Transtracheal oxygen, nasal CPAP and nasal oxygen in five patients with obstructive sleep apnea

Impact of nocturnal oxygen and CPAP on the ventilatory response to hypoxia in OSA patients free of overt cardiovascular disease

A primary characteristic of obstructive sleep apnea (OSA) is chronic exposure to intermittent hypoxia (IH) due to repeated upper airway obstruction. Chronic IH exposure is believed to increase OSA severity over time by enhancing the acute ventilatory response to hypoxia (AHVR), thus promoting ventilatory overshoot when apnea ends and perpetuation of apnea during sleep. Continuous positive airway pressure (CPAP), the gold-standard treatment of OSA, reduces the AHVR, believed to result from correction of IH. However, CPAP also corrects ancillary features of OSA such as intermittent hypercapnia, negative intrathoracic pressure and surges in sympathetic activity, which may also contribute to the reduction in AHVR. Therefore, the objective of this study was to investigate the impact of nocturnal oxygen therapy (to remove IH only) and CPAP (to correct IH and ancillary features of OSA) on AHVR in newly diagnosed OSA patients. Fifty-two OSA patients and twenty-two controls were recruited. The AHVR was assessed using a 5 min iscopanic-hypoxic challenge before, and after, treatment of OSA by nocturnal oxygen therapy and CPAP. Following baseline measurements, OSA patients were randomly assigned to nocturnal oxygen therapy (Oxygen, n = 26) or no treatment (Air; n = 26). The AHVR was re-assessed following two weeks of oxygen therapy or no treatment, after which all patients were treated with CPAP. The AHVR was quantified following ~4 weeks of adherent CPAP therapy (n = 40). Both nocturnal oxygen and CPAP treatments improved hypoxemia (p < 0.05), and, as expected, nocturnal oxygen therapy did not completely abolish respiratory events (i.e., apneas/hypopneas). Averaged across all OSA patients, nocturnal oxygen therapy did not change AHVR from baseline to post-oxygen therapy. Similarly, the AHVR was not altered pre- and post-CPAP (p > 0.05). However, there was a significant decrease in AHVR with both nocturnal oxygen therapy and CPAP in patients in the highest OSA severity quartile (p < 0.05). Nocturnal oxygen therapy and CPAP both reduce the AHVR in patients with the most severe OSA. Therefore, IH appears to be the primary mechanism producing ventilatory instability in patients with severe OSA via enhancement of the AHVR.

Effect of One Night of Nocturnal Oxygen Supplementation on Highland Patients With OSA: A Randomized, Crossover Trial

BACKGROUND

The treatment of OSA in highland residents is not established.

RESEARCH QUESTIONS

Does nocturnal oxygen supplementation (NOS) improve sleep-related breathing disturbances, nocturnal oxygenation, and cognitive performance in patients with OSA living at 3,200 m?

STUDY DESIGN AND METHODS

Forty patients with OSA permanently living in Shangri-La, China at 3,200 m (median age [interquartile range], 47.0 [44.0-53.0] years; oxygen desaturation index, 38.4/h [34.2/h-52.3/h]), were randomly assigned to receive nasal NOS and sham oxygen (ambient air), for one night each, at 2 L/min, in a crossover design, separated by a washout period of 2 weeks. During treatment nights polysomnography was performed, and further outcomes were evaluated the next morning. The primary outcome was the difference in apnea-hypopnea index (AHI) between nights with NOS and nights with sham oxygen.

RESULTS

During nights with sham oxygen, the median (interquartile range) total AHI was 43.4/h (31.1/h-67.5/h), the obstructive AHI was 41.9/h (28.5/h-66.8/h), and the central AHI was 0.6/h (0.1/h-1.3/h); blood oxygenation as determined by pulse oximetry (Spo₂) was 87.0% (84.5%-89.0%). In intention-to-treat analysis, NOS decreased the total AHI by a median of 17.9/h (95% CI, 8.0/h-27.1/h; P < .001), through a reduction in obstructive AHI by 16.0/h (95% CI, 6.8/h-26.0/h; P < .001) and central AHI by 0.4/h (95% CI, 0.1/h-0.9/h; P < .001). NOS also increased Spo₂ by 7.0% (95% CI, 6.0%-8.0%; P < .001). Heart rate during sleep and pulse rate in the morning after NOS were significantly reduced, but subjective sleep quality and cognitive performance showed no changes.

INTERPRETATION

In highland residents with OSA, NOS significantly improved sleep-related breathing disturbances and nocturnal oxygenation. NOS also reduced heart rate during sleep and morning pulse rate. If these beneficial effects are confirmed in longer term studies, NOS may be a treatment option for highland patients with OSA who cannot be treated by CPAP.

TRIAL REGISTRY

Chinese Clinical Trial Registry; No.: ChiCTR1800017715; URL: http://www.chictr.org.cn/showproj.aspx?proj=29768.

Comparing the effects of supplemental oxygen therapy and continuous positive airway pressure on patients with obstructive sleep apnea: a meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVE

Obstructive sleep apnea (OSA) is associated with hypertension, psychological impairment, neurocognitive dysfunction, and poor quality of sleep. Continuous positive airway pressure (CPAP) has been confirmed to effectively improve OSA, while the effects of supplemental oxygen therapy on OSA have still remained controversial. This meta-analysis aimed to compare the effects of supplemental oxygen therapy and CPAP on patients with OSA.

METHODS

PubMed, Cochrane library, EMBASE, and Web of Science databases were systematically searched from inception until April 2020. Randomized controlled trials (RCTs) that compared the effects of supplemental oxygen therapy and CPAP on patients with OSA were selected without language restriction.

RESULTS

In this meta-analysis, 8 RCTs that involved 887 patients were found eligible for further analyses. Pooled data showed that there was no significant difference in improving nocturnal oxygen saturation (SpO₂) level (95% confidence interval (CI) = - 1.17 to 1.53) or symptoms of depression (95%CI = - 0.69 to 1.19) between supplemental oxygen therapy and CPAP. Supplemental oxygen therapy was found less effective in reducing apnea-hypopnea index (AHI), time of SpO₂ < 90%, blood pressure, and improving quality of sleep compared with CPAP. A subgroup analysis based on flow rate of oxygen indicated that the effects of supplemental oxygen therapy on blood pressure significantly differed. Furthermore, an improvement in overall time of SpO₂ < 90% was correlated to duration of supplemental oxygen therapy.

CONCLUSIONS

CPAP is clinically effective for the treatment of patients with OSA. However, supplemental oxygen therapy can be cautiously used for improving nocturnal hypoxia and symptoms of depression when CPAP is not acceptable or not tolerated. Supplemental oxygen therapy is a promising option to alleviate partial disorders of OSA. Further studies need to focus on flow rate of oxygen and duration of supplemental oxygen therapy.

Treatment of Hypoxemia in Obstructive Sleep Apnea

Many patients suffering from obstructive sleep apnea (OSA) have intermittent oxygen desaturation associated with periods of apnea or hypopnea. Oxygen saturation levels below 90% are considered harmful.1 Usually, treatment is directed at correcting the apnea, which will in turn prevent hypoxemia. Unfortunately, many patients fail or are not candidates for nasal continuous positive airway pressure (CPAP) or surgical correction of their OSA. Forty-three patients with persistent OSA and nocturnal hypoxemia below 90% who were not candidates for additional surgical or CPAP therapy were treated with nocturnal oxygen supplementation. Standard symptoms associated with OSA and the Epworth Sleepiness Scale (ESS) were recorded before treatment and 30 days after the start of the treatment. In 21 patients, polysomnography studies were performed to compare the Respiratory Disturbance Index (RDI) score and minimum oxygen saturation levels when the patients were breathing room air or breathing 4 L/minute of oxygen by nasal cannula. Subjective symptoms of obstructive sleep apnea improved, and the ESS score significantly decreased after a 30-night treatment with oxygen. Split-night polysomnography showed a significant increase in minimum oxygen saturation during oxygen administration. The RDI did not significantly change with treatment. Oxygen administration for the correction of OSA-related nocturnal hypoxemia was both safe and effective in alleviation of OSA-related symptoms. It also appeared to have a beneficial effect on minimum oxygen saturation levels. Thus, oxygen therapy may be considered a treatment option in patients who fail to comply with CPAP and are not candidates for a surgical procedure.

Transtracheal oxygen and positive airway pressure: A salvage technique in overlap syndrome

The coexistence of sleep apnea-hypopnea syndrome (SAHS) with chronic obstructive pulmonary disease (COPD) occurs commonly. This so called overlap syndrome leads to more profound hypoxemia, hypercapnic respiratory failure, and pulmonary hypertension than each of these conditions independently. Not infrequently, these patients show profound hypoxemia, despite optimal continuous positive airway pressure (CPAP) therapy for their SAHS. We report a case where CPAP therapy with additional in-line oxygen supplementation failed to accomplish adequate oxygenation. Adding transtracheal oxygen therapy (TTOT) to CPAP therapy provided better results. We review the literature on transtracheal oxygen therapy and how this technique may play a significant role in these complicated patients with overlap syndrome, obviating the need for more invasive procedures, such as tracheostomy.

Obstructive sleep apnea and oxygen therapy: a systematic review of the literature and meta-analysis

BACKGROUND

Hypoxemia is an immediate consequence of obstructive sleep apnea. Oxygen (O2) administration has been used as an alternative treatment in patients with obstructive sleep apnea (OSA) who do not adhere to continuous positive airway pressure (CPAP) in order to reduce the deleterious effects of intermittent hypoxemia during sleep. This systematic review aims to investigate the effects of O2 therapy on patients with OSA.

METHOD

We conducted a systematic search of the databases Medline, Embase, Cochrane Central Register of Controlled Trials (1(st) Quarter 2011), Cochrane Database of Systematic Reviews (from 1950 to February 2011). Our search strategy yielded 4,793 citations. Irrelevant papers were excluded by title and abstract review, leaving 105 manuscripts. We reviewed all prospective studies that included: (1) a target population with obstructive sleep apnea, (2) O2 therapy and/or CPAP as a study intervention, (3) the effects of O2 on the apnea-hypopnea index (AHI), nocturnal hypoxemia, or apnea duration.

RESULTS

We identified 14 studies including a total of 359 patients. Nine studies were of single cohort design, while 5 studies were randomized control trials with 3 groups (CPAP, oxygen, and placebo/sham CPAP). When CPAP was compared to O2 therapy, all but one showed a significant improvement in AHI. Ten studies demonstrated that O2 therapy improved oxygen saturation vs. placebo. However, the average duration of apnea and hypopnea episodes were longer in patients receiving O2 therapy than those receiving placebo.

CONCLUSION

This review shows that O2 therapy significantly improves oxygen saturation in patients with OSA. However, it may also increase the duration of apnea-hypopnea events.

Pharmacotherapy of obstructive sleep apnea

Obstructive sleep apnea (OSA) is associated with serious comorbid illnesses and diminished quality of life. At this time, continuous positive airway pressure (CPAP) therapy is the treatment of choice. However, only half of those individuals who accept CPAP are still using it at the end of one year. Furthermore, efficacy for improving self-reported sleepiness appears to be greater for patients with severe sleep apnea and severe sleepiness than other patient groups. Some patients, notwithstanding optimized therapy and therapeutic adherence continue experiencing excessive daytime somnolence. Consequently, other treatment modalities have developed, including oral appliances, surgery and pharmacotherapy. It is widely believed, albeit not empirically demonstrated, that an effective medication to treat OSA would elicit better acceptance and adherence than having to use a machine for many hours on a nightly basis. Nonetheless, paucity of data (i.e. lack of large-scale randomized controlled trials), variability of perceived and actual benefits, and adverse side-effects of the drugs thus far tested have prevented the use of pharmacotherapy until now. In this paper we review the outcome data from published trials designed to evaluate efficacy and safety of various medications proposed for treating obstructive sleep apnea.

Analysis of the interplay between neurochemical control of respiration and upper airway mechanics producing upper airway obstruction during sleep in humans

Increased loop gain (a function of both controller gain and plant gain), which results in instability in feedback control, is of major importance in producing recurrent central apnoeas during sleep but its role in causing obstructive apnoeas is not clear. The purpose of this study was to investigate the role of loop gain in producing obstructive sleep apnoeas. Owing to the complexity of factors that may operate to produce obstruction during sleep, we used a mathematical model to sort them out. The model used was based on our previous model of neurochemical control of breathing, which included the effects of chemical stimuli and changes in alertness on respiratory pattern generator activity. To this we added a model of the upper airways that contained a narrowed section which behaved as a compressible elastic tube and was tethered during inspiration by the contraction of the upper airway dilator muscles. These muscles in the model, as in life, responded to changes in hypoxia, hypercapnia and alertness in a manner similar to the action of the chest wall muscles, opposing the compressive action caused by the negative intraluminal pressure generated during inspiration which was magnified by the Bernoulli Effect. As the velocity of inspiratory airflow increased, with sufficiently large increase in airflow velocity, obstruction occurred. Changes in breathing after sleep onset were simulated. The simulations showed that increases in controller gain caused the more rapid onset of obstructive apnoeas. Apnoea episodes were terminated by arousal. With a constant controller gain, as stiffness decreased, obstructed breaths appeared and periods of obstruction recurred longer after sleep onset before disappearing. Decreased controller gain produced, for example, by breathing oxygen eliminated the obstructive apnoeas resulting from moderate reductions in constricted segment stiffness. This became less effective as stiffness was reduced more. Contraction of the upper airway muscles with hypercapnia and hypoxia could prevent obstructed apnoeas with moderate but not with severe reductions in stiffness. Increases in controller gain, as might occur with hypoxia, converted obstructive to central apnoeas. Breathing CO2 eliminated apnoeas when the activity of the upper airway muscles was considered to change as a function of CO2 to some exponent. Low arousal thresholds and increased upper airway resistance are two factors that promoted the occurrence and persistence of obstructive sleep apnoeas.

Pharmacological management of sleep apnoea

Obstructive sleep apnoea poses a significant health hazard that is associated with leading causes of mortality and morbidity. Nasal continuous positive airway pressure is the primary treatment modality, with surgical treatments as alternatives. Oral appliances and pharmacological therapy remain adjunctive modalities. Non-specific treatments include weight loss, postural therapy and behavioural measures. Pharmacotherapy goals include the reduction of risk factors for sleep apnoea; correction of underlying predisposing metabolic diseases, such as hypothyroidism or acromegaly; treatment of associated symptoms, including excessive daytime sleepiness; and prevention of apnoeas/hypopnoeas. This paper reviews data supporting the treatment of sleep apnoea with various pharmacological agents, including intranasal corticosteroids, decongestant sprays, nicotine therapy, opiate antagonists, methylxanthine derivatives, oestrogen and progesterone, testosterone, thyroid hormone, growth hormone therapy for acromegaly, beta-blockers, alpha-adrenergic agonists, angiotensin-converting enzyme inhibitors, glutamate antagonists, acetazolamide, selective serotonin re-uptake inhibitors, tricyclic antidepressants, physostigmine, modafinil and TNF-alpha antagonists, in addition to supplemental oxygen, and carbon dioxide inhalation. Some of these drugs have received very little testing and are the subject of few research articles.

Transtracheal oxygen catheters

Over the past 20 years a variety of transtracheal catheters have been developed for long-term oxygen therapy. A modified Seldinger technique has been the standard in the past, but a more recent procedure for surgical creation of the tracheocutaneous tract presents a number of potential advantages. TTO should be administered as a program of care, and recent advances with a streamlined and shortened program have simplified and improved the delivery of a technology that has a number of potential benefits and established safety. TTO may further increase the oxygen conservation efficiency of demand oxygen controller devices, and studies have shown TTO to be a potential alternative to nasal oxygen, continuous positive airway pressure, and tracheotomy for severe obstructive sleep apnea. Very high flows (> 10 L/minute) of a humidified air/oxygen blend, termed transtracheal augmented ventilation, extend the physiologic benefits of TTO and have promise in both the outpatient nocturnal ventilatory support of patients with severe respiratory disease and in liberation of patients from prolonged mechanical ventilation.

High-flow transtracheal insufflation treats obstructive sleep apnea. A pilot study

To determine the effect of transtracheal insufflation (TTI) on obstructive sleep apnea (OSA), we examined breathing patterns in five tracheostomized patients with OSA at varying TTI flow rates when breathing with a closed tracheostomy. The breathing patterns and polysomnographic responses to air insufflation were studied as TTI was increased from 0 to 15 L/min for brief periods of non-rapid eye movement (NREM) sleep (Experiment 1). The frequency of sleep-disordered breathing episodes remained high at 0 and 5 L/min (87.0 +/- 33.7 and 79.4 +/- 24.4 episodes per hour NREM) and decreased significantly to 41.3 +/- 31.5 and 43.4 +/- 31.4 episodes/h NREM sleep at rates of 10 and 15 L/min, respectively (p = 0.003). At high levels of TTI (10 and 15 L/min), obstructive apneas and hypopneas decreased but periodic laryngeal obstructions were induced during stage 1 NREM sleep. To prevent laryngeal obstructions, a servo-control system was used to briefly interrupt TTI during these events. When this system was implemented for more prolonged periods of sleep (Experiment 2, total sleep time 176.6 +/- 12.5 min), high-flow TTI (hf-TTI, 15 L/min) led to an overall reduction in the combined frequency of obstructive apneas and laryngeal obstructions from 63.8 +/- 21.8 to 10.7 +/- 9.1 (p < 0.03) and was associated with a marked reduction in arousal frequency from 60.0 +/- 26.0 to 8. 3 +/- 5.4/h in NREM sleep, and from 67.5 +/- 3.5 to 0 +/- 0/h in rapid eye movement (REM) sleep. Our findings demonstrate that hf-TTI stabilized breathing patterns in apneic patients, and was safe and efficacious for prolonged periods of sleep.

Polyethylenimine shows properties of interest for cystic fibrosis gene therapy

Before being considered for a cystic fibrosis (CF) gene therapy trial, any gene delivery agent must be able to show that it produces low levels of toxicity as well as being able to protect the DNA from nuclease degradation. Here we show that complexes of linear polyethylenimine (L-PEI) and DNA can repeatedly be administered to animals (up to 21 consecutive days) without eliciting an immune response against PEI/DNA particles or inducing toxic side effects due to accumulation of PEI in the lungs. However, the host response to the exogenous protein resulted in some decrease of expression. PEI-mediated transfection was unaffected by treatment of the complexes with DNase (frequently used to reduce the viscosity of lung secretions in CF patients). Taken together, these properties make L-PEI a valuable vector for gene therapy of CF.

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.

Otolaryngologist's role in transtracheal oxygen therapy: the minitrach procedure

The modified Seldinger technique for transtracheal oxygen catheter insertion is relatively straightforward, but tract problems during subsequent oxygen therapy are not uncommon. With the modified Seldinger technique method, transtracheal oxygen is not initiated until 1 week after the procedure. Six to 8 weeks are required for tract epithelialization, which allows routine catheter removal and cleaning by the patient. Without removal, mucus tends to collect and form balls on the catheter tip, creating a management problem. Previous studies suggest a significant incidence of tracheal chondritis, keloid formation, and inadvertent catheter dislodgment. In 7% to 10% of patients, the epithelial tract cannot be recovered by medical personnel, and complete closure occurs. We have developed a surgical technique for the creation of a controlled tracheocutaneous tract. Highlights of the minitrach include skin flap elevation, cervical lipectomy, resection of a small window of tracheal cartilage, and approximation of the skin flaps to the window. We evaluated 33 patients who underwent the minitrach procedure as an access method for receiving transtracheal oxygen. When compared with results from 64 patients followed up for a similar period with the modified Seldinger technique, results with minitrach showed that transtracheal oxygen could be instituted sooner (<24 hours), and symptomatic mucus balls were reduced because the tract matured more quickly (approximately 14 days). With the minitrach there were no inadvertent catheter dislodgments, as compared with 41% of modified Seldinger technique patients who had one or more episodes of catheter dislodgment. Twelve percent of minitrach patients had a single episode of chondritis, as compared with 25% of the modified Seldinger technique patients, who had one or more episodes. The minitrach was well tolerated in this group of patients with severe pulmonary and/or cardiovascular disease. In 12 of these patients, a minitrach revision of their previous modified Seldinger technique tracts resolved recurrent problems with chondritis, lost tracts, and keloids. We conclude that the minitrach promotes early institution of transtracheal oxygen, simplifies an intense postprocedure educational and management process, facilitates tract maturation, and reduces the incidence of problems related to mucus balls, lost tracts, chondritis, and keloids. The minitrach can be used as a revision procedure to resolve tract problems encountered with modified Seldinger technique. We are now using the minitrach as the preferred procedure for the institution of transtracheal oxygen. The minitrach greatly improves and simplifies the transtracheal oxygen program, and the otolaryngologist becomes an important member of the transtracheal oxygen team.

Sleep-related breathing disorders. 5. Nasal continuous positive airway pressure treatment for obstructive sleep apnoea

CPAP should be considered the first line of treatment in patients with moderate to severe obstructive sleep apnoea. In our centre in Sydney this generally means patients with more than 20 apnoea/hypopnoeas per hour with repeated dips in oxyhaemoglobin saturation and usually some symptomatology. Despite this first line role of nasal CPAP, recent objective studies question whether earlier enthusiastic reports on adherence to CPAP are correct. The role of technical innovations in new CPAP machines in improving usage remains to be tested. The "drop out" rate from physician selection for a CPAP trial to highly compliant user is certainly more than 50% of patients. What happens to these patients? Data from some studies suggest that surgical treatments are used, at least in the USA, but in all probability many of these patients remain untreated. The challenge in the next decade is either to improve CPAP devices to increase usage in this group or to develop other treatment options. The role of intensive inhospital "acclimatisation" to CPAP also has yet to be objectively tested. It is unclear whether "intelligent" CPAP will make huge inroads in increasing the number of patients who accept CPAP trials, prescriptions, or compliance. It will have minimal impact on patients with mask problems or claustrophobia or those who feel that CPAP is inconvenient. There is a high likelihood that it will reduce technologist workload during CPAP titration studies. "Intelligent" CPAP may help to reduce total overnight mouth leakage and therefore reduce nasal side effects. The current expense of developing such devices will mean that they are unlikely to supersede much cheaper standard "one pressure" CPAP machines in the next few years.