Oxygen Prescription Research Articles

Oxigenoterapia portátil en la Comunidad de Madrid

Portable oxygen therapy using liquid oxygen has been available in the Madrid area since 1992 as part of a government program. The prescription of liquid oxygen theoretically requires the careful selection of patients who will benefit from a portable source of oxygen, as well as the performance of a series of treadmill tests with and without supplemental oxygen in order to assess the benefit derived from this expensive means of delivering therapy. As no studies had been done of whether these criteria for prescribing liquid oxygen were being met, we conducted telephone interviews with patients residing in the Madrid area who had portable oxygen sources at their disposal. Of a total of 190 patients, whose names were provided by oxygen supply companies, 145 could be evaluated. Liquid oxygen was not being used by 17%. Stress tests had not been performed before prescription of liquid oxygen in 65%. In conclusion, it can be suspected that a high percentage of patients receive liquid oxygen who do not meet the criteria for prescription and who have not performed the recommended tests, and that compliance is low.

The Effects of Exercise Testing on the Prescription of Oxygen Therapy

This study reviews the effects of using oxygen saturation measurements during exercise and the effects of the method of exercise testing on the prescription of oxygen therapy. Using cutaneous oximetry (designated A and B models) and co-oximetry, 25 of 41 patients (model A), 30 of 39 patients (model B), and 28 of 42 patients (co-oximetry) had an oxygen saturation measurement greater than 85 percent at maximal incremental exercise despite an arterial oxygen tension less than 55 mm Hg. Also, in a group of patients who underwent incremental followed by constant work rate testing, 9 of 28 exhibited a fall in arterial oxygen tension to 55 mm Hg or below only during the constant work rate testing. Oxygen saturation measurements cannot reliably be used as a substitute for arterial oxygen tension measurements for the prescription of oxygen therapy. The type of exercise study performed may influence the outcome of such oxygen prescription.

Adherence to entry criteria and one year experience of long-term oxygen therapy in Poland

The adherence to entry criteria and results of one year long-term oxygen therapy (LTOT) in Poland were analysed. Four hundred and seven patients with advanced respiratory failure due to chronic lung diseases qualified for LTOT were observed for one year in 12 regional LTOT centres. There were 315 patients with chronic obstructive pulmonary disease (COPD) and 92 with other chronic lung diseases. In 270 patients the prescription of oxygen was based on the single criterion of stable arterial oxygen tension (PaO2) less than or equal to 55 mmHg (7.3 kPa); and in the remaining 137 with less severe stable hypoxaemia (PaO2 56-65 mmHg) (7.4-8.6 kPa), on concomitant signs of cor pulmonale and/or of tissue hypoxia. Of 407 patients who started LTOT, 95 (23%) died during the first year of treatment. The mortality rate was 21% for COPD patients and 33% for patients with other lung diseases. After one year of LTOT 312 patients survived: 250 COPD patients and 62 with other lung diseases. Of these, 19 COPD patients (8%) and 9 with other chronic lung disease (15%) who had PaO2 less than or equal to 55 mmHg (7.3 kPa) when oxygen was prescribed, presented with PaO2 greater than 55 mmHg (7.3 kPa). From the 137 patients (106 with COPD and 31 with other lung diseases) who qualified with less severe hypoxaemia, 10 COPD patients (10%) and 5 (16%) with other lung disease had PaO2 greater than 65 mmHg (8.6 kPa).(ABSTRACT TRUNCATED AT 250 WORDS)

Uses and misuses of oxygen in hospitalized patients

purpose: To document the use/misuse of oxygen therapy as compared with antibiotics in internal medicine inpatients. To determine whether the same care was being taken in the prescription and administration of both forms of therapy. patients: Ninety-six eligible patients at a university teaching hospital were entered into a study examining the use of oxygen. They were compared with 60 patients for whom antibiotics were prescribed. material and methods: Three hundred thirty consecutive newly admitted patients were screened for the presence of either (1) oxygen apparatus at the bedside, (2) physician orders for oxygen, or (3) oxygen orders noted in nursing kardex. Those meeting one of these three criteria were observed on up to four occasions over 48 hours following study entry. Similarly, patients were screened for medical orders or nursing medication kardex notation for antibiotics and were also observed for proper prescription and administration of medication. Procedural errors, determined by kardex audit and direct patient observation, were compared for the individuals with specific oxygen orders and those receiving antibiotics. results: Oxygen delivery apparatus was found in the room in 17 of 96 patients without it ever having been ordered by the physician or noted in the nursing kardex. In 27 of 96 patients, oxygen was noted in the nursing kardex and administered to patients without a physician order. There were no cases of antibiotic therapy without a physician order. Observations of 47 patients with specific orders for oxygen revealed the following errors: (1) physician order incorrectly transcribed to nursing kardex (16%), (2) flow meter off (34%), (3) oxygen delivery apparatus improperly worn (57%), (4) wrong fractional inspired oxygen concentration (58%). Improper transcription of antibiotic orders occurred on only one occasion (2%), and antibiotics were improperly administered in 5%. Arterial blood gas determinations preceded oxygen orders in 61%, whereas microbiologic cultures preceded antibiotic orders in 87% of the patients. conclusions: We conclude that oxygen therapy is neither prescribed nor administered with the same attention that is given to other drugs such as antibiotics. Oxygen prescription and/or delivery is associated with significantly greater error than that seen with antibiotics. Education of medical personnel should stress more prudent prescription and use of oxygen in hospitalized patients.

POSTOPERATIVE HYPOXAEMIA AFTER MAJOR ABDOMINAL VASCULAR SURGERY

We have studied the severity and duration of nocturnal hypoxaemia before operation and for the first five nights after operation after elective major abdominal vascular surgery. Oxygen supplementation was almost 100% effective in keeping oxygen saturation greater than 90% during the early postoperative period; however, 50% of patients spent prolonged periods with an SpO2 less than 85% during at least one night after operation. The risk of severe hypoxaemia persists well beyond the current prescription of supplementary oxygen in these high risk patients. A significant association exists between the mean preoperative overnight saturation value and the nocturnal saturation observed subsequently in the later postoperative period.

Portable oxygen therapy: assessment and usage

Fifty portable oxygen assessments, based on 6-min walking tests, were reviewed to produce guidelines for assessment and prescription of portable oxygen, and to evaluate factors predicting benefit. Patients with a portable cylinder were questioned about benefits/difficulties and usage of portable oxygen. A significant improvement on the oxygen compared to the air walk was found (median 9.7%) which correlated with the oxygen desaturation on the baseline walk (r = 0.51, P less than 0.05). A placebo effect was demonstrated using an air cylinder (median improvement 6.1%). There was no correlation between improvement in walking distance and decrease in visual analogue scale (VAS) score of breathlessness. We recommend standard portable oxygen assessments based on a series of 6-min walks. Improvements of 10% in walking distance or VAS score from the oxygen to the air walk would lead to the patient being offered a portable oxygen cylinder.

Dysphagia as a Manifestation of Occult Hypoxemia: The Role of Oximetry During Meal Times

A 25-year-old woman with severe kyphoscoliosis reported a six-month history of increasing dysphagia to both liquids and solids. A barium swallow and esophageal motility studies showed no significant gastrointestinal abnormalities. Trials of antispasmodic agents were unsuccessful in relieving her symptoms. Pulmonary function tests showed a severe restrictive ventilatory defect (vital capacity = 0.67 L) with adequate oxygenation and alveolar ventilation as reflected by arterial blood gas testing during quiet wakefulness. However, continuous noninvasive oximetry demonstrated desaturation to 85 percent while eating. These transient episodes of desaturation were abolished by the administration of supplemental oxygen delivered by nasal prongs. Following the prescription of supplemental oxygen, dysphagia resolved immediately, with weight gain following over several weeks. We conclude that dysphagia may be a presenting feature of hypoxemia. This case report draws attention to the usefulness of continuous noninvasive monitoring of oxygenation and the clinical importance of at least some transient hypoxemic events.

Long-Term Home Oxygen Therapy

Oxygen therapy improves mortality and morbidity in hypoxemic patients with COPD. For best results, oxygen should be administered continuously. The general guidelines that qualify a patient for long-term home oxygen therapy are rather explicit, although there are some gray areas, such as increasing exercise performance in normoxemic COPD patients and the treatment of dyspnea in certain patients. The physiologic goals of oxygen therapy are to reverse or prevent tissue hypoxia under the various conditions of life. Patients often experience a fall in oxygen saturation during REM sleep and during exercise. Thus, the oxygen prescription should specify the oxygen setting during wakeful rest, sleep, and exertion. Pulmonary rehabilitation is the definitive long-term management for patients with chronic lung diseases by building endurance, strength, and coping skills. Patients undergoing pulmonary rehabilitation are taught to become active and mobile. The rehabilitation programs have a special role in helping patients to accept and properly administer their own oxygen therapy. Oxygen therapy should be based on mobility and portability. Improvements in the weight and bulk of oxygen containers and the introduction of oxygen-conserving devices have rendered oxygen systems more portable and less costly. The prescription initiates a clinical triad relationship between the patient, physician, and home oxygen vendor. Prescribing home oxygen is now more time-consuming, and the prescription process requires the careful attention of the physician. The prescription must include patient data, the diagnostic reasons for oxygen, the blood gases, the type of system, and the liter-flow for the various living conditions such as rest, sleep, and exertion. Reimbursement for oxygen via Medicare and other carriers will depend upon the physiologic data as well as the successful completion of a rather complex form. Oxygen therapy should be monitored by regular arterial blood gases or pulse oximetry where appropriate. Patients should have a blood gas sample taken upon any change of condition or adjustment of the oxygen flow setting. Successful oxygen therapy should be physician directed, based on a solid understanding of the physiologic processes involved.

Perioperative hypoxaemia detected by intermittent pulse oximetry.

Perioperative pulse oximetry was performed on one hundred consecutive abdominal surgical patients to audit our management of perioperative oxygenation. Oximetry was performed preoperatively, in the recovery room, and daily in the ward until discharge or the sixth postoperative day, with prescribed oxygen therapy continuing during measurement. Twenty-nine patients had saturations of 90% or less on a total of fifty-one occasions. Twenty-nine patients were prescribed prophylactic oxygen therapy, but seven had oxygen therapy stopped prematurely and were found to have saturations of 90% or less. In this group of patients, clinical assessment of oxygenation and the need for oxygen therapy was inadequate. Intermittent oximetry is rapidly and simply performed, and by detecting patients with arterial haemoglobin desaturation, could improve oxygen prescribing in the perioperative period.

Neuropsychological Effects of Short-term Discontinuation of Oxygen Therapy

Twelve patients receiving long-term oxygen therapy were assessed for possible detrimental neuropsychological effects of short-term withdrawal of oxygen. Patients served as their own controls and received either their usual oxygen prescriptions or room air, through nasal prongs, over four-hour periods on two successive days. A battery of neuropsychological tests assessing memory and learning, sustained concentration, and motor and visuomotor speed were administered. In the room-air condition, the mean arterial oxygen partial pressure fell from 86.1 +/- 25.7 to 59.1 +/- 11.7 mm Hg, and the mean oxygen saturation fell from 94.7% +/- 3.2% to 89.9% +/- 5.3%, but the mean carbon dioxide partial pressure did not change significantly. No significant differences in neuropsychological test scores were found between the two conditions, suggesting that four hours of mild hypoxemia causes no significant deficits in cognition in patients receiving long-term oxygen therapy. Paradoxically, low-order inverse correlations were found between arterial oxygen partial pressures and results of visuomotor speed and memory tests, suggesting that an improvement in performance may have taken place during oxygen withdrawal.