Obstructive sleep apnea hypopnea syndrome (OSAHS) is a modern common disease with increasing incidence of recurrent upper airway obstruction during sleep and causing apnea. The disease is characterized by recurrent episodes of collapsed upper airway obstruction during sleep, usually accompanied by decreased oxygen saturation (Sa02), and is mainly characterized by snoring, breath-holding, sleep structure disorders, repeated SaO2 decreases, and daytime sleepiness during sleep.
Patients with OSAHS often have repeated complete apnea during sleep, accompanied by different degrees of intermittent hypoxia, which can cause a variety of cardiovascular, cerebrovascular and metabolic disorder complications, seriously affecting patients’ quality of life and threatening their life safety, and can cause traffic accidents and other social safety problems. In recent years, with the development of modern science and the improvement of people’s demand for quality of life, people pay more and more attention to the diagnosis and treatment of OSAHS. This paper reviews the clinical application of continuous positive airway pressure ventilation (CPAP) in patients with obstructive sleep apnea hypoventilation syndrome.
I. The status of continuous positive airway pressure ventilation in the treatment of patients with obstructive sleep apnea hypoventilation syndrome
CPAP is the preferred treatment for OSAHS, especially for patients with chronic diseases such as hypertension, heart disease, diabetes mellitus, and those who are unwilling to undergo surgery, those who have poor results after uvulopalatopharyngoplasty, and those who are treated with central hypopnea. CPAP is particularly suitable for patients with chronic diseases such as combined hypertension, heart disease, diabetes mellitus, those who do not want to undergo surgery, those who have poor results after uvulopalatopharyngoplasty, and patients with sleep apnea hypoventilation syndrome with mainly central apnea.
The guidelines for the management of obstructive sleep apnea hypoventilation syndrome (2011 revision) emphasize that the treatment of OSAHS should follow the OSAS treatment strategy of non-invasive ventilation as the primary and preferred treatment and surgical treatment as a supplement and strict indications for surgery. It is a strong correction to the current situation of excessive and indiscriminate surgery for OSAS in China.
The principle of continuous positive airway pressure ventilation for obstructive sleep apnea hypoventilation syndrome
1, CPAP system mainly consists of an air pump and microprocessor. The microprocessor control system makes all parts of the ventilator work in a coordinated manner; the air pump generates airflow and outputs filtered airflow to the patient. The positive pressure is generated by the change in airflow delivered and the resistance within the system. This positive pressure counteracts the negative upper airway closure pressure and opens the upper airway collapse zone, i.e. the positive pressure provides a mechanical scaffold for the upper airway, which is the main principle of continuous positive airway pressure ventilation for the treatment of obstructive sleep apnea hypoventilation syndrome.
Restoring or enhancing pharyngeal dilator muscle function has now become a new strategy in the treatment of OSAHS. Studies have confirmed that CPAP also has the therapeutic effect of protecting and restoring the pharyngeal dilator muscle, and the damage to the pharyngeal dilator muscle in OSAHS can be reversed by CPAP treatment.
2. Contraindications.
(1) Chest x-ray or CT examination reveals pulmonary maculopathy;
(2) Pneumothorax or mediastinal emphysema;
(3) Significant decrease in blood pressure (blood pressure below 90/60 mm Hg, 1 mm Hg = 0.133 kPa), or in case of shock;
(4) Unstable hemodynamic parameters in patients with acute myocardial infarction;
(5) Cerebrospinal fluid leak, cranial trauma or intracranial pneumothorax;
(6) Acute otitis media, rhinitis, sinusitis when the infection is not controlled;
(7) glaucoma. Pulmonary herpes is common in the population, and it is debatable whether it is a contraindication.
Third, the basic operating principles and procedures
CPAP should be performed by a physician or respiratory therapist with knowledge of sleep medicine and training in the use of noninvasive ventilators; the following procedures need to be followed in the treatment of OSA with CPAP.
(1) Patients with OSAHS must be diagnosed by reliable diagnostic methods.
(2) Select good environmental and monitoring conditions for the CPAP treatment site.
(3) Educate the patient and family before use so that they understand the purpose of the treatment and precautions to be taken so that they can work closely with the operator.
(4) Allow the patient to choose a comfortable position.
(5) Select a nasal mask (or nasal mask), headband and suitable connectors (determine whether special connectors such as air leakage valves are needed) that match the patient’s facial shape, and select different sizes and shapes of connecting devices according to the characteristics of the patient’s facial structure and breathing habits, and determine the most suitable connection method through trial. Currently commonly used are nasal masks, oral and nasal masks, full face masks, nasal pillows and oral and nasal pillows, etc. Pay attention to their sealability.
The nasal mask needs to be worn according to the patient’s facial shape and the size of the nose. Generally, the nasal mask includes three sizes: large, medium and small, which can be measured by professional calipers before wearing, or the patient can be instructed to wear it depending on its suitability and comfort, and adjust the tightness of the fixed headband and the height of the frontal pad in different positions to observe the size of air leakage. The choice of nasal mask should follow the principle of good sealing performance, soft texture and easy to wear. The nasal pillow is suitable for patients with psychological fear or claustrophobia of wearing a nasal mask.
(6) Select the appropriate type of ventilator (CPAP, AutoCPAP, BiPAP, ASV).
(7) Connect the ventilator to the patient, position and adjust the tightness of the headband, connect the ventilator tubing, and instruct the patient to breathe with regular relaxation.
(8) Use all-night or split-night pressure titration to determine the appropriate therapeutic pressure; turn on the ventilator, set the ventilator initialization parameters according to the pressure titration, and then gradually increase the pressure of assisted ventilation so that the patient gradually adapts to CPAP treatment.
(9) There must be monitoring means to evaluate the efficacy during the use of CPAP, generally through polysomnographic respiratory monitors to determine whether CPAP therapy is effective.
(10) Follow-up visits are required during the first few weeks of CPAP treatment to determine whether the patient can use the ventilator correctly, whether the pressure set is appropriate, and whether the ventilator mode is correct.
(11) Long-term follow-up is required after CPAP treatment, with regular annual checks of the function of the mask, heated humidifier, ventilator, and any other problems during use.
(12) Regularly evaluate the efficacy of patients with OSAHS treated with CPAP, observe whether their daytime drowsiness improves, whether they snore at night, etc., and reasonably adjust the ventilator pressure according to their condition.
(13) Pay attention to the observation of treatment complications and adverse reactions.
(14) Patients are recommended to be observed in hospital treatment for 2 to 3 d, with follow-up monitoring by specialized technicians.
IV. Side effects of CPAP therapy and treatment
Possible side effects of CPAP treatment without timely management can affect patient compliance with CPAP treatment and affect the efficacy, so early detection and management is very important and is the key to determine the success of CPAP treatment (Table 2). Side effects are divided into several categories, related to nasal symptoms, face mask, and pressure, respectively.
The most common nasal symptoms include nasal congestion and runny nose, which are common and associated with the release of inflammatory mediators, due to a decrease in humidification of the inhaled air. Enhanced humidification can improve the symptoms, preferably with a heated humidification device. The use of an oronasal mask can increase the relative humidity of the inhaled air, but this type of mask is poorly tolerated. Humidification may reduce the likelihood of rhinorrhea. Topical inhaled glucocorticoids may be used to treat nasal symptoms associated with positive pressure ventilation.
Many nasal masks and nasal plugs have been used extensively over the years to improve patient comfort. Another side effect of positive pressure ventilation therapy is often related to inappropriate masks, including skin breakdown and air leakage. If air leaks are directed at the eyes, they can cause conjunctivitis. Air leaks can also interfere with sleep. Mask-related problems can be solved by choosing the right mask. Pressure-related problems include chest and ear discomfort, and increased intraocular pressure has been reported; pneumatic trauma (tympanic membrane and eustachian tube), although uncommon, has been associated with positive pressure ventilation therapy. Clinicians should be aware of the potential risks of positive pressure ventilation in certain patients, such as those with pulmonary herpes.
V. Follow-up
The key to successful CPAP therapy is patient compliance, physician experience and technician proficiency, as well as intensive health education and effective follow-up. Usually, the first week of CPAP treatment, the first month of CPAP treatment, and the first month of CPAP treatment are followed up closely.
In the first month of CPAP treatment, close follow-up visits should be made to find out what discomfort the patient is experiencing during wear, how well the treatment is working, how well it is being followed and tolerated, and whether any necessary treatment is needed. Patients should be advised to undergo PSG monitoring at the 6th month and after 1 year of CPAP treatment to see if the CPAP parameter settings need to be adjusted. CPAP can usually be applied for a long time or even worn for life in the absence of serious adverse conditions.