The management as well as survival of a patient with an acidotic exacerbation of chronic obstructive pulmonary disease has been revolutionized by the introduction and widespread utilization of non-invasive ventilation (NIV) according to Rennard, Rodriguez-Roisin, and Huchon (2007). Currently hospitals that do not have NIV do not admit patients with COPD. Non-invasive technique of offering respiratory support to spontaneously breathing patients is facilitated by the use of a close fitting nose mask or a face mask connected to a portable ventilator.
The mask can be easily removed to allow patients to eat, drink, take oral drugs, and communicate. Rennard, Rodriguez-Roisin & Huchon (2007) assert that non-invasive ventilation offers a two level form or respiratory support, bringing in inspiratory and expiratory positive airways pressure. Inspiratory positive airways pressure is often titrated up to 15-20cm water to help relieve of tiring respiratory muscles and minimize the work of breathing, and improve gaseous exchange in the alveoli. Expiration positive airways pressure is titrated at 4-6 cm water to help splint open the airway and flush carbon dioxide form the mask.
This pressure also minimizes the work of breathing through surmounting intrinsic positive end expiratory pressure and as a result reducing atelectasis and increasing the end tidal volume. A port in the face mask or a more proximal channel in the ventilator can be used to introduce oxygen. Although it is not a must to provide humidified oxygen, humidifiers can be included in the system. Duiverman et al (2008), argues that non-invasive ventilation is very beneficial in patients with hyperbaric respiratory failure. It can also be used as a therapeutic trial in cases where more invasive ventilatory support is not suitable.
Non-invasive ventilation have been shown to be beneficial over other support mechanisms through studies with various end points-such as mortality, need for intubation, cost effectiveness, and arterial blood gases. NIV, as Stockley (2007) points up, can be used in hospital wards, in intensive care units and in high dependency units. It can also be carried out in emergency departments although patients will not have an adequate time to react to conventional treatment. Non-invasive ventilation requires availability of experienced health care workers to start treatment, monitor progress, and solve any problem that might arise.
Maximal drug treatment, such as bronchodilators, antibiotics and corticosteroids, should be instituted for patients starting NIV. Facemasks should be chosen according to the size of the face of the patient. Although nasal masks are more comfortable, they require patients to breath through the nose. Patients with severe OCPD usually breathe through their mouth and therefore full face masks are preferable. Flow rate of oxygen is then set appropriately. It is initially set at 1-2 L/min and then titrated upwards to retain a saturation of at least 90%.
The respiratory and expiratory positive airways pressure are then set appropriately. Patients are kept adequately hydrated and also adequate calorific intake is maintained (Siafakas, Anthonisen and Georgopoulos, 2004). The progress of the non-invasive ventilation process is closely monitored. Various aspects that are continuously monitored include: pulse rate, respiratory rate, and oxygen saturation. Arterial blood gases are checked hourly. Reduction of carbon dioxide concentration in the blood and reduction in respiratory rate are good indicators of improvement.
If the condition of the patient does not improve after a period of time, the mask is checked for any leakage. The ventilator is also checked for synchrony with the patient’s respiratory efforts and the ventilators settings adjusted accordingly. Blood gases are rechecked within 4 hours of an adjustment in setting or earlier depending on the clinical condition of the patient (Windisch et al, 2009). Invasive mechanical ventilation is considered in patients whose partial carbon dioxide concentration, pH, have worsened and failed to improve within four hours of initiation of non-invasive ventilation.
Success is less likely to be achieved in patients who have severe acidosis. Furthermore, patients who remain acidotic for more than forty eight hours after initiation of treatment with NIV tend to have a poor prognosis and higher mortality if NIV is continued than if mechanical ventilation started. Long term endurance in patients with chronic obstructive pulmonary disease who require mechanical ventilation is usually lower as compared to those who require non-invasive ventilation alone (Rennard, Rodriguez-Roisin and Huchon, 2007).
Budweiser et al (2005) states that failure of non-invasive ventilation however should not be used as a rationale to decline mechanical ventilation and does not also mean that these patients will be difficult to wean. Weaning a patient from non-invasive ventilation is not a big problem as most patients auto wean through gradually minimizing their use after a few days. According to Currie (2006), non-invasive ventilation has got various benefits when used in the management of COPD. One of them is that it has a beneficial impact on the management of acute exacerbations.
This process has also made it easy for the correction of acidosis at an early stage. Studies as noted by Ehrman (2008), have shown that NIV can bring about pH improvement relatively rapidly thereby making it possible for other conventional therapy, such as oxygen therapy, bronchodilators and other medications to function and thus reverse the advancement of respiratory failure and minimize mortality. NIV also brings about improvement in minute ventilation, reduction in respiratory rate, and also improvement in transdiaphragmatic activity.
It also improves gaseous exchange and allows respiratory rest during respiratory breakdown. Patients comfort is also improved. As asserted by Currie (2006), the primary advantage of the use of non-invasive ventilation is avoidance of tracheal intubation as well as the ability to offer ventilatory assistance to patients who have respiratory breakdown as a result of severe COPD, who would be considered unsuitable for intubation. There is some problems associated ventilatory support of patients. One of them is that, though most patients tolerate treatment, some of them experience difficulties breathing with the machine.
The face mask may also lead to development of some problems such as claustrophobia, facial sore and persistent air leaks. All patients should be assessed on individual basis due to presence of a few contraindications of NIV (Ehrman, 2008). Conclusion Chronic obstructive pulmonary disease is a very severe disease that affects the respiratory system as a result of excessive smoking, exposure to second hand smoke or genetic disorder. Damage to the lungs as a result of COPD leads to poor oxygenation of blood and increases the concentration of carbon dioxide thereby causing acidosis.
The symptoms of the disease which start with a mild cough become severe with time. Ventilatory support is one of the techniques used for the treatment of COPD. The main work of the ventilatory support is to aid the work of breathing. Patients who are undergoing treatment for COPD using ventilatory support machine require close monitoring so as to evaluate their progress. The main advantage of the use ventilatory support is avoidance of tracheal intubation as well as the ability to offer ventilatory assistance to patients who have respiratory breakdown as a result of severe COPD, who would be considered unsuitable for intubation.
Reference:
Ambrosino N, Goldstein R. , (2008), Ventilatory support for chronic respiratory failure, ISBN 0849384982 Informa Health Care, Budweiser S. , et al. , (2005), Long-term reduction of hyperinflation in stable COPD by Non-invasive nocturnal home ventilation, Respiration Medicine, Vol 99:976 Currie G. , (2006), ABC of COPD, ISBN 1405147113: Wiley-Blackwell Duiverman M. , et al. , (2008), Nocturnal non-invasive ventilation in addition to rehabilitation in hypercapnic patients with COPD, Thorax, Vol 63:1052. Ehrman J. , et al. , (edn 2), (2008), Clinical Exercise Physiology, ISBN 0736065652: Human Kinetics