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Cough Assist Strategy for Pulmonary Toileting in Ventilator-Dependent Spinal Cord Injured Patients
The limited innervation of muscles supporting pulmonary functioning in spinal cord injured (SCI) patients indicates that these individuals are at a particularly high risk for atelectasis and other sequelae of ventilator dependency. As an alternative strategy to endotracheal suctioning for secretion management, our acute rehabilitation facility utilizes an assistive cough device. This device has not been commonly utilized in the SCI population, and studies concerning this device have primarily focused on individuals with neuromuscular diseases. In our experience, utilization of mechanical in-exsufflation has produced positive outcomes in terms of patient satisfaction, low rates of ventilator-acquired pneumonia, low incidence of complications, and ease of home discharge with patient or family using the device long term. This article describes the device, as well as the protocols associated with its use in one ventilator spinal cord center.
Pulmonary toileting for ventilator patients is always a challenge. For the special population of ventilator-dependent spinal cord injured (SCI) patients, the challenge of secretion management is magnified because of the limited ability of many of these patients to actively participate in a pulmonary hygiene program. The limited innervation of muscles supporting deep breathing and coughing place these patients at a higher risk for atelectasis and other sequelae of ventilator dependency.
Endotracheal suctioning is the most commonly employed technique for secretion management. This intervention has many associated risks and complications, ranging from tissue trauma and infection to cardiac dysrhythmias and cardiac arrest (American Association for Respiratory Care Clinical Practice Guideline, 1993). The alternative strategy utilized at our acute rehabilitation facility for ventilator- dependent SCI patients includes the use of mechanical in-exsufflation, also called an assistive cough device. This strategy has not been widely used in the SCI population, and studies involving the device have primarily focused on patients with neuromuscular diseases.
Studies have been conducted that demonstrate a patient preference for mechanical in-exsufflation over suctioning. One study, surveying 12 traumatic SCI patients with neurological levels of injury ranging from C-1 to C-8, found an 89% preference rate (Garstang, Kirshblum, & Wood, 2000). Another study, involving 29 patients with neurological diagnosis established an 84% preference rate (Massery, Sammon, Menon, & Cahlain, 2003). In our experience, utilization of mechanical in-exsufflation has produced positive outcomes in terms of patient satisfaction, a median rate of 0.0 in 2004 for ventilator-acquired pneumonia (per thousand ventilator days), low incidence of complications, and ease of home discharge with patient or family using the device long term. This article describes the device, as well as the protocols associated with its use in the ventilator spinal cord center at Kessler Institute for Rehabilitation.
Cough assist machines have been available on the medical market since the 1950s. Three different devices have been produced by two different companies. The first device was developed by Barach, Beck, and Smith and manufactured by the O.E.M. Company in the early 1950s. It had a production run of approximately 2 years and was called the Cof-flator. This device was designed for polio patients who were placed in the iron lung because of breathing difficulties. These patients, similar to present-day SCI patients, required assistance mobilizing and clearing secretions. This machine applied a negative pressure to the bronchial tubes to extract mucus, creating a suction effect similar to a vacuum. The O.E.M. Company went out of the medical supply business in the early 1960s and thus stopped producing the Cof- flator. Early in the 1990s, the Cof-flator reemerged for a second life. The J. H. Emerson Company, responsible for the rocking bed, mechanical ventilator, and the iron lung, began production of the device, naming it the Mechanical Insufflation-Exsufflation (MI-E) device (a.k.a. Cof-flator). It continues to be manufactured by J. H. Emerson Company and has gone through a series of evolutions.
The mechanical in-exsufflator, then and now, functions according to the same basic principle of clearing retained bronchopulmonary secretions, which in turn reduces the risk of infection and respiratory complications. The device utilized today first applies a positive pressure to the patient’s airway, via a breathing hose and interface, then rapidly shifts to a negative pressure. This rapid shift in pressure produces a high expiratory flow to the lungs, simulating a cough. The positive pressure inflates the lungs, preventing hypoventilation, and the negative pressure that follows compresses the air sacs, creating a gradient pressure that rids the lungs of mucus.
The in-exsufflator is a portable machine, approximately the size of a homecare ventilator, that requires electricity or an external battery to operate. Initial use requires assembly of a circuit (See Figure 1). A circuit consists of two lengths of corrugated tubing, a secretion collection chamber, a bacterial or viral filter, a patient interface (tracheostomy adapter, facemask, or mouthpiece), and a nipple adapter to tie in the airway monitor gauge. Circuits are changed every 24 hr—sooner if required because of secretion accumulation. Pressure settings must be checked prior to all treatments. After the machine is turned on, the operator may then detach the ventilator connection or oxygen source and attach the appropriate interface to the patient. Newer in-exsufflator models can be set to operate automatically or can be shifted to manual control. The manual control lever is pushed to the right to insuffalate the lungs for 2–3 s, and then shifted to the left to exsuffalate the lungs for 3–4 s, inducing a cough. At the end of the treatment episode, the machine is disconnected and turned off to avoid extended connection of the patient to the device. Because of the absence of an in-line oxygen source during treatment, patient status and sufficient oxygenation must be taken into consideration both pre- and posttreatment.
Mucus in the lining of the airways is present in all individuals and performs the function of trapping dust particles and bacteria. For people with ineffective cough mechanisms, this mucus can increase in amount and viscosity, leading to airway and lung infections. The in-exsufflator, as a noninvasive technique, can be of vital importance in improving lung volume and mobilizing secretions.
Indications for use of the in-exsufflator include fatigue and ineffective cough, as seen in individuals with poliomyelitis, muscular dystrophy, myasthenia gravis, cystic fibrosis, amyotrophic lateral sclerosis, spinal muscular atrophy, emphysema, bronchial asthma, bronchiectasis, and a variety of neurological disorders. Some of these disorders involve paralysis of the respiratory muscles, as seen in SCI, causing ineffective cough or the inability to clear secretions effectively because of reduced peak cough expiratory flows.
Mechanical hyperinflation has been shown to increase lung compliance—mechanical insufflation followed by suctioning or mechanical exsufflation—which induces positive changes in respiratory mechanics (Choi & Jones, 2005). Provision of mechanical in-exsufflation has also been shown to improve outcomes for neuromuscular disease patients with respiratory tract infections (Goncalves & Bach, 2005) and to be more effective in airway mucus management than conventional suctioning (Sancho, Servera, Vergara, & Marin, 2003; Vianello et al., 2005).
Our protocol was used to establish guidelines for the provision of mechanical inspiratory and expiratory pressure for our patient population with pulmonary compromise, to enable clearing airway secretions. The protocol that follows is implemented after the physician has reviewed the patient’s chest X ray and provided a written order allowing medical clearance for mechanical insufflation.
A high level of SCI patients are treated within our program. Their length of stay can range from 1 month to 1 year. Following the physician’s order, the in-exsufflator will be utilized while secretion management remains an issue. Prophylactic use may also be considered when secretions are not an issue. Benefits of the therapy include prevention of atelactasis, increased functional residual capacity, and intercostal musculature integrity by virtue of ongoing periodic lung expansion. A minor complication, experienced by a small number of patients upon initiation of the therapy, has been thoracic soreness or chest wall pain, similar to a pulled muscle. In these instances, the pressure is lowered and, then gradually increased, as tolerated, over a period of days.
Data indicate a very low rate of nosocomial- acquired ventilator pneumonia, less than 1%, as well as a low incidence of atelactasis and other sequelae of ventilator dependency. The success rate in weaning patients from mechanical ventilation, excluding cervical injuries above C-4, has been approximately 97%. We also reported a comparable success rate in decannulating the tracheostomy tube from these patients.
Medical effectiveness and patient comfort are the goal at Kessler Institute for Rehabilitation. Feedback from our patients who have experienced both endotrachial suctioning and mechanical in-exsufflation indicates that they prefer the latter technique, having found it less uncomfortable and more effective. Families and caregivers have had the same positive response and request the equipment upon discharge if pulmonary toileting must be continued for any length of time in the continuum of care. Implementation of this mechanical technique has been very positive. It is hoped that our results will raise the awareness of those treating the SCI population and further studies are encouraged to measure its effectiveness.
About the Authors
Karen Liszner, BSN MHA CRRN, is director of nursing and ancillary services and Michael Feinberg, BS RRT, is respiratory manager, both at Kessler Institute for Rehabilitation in West Orange, NJ. Address correspondence to Karen Liszner, 1199 Pleasant Valley Way, West Orange, NJ 07052, or e-mail firstname.lastname@example.org.
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Garstang, S., Kirshblum, S., & Wood, K. (2000) Patient preference for secretion management with spinal cord injury. Spinal Cord Medicine, 23(2), 80–85.
Goncalves, M., & Bach, J. (2005). Mechanical insufflation-exsufflation improves outcomes for neuromuscular disease patients with respiratory tract infections: A step in the right direction. American Journal of Physical Medicine & Rehabilitation, 84(2), 89–91.
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Sancho, J., Servera, E., Marin, J., Vergara, P., Belda, F., & Bach, J. (2004). Effect of lung mechanics on mechanically assisted flows and volumes. American Journal of Physical Medicine & Rehabilitation, 83(9), 698–703.
Sancho, J., Servera, E., Vergara, P., & Marin, J. (2003). Mechanical insufflation-exsufflation vs. tracheal suctioning via tracheostomy tubes for patients with amyotrophic lateral sclerosis: A pilot study. American Journal of Physical Medicine & Rehabilitation, 82(10), 750–753.
Vianello, A., Corrado, A., Arcaro, G., Gallan, F., Ori, C., Minuzzo, M., et al. (2005). Mechanical insufflation-exsufflation improves outcomes for neuromuscular disease patients with respiratory tract infections. American Journal of Physical Medicine & Rehabilitation, 84(2), 83–88.