Figure 1 MODULE 17: Cardiology IABP therapy PART 2 Intra-aortic balloon pump therapy by Kate O’Donovan Systole: deflation Diastole: deflation Decreased afterload Augmentation of Decreases cardiac work, diastolic pressure INTRA-AORTIC balloon pump (IABP) therapy was first introduced in Decreases myocardial oxygen Increases coronary perfusion the 1960s for the treatment of cardiogenic shock. Since then it has consumption; Increases assumed a pivotal role in the treatment of those with heart failure cardiac output and myocardial ischaemia and, according to Reid and Cottrell,1 is the most widely used mechanical support. Cardiovascular nurses ence of the dicrotic notch on the pressure waveform, which caring for these patients require skills and knowledge that enable triggers balloon inflation. This results in the movement of blood prompt recognition and treatment of sometimes life-threatening in the aorta into the coronary and up to the carotid arteries, thus complications associated with balloon pump therapy. This article increasing coronary and cerebral perfusion (see Figure 1). Defla- provides an overview of the function of the pump, indications, tion occurs at the end of diastole just before systole, which results potential complications and nursing care required. in aortic blood being displaced down toward the mesenteric How it works and renal arteries, increasing perfusion to these organs, and thus IABP therapy is a method of mechanically assisting and sup- reducing the afterload (the pressure in the aorta that the heart porting the coronary and systemic circulation in patients who has to pump against) (see Figure 1). The net result of inflation have myocardial pump dysfunction or in those with coronary and deflation is increased coronary and cerebral perfusion and ischaemia and/or undergoing complex high-risk percutaneous reduced myocardial workload respectively. coronary intervention. The IABP consists of a long polyurethane Indications type catheter with a 10-15cm balloon at the end. This catheter The goal of IABP therapy is to improve myocardial oxygen is normally inserted via the femoral artery and passed into the supply and reduce myocardial oxygen demand. Although it was descending thoracic aorta until the tip is positioned 2cm just originally designed to support patients in cardiogenic shock below the left subclavian artery2 and the lower end of the bal- the indications have expanded because of continued research. loon just above the renal arteries. The catheter tip is radiopaque Table 1 lists the many indications for IABP therapy. The most com- so its position can be evaluated on x-ray.3 The catheter attaches mon indications are low cardiac output due to left ventricular to a pressurised flush system, similar to that of an arterial line, and dysfunction and myocardial ischaemia. Other indications include also to the pump itself where helium is shuttled in and out of the septic shock, cardiac support for non-cardiac related surgery and catheter so that the balloon can inflate and deflate. The catheter support post correction of anatomical defects. comes in three sizes 34cc, 40cc, 50cc and is selected according to Nursing care the height of the patient. Prior to insertion of the IABP a baseline assessment is per- This type of therapy works by the balloon inflating and deflat- formed incorporating lower and upper limb perfusion. This serves ing in synchrony with the cardiac cycle. Therapy may be timed as a baseline for assessments post insertion. Upper limb assess- to 1:1, 1:2 or 1:3, implying that the balloon inflates and deflates ment is essential so that balloon migration obstructing blood according to each cardiac cycle, every second cardiac cycle or flow down the left subclavian artery can be detected promptly. every third cardiac cycle respectively. Inflation occurs just as dias- This assessment involves documentation of palpation of the rel- tole begins (diastole represents the heart relaxing, the ventricles evant pulses, assessing capillary refill, temperature and colour filling and getting ready for systole and the coronary arteries of the limbs. A set of baseline vital signs is recorded – heart rate, receiving their blood supply). Diastole is recognised as the pres- blood pressure, respiratory rate, oxygen saturations and tempera- Sponsored by an unrestricted grant from Merck Sharp & Dohme Ireland (Human Health) Ltd CardioWINMarch-SM-PG-AM.indd 1 22/02/2011 14:17:04 Continuing Education Table 1 Table 2 Indications for IABP therapy Elements of nursing care Increase coronary artery perfusion • Assess cardiovascular hourly, or more frequently depending on • Refractory unstable angina clinical acuity, noting mean arterial pressure, augmented pressure • Impending infarction heart rate, oxygen saturation and perfusion state (lower and • Acute myocardial infarction upper limb perfusion assessment) • Support during PCI • Assess and observe for any alteration in neurological status • Complications post myocardial infarction (VSD, papillary muscle rupture, acute mitral regurgitation) • Confirm timing, ratio and trigger of intra aortic balloon pump hourly • Myocardial contusion • Strict intake and output record – aim for output 0.5ml/kg/hr – report • Ischaemia related intractable ventricular arrhythmias any sudden decrease in urinary output (signs of decreased renal • Bridge to cardiac surgery perfusion due to low cardiac output or migration of the catheter to Reduction in afterload the renal arteries obstructing blood flow) • Ventricular failure unresponsive to pharmacological therapy • Ensure the transducer is level with the phlebostatic axis, flushed • Cardiogenic shock hourly and zeroed four hourly or on change of patient position. • Post-surgical myocardial dysfunction/low cardiac output Always flush with the pump on standby syndrome • Check all connections, observe the balloon catheter for presence • Bridge to cardiac transplantation of blood which may indicate balloon puncture/rupture hourly • Bridge to other form of circulatory support • Monitor for signs of pulmonary oedema or ischaemia ture, which are used to assess improvement or deterioration in • Monitor temperature two-to-four-hourly, observing for signs of the patient’s condition. infection such as erythema/inflammation and pain at the insertion Education plays a pivotal part in nursing care. This is a fright- site and a raised white cell count ening time for the patient and family. Patient education should • Observe for bleeding at cannulation sites, venepuncture sites, urinary include the reasons why the IABP is being inserted, what the catheter, and insertion site as a complication of anticoagulation pump does, potential complications, nursing care involved such therapy as hourly nursing assessments, and limitations. The limitations in • Educate the patient re importance of passive limb exercises, activity that the patient will experience should be explained such keeping the affected leg straight as bed rest and reduced movement of the affected leg. In relation to complications patients are educated about the risk of bleeding • Encourage deep breathing exercises to promote adequate ventilation and lung expansion preventing the development of at the insertion site and are advised to put pressure on the site chest infections when coughing or sneezing and to notify the nurse promptly if they experience pain in the lower back or a sudden burning, pain • Provide skin care and pressure area care – may need a pressure or wetness at the insertion site. relieving mattress and if needed two-hourly turns Patients and families are instructed to report symptoms that • Assist with nutrition and hydration as patient should be no higher may be suggestive of impaired peripheral perfusion such as tin- than 30° which is challenging when eating or drinking gling, numbness, coldness, pallor and pain to a nurse as this may • Provide on going psychological support and education as required be indicative of limb ischaemia. Aside from gathering the equipment specific to IABP inser- the blood into the coronary and carotid arteries), mean arterial tion, nursing care involves preparing the patient, eg. attaching pressure, temperature, respiratory rate and oxygen saturations.3 the patient to the pump’s ECG leads and labelling them, setting The aim is that the mean arterial pressure is maintained between up the transducer and levelling it with the patient’s phlebostatic 60-70mmHg which indicates adequate peripheral perfusion.5 axis (fourth intercostal space mid axilla which is the level of the This is confirmed by the patient being warm to touch, good cap- left atrium), in addition to prepping the groin site. The patient is illary refill, no evidence of cerebral hypoxia and urinary output assessed for their tolerance of lying flat and also their need for ≥ 0.5ml/kg/hr. Cardiovascular assessment is performed hourly or sedation or anxiolytics as per hospital guidelines. more frequently if haemodynamic status deteriorates. Following insertion, nursing care involves cardiovascular/ Regarding the IABP, the pump should be checked hourly for haemodynamic assessment, fluid balance, positioning and pres- correct settings such as timing, balloon inflating to its maximum sure area care, observation of the balloon catheter and line, the capacity and that the trigger is at the correct setting. As with any catheter insertion site, limb perfusion, neurological status and invasive haemodynamic monitoring system the pressure bag should providing psychological support for patient and family.