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| Journal of the New Zealand Medical Association,
21-July-2006, Vol 119 No 1238
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Prescribing oxygen therapy. An audit of oxygen prescribing
practices on medical wards at North Shore Hospital, Auckland, New Zealand
Matthew Boyle, Janice Wong
Oxygen may be a life-saving therapy and is an important aide
in the treatment of various conditions (Figure 1). Oxygen can, however, cause
dangerous effects (Figure 2); it should be considered a drug and therefore only
be available by prescription.
Figure 1. American College of Chest Physicians and
National Heart, Lung, and Blood Institute recommendations for instituting oxygen
therapy.1
It is generally accepted that in order to ensure safe and
effective treatment, oxygen prescriptions should cover the flow rate,
concentration, delivery system, duration, and monitoring of treatment.1 It is,
however, recognised that oxygen is poorly prescribed by doctors.1
Figure 2. Dangers of oxygen
therapy.1,2
A previous study,3 conducted in Manchester, England, showed
that only 55% of inpatients receiving oxygen therapy had it prescribed. After
introduction of a specific oxygen prescription chart, this oxygen prescription
rate rose to 91%.
Another study,4 conducted in 1992 in Christchurch, New
Zealand, showed that one third of inpatients receiving oxygen did not have it
prescribed. A further study,5 conducted in Sunderland, England, showed that only
16% of inpatients receiving oxygen therapy had it prescribed. Additional studies
have shown that oxygen is not prescribed and administered with the same
procedural care as other medications,6 and that oxygen therapy is often
administered excessively.7
Waitemata District Health Board Clinical Practice Guidelines
clearly state that the assessment of oxygen requirement and the prescription of
oxygen should only be carried out by medical staff. However, in an emergency and
for patient safety, the Guidelines allow oxygen to be initiated by a nurse or
midwife while the patient is awaiting medical assistance.
When administered correctly, with careful evaluation of its
potential benefits and side effects, oxygen may be life-saving. It is clear,
however, that oxygen is often administered to patients without prescription.
In order to monitor and promote the safe administration of
oxygen at North Shore Hospital, we conducted a brief audit of inpatient oxygen
prescription.
MethodThe audit was undertaken between 14 April 2005 and 14
May 2005.
Patients were randomly selected for chart review from
the general medical wards at North Shore Hospital, Auckland. A random number
generator was used to select dates of review and wards for review. Inpatients on
reviewed wards were then assigned numbers and a random number generator was used
to select patients for chart review. Those patients receiving oxygen therapy as
documented in their observation chart were included in the audit.
To avoid bias, those patients under the care of the
author’s medical team were excluded. All ward personnel, other than the
author’s medical team, were unaware of the audit. To reduce the effect of
inaccurate recharting, the precise date at which oxygen had been administered
was correlated with the patient’s medication chart for that date to
examine whether the administrated oxygen had been prescribed.
A total of 100 inpatients from general medical wards
were included in the audit, with principle diagnostic categories of respiratory
(52 patients), cardiovascular (37 patients), neurology (6 patients), and other
(5 patients).
For each patient, the clinical diagnosis, oxygen
prescription (if present), and initial medical plan were analysed in conjunction
with the oxygen flow rate and oxygen saturations (as documented in the
observation chart). Laboratory records were reviewed to assess arterial blood
gas analyses.
ResultsOnly 8 of the 100 patients (8%) receiving oxygen had oxygen
prescribed in their medication chart (Figure 3), and the majority (75%) of the
oxygen prescriptions were inadequate with respect to recommended guidelines for
safe oxygen prescription.1 As a result, only 2 of the 100 patients (2%)
receiving oxygen had an adequate oxygen prescription. Fourteen of the 100
patients (14%) receiving oxygen had oxygen therapy listed in their initial
medical plan.
 The level of oxygen that was administered during the study
varied between 1–5 L/min.
Of the 92 patients receiving oxygen without prescription, 14
had a previous diagnosis of chronic obstructive pulmonary disease, with 5 of
these patients having previously documented carbon dioxide retention on arterial
blood gas analysis.
Of the 100 patients receiving oxygen, 19 had arterial blood
gas analysis performed during the audit.
DiscussionOxygen therapy can be life-saving; treatment of hypoxaemia
is essential. Oxygen is a drug, however, and should be prescribed as it can have
detrimental effects. Current rates of oxygen prescription in medical wards at
North Shore Hospital are unsatisfactory; only 8% of patients who were receiving
oxygen during the study had oxygen prescribed, with the majority of oxygen
prescriptions being inadequate.
It should be noted that 19% of patients receiving oxygen had
arterial blood gas analysis performed during the study; this indicates a
moderately higher level of medical monitoring than is suggested by the low
prescription rate. In any case, the poor oxygen prescription rate seen during
our audit carries serious potential consequences.
The possible adverse effects of oxygen therapy include
respiratory system toxicity (e.g. tracheobronchitis, absorption atelectasis,
bronchopulmonary dysplasia, and acute and chronic parenchymal lung injury),
maladaptive physiologic responses (e.g. hypercapnia in patients with chronic
obstructive pulmonary disease), nonmedical adverse effects (e.g. fire hazards)
and the Paul-Bert effect (an adverse effect which is only seen in patients
exposed to hyperbaric oxygen).1,2
Although all very serious potential adverse effects, it is
uncommon to see these effects in non-sedated medical inpatients receiving low
flow oxygen such as those in our audit.
Tracheobronchitis, absorption atelectasis, bronchopulmonary
dysplasia, and acute parenchymal lung injury have been observed in patients
breathing high concentrations of oxygen, however have not been seen in patients
receiving low-flow oxygen therapy.8–12 In contrast, histologic changes
consistent with chronic parenchymal lung injury have been seen in patients
receiving low-flow oxygen therapy (1–6 L/min).13,14 These changes are only
seen after at least 7 months of oxygen therapy, however, and do not appear to
contribute toward mortality.13
Elevation of arterial carbon dioxide tension in patients with chronic obstructive pulmonary disease treated with oxygen has been noted for years.15 Fourteen patients who were receiving oxygen without prescription during our audit had a previous diagnosis of chronic obstructive pulmonary disease; five of these patients had previously documented carbon dioxide retention on arterial blood gas analysis. Although our audit did not extend to recording unfavourable events, this raises the very serious concern of oxygen-associated respiratory depression and detrimental hypercapnia. Due to this concern, it is generally recommended that (until arterial blood gas analysis is available) only low-flow oxygen is used in patients with chronic obstructive pulmonary disease.16 Nonmedical hazards of oxygen therapy include fire hazards
and the hazards associated with high-pressure oxygen cylinders, oxygen
concentrators, and oxygen delivery systems. These hazards are more commonly
associated with long-term oxygen therapy than inpatient oxygen therapy.17
Despite the dangers of unregulated oxygen therapy,
hypoxaemia is a much graver situation. Hypoxaemia accounts for more deaths and
permanent disability than can be justified by the relatively small possible
risks associated with oxygen therapy.1 Descriptions in the literature of
inpatient low flow oxygen therapy resulting in clinically significant adverse
effects are scarce. While striving to improve oxygen prescription rates, care
must be taken not to overstate the potential dangers of oxygen and inadvertently
promote inadequate management of hypoxaemia.
Our audit clearly illustrates the need for improved oxygen
prescription at North Shore Hospital. Such improvements may be seen with
educational initiatives such as lectures and in-service instruction for junior
doctors, or with possible revisions of the current prescription chart to provide
a more specific prescription chart for oxygen. Further more in-depth audits of
oxygen prescription at North Shore Hospital are warranted to examine any adverse
effects stemming from the current poor prescription rate, and to evaluate any
future initiatives.
Author information:
Matthew J Boyle, House Officer, General Medicine, North Shore
Hospital; Janice Wong, Consultant Physician, General Medicine, North Shore
Hospital; Auckland
Correspondence: Dr
Matthew Boyle, General Medicine, North Shore Hospital, Private Bag 93-503,
Takapuna, Auckland. Email: drmattboyle@hotmail.com
References:
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