral epidemics such as SARS, Ebola is not commonly accompanied by respiratory symptoms.⁹ Possible reasons for patients developing respiratory distress might be secondary to fluid overload, respiratory muscle fatigue, or hemoptysis. Transfusion-related acute lung injury could occur.

Non-respiratory reasons for requiring intubation include neurological deterioration (e.g., confusion, and seizures) or to assist management during progressive shock. There is also the potential requirement for a surgical procedure during the course of the patient’s illness—for example evacuation of uterus and curettage following miscarriage in a pregnant patient with EVD.

Noninvasive ventilation is relatively contraindicated in EVD due to an increased risk of transmission to health care workers from aerosolization of fluids containing the virus and a high incidence of vomiting and thus aspiration risk.¹

In Guinea’s largest public hospital, the intensive care unit (ICU) lacks both piped oxygen and mechanical ventilators.⁹ There is only a single ICU in Sierra Leone,¹⁰ which could theoretically manage a patient with an endotracheal tube. Tracheal intubation and ventilation are not practical options in most West African outbreak locations.⁹ It is more likely to be employed in a traveler who has returned to a first-world country. An anesthesia practitioner could be called upon to perform tracheal intubation in such a patient with EVD.

What Preparations Are Required Prior to Intubating the EVD Patient?

Many lessons were learnt from the SARS epidemic and the subsequent spread to health care workers. In Toronto, Canada, half of the SARS cases involved health care workers.¹¹ Although there are distinct differences in the way EVD is spread, the level of precaution required should not diminish. Tracheal intubation in a patient with EVD should occur in an isolated area, ideally in an airborne infection isolation room,¹² away from other patients and staff, with entry and exit into the room restricted during and immediately after the procedure.¹² The number of staff involved should be minimized.¹²

Plans to secure the airway in a patient with EVD should be made electively in order to avoid the need for a practitioner to rush to a deteriorating patient, which could result in errors made in donning personal protective equipment (PPE).^1,11 This might mean that tracheal intubation should occur earlier than you would otherwise consider. The most experienced practitioner available should manage the airway to reduce the time and number of attempts required.¹¹ Although Ebola is not an airborne virus, it is possible that during airway maneuvers, aerosolized saliva or other fluids containing the virus can result in transmission to health care workers. Intubation, extubation, and mask-ventilation are considered to be aerosol-generating procedures¹² and anyone involved in these procedures in patients with EVD must take extra precautions. The choice lies between a well-fitting N95 mask or a powered air purification respirator system (PAPR, Figure 32–1).^1,13 A PAPR with a self-contained filter and blower unit integrated inside the helmet is preferred.¹³