Use of PEEP in Ventilation - Research Proposal Example

Abstract: Objective: The purpose of this paper is to arrive at a considerable understanding of the impact of the use of PEEP in ventilated patients and to identify the strategies to improve the care settings. Design: Twenty journals on the use of PEEP in patients in need of external mechanical ventilation intervention were examined. Results: Three main views were extracted from the literature reviewed. They are : - Need for ventilation in patients with respiratory failure. Use of PEEP and its implication. Evolving modalities to improve the health care settings on ventilated patients. Search strategy: Databases JOURNAL OF AMERICAN MEDICAL ASSOCIATION & NEW ENGLAND JOURNAL OF MEDICINE were searched using search terms ‘ PEEP’, ARDS, COPD, & AUTO-PEEP. Findings: On sifting the contents of the literature reviewed it was found that fixing the level of use of PEEP is still an issue of concern among all the medical professionals. This is because of the fact that the effect of using PEEP is yet to be clinically understood in its fullest sense. The mechanical expertise presently being used in the application of PEEP on ventilated patients is quite scanty and requires more researches to be done on the way. Researches if done in conjunction with pathologic experts and haematologists would have a constructive approach and yield better results of showing better methods for PEEP use. INTRODUCTION: A ventilator is a mechanism that provides sufficient oxygen to a patient from externally. Normally, during passive exhalation, the alveolar pressure is the same as the atmospheric pressure at the end of exhalation. Positive end expiratory pressure (PEEP) is used mainly to recruit or stabilize lung units and improve oxygenation in patients with hypoxemic respiratory failure thereby the pressure of the alveoli at the end of exhalation is maintained at appropriate level. Measurement of respiratory system mechanics in patients who are subjected to external mechanical ventilation suffering from low tidal volumes is important to assess the status of the ailment and to choose appropriate ventilator settings. (Pilar Saura & Lluis Blanch, 2002). Researches so far carried out have thrown light on the descriptive side of application of PEEP. However no controlled studies have been done to demonstrate the best method of choosing the level of PEEP. In fact most physicians hesitate to use PEEP level more than 10cm H2O.(Jesus Villar, 2003,) NEED FOR VENTILATION IN PATIENTS WITH RESPIRATORY FAILURE: The primary function of the lungs involves the transfer of oxygen from the inhaled air into the blood and the transfer of carbon dioxide from the blood into the exhaled air. Whenever a patient suffers from the malfunctioning of lungs due to improper gas exchange he is supposed to be within the enclave of respiratory failure. ARDS, the Acute Respiratory Distress Syndrome is often the fertile soil for respiratory failure to get nurtured. In ARDS there is sudden respiratory failure due to the rapid accumulation of fluid in the lungs following an abrupt increase in the permeability of the normal barrier between the capillaries and the alveoli air sacs in the lungs. This damages the capillaries and alveoli air sacs. Leakage of fluid from the damaged capillaries to air sacs causing some sacs to collapse and some sacs filled with the fluid. This makes the lung stiff. Gas exchange is quite improbable at this point and the amount of oxygen in the blood drops considerably. Thus ARDS is the most serious response to acute lung injury although it is not a specific disease itself.. ARDS is generally characterised by the de-recruitment of alveoli and paucity of airway secretion, bronchospasm or dynamic hyper inflation. (Thomas W. K. Lew, et al 2003)Unlike ARDS, COPD is a chronic obstructive pulmonary disease. In COPD the alveolar attachments that normally keep the smaller airways open via radial traction are lost. The pleural pressure in COPD patients becomes positive during exhalation resulting in compression and collapse of airways. And dynamic hyperinflation. This condition can be helped by applying external PEEP only. (Majid. M. Mughal et al, 2005) Auto PEEP is the most important crisis in critical care management. For reasons, the lungs may not deflate fully before next breath starts, and the pressure remains elevated. This can be managed by applying external PEEP. But if this arises automatically or inadvertently it is named auto PEEP. Auto PEEP occurs on patients subjected to mechanical ventilation, in three types. Auto-PEEP with dynamic hyperinflation with intrinsic respiratory flow limitation is mainly ascribed to the closure of airways which limits the expiratory flow. Auto-PEEP with dynamic hyperinflation without expiratory flow limitation is largely due to the increase in volume of the air delivered per minute. (usually >20L/minute) . auto-PEEP without dynamic hyperinflation may also be caused by alveolar pressure often with normal or even low lung volumes. Strong expiratory muscle activity usually ascribes to such alveolar pressure without lung distension. The consequences of auto PEEP are : increasing the work load of breathing, worsening the gas exchange and causing haemo dynamic compromise. In many cases improper recognition of auto PEEP is the chief problem in critical care. (Majid M. Mughal, et al 2005) . Auto- PEEP and ventilator induced PEEP was found to exhibit a maldistribution among lung units. At a tracheal level of 12.7 cm H2O , the low lung unit showed 15.8 cm H2O while the fast lung unit showed 10.1 cm H2O (RM Kacmarek, et al , 1995) USE OF PEEP AND ITS IMPLICATIONS: While taking the decision to use PEEP its of great importance to fix the level of PEEP and monitor the patient’s every stage so that auto- PEEP developed can be managed. This is because the very use of mechanical ventilator at several times lead to auto-PEEP. Although PEEP has the tendency to decrease the expiratory shunting by maintaining alveolar patency, it does not prevent accumulation of interstitial lung water. But actually PEEP favors accumulation of lung water. Commonly employed levels of PEEP result in 7% incidence of pneumothorax. (K.S. Wayne, 1976,). Attention to clinical and physiological aspects of the case is mandatory. Pulmonary complications like resorption of interstitial and pleural fluid were often identified roentgenographically especially before they became clinically apparent. Consistent correlation between roentgenographic changes and the ventilatory pressures employed was not observed. This still clearly indicates that clinical focus on cases of ventilation is still to be sharpened..( A. R. Altman and T. H. Johnson, 1979)Both the conventional ventilation and protective ventilation are in vogue. However the protective ventilation was relatively found to have associated with improved survival at 28 days.( Marcelo Britto Passos Amato et al 1998)The concept of VILI – ventilator induced lung injury—was conceived and designed by Leonard D.Hudson in 1999 on an animal model.(Leonard D. Hudson,1999)Development of ‘cell suicide’—epithelial cell apoptosis—in the kidney and small intestine explains the evidence of organ dysfunction. Yomiko Imai et al, (2003) observed a decrease in morbidity and mortality in patients on whom treatments were offered with a lung protective strategy. (Yumiko Imai, et al 2003). Setting of PEEP is also a matter of concern. In contrast with endotracheal mechanical ventilation, the full facemask covering bothe the nose and mouth is gaining preference presently.(Laurent Brochard, 2002). The increase in (SPL) hydrostatic superimposed pressure causes atelectasis. Careful maintenance of PEEP to a given lung at a level equal or greater than SPL can prevent atelectasis. (L. Gattinoni, et al, 1993) EVOLVING MODALITIES TO IMPROVE HEALTHCARE SETTINGS: Since the benefits of using increased levels of PEEP and recruitment manoeuvres are yet to be evaluated to viable adherence, hesitation on the part of many physicians to use PEEP level around 10 cm H2O is understandable. The present RCTs of alternative ventilation modes like, high frequency oscillation does not demonstrate any significant survival advantage on patients with ARDS with life threatening hypoxemia. (Eddy Fan, Dale M. Needham, Thomas E. Stewart, 2005) .Ventilator weaning protocols are also to be handled with diligent care. Studies conducted by Adrienne G.R. et al (2002) demonstrated that extubation failure rates were not significantly established in their RCT. Among weaning successes, median duration of weaning was not significantly different for PSV, VSV & no protocol, which were 1.6 days, 1.8 days and 2.0 days respectively. The RCT conducted in the paediatric care units yielded two more findings that male kids more frequently failed extubation and an increased use of sedation had the impact on extubation failure and extubation success. One can arrive at a conclusion on review of this RCT that individual breath pattern is a factor that necessarily must be considered as a criterion of weaning protocol.( Adrienne G. Randolph et al 2002,). The role of physicians in critical care of the patients in ventilation is greatly impacting the strategic levels of their operations. Nicolo patroniti (2003) discusses various factors like, VILI , low Vt strategy, use of higher respiratory rate to maintain acceptable PCO2 and p H levels. These multi directional factors, they assert, eventually lead the clinicians to a better understanding of the basic physiology only. Hence they establish that before arriving at a conclusive decision, it is of foremost important to focus on basic physiology and monitor appropriately. (Nicolo Patroniti and Antonio Pesenti, 2003). The PEEP setting strategies are constantly under the growing researches and changes are to be accepted, since inscription of a definite verdict has the danger of nullifying the past and recent past histories. The level of pressure delivered by the ventilator is usually adjusted in accordance with the patient’s respiratory frequency. However, the frequency signals could not be well defined although they exhibit a satisfactory level of respiratory – muscle rest. 16 to 30 breaths per minute is the commonly recommended rate of breath rate by almost all physicians. Recent researches however are leading the scientists to adopt a trend to work on the basis of consensus of opinion rather than on data from studies. Paying more attention towards high airway pressure than to the oxygen toxicity is one of the examples for this trend of opinion based researches. An important challenge for researchers is to identify elements of our current knowledge that can be incorporated into a clinical management scheme to improve the outcome for patients who require ventilatory assistance.(Martin J. Tobin, 2001) CONCLUSION: Use of PEEP in ventilated patients is not simply connecting a patient to a system of monitoring or regular feeding. It involves several factors to be considered before, during and at the end of usage. The factors to be accounted for before the use of PEEP may simply be the question whether the patient requires mechanical ventilation. Once an answer in affirmative is obtained then begins the lot of work and decision making tasks to get a patient fixed with mechanical ventilator and setting the PEEP comprises several clinical and biological factors to be care fully judged. During the ongoing process of mechanical ventilation diligent monitoring not only the mechanical effects but also the patients’ response to the pressure applied have to be made. Researches so far done have clearly established that gripping the clinical factors like patient’s acceptance/resistance , their breathing frequency changes after implanting the PEEP along with mechanical features of PEEP setting is equally important . Again in terms of Martin J. Tobin, identifying the right elements of our current knowledge and incorporating them into a clinical management to improve the outcome of the ventilated patients although is a challenge to many researchers, is a must to be carried out. Reference list— Adrienne G. Randolph,; David Wypij; Shekhar T. Venkataraman; James H. Hanson; Rainer G. Gedeit; Kathleen L. Meert; Peter M. Luckett; Peter Forbes; Michelle Lilley; John Thompson; Ira M. Cheifetz; Patricia Hibberd; Randall Wetzel; Peter N. Cox; John H. Arnold, 2002, “Effect of Mechanical Ventilator Weaning Protocols on Respiratory Outcomes in Infants and Children”, JAMA ,2002, 288: 2561-2568 A. R. Altman and T. H. Johnson, “Roentgenographic findings in PEEP therapy;Indicators of pulmonary complications”, 1979, JAMA, Vol. 242:8 Eddy Fan, Dale M. Needham, Thomas E. Stewart, 2005, “Ventilatory Management of Acute Lung Injury and Acute Respiratory Distress Syndrome”, JAMA, Vol. 294:22; 2889-2896 Jesus Villar, 2003, “Positive end-expiratory pressure or no positive end-expiratory pressure: is that question to be asked?”, Critical Care 2003, 7:192 RETRIEVED on 25.12.2006 @ www.ccforum.com ). K.S. Wayne, 1976, “Positive end-expiratory Pressure (PEEP)ventilation. A review of mechanism and actions.”JAMA, Vol. 236 :12 Laurent Brochard, 2002, “Noninvasive Ventilation for Acute Respiratory Failure, JAMA, Vol.288: 932-935 Leonard D. Hudson, “Progress in Understanding Ventilator Induced Lung Injury, JAMA, 1999,282:77-78 L. Gattinoni, L. D'Andrea, P. Pelosi, G. Vitale, A. Pesenti and R. Fumagalli , Italy , 1993, “Regional effects and mechanism of positive end-expiratory pressure in early adult respiratory distress syndrome”, JAMA.Vol.269: 16) Majid M. Mughal, Daniel A. Culver, Omar A. Minai &Alejandro C. Arrolgia, “ Auto-positive end-expiratory pressure: Mechanisms and treatment, Cleaveland Clinic Journal of Medicine, Vol.72:9, 2005:801-809 Marcelo Britto Passos Amato., Carmen Silvia Valente Barbas., Denise Machado Medeiros, Ricardo Borges Magald, Guilherme Paula Schettino, Geraldo Lorenzi-Filho, Ronaldo Adib Kairalla, Daniel Deheinzelin, Carlos Munoz, Roselaine Oliveira, Teresa Yae Takagaki, and Carlos Roberto Ribeiro Carvalho, “Effect of a Protective-Ventilation Strategy on Mortality in the Acute Respiratory Distress Syndrome”, NEJM,1998. Vol.338:347-354 Martin J. Tobin, 2001, “Advances in Mechanical Ventilation”, NEJM, Vol.344:26: 1986-1996 Nicolo Patroniti and Antonio Pesenti, 2003, “Low tidal volume, high respiratory rate and auto-PEEP: The importance of the basics, Critical Care, 2003; 7(2): 105-106 RETRIEVED from www.pubmedcental.nih.gov on 25.12.2006) Pilar Saura & Lluis Blanch, “How to Set Positive End- Expiratory Pressure”, Respiratory Care 2002; (3):279-292 RETRIEVED on 25.12.2006 @ www.rcjournal.com RM Kacmarek, M Kirmse, M Nishimura, H Mang and WR Kimball,1995, “The effects of applied vs auto-PEEP on local lung unit pressure and volume in a four-unit lung model” Chestjournal. Vol.108: 1073-1079 retrieved from www. Chestjournal.org on 26.12.2006) Thomas W. K. Lew, ; Tong-Kiat Kwek, ; Dessmon Tai, ; Arul Earnest, ; Shi Loo, ; Kulgit Singh, ; Kim Meng Kwan, ; Yeow Chan, ; Chik Foo Yim, ; Siam Lee Bek, ; Ai Ching Kor, ; Wee See Yap, ; Y. Rubuen Chelliah, ; Yeow Choy Lai, ; Soon-Keng Goh, “Acute Respiratory Distress syndrome in Critically ill Patients With Severe acute Respiratory Syndrome, Journal of American Medical Association, Vol.290: 374-380; 2003 Yumiko Imai, ; Jean Parodo ; Osamu Kajikawa ; Marc de Perrot ; Stefan Fischer ; Vern Edwards; Ernest Cutz ; Mingyao Liu ; Shaf Keshavjee ; Thomas R. Martin; John C. Marshall; V. Marco Ranieri; Arthur S. Slutsky, “Injurious Mechanical Ventilation and End-Organ Epithelial Cell Apoptosis and Organ Dysfunction in an Experimental Model of Acute Respiratory Distress Syndrome”, JAMA, 2003,289:2104-2112 Read More