Introduction
The mortality and morbidity rates for patients who suffer from VAP are approximately 27 percent. VAP also leads to a high increase in healthcare costs for individuals receiving treatment for the disease as they have to stay in the hospital for a duration of five to seven days. The cost of receiving VAP treatment is calculated to be $40,000 per hospital admission per patient. This amounts to $1.2 billion per year. Despite the various efforts to contain the disease, the disease continues to experience high mortality rates with estimated patient deaths amounting to 30 percent.
Background: Pathophysiology of VAP
Mayall (2001) defines ventilator-associated pneumonia as patients who have pneumonia and have been placed on mechanical ventilation equipment for more than 48 hours. VAP is a type of pneumonia that is caused by a bacterium that occurs in patients receiving mechanical ventilation support. If the infection occurs within the first 48 to 72 hours, it is referred to as an early-onset infection which is caused by three types of bacteria that are Staphylococcus aureus, Haemophilus influenzae and Streptococcus pneumoniae. The VAP infection that occurs after 72 hours is referred to as late onset and it’s caused by Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter (Craven 2000).
Bacterial colonization occurs when colonies of bacteria form in the endotracheal tube that is used to support the mechanical ventilator. If not dealt with, the bacterial colonies will spread to the lungs and other different parts of the body such as the sinus cavities, the teeth, oropharynx and the gastro intestinal tract. It can also be caused by sources from outside the body such as patient-to-patient contact and the ventilation circuits in the ventilation machine (Kunis et al. 2003).
The endotracheal tube connected to the ventilator circuit provides a direct route for the bacteria to move to the host’s upper and lower airways. Any oral secretions by the host create a biofilm above the cuff of the endotracheal tube which creates a perfect environment for bacterial colonization. The biofilm that forms around the tube is usually dislodged by instilling saline into the tube, by tracheal suctioning, changing the position of the tube or coughing reflexes (Morehead and Pinto 2002).
The aspiration of gastric contents is also seen to be another cause of VAP. This is because the stomach acts a storage unit for bacteria in the body because of the digestion of food. Patients that are undergoing mechanical ventilation usually have a nasogastric tube inserted inside their gastric systems for feeding purposes as well as for passing medication to the patient. The presence of the gastric tube however affects the processes that take place in the gastroesophageal sphincter resulting in increased reflux in the gastrointestinal chamber. The increased reflux creates an environment for bacterial colonization in the upper airway (Ferrer and Artigas 2001).
Diagnosing VAP
Every patient who is intubated and undergoing mechanical ventilation is at risk of contracting VAP. Diagnosing this disease in its early stages is therefore very critical. Diagnosing VAP is a difficult task as it is difficult to tell whether the patient has symptoms of the disease. The most reliable diagnosis is by conducting microbiological tests on the patient’s sputum to determine the presence of bacterial colonies. VAP symptoms can also be identified through the use of clinical findings of the disease. Another technique that can be used is to conduct an invasive test on the patient referred to as a bronchoscopy.
A bronchoscopy procedure involves conducting a diagnosis on the patient suspected to have VAP by conducting a chest radiograph that visualizes a new or progressive infiltration of the disease (Porzecanski and Bowton 2006). The most common symptoms that are used to diagnose a patient suspected to have VAP include checking their aspiration, evidence of pulmonary embolism, haemorrhaging, evidence of an acute respiratory syndrome and pulmonary edema (Schelder 2003).
VAP Risk Factors
The most common risk factor of ventilator associated pneumonia is the endotracheal tube that supports the function of the mechanical ventilation unit. The tube provides a direct passageway into the lungs thereby transporting the bacteria to these areas. Any patient who has an endotracheal tube inserted into their body is at risk of contracting VAP but there are those patients who are at a 95 percent risk of getting the disease. The three risk factors that might increase the incidence of VAP are device related; host related and personal related risk factors. The risk factors for host related infections include immunosuppression, acute respiratory or chronic diseases, and lung diseases that are characterised by chronic obstructiveness, emphysema and asthma (Augustyn 2010).
Device related risk factors include the endotracheal tube, stress ulcer treatment, the mechanical ventilation machine, supine position of the patient, nasal intubation route, bolus enteral feeding, instillation of saline and the placement of the nasogastric tube (Hooser 2010). Personal risk related factors for VAP include patient to patient contact especially in patients that are receiving intubations and mechanical ventilation support, poor training of medical staff on VAP prevention strategies, improper use of antibiotics, and non-conformance to hand washing protocols (Rello et al 2002).
Prevention Strategies
The nursing interventions that are used to prevent the occurrence of VAP include staff education, reduction of bacterial colonization and aspiration avoidance. Staff education involves sensitizing health care providers particularly nurses on hand washing protocols. Nurses are advised to wash their hands meticulously for ten seconds before they handle the patient’s endotracheal tubes. They are also advised to wear gloves when in contact with oral and endotracheal secretions of their patients. All health care staff should undergo education that will sensitise them more on VAP and the prevention strategies that can be used to minimise the risk of contracting the disease among patients (Kollef 2004).
The strategies that can be used to reduce bacterial colonization include carrying out common suction protocols which involve using the same suction methods to reduce VAP transmittions, closed suction systems can also be used to create a barrier in the endotracheal tube that will separate the contaminated catheter from the host (Hooser 2010). Aspiration prevention procedures involve any intervention strategies that will reduce the chances of aspiration as this process is related to the pathogenesis of VAP. Such strategies include the use of regular oral suctions, post pyloric feeding tubes which provide an alternative route for food and medicine through a percutaneous gastric tube and early extubation which involves weaning the patient off the ventilation system as soon as they have shown signs of healing (Hooser 2010).
Isotonic Saline Instillation before Tracheal Suctioning (ISIBTS) in Preventing VAP
Saline lavage or instillation is another method that can be used to prevent incidences of VAP infections. It involves using a saline instillation that will dislodge the bacterial biofilm located on the tube by liquefying it. This method has however not received much support from medical researchers and practitioners who are concerned with treating ventilator associated pneumonia (Freytag et al 2003). This method of treating VAP is controversial because the process of saline instillation has been deemed to be detrimental to the patient as saline instillation liquefies and dislodges the bacterial biofilm from the endotracheal tube to the lower airways.
However most researchers have viewed the use of saline instillation as a way of preventing plugs of mucus from forming in the endotracheal tubes by liquefying the oral secretions that form around the tube (Moore 2003). However, one study that was conducted on the use of saline showed that the instillation did not thin any of the secretions in the endotrachael tube. The process however reduced the amount of oxygen in the lungs which in turn increased the patient’s blood pressure and their heart rate (Moore 2003).
Other researchers have seen the use of saline instillation/lavage as an effective airway management technique. This is because the instillation of the isotonic saline before any tracheal suctioning is conducted dilutes any oral secretions by the patient. A survey conducted in the United States showed that 74 percent of medical institutions had policies that allowed the use of isotonic saline instillation in their treatment procedures. However its use before any tracheal suctioning was performed was a major cause of controversy among medical practitioners and researchers (Sole et al 2003).
Medical evidence has shown that ISIBTS is both a beneficial and dangerous technique of treating ventilator associated pneumonia. It is viewed to be dangerous because it has a high probability of increasing the incidence of VAP in the patient since the saline instillation procedure before suctioning dislodges the colonized bacteria in the endotracheal tube to the lower airways. On the other hand ISIBTS decreases the incidence of VAP since it increases the amount of secretions by initiating cough reflexes that push the secretions up the trachea for suctioning.
Other reasons for supporting the use of saline instillation have mostly been based on theoretical work. Some authors have viewed the biofilm that forms around the endotracheal tube to be a reservoir for VAP bacteria. Therefore, rinsing the tube with saline instillation will decrease the chances of VAP occurring. ISIBTS also improves the removal of secretions that accumulate in the tube’s cuff clearing the airway and decreasing cases of VAP and atelectasis from occurring (Caruso et al 2009).
Research on the effective use of ISIBTS in Ventilator Associated Pneumonia
The first research analysed in this paper involved comparing the incidence of VAP with or without the use of saline instillation before tracheal suctioning. The research design involved the use of a randomized clinical trial. Patients that had mechanical ventilation of more than 72 hours were chosen for the clinical trial after which they were divided into two groups which were the intervention group made up of 130 patients who received ISIBTS of 8ml and the control group of 132 patients who did not receive any ISIBTS. The diagnosis for VAP was based on bronchoalveolar lavage cultures and cases of atelectasis that were recorded from chest radiographies (Caruso et al 2009).
The results showed that there was a similarity between the baseline demographics for the two groups that were being studied. The results showed that the discovered cases of VAP were similar for both groups with the microbiological proven cases of VAP being lower in the saline group with a probability of 0.008 and an incidence density of p<0.01. The Kaplan-Meier curve analysis technique was used to measure the proportion of patients who did not have any VAP which was estimated to be p=0.02. The relative risk reduction in the group that was receiving ISIBTS was 54 percent while the number of patients in need of ISIBTS was 8 percent. The study concluded that the use of ISIBTS decreases the occurrence of VAP in patients (Caruso et al 2009).
Reeve (2009) performed research to find out if the use of ISIBTS reduced incidences of VAP. The study was performed in a medical and surgical intensive care unit at a Brazilian hospital. The study incorporated a controlled trial and blinded outcome research design. The participants that were selected for the study were those who had undergone mechanical ventilation using an endotracheal tube for more than 72 hours. 130 participants were allocated to the saline intervention group while 132 participants were allotted to the control group with the saline group receiving 8ml saline instillation before tracheal suctioning was performed (Reeve 2009).
The nursing interventions used for both the control and intervention group involved the use of closed tracheal suctioning machines that had moisture and heat exchange systems. Suctioning was performed when the patients exhibited signs of visible secretions, increased respiratory pressure and incidences of ventilator patient asynchrony. The primary outcome that was being measured was the incidence of VAP which was confirmed once the colony of bacteria exceeded the 1000 colony forming units/ml. The results showed that 14 out of the 130 patients in the saline group developed VAP while 31 out of the 132 patients in the control developed VAP.
The relative risk reduction was 0.54 which indicated one out of every eight patients avoided contracting VAP when they used ISIBTS. The study concluded that ISIBTS decreased the occurrence of VAP in mechanically ventilated adults (Reeve 2009).
Halm (2008) conducted research by consulting various studies conducted by other researchers. The evidence was experimental and non experimental as well as qualitative in nature. Patients who were undergoing mechanical ventilation were selected for the study as well as dogs that were put under anaesthesia. The physiological and psychological effects that were measured were sputum recovery and oxygenation. The interventions that were in use were 2, 5 and 8ml normal saline used on physiological parameters at intervals of 5 to 20 minutes. 14 studies that were conducted on sputum recovery showed that 3 out of 5 studies had increased sputum recovery when saline instillation was conducted (Halm 2008).
Nine out of the fourteen studies that were carried on oxygenation in VAP showed that the use of saline was directly associated with a decrease in oxygen and saturation levels which got worse after a suctioning procedure was conducted. The average oxygen saturation rate from the results showed that it was one to two percent when compared to the use of saline. This was because normal saline impaired the gas exchange process in the body that in turn increased the level of desaturation.
The results of the 14 studies showed that the use of normal saline with suctioning led to an increase of VAP because the instillation procedure did not thin mucus secretions. They however noted that saline instillation worked in situations where a cough was necessitated to clear the endrotracheal tube airway after suctioning (Halm 2008).
Another study was done to determine the efficiency and safety of using normal saline instillation in ventilator associated pneumonia. There are different methods that were incorporated while conducting the study, and they included systematic reviews of 65 scientific articles, crossover trials and randomised controlled trials. The outcomes that were expected from the systematic reviews included oxygenation, sputum recovery, tube patency and the incidence of VAP.
The results of the study showed that the use of saline increased the sputum recovery with a confidence level of 0.10 to 0.90. The heterogeneity of the methodology for this study however made it difficult to perform meta-analyses on tube patency, oxygenation levels and VAP. This study revealed that there was poor literature review on the use of saline instillation before tracheal suctioning in VAP. It showed that there were few benefits or disadvantages of using the technique in VAP treatments (Paratz and Stockton 2009).
Another study showed that the use of saline instillation before performing tracheal suction left negative consequences on the part of the patient. The use of saline instillation was also seen to be a potential contributor to increased cases of VAP when the saline was used before the insertion of the endotrachael tube. Researchers who performed studies on tracheal suctioning found that the procedure dislodged up to 60,000 colonised bacteria into the lower airways while the use of 5ml normal saline saw the dislodgement of 310,000 bacterial colonies into the airways.
The researchers noted the rationale for using saline instillation before suctioning was to liquefy the mucus secretions in the tube. However mucus was not liquefied by saline which rendered the procedure ineffective. This research showed that saline instillation did not have any positive effects in reducing VAP despite the treatment being used in treating the disease (Puchalski 2007).
Camargo et al (2004) conducted research on the use of saline treatment in VAP and whether instillations led to increased mortality rates. The research was conducted on 106 patients who were in the ICU and under mechanical ventilation. The parameters that were used were clinical and radiological parameters that analyzed tracheal aspirates in quantitative and qualitative forms. The results of the study showed that there was increased specificity of 48% and 78% in tracheal aspirates that were analyzed quantitatively when compared to the qualitatively analyzed tracheal cultures that reflected an increased specificity of 23 percent.
Conclusion
The analysis of the research conducted by the various authors of the articles highlighted the varied reactions to the use of saline instillation in treating VAP before conducting any tracheal suctioning. While some researchers have argued that saline instillation is useful in dislodging secretions and biofilms from the endotracheal tube, others have viewed the liquidification of these secretions to be harmful to the patient as they are pushed into the lower airways, increasing the incidences of ventilator associated pneumonia. Most of the researchers in general have viewed the use of saline instillation before tracheal suctioning will lead to incidences of ventilator associated pneumonia.
References
Augustyn, B., (2007) Ventilator associated pneumonia risk factors and prevention. Critical Care Nurse, Vol.27, pp32-39.
Camargo, L.F., De Marco, F.V., Silvia, C., Barbas, V., Hoelz, C., Bueno, M.A., Rodrigues, M., Amado, V.M., Caserta, R., Martino, M.D.V., Pasternak, J., and Knobel, E. (2004) Ventilator associated pneumonia: comparison between quantitative and qualitative cultures of tracheal aspirates. Critical Care Journal, Vol.8, pp 422-430.
Caruso, P., Denari, S., Ruiz, S.A.L., Demarzo, S.E. and Deheinzelin, D. (2009) Saline instillation before tracheal suctioning decreases incidence of ventilator associated pneumonia. Critical Care Medical Journal, Vol, 37, No.1.
Craven, D.E., (2000) Epidemiology of ventilator associated pneumonia. Chest. Vol. 117, pp186-187.
Ferrer, R., and Artigas, A., (2001) Clinical review: non-antibiotic strategies for preventing ventilator associated pneumonia. Critical Care, Vol.6, No.1, pp.45-51.
Freytag, C.C., Konig, W., and Welte, T., (2003) Prolonged application of closed in-line suction catheters increases microbial colonization of the lower respiratory tract and bacterial growth on catheter surface. Journal of Infection, Vol.31, pp31-37.
Halm, M.A. (2008) Instilling normal saline with suctioning: beneficial technique or potentially harmful sacred cow? American Journal of Critical Care, Vol.12, pp.469-472.
Hooser, D.T. (2010) Ventilator associated pneumonia: best practice for caregivers. NY: Kimberly Clark.
Kollef, M.H., (2004) Prevention of hospital-associated pneumonia and ventilator associated pneumonia. Critical Care Journal, Vol.32, pp.1396-1405.
Kunis, K.A., et al. (2003) Ventilator associated pneumonia in the ICU: its pathophysiology, risk factors and prevention. American Journal of Nursing, Vol.133, No.8, pp 64AA-64GG.
Mayall, G.C. (2001) Ventilator associated pneumonia or not? Contemporary diagnosis. Emerging Infectious Diseases, Vol. 7, pp. 200-204.
Moore, T., (2003) Suctioning techniques for the removal of respiratory secretions. Nursing Stand, Vol.18, No.9, pp. 47-55.
Morehead, R.S., and Pinto, S.J., (2002) Ventilator associated pneumonia. Arch Intern Medical Journal, Vol.160, No.3, pp1926-1930.
Paratz, J.D. and Stockton, K.A. (2009) Efficacy and safety of normal saline instillation: a systematic review, Journal of Physiotherapy, Vol.95, No.4, pp.241-250.
Porzecanski, I., and Bowton, D.L., (2006) Diagnosis and treatment of ventilator associated pneumonia. Chest, Vol.130, pp 597-604.
Puchalski, M.L. (2007) Should normal saline be used when suctioning the Endotracheal tube of the Neonate? Web.
Reeve, J.C. (2009) Instillation of normal saline before suctioning reduces the incidence of pneumonia in intubated and ventilated adults. Critical Care Medicine, Vol. 37, No.1, pp.32-8.
Rello, J., Ollendorf, D.A.and Oster, G. (2002) Epidemiology and outcomes of ventilator associated pneumonia in a large US. Chest Journal, Vol.122, pp 2115-2121.
Schleder, B.J., (2003) Taking charge of ventilator-associated pneumonia. Nursing Management, Vol. 8, pp.29–32.
Sole, M.L., Byers, J. F., and Judy, J.E., (2003) Survey of suctioning techniques and airway management practices. American Journal of Critical Care, Vol.12, pp 220-230.