April 8, 2008
Oxygen as a Medication
In our December 2007 “What’s New in the Patient Safety World” column we speculated that one of the contributing factors to the occurrence of 1000-fold heparin overdoses may be that “heparin flush” is often not looked upon as a medication. The same can be said for another substance that should be considered a medication – oxygen.
Think about it – it’s a chemical given for specific indications, in a specific dose, via a specific route, for an intended duration. Its use needs to be monitored using clinical and laboratory parameters. Its effects are influenced by existing comorbidities affecting specific organ systems. It has both beneficial effects and potentially harmful effects. Sure sounds like a drug to us!
But oxygen therapy seldom gets the same degree of respect that therapy with other medications gets. Numerous surveys or audits (eg. Boyle 2006) in acute hospitals have revealed that there is often no formal prescription for oxygen therapy and, when there is, the prescription is often inadequate or inappropriate.
While oxygen is obviously very helpful or lifesaving in many circumstances, it does have potential adverse effects as well. Several of our previous columns have focused on nonclinical adverse consequences such as surgical fires or neonatal nursery fires and the role of oxygen in fires. And we’ve talked about oxygen canisters becoming potentially lethal projectiles in MRI suites. And oxygen has been involved in various ways in cases of tubing misconnections. But there are also potential clinical physiological adverse consequences of oxygen therapy. Obviously in the newborn, hyperoxygenation is associated with the risk of retinopathy of prematurity and potential pulmonary complications. And in the patient with COPD, precipitation of hypercapnia and respiratory depression is a well-known potential complication of oxygen therapy.
Perhaps the most important consideration in oxygen therapy is the order for it. Much like our discussion on inappropriate use of Foley catheters, oxygen therapy seems to have a way of simply “popping up” on patients in the hospital. It often gets started in the ER, or the post-op recovery room, or other location without adequate documentation of the reasons for its use. It is thus critical that an appropriate order for oxygen always be written (or otherwise entered entered into a CPOE system). That order should include an indication for the oxygen therapy. Each hospital should go through the exercise of establishing a list of the indications for oxygen use. This is not just of practical value – it may have educational value as well. For years, those of us who are neurologists commonly began stroke patients routinely on oxygen therapy. In fact, a stroke by itself is not an appropriate indication for oxygen therapy. A study (Pancioli 2002) looked at oxygen utilization on an inpatient stroke population and found that only 45.6% of days of oxygen use were justified by evidence-based criteria they developed.
The order should also include the desired oxygen concentration or flow rate, method of delivery (eg. mask, nasal prongs, etc.), duration of therapy, and the method of monitoring the effectiveness or potential adverse effects of therapy (such as pulse oximetry or arterial blood gases). Because the order may be somewhat complex, some organizations (see Dodd 2000) have developed an “oxygen prescription chart” or other formal preprinted order set. All the complexities of the oxygen therapy order can also be captured more completely by using a CPOE system.
Compliance with orders for oxygen therapy should also be assessed. How many times have you gone into a patient room and seen the nasal prongs hanging down on his/her neck or being worn on his/her forehead like a sweatband or bandana!
Monitoring the effectiveness of oxygen therapy is usually accomplished noninvasively by pulse oximetry. However, remember that this only measures oxygen saturation and does not provide any assessment of the CO2 and pH status. You’d be surprised how often COPD patients who even have a history of hypercapnia fail to be adequately monitored for hypercapnia. Though hypercapnia may be looked for in other ways (eg. capnography), most often we still look to arterial blood gases before and after initiation of oxygen therapy as the best measure of CO2 status.
The duration of oxygen therapy is often difficult to predict or estimate. Just as each facility should establish criteria for use of oxygen, each facility should develop criteria for cessation of oxygen therapy.
Problems maintaining adequate oxygenation are particularly a problem during transport of patients (within or outside of facilities). The Pennsylvania Patient Safety Authority highlighted this issue in a Patient Safety Advisory in 2005 “Continuity of Oxygen Therapy During Intrahospital Transport”. They reviewed numerous reports to the Pennsylvania Patient Safety Reporting System (PA-PSRS) and looked at failure modes in the many steps involved in maintaining adequate oxygen therapy during transport. They noted that oxygen therapy has been reported to be interrupted in as many as 55% of transports. Failure modes indentified included: failure to treat with oxygen when ordered, failure to initiate flow from the oxygen source, failure to connect the oxygen tubing to the source, failure to place the oxygen delivery device on the patient, and failure to anticipate the oxygen demand and provide an adequate supply throughout the transport.
They suggested standardization of procedures for transport, a formalized hand-off, and clarification of responsibilities for individuals involved. They provided examples from two facilities that addressed these issues. One facility developed a formal communication tool that included details such as the oxygen delivery device, flow rate, PSI, and minutes of oxygen available in the cylinder. The latter is especially important because the sorts of delays that are common when patients are transported away from their rooms (eg. to physical therapy or radiology) make running out of oxygen in the cylinder particularly likely. The above advisory includes a nice table for estimating the amount of oxygen left in the cylinder. They also stress, however, the need to maintain stores of strategically placed oxygen sources throughout the facility and a procedure to ensure that those sources are full and functional. Appropriate education and training of all personnel involved in transports is obviously important.
They include the mnemonic “START” from Harborview Medical Center in Seattle to help staff remember important steps involved:
Supply adequate oxygen for the trip
Turn on the oxygen cylinder
Apply the cannula or mask to the patient
Rate as ordered and verified
Trace the connections from the patient to the oxygen source
Mark Daly at the McGill University Health Centre led a project called “O2 Ticket to Ride” that included a two-sided form to be utilized for all transports to ensure adequacy of oxygen therapy. One side had places for documentation of key items such as noted above. The other side had a chart for estimating how long the oxygen should last.
We like the concept of a structured hand-off with a formal communication tool for transport. Many of the same issues that arise for oxygen therapy may apply to other modalities during transport (eg. IV fluids, other medications) and could be addressed in such a tool.
As you implement a plan for management of oxygen therapy, be sure to consider potential unintended consequences. Untreated or undertreated hypoxemia is likely to be a much more frequent cause of patient harm than some of the rarer adverse effects due to oxygen therapy itself.
Implement a good strategy for managing the drug “oxygen” and you will also make your CFO happy. The Pancioli study noted above identified potentially substantial financial savings if oxygen were only used for those stroke patients meeting appropriate criteria for use.
Update: See also our June 10, 2008 Patient Safety Tip of the Week “Monitoring the Postoperative COPD Patient” and our January 27, 2009 Patient Safety Tip of the Week “Oxygen Therapy: Everything You Wanted to Know and More!” and our October 6, 2009 Patient Safety Tip of the Week “Oxygen Safety: More Lessons from the UK”.
Boyle M, Wong J. Prescribing oxygen therapy. An audit of oxygen prescribing practices on medical wards at North Shore Hospital, Auckland, New Zealand.
Journal of the New Zealand Medical Association 2006; 119: http://www.nzma.org.nz/journal/119-1238/2080/
Pancioli AM, Bullard MJ, Grulee ME, Jauch EC, Perkis DF. Supplemental Oxygen Use in Ischemic Stroke Patients. Does Utilization Correspond to Need for Oxygen Therapy?
Arch Intern Med. 2002;162:49-52. http://archinte.ama-assn.org/cgi/content/full/162/1/49
Dodd ME, Kellet F, Davis A, Simpson JCG, Webb AK, Haworth CS, Niven R McL. Audit of oxygen prescribing before and after the introduction of a prescription chart. BMJ 2000;321:864-865 http://www.bmj.com/cgi/content/full/321/7265/864?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=dodd&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT
Pennsylvania Patient Safety Authority. Patient Safety Advisory.
Continuity of Oxygen Therapy During Intrahospital Transport. September 2005.
Canadian Patient Safety Institute. McGill University Health Centre project: O2 Ticket to Ride. http://www.patientsafetyinstitute.ca/Canadian_Profiles/Mark_Daly.html
Gosbee J, DeRosier JM. Oxygen (Compressed Gas) Cylinder Hazard Summary. VA National Center for Patient Safety. July 2002. http://www.va.gov/ncps/SafetyTopics/O2Cylinder.html
FDA Patient Safety News. Preventing Deaths and Serious Injuries From Medical Gas Mix-Ups. February 2002. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/psn/printer.cfm?id=114