Long-term oxygen therapy: physiologic and economic considerations.

Long-term oxygen therapy appears to be a safe means of treating hypoxemia. It can provide many physiologic improvements and prolongs life in persons with severe chronic arterial hypoxemia at rest. Recent studies suggest that arterial hypoxia is common during exercise and sleep, and it is likely that some patients with intermittent desaturation would benefit physiologically from supplemental oxygen. Oxygen is an expensive drug, and we do not know whether its benefits are greater than its costs in patients who are not hypoxic at rest. I believe that low-flow oxygen administered as continuously as possible should be strongly considered for all patients whose PaO2 is 55 mm Hg or less at rest, regardless of whether they have cor pulmonale, and for all patients with cor pulmonale, regardless of their PaO2.     

Home oxygen therapy

Oxygen therapy is one of the principal non-pharmacologic treatments for severe chronic obstructive pulmonary disease (COPD) patients. Home oxygen therapy(HOT), or long-term oxygen therapy(LTOT) for 15 hours or more per day, can improve the survival rate of severe COPD patients with beneficial effects on hemodynamic state, hematological characteristic, exercise capacity, lung mechanics, and mental state. Oxygen therapy is indicated in cases of severe chronic respiratory failure with PaO2 of 55 Torr or less, or in cases with PaO2 of 60 Torr or less in whom there is remarkable hypoxia during sleep or during exercise. The induction of oxygen therapy needs evaluations of oxygen desaturation during exercise and sleep as well as hypoxia at rest. It also required to consider CO2 narcosis.     

A nationwide system of long-term oxygen therapy: the Polish experience

Poland's Institute of Tuberculosis and Lung Diseases oversees 49 provincial clinics, which provide and monitor LTOT for patients with COPD, interstitial pulmonary fibrosis, and other pulmonary conditions. Because of limited resources, eligibility for LTOT is fairly strictly defined, and LTOT equipment is distributed to and retained only by nonsmoking patients who continue to demonstrate need of the equipment (i.e., those who have ongoing hypoxemia that can benefit from LTOT). This national LTOT system provides a large, nonselected population suitable for LTOT research, and recent studies have produced important data regarding survival, pulmonary hemodynamics, and the effect of withdrawing LTOT from patients whose oxygenation has recovered to above the LTOT qualification level of PaO2 < or = 55 mm Hg.     

Efficacy and indications of home oxygen therapy for patients with chronic obstructive pulmonary disease]

Efficacy of home oxygen therapy (HOT) is well established for patients with chronic obstructive pulmonary disease who fall into chronic respiratory failure. We should consider now how the quality of life improves with HOT in those patients. According to the guideline of the Japanese Respiratory Society, indications of HOT are as follows: 1) A PaO2 of less than 55 Torr at rest while breathing room air, 2) A PaO2 between 55 Torr and 60 Torr in the presence of clear evidence of cor pulmonale, pulmonary hypertension, or a long history of severe hypoxemia during sleep or during exercise. Further studies are definitely required to pick up the patients who do not necessarily meet these indications but who may benefit from HOT.     

Long-term oxygen therapy in Australia.

Thoracic physicians in New South Wales, Australia, and conservative in their administration of long-term oxygen therapy. Relatively few patients are being treated with it at present. Those who are use oxygen cylinders and concentrators in their homes. Use of long-term therapy is restricted to two groups: first, well-motivated patients who, after investigation and treatment, continue to have PaO2 values below 60 mm Hg and evidence of complications arising from hypoxia; and second, a few patients who have central apnea and severe desaturation of hemoglobin during sleep.     

Chronic oxygen therapy.

Chronic low flow oxygen is useful therapy for patients with chronic obstructive lung disease who are crippled by hypoxemia despite optimal programs of usual respiratory care. Patients should be considered for chronic oxygen therapy who have (a) a resting Pao2 less than 55 mm Hg while breathing room air; or (b) profound tissue hypoxemia measured by mixed venous Pao2 and suggested by symptoms such as cor pulmonale and congestive heart failure; or (c) pulmonary hypertension or polycythemia even though daytime Pao2 is greater than 55 mm Hg. Arterial blood must be obtained to demonstrate hypoxemia and assess the benefits of oxygen therapy. Patients on chronic oxygen must remain under close medical supervision. There are no absolute contraindications to chronic oxygen therapy, other than refusal of the patient to quit smoking. Complications of therapy appear to be negligible. The exciting suggestion of improved prognosis in patients with chronic obstructive lung disease on oxygen therapy and the possibility of delaying the long-term sequelae of chronic respiratory failure bear careful watching in the future.     

Arterial oxygen values achieved by COPD patients breathing oxygen alternately via nasal mask and nasal cannula.

Ten patients with known but clinically stable chronic obstructive pulmonary disease (COPD) were studied while breathing low-flow (1-2 L/min) supplemental oxygen by nasal cannula and by biflow nasal mask. Although the increase in inspired oxygen when breathing with the cannula has been documented, the nasal mask has not been tested by measurement of PaO2 change. The mean age of the group was 64.6 years, and their mean PaO2 was 54 +/- 10.5 torr while they were at rest and breathing room air. Patients were each given oxygen alternately with the mask and cannula, with no change in flowrate; time was allowed between the two for equilibration and return to baseline values. PaO2 values were compared by t test for nonindependent samples, which provided a t value of 1.893, with P = 0.09. Differences in measured arterial saturation (SaO2) and PaCO2 also proved to be insignificant when patients breathed via the two devices. The conclude that the nasal cannula and the biflow nasal mask produce comparable PaO2 in patients who may need low-flow supplemental oxygen at rest. The mask can be considered an alternative oxygen appliance if preferred by patients because of comfort.     

Long-term oxygen therapy vs long-term ventilatory assistance

The use of positive-pressure nasal ventilation in combination with LTOT in stable COPD patients with hypercapnic respiratory failure controls hypoventilation and improves daytime ABGs, sleep, and quality of life. Nasal ventilation in COPD is unlikely to produce benefit unless used with supplemental oxygen therapy at night. The patients who show the greatest reduction in overnight PaCO2 with ventilation are the patients most likely to benefit from long-term ventilatory support. Although there is now evidence for short-term benefit from NPPV in hypercapnic COPD, large multicenter studies with survival, exacerbations, and hospital admissions as the primary end points are required to evaluate longer-term effects of this potentially important intervention.     

Pathophysiology and clinical effects of chronic hypoxia

Hypoxia exists when there is a reduced amount of oxygen in the tissues of the body. Hypoxemia refers to a reduction in PO2 below the normal range, regardless of whether gas exchange is impaired in the lung, CaO2 is adequate, or tissue hypoxia exists. There are several potential physiologic mechanisms for hypoxemia, but in patients with COPD the predominant one is V/Q mismatching, with or without alveolar hypoventilation, as indicated by PaCO2. Hypoxemia caused by V/Q mismatching as seen in COPD is relatively easy to correct, so that only comparatively small amounts of supplemental oxygen (less than 3 L/min for the majority of patients) are required for LTOT. Although hypoxemia normally stimulates ventilation and produces dyspnea, these phenomena and the other symptoms and signs of hypoxia are sufficiently variable in patients with COPD as to be of limited value in patient assessment. Chronic alveolar hypoxia is the main factor leading to development of cor pulmonale--right ventricular hypertrophy with or without overt right ventricular failure--in patients with COPD. Pulmonary hypertension adversely affects survival in COPD, to an extent that parallels the degree to which resting mean pulmonary artery pressure is elevated. Although the severity of airflow obstruction as measured by FEV1 is the best correlate with overall prognosis in patients with COPD, chronic hypoxemia increases mortality and morbidity for any severity of disease. Large-scale studies of LTOT in patients with COPD have demonstrated a dose-response relationship between daily hours of oxygen use and survival. There is reason to believe that continuous, 24-hours-per-day oxygen use in appropriately selected patients would produce a survival benefit even greater than that shown in the NOTT and MRC studies.     

Medications for COPD: a review of effectiveness

Chronic obstructive pulmonary disease (COPD) is a common problem among patients presenting to primary care. This condition has multiple individual and combined treatment regimens. The goals of treatment are to improve quality of life, exercise tolerance, sleep quality, and survival; and to reduce dyspnea, nocturnal symptoms, exacerbations, use of rescue medications, and hospitalizations. All patients benefit from bronchodilator medications as needed. Long-acting inhaled anticholinergics are probably more beneficial than short-acting formulations. Use of inhaled corticosteroids might benefit patients with mild COPD who have an inflammatory component or significant reversibility on spirometry. Patients with moderate to severe disease benefit from the use of long-acting inhaled anticholinergics, inhaled corticosteroids, and possibly a long-acting beta2 agonist or mucolytics. For rescue therapy, short-acting beta2 agonists or combination anticholinergics with a short-acting beta2 agonist should be used. Inhaled corticosteroids should be considered before initiating a long-acting beta2 agonist. Caution should be used if a long-acting beta2 agonist is discontinued before initiation of an inhaled corticosteroid because this may precipitate exacerbations. Evidence to support the use of mucolytics, oral theophylline, and oral corticosteroids is limited. Patients with severe hypoxemia (i.e., arterial oxygen pressure less than 55 mm Hg or oxygen saturation less than 88 percent) should be given continuous oxygen.     

Improving paediatric and newborn life support training by the use of modified manikins allowing airway occlusion

OBJECTIVE: To assess the management of patients with blunt traumatic pulmonary contusion admitted to our hospital. To identify the role of early blood gas analysis, non-invasive ventilation and to assess the validity of the current Advanced Trauma Life Support manual statement that "Patients with significant hypoxia, i.e. PaO(2)<65 mm Hg or 8.6 kPa on room air, SaO(2)<90%, should be intubated and ventilated within the first hour after injury". SETTING: A 24 bed Intensive Care Unit in a major Trauma Centre situated in South Western Sydney, Australia. METHODS: Retrospective review of adults with blunt traumatic pulmonary contusion identified from the trauma registry. RESULTS: A total of 75 patients with an age range of 16-81 years were identified over a 2-year period. Arterial blood gas measurement was available for 32 patients during the immediate resuscitative period (<1 h from admission). All patients received supplemental oxygen and a PaO(2)/FiO(2) ratio was calculated. Seven patients had significant pulmonary contusion, indicated by an initial PaO(2)/FiO(2) ratio of <300, and were treated successfully with non-invasive ventilatory support. A further five patients without arterial blood gas (ABG) analysis on admission but with PaO(2)/FiO(2) ratio of <300 in the ICU were also managed with non-invasive ventilatory support. Multi-modal analgesia was commonly used. CONCLUSIONS: All major trauma patients admitted to our hospital received supplemental oxygen. Interpretation of ABG breathing room air was not used as an indicator for intubation. Most decisions to intubate early were based on clinical need. Patients with significant pulmonary contusion required intubation for reasons other than respiratory failure. Patients with significant pulmonary contusion were managed safely with non-invasive ventilatory support. Further investigation will determine the role of non-invasive ventilatory support in the management of these patients.     

Assessing need for long-term oxygen therapy: a comparison of conventional evaluation and measures of ambulatory oximetry monitoring

BACKGROUND: Appropriate identification of hypoxic patients with chronic obstructive pulmonary disease (COPD) is important because of the demonstrated survival benefit of long-term oxygen therapy (LTOT) and its associated cost. Resting oxygen saturation (measured via pulse oximetry [S(pO2)]) and lowest exercise S(pO2) (during a 6-min walk test) is the standard method of determining LTOT requirements, but that method does not measure the patient's oxygenation during sleep or activities of daily living. We hypothesized that values obtained via the standard method would correlate poorly with values obtained via ambulatory oximetry monitoring. METHODS: We conducted a prospective, cohort study in an out-patient pulmonary clinic in a tertiary care referral center, with 20 stable COPD patients who were being evaluated for LTOT with conventional evaluation versus 16-24 hours of ambulatory oximetry. RESULTS: The resting S(pO2) did not correlate well with mean ambulatory S(pO2) (r = 0.64) or the percent of monitored time spent with S(pO2) < 88% (r = 0.49). The lowest exercise S(pO2) also did not predict mean ambulatory S(pO2) (r = 0.39) or the percent of monitored time spent with S(pO2) < 88% (r = 0.32). Conventional evaluation overestimated LTOT requirements with 16 of the 20 patients developing an S(pO2) < 88%, most of them with exercise only (ie, most had normal resting S(pO2)). With ambulatory monitoring, however, only 3 of the 16 patients spent > 10% of the monitored time with S(pO2) < 88%. CONCLUSION: There was a poor relationship between the conventional oxygenation assessment method and continuous ambulatory oximetry during LTOT screening with COPD patients.     

通气程度对颅脑损伤患者脑氧供需平衡的影响

背景不适当的过度通气可能诱使脑血管收缩,导致脑低灌流和氧供需失衡.目的探讨过度通气对严重颅脑伤患者颈内静脉球血氧饱和度、脑动静脉氧含量差和脑静动脉血乳酸差的影响.设计病例分析.单位汕头大学医学院第一附属医院麻醉科.对象选择汕头大学医学院第一附属医院2002-01/07收治的严重颅脑损伤急诊手术患者16例进行观察.方法颅脑损伤手术患者全身麻醉后,调节呼吸频率使二氧化碳分压达30 mm Hg并维持15 min,然后提高呼吸频率使二氧化碳分压达到25 mm Hg亦维持15 min,再降低呼吸频率以使二氧化碳分压恢复至30 mm Hg同样维持15 min,改变吸入氧浓度以使血氧分压稳定在100～150 mm Hg,并于上述二氧化碳分压改变并维持15 min后,分别采集动脉和颈内静脉球血液进行血气分析.调高吸入氧浓度将血氧分压增至200～250 mm Hg,再重复上述通气调节依此将二氧化碳分压改变为30→25→30mm Hg,测定颈内静脉球血氧饱和度、脑动静脉氧含量差及脑静动脉血乳酸差.主要观察指标血氧分压和二氧化碳分压变化对颈内静脉球血氧饱和度、脑动静脉氧含量差和脑静动脉血乳酸差的影响.结果16例患者符合标准并完成数据采集.当动脉血氧分压为100～150 mm Hg及200～250 mm Hg,动脉血二氧化碳分压从30 mm Hg降至25 mm Hg时,可使颈内静脉球血氧饱和度明显降低、脑动静脉氧含量差明显升高,但血氧分压200～250mm Hg与血氧分压100～150mm Hg相比,颈内静脉球血氧饱和度的绝对值均明显较高,脑动静脉氧含量差绝对值明显较低.与基础值相比,血氧分压100～150 mm Hg、二氧化碳分压30 m Hg及25mmHg和血氧分压200～250 mm Hg、二氧化碳分压25 mm Hg时,脑静动脉血乳酸差均明显升高.结论较高动脉血氧水平(血氧分压200～250 mm Hg)和中度过度通气(二氧化碳分压30mm Hg)对脑氧供需平衡无明显影响.     

Long-term oxygen therapy: conference summary

With Jan's presentation, the conference concluded. In looking back on it, I think it is obvious that the group heard a very comprehensive, state-of-the-art review of this very important topic. Obviously, LTOT has enormous clinical and financial impact for millions of patients around the world. Indeed, LTOT is one of the few therapies available that has clearly been shown in randomized controlled trials to impact mortality. There are many questions that remain, however. To me, the most important of these questions involve the diagnosis and management of patients who do not have resting hypoxemia but who do have NOD and/or XOD. How aggressively should we "screen" for these conditions? If we find them, do we treat continuously or just during the hypoxemic episodes? What is the role of supplemental oxygen during rehabilitative exercises (including usage in patients who don't become hypoxemic)? The answers to these questions will clearly have substantial clinical and financial impact. Other memorable aspects of this conference included the tireless efforts of Ray Masferrer to pull this conference off, the special camaraderie of the participants that made the discussions so productive, and the lovely location that gave the conference an atmosphere of high quality. I'd like to recognize and thank two important groups. First, the American Association for Respiratory Care did a superb job of organizing the conference and providing the journal Respiratory Care as a forum to publish the proceedings. Second, our 3 industry sponsors not only provided critical funding support but also gave the group important perspectives during many of the discussions. These kinds of industry-profession collaborations benefit everyone. Finally, I'd like to extend my congratulations to all the speakers for jobs well done and to thank them for making my job as summarizer an enjoyable one.     

A Smart-Phrase to Improve Documentation of Supportive Measures for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive lung disease of unknown cause occurring in adults and affecting approximately 5 million people worldwide. The American Thoracic Society 2015 guidelines provide recommendations for the treatment of patients with IPF, including supportive care measures such as oxygen therapy, pulmonary rehabilitation, gastric acid therapy, sleep apnea, vaccinations, lung transplant evaluation, and pulmonary hypertension assessment. A smart-phrase was developed that outlines the supportive care measures for the IPF patient, which was then implemented into a new patient clinic note in the electronic medical record. Documentation of the measures improved significantly after implementation of the smart-phrase.     

Sleep and medical disorders

Extensive evidence links cardiovascular disease and sleep disordered breathing. OSA has adverse effects on blood pressure, cardiovascular status,and mortality. Effective CPAP therapy can improve blood pressure and cardiac function in patients who have OSA. Patients who have congestive heart failure have a high prevalence of sleep-disordered breathing, with OSA occurring in 30% of such patients and Cheyne-Stokes respiration in 40%.CPAP is the preferred mode of therapy for both types of sleep-disordered breathing in patients who have coexistent congestive heart failure. Nocturnal worsening of asthma is a common manifestation of this disease that indicates increased disease severity. Therapy focuses on judicious use of long-acting bronchodilators, and the presence of OSA should also be considered. COPD is frequently associated with impaired sleep, likely because of chronic dyspnea and sleep-associated hypoxemia. Appropriate therapy again includes long-acting bronchodilators and possibly nocturnal supplemental oxygen.Gastroesophageal reflux during sleep may lead to prolonged episodes of esophageal acid exposure and may be a common sequela of OSA, perhaps triggering nocturnal worsening of asthma. Endstage renal disease and chronic dialysis are commonly associated with a host of troublesome sleep problems,including OSA, RLS, PLMD, and daytime sleepiness.     

Oxygen therapy and exercise response in lung disease

Lung disease affects exercise performance through a number of mechanisms, including hypoxemia, abnormal ventilatory mechanics, abnormal ventilatory muscles, abnormal ventilatory patterns, abnormal right heart function and subjective dyspnea. Supplemental oxygen improves hypoxemia and thus improves exercise impairment resulting from hypoxemia-related reductions in oxygen delivery. Supplemental oxygen also reduces exercise ventilation. This, in turn, reduces ventilatory muscle work, and the concomitant permissive hypercapnia may have beneficial effects at the cellular level. Additionally, in obstructive disease patients, an improved ventilatory pattern may reduce air trapping. Supplemental oxygen may also improve right ventricular dysfunction in patients with underlying right ventricular dysfunction. Finally, supplemental oxygen may reduce dyspnea caused by oxygen-related carotid body activity. Important questions remain. First, is long-term oxygen use of benefit in patients with only exercise hypoxemia? Second, is exercise conditioning possible in patients with exercise hypoxemia? Third, does supplemental oxygen enhance exercise conditioning efforts in those patients with CLD but without exercise hypoxemia? If the answer to this last question is yes, what selection criteria should be used to identify those who would benefit? The answers to all of these questions will have enormous impact on our approach to the optimal management of CLD patients.     

Hypoxemia during sleep in patients with chronic obstructive pulmonary disease: significance, detection, and effects of therapy

NOD is a common event in patients with symptomatic COPD who are not hypoxemic while awake. Up to 45% of these patients may have significant oxyhemoglobin desaturation during sleep, and most have evidence of pulmonary arterial hypertension. Although intuitively it would seem that supplemental oxygen during sleep should be of medical benefit in COPD patients with NOD, studies to data have not substantiated this idea. Medicare requirements for prescribing nocturnal oxygen are relatively liberal and there is the possibility of misuse, which would cause a substantial increase in the cost of home health care. A well designed multicenter study is needed to provide appropriate indications and guidelines for therapy in these patients.