Is the pulmonary artery catheter useful? from Best Practice and Research clinical Anaesthesiology Vol. 19, No. I, pp97-110, 2005 by R3 黃信豪 Introduction More than 1.5 million PACs are used each year in the USA, and half of them are placed in high-risk trauma and surgical patients. Majority of clinicians believe that the information provided by PAC monitoring is useful in guiding therapy and improving outcomes despite no literature could prove it. This article will review and discuss the clinical utility, potential benefits, and harms of PAC, and provide recommendations for future research in this area. Risks and harms of pulmonary artery catheterization (PAC) Insertion of a PAC result in morbidity associated with obtaining central venous access. A review article by Shah KB ( anesthesiology 2004; 100: 1411-1418 ) showed low incidence of morbidity associated with this procedure. The complications associated with PAC insertion including: 1.hemorrhage or hematoma with airway compromise – more frequently with int. jugular approach. Risks and harms of pulmonary artery catheterization (PAC) 2.pneumothorax and hemothorax –more frequently with subclavian approach. 3.air embolization or other embolization due to cath. fragments and carotid artery plaque after arterial puncture. 4.Horner’s syndrome due to adjacent structures damage. 5.thoracic duct injury. 6.brachial plexus injury. 7.transient phrenic nerve injury. Risks and harms of pulmonary artery catheterization (PAC) The factors that were thought to reduce complication rates of PAC insertion: 1.experience 2.appropriate supervision 3.attention to detail 4.ultra-sound guided may reduce some complications especially in patients with difficult anatomy and in teaching situations. Risks and harms of pulmonary artery catheterization (PAC) The primary concern during advancement of the PAC is the occurrence of arrhythmias. The complications related to the maintenance of PACs including: 1.thrombosis –commonly occurs 2.embolization –may due to balloon rupture 3.pulmonary infarction 4.pulmonary artery rupture –risk factors including old age, pulmonary hypertension, improper inflation. 5.infection –remove the PAC as soon as it is no longer needed, but no schedule replacement is suggest Information obtained by the PAC Clinical manifestations of serious underlying pathophysiology in critically ill patients often lag behind more subtle hemodynamic changes. PAC was initially designed to measure pulmonary a. pressure and pulmonary a. wedge pressure. Today, the information that could obtained from PAC including: a. left ventricular end-diastolic pressure (LVEDP) –used as a surrogate to assess left ventricular preload Information obtained by the PAC b. pulmonary capillary wedge pressure (PCWP) –used to indirectly estimate LVEDP. c. pulmonary artery occluded pressure (PAOP) –use to estimate PCWP d. pulmonary artery end-diastolic pressure (PAEDP) –used as an estimate of PCWP to avoid the potential for pulmonary infarction or pulmonary artery rupture. e. right atrial pressure (RAP) –may provide information of right ventricular performance f. cardiac output (CO) – may useful in the diagnosis of complex medical problems and assessing the response to therapeutic interventions. Information obtained by the PAC g. continuous mixed venous oxygen saturation (SvO2) – assessment of global tissue oxygenation, which varies directly with CO, Hb, SaO2, and metabolic rate. h. right ventricular ejection fraction (RVEF) –as a determinant of LV preload i. right ventricular end-diastolic volume (RVEDV) and right ventricular end-diastolic volume index (RVEDVI) – was the best indicator of cardiac preload than PAOP, especially when patient receiving mechanical ventilation and PEEP (up to 50 cmH2O). Pulmonary artery catheterization and clinical outcomes Over 1500 articles and abstracts relating to PACs published between 1972 and 2002, but only 28 of these were controlled studies of the impact of PAC on clinical outcomes. Preoperative monitoring: 1.the role of PAC monitoring in hemodynamic optimization prior to high-risk surgery remains controversial. 2.two studies ( by Wilson J, BMJ 1999; and Boyd O, JAMA 1993) showed that the mortality rate reduced by 75% when the PAC was used to elevate oxygen delivery. Pulmonary artery catheterization and clinical outcomes 1991; Valentine 3. but three studies (Brlauk JF, Annals of surgery RJ, Journal of Vascular Surgery 1998; Bender JS, Annals of surgery 1997) showed no differences in perioperative mortality were observed. 4. However, preoperative tune-up by PAC resulted in a. fewer adverse intraoperative events b. less postoperative cardiac morbidity c. and less early graft thrombosis in the third study Pulmonary artery catheterization and clinical outcomes Intra-operative monitoring: Non-cardiac surgery 1. In two groups of patient with previous MI, the incidence of re-infarction was significantly reduce in group with PAC used compared to control group. The authors suggested that aggressive hemodynamic monitoring was associate with improved outcomes in these patients. (Rao TLK, anesthesiology 1983). 2. A threefold increase in the incidence of major post- operative cardiac events occurred in patients receiving PACs. (Polanczyk CA, JAMA 2001) Pulmonary artery catheterization and clinical Cardiac surgery outcomes 1. The PAC-monitored patients had an increased postoperative weight gain and intubation times. (Stewart RD, The Annals of Thoracic surgery 1998) 2. In a study of patients with left main coronary artery disease, mortality was significantly less in subjects monitored with PAC compared to those monitored with CVP. (Moore CH, The Annals of Thoracic surgery 1978) 3. Patients undergoing CABG monitored with CVPs or PACs have no differences in major morbidity, mortality, or ICU length of stay. (Tuman KJ, Anesthesiology 1989) Pulmonary artery catheterization and clinical outcomes Vascular surgery 1. The mortality rate was significantly increased in the patients with the abdominal aortic aneurysm at the hospital which routinely used PAC monitoring and inotropes. (Sandison AJ, European Journal of vascular and Endovascular surgery 1998) 2. A prospective cohort of 61 patients had a reduced incidence of renal dysfunction when fluid balance was monitored with a PAC when compared to a historical control group. (Hesdorffer CS, Clinical Nephrology 1987) 3. Two randomized trials in low-risk patients undergoing AAA surgery have been published. No significant differences were observed between the groups in morbidity, mortality, or hospital length of stay. (Isaacson IJ, Journal of vascular surgery 1990; Joyce WP, European Journal of Vascular Surgery 1990) Pulmonary artery catheterization and clinical outcomes Post-operative monitoring: 1. Two trials from the University of Hawaii randomized critically ill patients showed morbidity and mortality were not reduced in the treatment group. (Yu M, Critical Care Medicine 1993; Yu M, Critical Care Medicine 1995) 2. No differences in the number of dysfunctional organs, length of ICU stay, or mortality rate by a largest randomized clinical trial. (Gattinoni L, NEJM 1995) Summary of evidence from clinical trials Despite three decades of use, there is still vigorous debate about the efficacy and utility of PACs during peri-operation. On the basis of evidence currently available, it is difficult to draw meaningful conclusions about the impact of PACs on morbidity or mortality. The interpretation of many clinical trials is significantly limited by important flaws in study design, including: Summary of evidence from clinical trials 1. Inadequate sample size 2. Lack of randomization 3. Lack of standardization of treatments or therapies based on PAC data 4. Uncertainty relating to ‘optimal’ hemodynamic values required to improve outcomes 5. Heterogeneity of patient populations enrolled in clinical trials 6. Lack of standardization of user knowledge Summary of evidence from clinical trials There are three interrelated variables should be assessed in determining the appropriateness of PAC monitoring: 1. Patients should be examined for evidence of significant organ dysfunction that may increase the risk of hemodynamic disturbances 2. Major surgical procedures may be associated with hemodynamic disturbances that may damage organ systems 3. Benefits from PAC can be obtained only if the physicians and nurses using the PAC demonstrate competence in the basic technical and cognitive skills. Conclusion The pulmonary artery catheter is an important tool in the quantitative assessment of cardiopulmonary function in the peri-operative period. PAC allows the clinician to determine several important hemodynamic indices, which potentially allows for prompt diagnostic assessment and therapeutic interventions. On the basis of currently available evidence, it is uncertain whether PAC improves, worsens, or has no effect on major outcomes in critical patients. Conclusion Additional large-scale, randomized clinical trials, using protocols to define treatment endpoints, are needed to demonstrate the effectiveness of PACs. All care-givers must be skilled in the management of PACs and the interpretation of the data, and must employ the appropriate intervention for the patient in order to observe improved outcomes.
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