key: cord-0008796-mr041i52
authors: Ngan Kee, Warwick D; Leung, Tse N
title: Severe acute respiratory syndrome (SARS)
date: 2003-06-28
journal: Int J Obstet Anesth
DOI: 10.1016/s0959-289x(03)00061-x
sha: 598b562020e531d242daff412aff50cc8f7bc3bf
doc_id: 8796
cord_uid: mr041i52

nan

Severe acute respiratory syndrome (SARS) has become a major global health hazard that has affected countries in the Asia-Pacific region particularly badly. On 12 March 2003 , the World Health Organization (WHO) issued a global alert for the first time in a decade, 1 and on 2 April 2003, the first travel advisory in its 55 year history. 2 The novel coronavirus (SARS-CoV) thought to be responsible for SARS 3;4 has demonstrated unusual predilection for clustering of cases linked to particular individuals or settings and a worrying and frankly frightening ability to spread to healthcare workers and patients in hospitals. All specialties need to be alert. Those who care for obstetric patients are no exception.

Knowledge of the pathogenesis, clinical features, epidemiology and therapy of SARS in adults and children has been acquired and disseminated at an unprecedented rate, aided by modern technology, international cooperation and the internet. [3] [4] [5] [6] [7] [8] [9] However, data for pregnant patients are limited to anecdotal experience with the small number admitted to hospital. WHO and the Centers for Disease Control and Prevention (CDC) have published diagnostic criteria for SARS that are currently based on clinical (temperature >38°C, symptoms of respiratory illness, radiographic evidence of pneumonia, autopsy findings), epidemiological (close contact within 10 days with a person known or suspected to have SARS or travel within 10 days to an affected area) and laboratory (isolation of SARS-CoV, detection of antibody to SARS-CoV or detection of SARS-CoV RNA) features. 10;11 There is no reason why pregnant patients should be different. Whether pregnancy itself alters the presentation or course of SARS is unknown. Features of pregnancy that may be important include increased metabolic rate, oxygen requirement, carbon dioxide production and cardiac and respiratory work and decreased cellular immunity. Increased pulmonary blood volume and decreased plasma oncotic pressure may predispose to the development of adult respiratory distress syndrome. In Hong Kong, as of early May 2003, five pregnant women beyond 24 weeks of gestation had been diagnosed with SARS. Four required admission to the intensive care unit. Two died.

Management of pregnant women with SARS will depend on the maternal condition, gestational age, fetal well-being and maternal wishes. Current medical treatment of SARS includes use of antiviral agents, such as ribavirin, and corticosteroids. Ribavirin has teratogenic effects in animals. 12 Although fewer data are available for humans, 13 for patients less than 24 weeks' gestation the option of termination of pregnancy should be discussed. After 24 weeks' gestation, the maternal and fetal risks of continuation of pregnancy must be balanced against the morbidity and mortality of preterm delivery. The timing and mode of delivery remain contentious issues among obstetricians. In general, continuation of pregnancy is favoured, especially for gestations less than 32-34 weeks, but maternal deterioration or poor response to medical therapy warrants consideration of early delivery.

Similarly, the effect of maternal SARS on neonatal outcome is unclear. At the time of writing, three neonates from mothers with SARS in Hong Kong had been admitted to the neonatal intensive care unit. Their gestations ranged from 27 to 32 weeks, and their problems were similar to those of other premature infants. Two suffered gut perforation; both of their mothers had received high dose corticosteroids before delivery but whether this contributed to their outcome is unknown. Vertical transmission of SARS is another concern. This has not been confirmed in our cases. However, current clinical diagnostic criteria are not easily applied to neonates and it is difficult to differentiate between the clinical features and radiological changes of SARS and those of respiratory distress syndrome caused by prematurity.

Optimal anaesthetic care for pregnant patients with SARS is controversial and there are arguments for and against both regional and general anaesthesia for labour and delivery. A concern of regional anaesthesia is the potential for spread of virus to the central nervous system. However, this argument has not precluded use of regional anaesthesia with other viral infections, most notably human immunodeficiency virus (HIV). 14 SARS-CoV has been identified in the cerebrospinal fluid of patients with SARS, which could mean that, as with HIV, fears of seeding infection by lumbar puncture are exaggerated. Regional anaesthesia adversely affects pulmonary mechanics, 15 however, and its use may not be tolerated in patients with compromised respiratory function. Furthermore, logistics and resource limitations may preclude provision of safe regional analgesia in an isolation area. On the other hand, general anaesthesia in pregnant patients with SARS has the same disadvantages as in healthy patients. There is additional concern that it may adversely International Journal of Obstetric Anesthesia (2003) 12, 151-152 Ó 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0959-289X(03)00061-X affect immune function. 16 Importantly, tracheal intubation is considered to carry a very high risk of cross-infection to operating theatre staff. 17 Regardless of mode of anaesthesia, wound pain may further compromise postoperative respiratory function and increase the requirement for prolonged mechanical ventilation.

Beyond the clinical considerations for the welfare of mother and fetus, the unique and overriding consideration for management of patients with SARS is prevention of cross-infection to staff. Over 20% of cases of SARS in Hong Kong have been in healthcare workers. What does this mean for obstetric care? There should be designated areas, preferably with negative pressure, for SARS patients. Labour wards should be considered ultra-high risk areas because of the nature of delivery and the procedures performed. Hospital infection control guidelines are available on the websites of WHO (http://www.who.int/ csr/sars/guidelines/en) and CDC (http://www.cdc.gov/ ncidod/sars/clinicians.htm). These should be taken very seriously. A case-control analysis of staff exposed to index patients highlighted the importance of hand-washing, use of gloves and gowns and especially wearing of masks to prevent spread by droplets. 18 Unfortunately, many healthcare workers have been infected despite the implementation of protective measures and sadly some have died. Factors that may have contributed to infection among hospital staff include failure to apply isolation precautions to cases not yet identified as having SARS, breaches of procedure, and inadequate precautions. 17 Labour ward staff in countries affected by SARS must maintain an extremely high index of suspicion. As we have progressed through multiple generations of infection, it has not always been possible to establish links between patients and known sources of infection. It is not known whether patients are infectious before they develop symptoms. Cases reported may only be those with the most severe clinical symptoms of infection with SARS-CoV; 7 the possibility of subclinical infection raises the spectre of asymptomatic carriers. But treating every pregnant patient as potentially infectious, as we are currently doing in Hong Kong, has considerable logistic, clinical and financial implications.

If you are in a country that is already affected, until SARS fully reveals its hand, it is paramount to continue to implement rigid public health measures and strict inhospital precautions. If you are fortunate enough so far to have been spared, the phenomenon of modern air

Update 18 -SARS outbreak: WHO investigation team moves to China

Coronavirus as a possible cause of severe acute respiratory syndrome

A novel coronavirus associated with severe acute respiratory syndrome

A major outbreak of severe acute respiratory syndrome in Hong Kong

Identification of severe acute respiratory syndrome in Canada

Epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in Hong Kong

Clinical progression and viral load in a community outbreak of coronavirus-associated SARS pneumonia: a prospective study

Clinical presentations and outcome of severe acute respiratory syndrome in children

World Health Organization. Case definitions for surveillance of severe acute respiratory syndrome

Updated interim US case definition of severe acute respiratory syndrome

Safety issues related to the administration of ribavirin

Complications of measles during pregnancy

Parturients infected with human immunodeficiency virus and regional anesthesia. Clinical and immunologic response

Respiratory effects of spinal anaesthesia for caesarean section

Immunomodulation: an important concept in modern anaesthesia

SARS: experience at Prince of Wales Hospital, Hong Kong

Effectiveness of precautions against droplets and contact in prevention of nosocomial transmission of severe acute respiratory syndrome (SARS)