Infection with the H1N1 virus causes upper and lower respiratory tract inflammation and fever. In rare cases, ICU admission, intubation and mechanical ventilation is required. High oxygen concentration and high inflating pressure ventilator management can damage the lungs, adding to the risk of dying. Patient support with ECMO while the lungs are failing, removes the risk of harmful ventilation, and allows more time for the inflammation to subside and lungs to recover.
In the 2009 Australia/New Zealand outbreak, 201 patients with confirmed or suspected H1N1 were treated in ECMO centers. Most of these patients recovered, but ECMO was utilized for 68 patients who failed to respond to conventional measures, with 79% recovered and survived at time of reporting. For detailed descriptions of the ECMO experience in the recent H1N1 epidemic in Australia/New Zealand (see references at bottom of page).
ECMO is the use of a modified heart-lung machine to take over the function of the heart and lungs for days or weeks in patients with acute, severe, heart or lung failure. ECMO has been used in over 40,000 patients of all ages. Because ECMO has potential complications, it is only used in patients who have high risk of dying. ECMO is complicated and used only in experienced centers. The limiting factor is not equipment, but people with the expertise in the technique. The outcome depends on whether the heart or lungs can recover with continuing time and treatment. Recovery and survival when ECMO is utilized in adult respiratory failure is currently about 50%. There are 160 ECMO centers in the Extracorporeal Life Support Organization ( ELSO); 126 are in North America.
ECMO is a complex technique and requires thorough preparation, appropriate equipment, institutional commitment, practice and a dedicated team. If you are considering ECMO for a critically ill H1N1 patient and your center is not prepared, it is better to refer the patient and not attempt ECMO until your center is well-trained and prepared to do it. If transport is not possible, continue optimal conventional therapy. If the patient is dying despite optimal therapy and your center is attempting ECMO anyway, additional support and advice should be sought from nearby ELSO centers.
Referral to an ECMO center should be considered for a patient in an ICU who is on a ventilator and requires high oxygen concentration ( over 80%) to keep adequate blood oxygenation. H1N1 also causes septic shock, and referral should be considered for patients who require 2 or more medications to treat shock. H1N1 infection often progresses very rapidly in severe cases, so referral may be on the first or second day in the ICU. Review of early ELSO H1N1 registry data through October 2009 shows 72% survival when ECMO is instituted within 6 days of intubation; 31% when patients have been intubated 7 days or longer. At this time, transportation on ECMO is limited to a few centers and private services.
The indication to use ECMO in an experienced ECMO center is progressive lung failure(PaO2 under 80 on FiO2 1.0) or shock (hypotension on 2 vasoactive drugs)despite optimal treatment. The results are best when ECMO is instituted within 6 days of intubation (see H1N1 registry results). Vascular access is by venovenous cannulation for most cases; venoarterial cannulation for profound shock or arrhythmia. Extracorporeal blood flow begins at 70 cc/kg/min, then is maintained at a level to provide full support on low ventilator settings and drug levels. Anticoagulation is maintained by continuous infusion of heparin, monitored frequently. All aspects of management are described in the guidelines.
In H1N1, lung function often stops altogether for days or weeks, so the patient is completely dependent on ECMO perfusion. Lung function usually returns in 1-2 weeks, but may take a month or more. If lung function has not recovered in a month, the chance of recovery is small. One or two H1N1 cases can strain the capacity of any ICU and ECMO team, particularly when ECMO availability is needed for other patients. Anticipating this epidemic, ECMO centers are making plans for dealing with resource allocation.
Finding ECMO referral centers: Find a center appropriate for your patient, (pediatric or adult pulmonary, location. ECMO center contact information is available in the ELSO directory.
H1N1 Registry: ELSO has established a registry of H1N1 ECMO cases. The updated report is on the H1N1 registry site.
Management guidelines: The Management Guidelines are available in the Resources section. The General Guidelines apply to all cases. There are patient specific guidelines for age groups and diagnoses. Specific guidelines on H1N1 is also available in the guidelines section. This document is a supplement to the general guidelines.
Extracorporeal Membrane Oxygenation for 2009 Influenza A(H1N1) Acute Respiratory Distress Syndrome. The Australia and New Zealand Extracorporeal Membrane Oxygenation (ANZ ECMO) Influenza Investigators. JAMA. 2009;302(17):1888-1895. Published online October 12, 2009 (doi:10.1001/jama.2009.1535).
Critical Care Services and 2009 H1N1 Influenza in Australia and New Zealand. The ANZIC Influenza Investigators. N Engl J Med. 2009 Oct 8. [Epub ahead of print].
The H1N1 registry form was developed to track H1N1 cases that have been placed on ECMO.
At this time ELSO has stopped collecting additional information on H1N1 cases. Please use the standard data collection instrument and code these patients using the 488.1 ICD-9 code.
Statistics from the H1N1 Registry as of April 13, 2011.
Number of cases: 323 (from 76 centers)
Average hours on ECMO: 296 (count=313)
|Off ECMO, 11 in hospital||11|
| || |
| || |
| 1. Under 5 Years||37||369||34||22||11||3||1|
|2. >= 5 Years and < 10 Years||20||340||20||12||8||0||0|
|3. >= 10 Years and < 15 Years||28||410||28||9||14||0||5|
|4. >= 15 Years and < 20 Years||20||330||19||11||7||1||1|
|5. >= 20 Years and < 30 Years||69||216||68||45||20||1||3|
|6. >= 30 Years and < 50 Years||104||286||102||78||24||2||0|
|7. 50 Years and over||45||279||42||19||22||3||1|
|1. 0-2 days||161||293||155||106||46||6||3|
|2. 3-6 days||78||300||76||47||25||2||4|
|3. >= 7 days||82||301||80||43||34||2||3|
Count - Number of H1N1 cases
AvgHrsOnECMO - Average hours on ECMO
CntAvgHrs - Number of cases used for AvgHrsOnECMO