Successful management of life-threatening respiratory failure from H1N1 influenza

Abstract

We report the outcome of a pregnant woman with a life-threatening acute respiratory distress syndrome from a novel influenza A (H1N1) virus infection 3 d postpartum successfully managed by veno-arterial extracorporeal membrane oxygenation. The patient was successfully weaned from extracorporeal membrane oxygenation (ECMO) on day 10. Novel H1N1 virus infection was identified by real-time reverse transcription-polymerase chain reaction. Veno-arterial ECMO in this patient carried a number of specific advantages namely maintaining haemodynamic stability obviating the need for inotrope support and improving oxygenation compared to alternative approaches such as veno-venous ECMO and pumpless devices. Femoral arterial and venous cannulae were inserted in a pure percutaneous method allowing rapid establishment of extracorporeal circulation. Given the high mortality of acute respiratory distress syndrome following novel H1N1 virus infection, we advocate the use of ECMO when conventional mechanical ventilation fails.

Key Words: Respiratory failure; Influenza A; Extracorporeal membrane oxygenation; Pregnancy; Outcome

Core tip: Novel influenza A virus infection can result in acute respiratory distress syndrome extremely difficult to manage with conventional mechanical ventilation and non-invasive therapy. Veno-arterial extracorporeal membrane oxygenation can provide respiratory and circulatory support in these patients. We successfully weaned a postpartum patient after 10 d of extracorporeal membrane oxygenation. Furthermore, by employing the pure percutaneous method of cannulae insertion, we minimized implantation time and trauma.

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is a life-threatening complication of influenza. It has been reported after novel influenza A (H1N1) virus infection and is a major cause of death in these patients[1]. The virus causes lung damage from direct injury to the respiratory epithelium and can be associated with secondary cytokine storm[1]. The management comprises aggressive supportive care, with positive pressure ventilation and high oxygen concentrations. However, mechanical ventilation carries the risk of barotrauma and oxygen toxicity, further aggravating lung injury[2]. In a series of ARDS in patients with H1N1 virus infection, mortality among the patients requiring mechanical ventilation was 58%[1] compared to 30% for other causes of ARDS. A number of adjuvant strategies have been employed for treatment of ARDS, and the use of extracorporeal membrane oxygenation (ECMO) has shown to reduce the ventilator-induced lung injury and mortality in certain patients[3,4]. The outcome of ECMO has not been specifically reported in patients with ARDS secondary to novel H1N1 virus infection but can improve survival by 50% regardless of the etiology[5,6].

CASE REPORT

A 41-year-old woman (para 5, gravida 2) was transferred from-the-department of obstetrics for acute respiratory distress 3 d following a normal vaginal delivery of a 37 wk term baby boy. The previous gynaecological, medical and surgical history were unremarkable. A few days before delivery she had fever (39 °C) and a flu-like illness. On the third post-partum day, the patient developed increasing dyspnoea. This was followed by severe hypoxemia, acute respiratory distress syndrome, and an inability to achieve adequate oxygenation with conventional ventilation modalities (SaO₂ < 90%, arterial pO₂ = 49 mmHg and pCO₂ = 29 mmHg). Her chest X-ray showed bilateral widespread alveolar infiltrates (Figure 1). She had a white cell count of 2.98 × 10⁹/L with predominant neutrophilia (88.6%) and lymphocyotosis (10.1%), and C-reactive protein of 179 mg/L. She was transferred to the intensive care unit where orotracheal intubation and advanced mechanical ventilation (fraction of inspired oxygen of 1.0 and positive end-expiratory pressure of 15 cm H₂O including inhaled nitric oxide at 10 PPM) did not significantly improve the respiratory status (SpO₂ < 70%). Consequently, veno-arterial ECMO was established with an 18Fr cannula inserted into the right common femoral artery and a 22Fr venous cannula in the right femoral vein, associated with volume resuscitation. This lead to reversal of hypercapnia and improved oxygenation.

Figure 1 Chest-X ray showing bilateral infiltrates.

The patient was successfully weaned from ECMO on day 10. Bacterial cultures of blood, urine and tracheal aspirate were negative. Novel H1N1 virus infection was documented by testing of respiratory (bronchoalveolar lavage) specimens with real-time reverse transcription-polymerase chain reaction.

DISCUSSION

The patient was previous healthy and although pregnancy is known to increase the risk for influenza-associated morbidity and mortality during seasonal influenza epidemics[7,8] and pandemics[9,10], there seems to be a disproportionate increase in lethality for young, healthy individuals infected with HP strains of H1N1 viruses which correlates with a significant increase in the recruitment of inducible NOS-producing dendritic cells to the pneumonic lung, explaining the severity of the presentation[11]. The Centers for Disease Control and Prevention have reported a total of 20 cases of novel H1N1 virus infection among pregnant women in the United States, of which one patient developed ARDS and died[12]. In metropolitan France, 3 cases of infection in pregnant women were reported (out of a total of 921 confirmed or probable cases), none of which were associated with complications[13]. The use of veno-arterial ECMO in this patient maintained hemodynamic stability obviating the need for inotrope support and is less cumbersome than veno-venous ECMO. It was inserted in a pure percutaneous method using the Seldinger’s technique allowing rapid establishment of extracorporeal circulation. After puncture of the vessel, a soft tipped guide-wire was passed through the needle. Dilatators were passed stepwise over the guide-wire to enlarge the access until the cannula size was achieved. The cannula was inserted and connected to the ECMO system. Thus percutaneous femoral cannulation carries the advantage of allowing an expeditious procedure in an emergency situation[14]. Because novel H1N1 virus infection complicated by ARDS is associated with a high mortality, ECMO should be considered when conventional mechanical ventilation fails.