Expiratory positive airway pressure

Casanova et al., in a one-year study (145), randomized 52 COPD patients to standard care or standard care plus NIV with outcomes that included rate of acute exacerbations, hospital admissions, need for intubation and mortality at three, six, and 12 months. Bi-level positive pressure in spontaneous mode was implemented at an expiratory positive airway pressure of 4 cmH20 and an inspiratory positive airway pressure level of 12 cmH20, adjusted to decrease dyspnea and accessory muscle use. Five of the NIV group (total n = 26) did not tolerate it and the remainder used it for 6.2 hours per 24 hours, with only a few using it for less than 3 hr/day. One-year survival was similar between groups, as was the number of exacerbations. The breathlessness scores decreased in the NIV group, but only one psychomotor test improved. There was no evidence that the results were better in more hypercapnic patients (Paco2 > 7.3 kPa) or in those who used NIV for >5 hours per 24 hours. 

Sanders MH, Kem N. Obstructive sleep apnea treated by independently adjusted inspiratory and expiratory positive airway pressures via nasal mask. Physiologic and clinical implications. Chest 1990 98 317-324. 

Elliott MW, Simonds AK. Nocturnal assisted ventilation using bilevel positive airway pressure the effect of expiratory positive airway pressure. Eur Respir J 1995 8 436-440. 

Abbreviations-. IPAP/EPAP, ratio of inspirat(xy positive airway pressure and expiratory positive airway pressure NP ABG, arterial blood gas 6-MWD, six-minute walking distance 6-MWT, six-minute walk test HRQL, health-related quaUty of Ufe RVEL, right ventricular ejection fraction LVEF, left ventricular ejection fraction NIPPV, noninvasive positive pressure ventilation O2, oxygen Til, tension time index. 

Removal from exposure and airway support with adequate ventilation are the priorities. Pulmonary oedema should be treated with continuous positive airway pressure (CPAP) or, in severe cases, with mechanical ventilation and positive end expiratory pressure (PEEP). 

A. Supplemental oxygen. Provide supplemental oxygen to maintain a PO2 of at least 70-80 mm Hg. If a PO2 greater than 50 mm Hg cannot be maintained with an FIO2 of at least 60%, consider positive end-expiratory pressure or continuous positive airway pressure. 

Positive Airway Pressure in Spontaneous Mode Pressure Support in Spontaneous Mode Breath Delivery Control Mandatory Volume-Controlled Inspiratory Flow Delivery Pressure-Controlled Inspiratory Flow Delivery Expiratory Pressure Control in Mandatory Mode Spontaneous Breath Delivery Control... 

Selected simple, cost-effective measures, the implementation of which should decrease the incidence of NP in susceptible persons, are summarized in Table 1 (1,2,74,75). It is recommended that pneumococcal and influenza vaccinations be offered to all persons 65 years of age or older or those with chronic underlying disease. Optimizing health care maintenance strategies may decrease the need for hospital admission. Smoking cessation should be encouraged in all patients and particularly in those in whom elective surgery is planned. Patients with chronic obstructive pulmonary disease may benefit from incentive spirometry, positive end-expiratory pressure, or continuous positive airway pressure by face mask (1,2,74,75). 

Use incentive spirometry, positive end-expiratory pressure, continuous positive airway pressure by mask. 

As can be seen in Figure 18.2b, the airway pressure at the end of exhalation may not end at atmospheric pressure (zero gauge). The positive end expiratory pressure or PEEP is sometimes used to prevent the alveoli from collapsing during expiration (Pierce, 2007). In other cases, the expiration pressure is... 

Positive end expiratory pressure (PEEP) A therapist-selected patient s airway pressure level that the ventilator maintains at the end of expiration in either mandatory or spontaneous breathing. 

The variable controlled during the expiratory phase is known as the baseline variable, most commonly, pressure, typically expressed as EPAP or PEEP. It is necessary to have a positive baseline pressure in bi-level devices to assure CO2 washout. Bi-level devices have also been shown to be effective in managing upper airway collapse, in patients with obstructive sleep apnea and overlap (14). Einally, a positive baseline pressure has been shown to decrease the work of breathing associated with intrinsic PEEP and improve... 

Bi-level NIV may be used as a first-line treatment, with supplemental oxygen (27). Expiratory airway pressure is titrated to control h5q)opneas and apneas, and inspiratory airway pressure is added to control Paco2. If bi-level NIV fails, nasal volume ventilation may be used (29). In many patients with OHS and predominant OSA, once hypercapnia has improved (which may take several weeks) nCPAP may be used (29). Thirteen obese patients (n = 13) with a BMI > 35, aged 28-69 years with severe OSAS and hypercapnia (8.2 0.3 kPa) and failing to respond to initial CPAP therapy, were treated via a nasal nocturnal volume-cycled ventilator, which was tolerated by all patients. Significant improvements in daytime arterial blood gas levels were obtained after 7 to 18 days of nasal intermittent positive pressure ventilation (29) in 10 of the 13 patients three months later, 12 of the 13 patients could be converted to nCPAP therapy and one patient remained on NIV. In another study (37), the same results were observed after three months of home nocturnal bi-level NIV in seven patients, three of whom had severe obesity. 

Several devices are also available to promote airway clearance. Flutter valve devices employ oscillating positive expiratory pressure (OPEP) to cause vibratory air flow obstruction and an internal percussive effect to mobilize secretions. Intrapulmonary percussive ventilation (IPV) provides continuous oscillating pressures during inhalation and exhalation. Finally the most commonly used technique is high-frequency chest compression (HFCC) with an inflatable vest that provides external oscillation. Vest therapy is often preferred by patients because they can independently perform the therapy even from an early age.5,14... 

An intrathoracic obstruction is more likely to allow gas flow during inspiration as the negative intrathoracic pressure generated helps to pull the airways open. As such, the inspiratory limb of the curve may be near normal. In contrast, the positive pressure generated during forced expiration serves only to exacerbate the obstruction, and as such the expiratory limb appears similar to that seen in obstructive disease. Both TLC and RV are generally unaffected. 

Steam inhalation and cough suppressants may relieve upper airway symptoms, sore throat, nonproductive cough, and hoarseness. Appropriate antibiotic therapy should only be instituted following confirmation of infection by positive sputum tests (Gram stain and culture). Intubation should be accomplished prior to the development of laryngeal spasm or edema so that adequate ventilation is established and suction of necrotic and inflammatory debris can be facilitated. Oxygen may be required as well. Early use of positive expiratory pressure (PEEP) or... 

For aerosol inhalation, the complete lack of useful clinical experience leaves one to speculate based on animal studies or human poisoning from comparable chemical agents. The first priorities should be immediate evacuation and decontamination to reduce the risks of further exposure or secondary aerosols for the patient and health care provider, combined with providing adequate ventilation and any necessary airway support. Pulmonary edema likely wiU evolve during the 12-36 h following exposure, and this may be amenable to treatment with antiinflammatory drugs, bronchodilators, oxygen, endotracheal intubation, and, in extreme cases, continuous or mechanical supplemental positive end-expiratory pressure (Franz and Jaax, 1997 Audi et al., 2005). 

Although the ventilator can supply positive end-expiratory pressure (PEEP), it can also develop within the alveoli because of either inadequate expiratory time or collapsed airways during expiration (or both). Often called intrinsic PEEP or air trapping, it depends on three factors minute ventilation, the expiratory time fraction, and the respiratory systems expiratory time constant (the product of resistance and compliance) (9). As minute ventilation increases, the expiratory time fiaction decreases, and the time constant lengthens, the potential for intrinsic PEEP to develop increases (9). 

The most common causes of failure to wean include chronic obstructive pulmonary disease (COPD) exacerbations, neuromuscular diseases, h) oxic respiratory failure, post surgical complications (2), and heart failure. Weaning from the tracheostomy must consider the balance of respiratory muscle function and work of breathing. The work of breathing is determined by ventilatory demand, compliance of the lungs and chest wall, airway resistance, and intrinsic positive end-expiratory pressure (PEEPi). Adequacy of ventilatory drive and neuromechanical output can be assessed from the respiratory rate, airway occlusion pressure at 100 milliseconds (Po.i), maximum inspiratory pressure (MIP), and maximum voluntary ventilation (MW). 

Respiratory muscle assistance involves the manual or mechanical application of forces to the body or pressure changes to the airway to assist inspiratory or expiratory muscle function. Negative pressure applied to the airway during expiration assists the expiratory muscles for coughing, just as positive pressure applied to the airway during inhalation (noninvasive IPPV) assists inspiratory function. 

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