Featured Research

from universities, journals, and other organizations

H1N1: Mechanical ventilation for patients with lung damage don't always work as planned

Date:
November 13, 2009
Source:
St. Michael's Hospital
Summary:
As more people are diagnosed with H1N1 influenza infection, some will be admitted to hospital. The most severely affected may be treated in the intensive care unit and placed on a mechanical ventilator to help them breathe while they recover from the infection.

As more people are diagnosed with H1N1 influenza infection, some will be admitted to hospital. The most severely affected may be treated in the intensive care unit (ICU) and placed on a mechanical ventilator to help them breathe while they recover from the infection.

While mechanical ventilation clearly saves the lives of many people felled by serious illness, in some cases, this supportive measure has been known to damage the lungs, says Dr. Arthur S. Slutsky, a scientist at St. Michael's Hospital in Toronto.

"In clinicians' previous zeal to maintain relatively normal blood gas values, they have ventilated patients using relatively large tidal volumes," Dr. Slutsky explains. "They also tended to ventilate patients in the supine position -- that is, while they lay on their backs."

("Tidal volume" refers to the normal volume of air displaced in the lungs between normal inhalation and exhalation when extra effort is not applied. Other studies have found that lowering tidal volumes decreases mortality rates in ventilated patients.)

"Ventilation is what we call a physiological-based treatment," he explains. "We look at the patient's current physiological state, then devise and use treatments aimed at altering this state, hoping the change will translate into recovery."

In the case of severe H1N1 infection of the lungs, patients can develop severe hypoxemia -- an abnormally low amount of oxygen in the arterial blood which is the major result of respiratory failure.

In an editorial published this week in the Journal of the American Medical Association (JAMA), Dr. Slutsky comments on new research published by Fabio S. Taccone and colleagues from the University of Milan in Milan, Italy.

The researchers looked at whether patients with Acute Respiratory Distress Syndrome (ARDS) who were mechanically ventilated in the prone position (lying on their stomachs) did better than patients ventilated while they were supine (lying on their backs), as is the standard approach. As in other studies of this physiological-based treatment, blood oxygen levels increased in the prone treatment group. But in the end, the mortality rate among these patients was not statistically different from that of the control group.

In his editorial, Dr. Slutsky asks the following question: "Today, 35 years after prone ventilation was suggested and after hundreds of articles have been published, including more than 150 review articles and more than 10 meta-analyses, why are more definitive conclusions about prone ventilation not available?"

Unfortunately, he says, very few large companies have a commercial interest in this type of intervention -- for example, changing a ventilated patient from a supine to a prone position. This explains why funding for such research is hard to obtain and why clear answers about the usefulness of physiological interventions are often lacking.

In this regard, prone ventilation is similar to other physiologically-based interventions for which the effect on important clinical outcomes has not been conclusively proven. In some cases, these physiological "fixes" do not always work as planned -- interventions that improve one physiological value may actually worsen another.

In his editorial, Dr. Slutsky says that basing treatments strictly on physiological endpoints -- in this case, increasing oxygenation in the blood by mechanically increasing volumes of air in the lungs and changing patients' position during treatment -- is "seductive" for several reasons:

  • In many ways, the intensive care unit is a physiology laboratory in which patients' vital signs and other functions are monitored and treated around the clock, seven days a week. By explaining why a patient has a physiological abnormality such as a decrease in oxygenation or worsening kidney function, these measurements can suggest therapies to correct the abnormal physiology.
  • Many physiological interventions can be quickly instituted and monitored at the bedside. They are usually relatively inexpensive or seen as "free," which makes them attractive and easy to implement.

"But while physiological insights developed at the bedside have led to important, lifesaving therapies, it's been difficult to obtain convincing proof of better clinical outcomes for many such interventions," Dr. Slutsky says.

One solution would be to design large, simple, generalizable trials undertaken by a large global network of investigators. "The time for this may be especially opportune because the world's critical care community is coalescing around an initiative to perform large-scale clinical trials to rapidly address the potential H1N1 pandemic," he says, adding that such trials are necessary to "separate fact from seduction."

Dr. Art Slutsky is a researcher in the Keenan Research Centre at the Li Ka Shing Knowledge Institute of St. Michael's Hospital, and Professor of Medicine, Surgery and Biomedical Engineering at the University of Toronto. He is also Director of the Interdepartmental Division of Critical Care Medicine, University of Toronto.


Story Source:

The above story is based on materials provided by St. Michael's Hospital. Note: Materials may be edited for content and length.


Cite This Page:

St. Michael's Hospital. "H1N1: Mechanical ventilation for patients with lung damage don't always work as planned." ScienceDaily. ScienceDaily, 13 November 2009. <www.sciencedaily.com/releases/2009/11/091112121607.htm>.
St. Michael's Hospital. (2009, November 13). H1N1: Mechanical ventilation for patients with lung damage don't always work as planned. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2009/11/091112121607.htm
St. Michael's Hospital. "H1N1: Mechanical ventilation for patients with lung damage don't always work as planned." ScienceDaily. www.sciencedaily.com/releases/2009/11/091112121607.htm (accessed July 28, 2014).

Share This




More Health & Medicine News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Ebola Virus Threatens West Africa

Deadly Ebola Virus Threatens West Africa

AP (July 28, 2014) West African nations and international health organizations are working to contain the largest Ebola outbreak in history. It's one of the deadliest diseases known to man, but the CDC says it's unlikely to spread in the U.S. (July 28) Video provided by AP
Powered by NewsLook.com
$15B Deal on Vets' Health Care Reached

$15B Deal on Vets' Health Care Reached

AP (July 28, 2014) A bipartisan deal to improve veterans health care would authorize at least $15 billion in emergency spending to fix a veterans program scandalized by long patient wait times and falsified records. (July 28) Video provided by AP
Powered by NewsLook.com
Two Americans Contract Ebola in Liberia

Two Americans Contract Ebola in Liberia

Reuters - US Online Video (July 28, 2014) Two American aid workers in Liberia test positive for Ebola while working to combat the deadliest outbreak of the virus ever. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins