Exercise tolerance during nasal cannula and transtracheal oxygen delivery

Oxygen therapy during exercise training in chronic obstructive pulmonary disease

BACKGROUND

Exercise training within the context of pulmonary rehabilitation improves outcomes of exercise capacity, dyspnea and health-related quality of life in individuals with chronic obstructive pulmonary disease (COPD). Supplemental oxygen in comparison to placebo increases exercise capacity in patients performing single-assessment exercise tests. The addition of supplemental oxygen during exercise training may enable individuals with COPD to tolerate higher levels of activity with less exertional symptoms, ultimately improving quality of life.

OBJECTIVES

To determine how supplemental oxygen in comparison to control (compressed air or room air) during the exercise-training component of a pulmonary rehabilitation program affects exercise capacity, dyspnea and health-related quality of life in individuals with COPD.

SEARCH STRATEGY

All records in the Cochrane Airways Group Specialized Register of trials coded as 'COPD' were searched using the following terms: (oxygen* or O2*) AND (exercis* or train* or rehabilitat* or fitness* or physical* or activ* or endur* or exert* or walk* or cycle*). Searching the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, EMBASE and CINAHL databases identified studies. The last search was carried out in June 2006.

SELECTION CRITERIA

Only randomized controlled trials (RCTs) comparing oxygen-supplemented exercise training to non-supplemented exercise training (control group) were considered for inclusion. Participants were 18 years or older, diagnosed with COPD and did not meet criteria for long-term oxygen therapy. No studies with mixed populations (pulmonary fibrosis, cystic fibrosis, etc) were included. Exercise training was greater than or equal to three weeks in duration and included a minimum of two sessions a week.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion in the review and extracted data. Weighted mean differences (WMD) with 95% confidence intervals (CI) were calculated using a random-effects model. Missing data were requested from authors of primary studies.

MAIN RESULTS

Five RCTs met the inclusion criteria. The maximum number of studies compared in the meta-analysis was three (31 on oxygen versus 32 control participants), because all included studies did not measure the same outcomes. When two studies were pooled, statistically significant improvements of oxygen-supplemented exercise training were found in constant power exercise time, WMD 2.68 minutes (95% CI 0.07 to 5.28 minutes). Supplemental oxygen increased the average exercise time from 6 to 14 minutes; the control intervention increased average exercise time from 6 to 12 minutes. Constant power exercise end-of-test Borg score (on a scale from 1 to 10) also showed statistically significant improvements with oxygen-supplemented exercise training, WMD -1.22 units (95% CI -2.39 to -0.06). One study showed a significant improvement in the change of Borg score after the shuttle walk test, by -1.46 units (95% CI -2.72 to -0.19). There were no significant differences in maximal exercise outcomes, functional exercise outcomes (six-minute walk test), shuttle walk distance, health-related quality of life or oxygenation status. According to the GRADE system most outcomes were rated as low quality because they were limited by study quality.

AUTHORS' CONCLUSIONS

This review provides little support for oxygen supplementation during exercise training for individuals with COPD, but the evidence is very limited. Studies with larger number of participants and strong design are required to permit strong conclusions, especially for functional outcomes such as symptom alleviation, health-related quality of life and ambulation.

The effect of tracheal gas insufflation on gas exchange efficiency

Transtracheal gas insufflation (TGI) improves gas exchange efficiency, but is associated with hyperinflation, and usually requires ventilator adjustment to compensate for the increased gas flow. Although bidirectional TGI (Bi-TGI) minimizes hyperinflation, it does not preclude the need to reduce tidal volumes to prevent hyperinflation. A flow-compensation system was developed by Respironics (Murrysville, PA) to match TGI flows; however, neither that nor the efficacy of Bi-TGI have been tested in vivo. We tested the hypotheses that flow compensation allows for a constant minute ventilation; Bi-TGI produces less hyperinflation than does unidirectional TGI (Uni-TGI), and endotracheal tube size influences the degree of hyperinflation during TGI. Seven anesthetized intact dogs were studied during positive-pressure ventilation using the Respironics flow compensation system. Measurements were made during steady-state conditions at constant and measured levels of CO(2) production. Gas exchange efficiency (assessed by expired gas analysis for dead space) and hyperinflation (measured as an increase in pleural pressure) were compared during Bi- and Uni-TGI and for endotracheal tube sizes varying from 7 to 10F. Bi- and Uni-TGI could be delivered at constant minute ventilation without adjusting ventilatory setting when the flow compensation circuit was present. Uni-TGI produced more hyperinflation than did Bi-TGI with all sizes of endotracheal tube, and hyperinflation was universally present as tube size decreased to 7.5F. We conclude that this new flow compensation system allows for the delivery of TGI without the need for adjustments to the ventilator settings, and that Bi-TGI produces less hyperinflation than does Uni-TGI, even with small diameter endotracheal tubes.

The use of oxygen in the palliation of breathlessness. A report of the expert working group of the scientific committee of the association of palliative medicine

Dyspnoea is a common, distressing symptom and difficult to control with medical treatment. The role of oxygen in reducing the severity of the symptoms and improving quality of life is still unclear. A working party of the Association of Palliative Medicine Science Committee set out to examine the evidence concerning the use of oxygen for the palliation of breathlessness in COPD, advanced cancer and chronic heart failure and to make recommendations for clinicians working in palliative care. There were very few randomised controlled trials available for any of these conditions. There was no evidence available for heart failure, very little for advanced cancer and although there were a number of trials on the use of oxygen in COPD very few, until recently, used reduction of breathlessness as an outcome measure. Recommendations are made on the basis of the evidence available and expert opinion such as the Royal College of Physicians report on the use of domiciliary oxygen. Oxygen use has to be tailored to the individual and a formal assessment made of its efficacy for reducing breathlessness and improving quality of life for that person [corrected].

Effect of Tracheal Gas Insufflation During Weaning From Prolonged Mechanical Ventilation: A Preliminary Study

• Background Tracheal gas insufflation reduces inspired tidal volume and minute ventilation in spontaneously breathing patients and may facilitate weaning from mechanical ventilation.

• Objective To determine if tracheal gas insufflation can reduce ventilatory demand during weaning trials in patients who require prolonged mechanical ventilation.

• Methods A reduction in ventilatory demand was defined as a relative decrease in tidal volume, minute ventilation, and mean inspiratory flow during trials with tracheal gas insufflation compared with the values during trials without this therapy. A total of 14 subjects underwent T-piece trials with and without insufflation (flow rate 6 L/min) on 2 consecutive days; the order of insufflation was randomized. Tidal volume, minute ventilation, and mean inspiratory flow were measured at baseline (without insufflation) and 2 hours later.

• Results Differences in ventilatory demand were not significant when comparisons were made for condition (tracheal gas insufflation vs no flow) or time (baseline vs 2 hours) for the total group (P = .48). Subjects were classified post hoc as responders (n = 9) or nonresponders (n = 5). Comparisons between responders and nonresponders indicated a significant (P = .02) 3-way multivariate interaction for group (responder vs nonresponder), condition (tracheal gas insufflation vs no flow), and time (baseline vs 2 hours) for ventilatory demand variables.

• Conclusion Tracheal gas insufflation can reduce ventilatory demand during weaning trials in some patients who require mechanical ventilation.

Long-term clinical experience with transtracheal oxygen catheters

OBJECTIVE

To evaluate and discuss the use of transtracheal oxygen catheters for the treatment of chronic hypoxemia and to discuss the complications associated with the placement and care of these devices.

DESIGN

We conducted a retrospective study at a tertiary medical center and reviewed the pertinent literature.

MATERIAL AND METHODS

The medical records of 56 patients who received a transtracheal oxygen catheter between January 1987 and June 1992 at our institution were reviewed for demographic data, diagnosis leading to catheter placement, complications related to catheter use, reason for catheter removal, and duration of use. Follow-up results were established by documentation in the medical records or telephone interview.

RESULTS

During the study period, 39 men and 17 women received a transtracheal catheter. More than half the patients (52%) had chronic obstructive pulmonary disease. The duration of use of the catheter ranged from 2 days to more than 6 years, and the most frequent cause for removal of the catheter was death. Of the 56 patients, 42 died with the catheter in place, 24 within the first year after placement. Complications ranged from mucous plugging (38 % of patients) to pneumothorax (4%), and no patient died of a catheter-related complication. Overall, 55% of patients had their catheter for less than 1 year after placement.

CONCLUSION

In patients with transtracheal oxygen catheters, problems related to mucous plugging are common, but severe complications such as pneumothorax and pneumomediastinum are uncommon. Although selection factors that would identify ideal candidates for transtracheal oxygen therapy have not been established, such a catheter is best placed in highly motivated patients who can physically manage the daily care of this device.

Home oxygen therapy

Home oxygen therapy has well-established benefits for patients with chronic obstructive pulmonary disease and resting hypoxemia. The indications for therapy have been clearly defined in the United States by the Health Care Financing Administration (HCFA), and these guidelines have been accepted by most third-party payers. Controversies regarding the use of oxygen during sleep and exercise when daytime hypoxemia is not present have important therapeutic and financial implications. HCFA has recently proposed a substantial reduction in reimbursement for home oxygen which could have a major adverse effect if done on a global, across-the-board, basis. Some of the new technological developments in oxygen delivery systems are presented in this article.

Tracheal gas insufflation improves ventilatory efficiency during metacholine-induced bronchospasm

INTRODUCTION

Barotrauma and cardiovascular insufficiency are frequently encountered problems in patients with acute bronchospastic disease who require mechanical ventilation. Permissive hypercapnia is a recognized strategy for minimizing these adverse effects; however, it has potential risks. Tracheal gas insufflation (TGI) has been shown to increase carbon dioxide elimination efficiency and thus could permit mechanical ventilation at lower peak airway pressures without inducing hypercapnia. However, caution exists as to the impact of TGI on lung volumes, given that expiratory flow limitation is a hallmark of bronchospastic disease.

PURPOSE

To examine these issues, we studied ventilatory and hemodynamic effects of continuous TGI as an adjunct to mechanical ventilation before and after methacholine-induced bronchospasm.

MATERIALS AND METHODS

Ten anesthetized, paralyzed dogs were ventilated on volume-controlled mechanical ventilation during administration of continuous TGI (0, 2, 6, and 10 L/min) while total inspired minute ventilation (ventilator-derived minute ventilation plus TGI) was kept constant. In an additional step, with TGI flow of 10 L/min, total inspired minute ventilation was decreased by 30%.

RESULTS

PaCO2 decreased (44 +/- 7 mm Hg at zero flow to 34 +/- 7 mm Hg at 6 L/min and 31 +/- 6 mm Hg at 10 L/min, respectively, P < .05), as did the dead space to tidal volume ratio at TGI of 6 and 10 L/min compared with zero flow. There were no significant changes in end-expiratory transpulmonary pressure, mean arterial pressure, or cardiac output. During the highest TGI flow (10 L/min), with a 30% reduction of total inspired minute ventilation, both PaCO2 and peak airway pressure remained less than during zero flow conditions.

CONCLUSION

We conclude that TGI increases carbon dioxide elimination efficiency during constant and decreased minute ventilation conditions without any evidence of hyperinflation or hemodynamic instability during methacholine-induced bronchospasm.

Home oxygen therapy

Both the efficacy and the indications for LTOT have been well defined. Most of the studies performed have focused on patients with hypoxemia caused by COPD, and the benefits observed are assumed to apply to all patients with correctable hypoxemia. For Medicare patients, oxygen is reimbursed under a prospective payment system with all delivery systems considered to be cost and therapeutically equal. Because there are, in fact, substantial clinical differences in the medical indications for individual oxygen delivery systems, it is imperative that the prescribing physician be prepared to order the therapy that is most appropriate for each patient. Most home oxygen therapy is now being ordered by primary care physicians, often functioning as gatekeepers in managed care organizations. Education of primary care physicians in this area is often inadequate, and decisions for therapy should not be delegated to the equipment suppliers. If the study of home oxygen therapy conducted by the Office of the Inspector General were repeated today, less misuse of home oxygen would probably be found because of more clearly defined indications and requirements for therapy, but it is likely that the study would find that the level of knowledge of the prescribing physician has not maintained pace with the advances in technology. Continuing education for primary care physicians in this area of respiratory care is essential for appropriate medical management now and in the future.

Effect of low flow and high flow oxygen delivery on exercise tolerance and sensation of dyspnea. A study comparing the transtracheal catheter and nasal prongs

HYPOTHESIS

We hypothesized that high flow transtracheal oxygen (HFTTO) will improve exercise tolerance as compared with low flow transtracheal oxygen (LFTTO) and that transtracheal oxygen (TTO) will increase exercise tolerance with less dyspnea as compared with nasal prongs (NP) at equivalent oxygen saturation (SaO2).

PATIENT SELECTION

Ten subjects, six male and four female, who were already receiving TTO were recruited for the study.

STUDY DESIGN

Each subject underwent a total of four modified progressive treadmill tests in a single-blind randomized fashion on two separate days. Two tests were performed with the patients receiving LFTTO and HFTTO while the other two were performed with low- and high-flow oxygen by NP. The flows were adjusted to provide equivalent oxygen saturations at rest for respective groups.

RESULTS

The mean +/- SD exercise distance with HFTTO (1,134 +/- 631 ft) was 2.5 times greater than with LFTTO (446 +/- 328 ft; p < 0.006); and high-flow NP (HFNP [1207 +/- 763 ft]) was 2.38 times greater than with low-flow NP (LFNP[492 +/- 487 ft; p < 0.005]). There was no significant difference in exercise distance and dyspnea scores with HFTTO as compared with HFNP and LFTTO versus LFNP.

CONCLUSION

We conclude that the use of high-flow oxygen via both transtracheal catheter and NP significantly increased exercise tolerance in our COPD patients when compared to low-flow oxygen. Transtracheal oxygen did not increase maximum exercise tolerance with less dyspnea as compared with oxygen via NP at equivalent SaO2.

The effects of transtracheal gas delivery on central inspiratory neuromuscular drive

Previous studies have shown transtracheal delivery of low-flow oxygen (TTO) decreases inspired minute ventilation (Veinsp) and have postulated that this would result in a decrease in the work of breathing (WOB). We hypothesized that a fall in central inspiratory neuromuscular drive (CIND) with TTO would reflect a fall in WOB. We measured resting ventilatory parameters (RVP) and CIND by the mouth occlusion pressure technique (MOP) at different gas flow rates through the catheter in 21 subjects (13 men, 8 women; mean age, 60 +/- 10.6 years) with severe COPD with a mature intratracheal oxygen catheter (ITOC). We also constructed a lung/chest wall analog (LCA) to determine if flow through the catheter would alter pressure changes during inspiration. Inspiratory tidal volume (Vtinsp) and minute ventilation (Veinsp) decreased proportionally to the gas flow rate through the catheter. However, with increasing flow through the catheter, P0.1 increased in the LCA, presumably due to the Bernoulli effect. The lack of a similar change in the subject group suggests that CIND does, in fact, fall, and that possibly there is a decrease in WOB. This effect may be of benefit to patients with severe COPD.

Transtracheal delivery of gas decreases the oxygen cost of breathing

Transtracheally administered gases decrease inspired minute ventilation in both dogs and humans. To test if this is associated with a decrease in the oxygen cost of breathing and to evaluate subsequent changes in the breathing pattern, we studied five patients with chronic respiratory diseases while they spontaneously breathed air and different flows of tracheally administered gases. In a blinded crossover design, the gas consisted of either oxygen or air at 2, 4, and 6 L/min. Oxygen cost of breathing was estimated by the calculation of pleural pressure-time index (PPTI). The pattern of breathing was evaluated utilizing the tension time index for the diaphragm (TTdi). There were significant decreases in PPTI when the patients received 2, 4, and 6 L/min of transtracheal oxygen or air. TTdi also decreased as gas flow increased. This drop was significant at 6 L/min flow for both gases. We conclude that transtracheally administered gas reduces the oxygen cost of breathing. It also changes the respiratory pattern of the diaphragm to a less demanding pattern. This may offer an alternative form of treatment to rest overworked respiratory muscles.

Acute respiratory compromise resulting from tracheal mucous impaction secondary to a transtracheal oxygen catheter

Transtracheal oxygen catheters are being increasingly used because of savings in oxygen usage and patient preference. The complications of the catheter are believed to be minor and easily managed. Inspissated mucous collections that form at the tip of the SCOOP 1 (Transtracheal Systems, Denver, Colorado) catheter have been reported but are usually easily expectorated by the patient. This report describes a patient who had development of acute respiratory compromise from crusted mucoid impaction of the trachea secondary to transtracheal catheter use. General anesthesia and rigid bronchoscopy were required for removal of the obstructing impaction. Unexplained worsening of respiratory symptoms in patients with transtracheal oxygen catheters should be addressed by prompt stripping of the catheter.

Nasal cannula and transtracheal oxygen delivery. A comparison of patient response after 6 months of each technique

The purpose of this study was to compare the efficacy of transtracheal (TT) oxygen delivery to that of nasal cannula delivery in subjects with chronic obstructive pulmonary disease (COPD). Twenty subjects (14 men, 6 women) were followed for 6 months during nasal cannula delivery. A TT catheter was then inserted, and measurements were repeated during TT use. With TT delivery, subjects required 45% less oxygen at rest and 39% less during exercise (p less than 0.0001). Oxygen use, measured by pounds of oxygen delivered to the home, also decreased, but the magnitude of change was less than anticipated (mean, 14%; range, +4% to -32%). Hospital days decreased from 12 +/- 10 during nasal cannula use to 4 +/- 6 during TT use (p less than 0.002). Exercise tolerance, as measured by a 12-min walk distance, was greater during TT use (p less than 0.0001). No change was seen in spirometry or acid-base balance. Also, no change was seen in Profile of Mood States, Sickness Impact Profile or Katz Adjustment Scale scores. Some problems were encountered relating to use of the catheter (displacement, mucus balls), but they were minor, and most were confined to the initial 2 months of TT use when the tract was immature. Our experience suggests that, in addition to decreasing oxygen flow rate, use of TT delivery may confer benefits that result in improved exercise tolerance and decreased hospitalization in patients with COPD.

The use of a short-length transtracheal oxygen catheter in patients of small stature with restrictive lung disease

Transtracheal oxygen therapy is being used with increasing frequency because it is an effective mode of oxygen delivery and is well tolerated by patients. An increase in cough and mild intermittent hemoptysis are not uncommon in the early postinsertion period but usually resolve spontaneously. Herein we present two individuals of short stature with restrictive lung disease who had persistence of excessive cough and mild hemoptysis after insertion of a standard catheter (SCOOP). Bronchoscopic evaluation in one revealed erosions of the mucosa over the carina and take-off of the right main-stem bronchus. Symptoms resolved in both individuals following placement of a shorter catheter. We suggest that greater consideration be given to matching transtracheal catheter length to patient lung size, particularly in the face of severe restrictive lung disease.

Transtracheal oxygen delivery

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Transtracheal delivery of oxygen: efficacy and safety for long-term continuous therapy

Transtracheal (TT) oxygen delivery involves administration of oxygen percutaneously through a catheter inserted in the suprasternal trachea. Transtracheal oxygen delivery has been proposed as a means of overcoming the high visibility, inconvenience, and discomfort associated with nasal cannula use. This report describes our experience using TT delivery in 40 patients with chronic obstructive pulmonary disease (n = 32) and other types of lung disease (n = 8). Overall acceptance of TT catheter use was high and only 5 subjects elected to discontinue use. We believe the TT route is a relatively safe approach for oxygen administration and a promising method of improving patient compliance. It also offers the potential of more adequately oxygenating patients with refractory hypoxemia.

Dyspnea: a sensory experience

Dyspnea--an unpleasant or uncomfortable awareness of breathing or need to breathe--is a common symptom of patients with cardiopulmonary disease. Although often thought of as a single symptom, dyspnea probably subsumes many sensations. Experimental conditions used to induce dyspnea are characterized by discrete groups or clusters of descriptive phrases. Similarly, as the language of dyspnea is refined further, different disease states may be distinguishable by the nuances of breathlessness described by patients. Evidence is gathering that the sensations of dyspnea are modified by information from a variety of receptors throughout the respiratory system. The sense of effort, although still important in the breathlessness associated with mechanical loads, is insufficient to explain the dyspnea arising from a number of experimental and clinical conditions. As our understanding of the interactions between effort and afferent information from the respiratory system grows, new therapeutic interventions to alleviate dyspnea are likely to follow.