Recommendations for the Use of Mechanical Circulatory Support: Ambulatory and Community Patient Care: A Scientific Statement From the American Heart Association
2017; Lippincott Williams & Wilkins; Volume: 135; Issue: 25 Linguagem: Inglês
10.1161/cir.0000000000000507
ISSN1524-4539
AutoresJennifer L. Cook, Monica Colvin, Gary S. Francis, Kathleen L. Grady, Timothy M. Hoffman, Mariell Jessup, Ranjit John, Matthew C. Kiernan, Judith E. Mitchell, Francis D. Pagani, Michael Petty, Pasala Ravichandran, Joseph G. Rogers, Marc J. Semigran, John M. Toole,
Tópico(s)Cardiac Arrest and Resuscitation
ResumoHomeCirculationVol. 135, No. 25Recommendations for the Use of Mechanical Circulatory Support: Ambulatory and Community Patient Care: A Scientific Statement From the American Heart Association Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUBRecommendations for the Use of Mechanical Circulatory Support: Ambulatory and Community Patient Care: A Scientific Statement From the American Heart Association Jennifer L. Cook, MD, FAHA, Chair, Monica Colvin, MD, FAHA, Co-Chair, Gary S. Francis, MD, FAHA, Kathleen L. Grady, PhD, RN, MS, FAHA, Timothy M. Hoffman, MD, FAHA, Mariell Jessup, MD, FAHA, Ranjit John, MD, Michael S. Kiernan, MD, FAHA, Judith E. Mitchell, MD, FAHA, Francis D. Pagani, MD, PhD, FAHA, Michael Petty, PhD, RN, Pasala Ravichandran, MD, Joseph G. Rogers, MD, FAHA, Marc J. Semigran, MD, FAHA and J. Matthew Toole, MD, FAHAOn behalf of the American Heart Association Heart Failure and Transplantation Committee of the Council on Clinical Cardiology; Council on Cardiopulmonary, Critical Care, Perioperative and Resuscitation; Council on Cardiovascular Disease in the Young; Council on Cardiovascular and Stroke Nursing; Council on Cardiovascular Radiology and Intervention; and Council on Cardiovascular Surgery and Anesthesia Jennifer L. CookJennifer L. Cook , Monica ColvinMonica Colvin , Gary S. FrancisGary S. Francis , Kathleen L. GradyKathleen L. Grady , Timothy M. HoffmanTimothy M. Hoffman , Mariell JessupMariell Jessup , Ranjit JohnRanjit John , Michael S. KiernanMichael S. Kiernan , Judith E. MitchellJudith E. Mitchell , Francis D. PaganiFrancis D. Pagani , Michael PettyMichael Petty , Pasala RavichandranPasala Ravichandran , Joseph G. RogersJoseph G. Rogers , Marc J. SemigranMarc J. Semigran and J. Matthew TooleJ. Matthew Toole and On behalf of the American Heart Association Heart Failure and Transplantation Committee of the Council on Clinical Cardiology; Council on Cardiopulmonary, Critical Care, Perioperative and Resuscitation; Council on Cardiovascular Disease in the Young; Council on Cardiovascular and Stroke Nursing; Council on Cardiovascular Radiology and Intervention; and Council on Cardiovascular Surgery and Anesthesia Originally published30 May 2017https://doi.org/10.1161/CIR.0000000000000507Circulation. 2017;135:e1145–e1158Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: January 1, 2017: Previous Version 1 Mechanical circulatory support (MCS) offers a surgical option for advanced heart failure when optimal medical therapy is inadequate. MCS therapy improves prognosis, functional status, and quality of life.1,2 The INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) tracks patient selection and outcomes for all implanted US Food and Drug Administration–approved MCS devices. From June 2006 until December 2014, >15 000 patients received MCS, and >2000 implantations are performed annually. One-year survival with current continuous-flow devices is reported to be 80%, and 2-year survival, 70%.3 In patients awaiting heart transplantation, MCS provides a bridge to transplantation, and for others who are ineligible for heart transplantation, MCS provides permanent support or destination therapy. Indications and absolute and relative contraindications to durable MCS are listed in Table 1.Table 1. Indications and Contraindications to Durable Mechanical SupportIndications: combination of the following: Frequent hospitalizations for heart failure NYHA class IIIb–IV functional limitations despite maximal therapy Intolerance of neurohormonal antagonists Increasing diuretic requirement Symptomatic despite CRT Inotrope dependence Low peak Vo2 ( 80 y for DT Obesity or malnutrition Musculoskeletal disease that impairs rehabilitation Active systemic infection or prolonged intubation Untreated malignancy Severe PVD Active substance abuse Impaired cognitive function Unmanaged psychiatric disorder Lack of social supportCRT indicates cardiac resynchronization therapy; DT, destination therapy; NYHA, New York Heart Association; Vo2, oxygen consumption; and PVD, peripheral vascular disease.As of July 2014, 158 centers in the United States offer long-term MCS.3 Patients often live a substantial distance from the implanting center, necessitating active involvement of local first responders (emergency medical technicians, police, and fire department personnel), emergency department staff, primary care, and referring cardiologists. Because patients with MCS are becoming increasingly mobile, basic knowledge of equipment is necessary for personnel in public areas such as schools, public transportation, and airplanes/airports. Ambulatory patients with MCS can span the entire age spectrum from pediatrics to geriatrics. The aim of this document is to provide guidance for nonexperts in MCS and to facilitate the informed assessment, stabilization, and transport of the patient with MCS back to the MCS center for definitive therapy. In addition, the principles herein provide a foundation for emergency management and a framework to address the management of known MCS-associated complications and expected comorbid medical problems.Equipment OverviewCurrently in the United States, the most frequently used durable devices are continuous-flow devices with axial (HeartMate II, St. Jude Corp, Minneapolis, MN) or centrifugal (HeartWare Ventricular Assist System, HeartWare Corp, Framingham, MA) flow (Figure 1A–1D). Excision of a round "core" from the left ventricular (LV) apex allows the device to be positioned within the LV. Anastomosis of the outflow cannula occurs at the ascending aorta. The pump is powered through the percutaneous lead (power cord) that exits through the abdominal wall. The percutaneous lead is attached to a controller that weighs between 1 and 1.5 lb, which operates the device and records data on operation. Typically, patients wear batteries during the day (lasting up to 12 hours) and plug into household power while their batteries charge at night. Practical field guides are available for further reference.4Download figureDownload PowerPointFigure 1. A through D, US Food and Drug Administration–approved devices.A and B, HeartMate II ventricular assist system. HeartMate II, HeartMate 3, and St. Jude Medical are trademarks of St. Jude Medical Inc or its related companies. Reproduced with permission of St. Jude Medical. Copyright © 2017. All rights reserved. C and D, HeartWare ventricular assist system. Reproduced with permission from HeartWare.All patients are issued a backup controller and spare batteries that they carry with them at all times. When transported to the emergency room, patients should be instructed to bring this equipment and contact information for their MCS center. Ideally, if time and the patient's condition allow, peripheral equipment, including the battery charger and alternating-current power charger, should be brought to the emergency department, particularly if the responding emergency/urgent care center does not have this equipment available (Table 2).Table 2. Equipment to Be Transported With PatientImplanting center informationBackup controllerBackup batteriesAC power sourceBattery chargerAC indicates alternating current.Ambulatory patients will present on battery support. Care providers should evaluate the remaining battery life as displayed on the battery "fuel gauge." When emergency care is requested in patients' homes, responders may find the patient connected to household power. Before transport, patients will need to be connected to battery support. Failure to switch the power will lead to pump stoppage.Controller Display ParametersOn the device controller, a display reports parameters that can be considered device "vital signs." These include the speed (revolutions per minute), power (Watts), and flow (liters per minute; Figure 2A and 2B and Table 3).Table 3. Normal ParametersRPMPower, WFlow, L/minPulsatilityHeartMate II8000–10 0005.0–8.04.0–7.05.0–8.0HeartWare Ventricular Assist Device2400–32003.0–7.03.5–7.0RPM indicates revolutions per minute.Download figureDownload PowerPointFigure 2. A and B, Display monitors.A, HeartWare Controller. Reproduced with permission from HeartWare. B, HeartMate II controller. HeartMate II, HeartMate 3, and St. Jude Medical are trademarks of St. Jude Medical Inc or its related companies. Reproduced with permission of St. Jude Medical. Copyright © 2017. All rights reserved.The device is adjusted by the implanting center to optimize LV unloading and to provide the best combined cardiac output (CO). The CO is contributed by both the MCS device and native heart flow. The speed remains fixed unless manually reprogrammed by the MCS center. The power required is measured and recorded. Typically, higher revolutions-per-minute speeds correlate with higher power. The flow is calculated with device-specific algorithms. The HeartMate II device displays an additional pulsatility index parameter, which reflects the change in device flow over the cardiac cycle.Comanagement of the Stable PatientLongitudinal care of patients with MCS requires a multidisciplinary team to manage comorbid conditions. The implanting center typically maintains close follow-up; however, referring physicians and other specialty providers (often in outlying locations) participate in the coordinated plan of care. All participating practitioners benefit from an understanding of the unique challenges in this patient population.Returning to NormalcyMany signs and symptoms of heart failure (eg, shortness of breath, paroxysmal nocturnal dyspnea, and fluid weight gain) abate fairly soon after surgery. Other symptoms may resolve over a longer period of time (eg, fatigue, poor energy level, and decreased strength).5 Thus, early mobilization and rehabilitation are important to a successful recovery. Aggressive physical and occupational therapy should begin as soon as possible after MCS surgery, and cardiac rehabilitation should continue beyond hospital discharge.6A patient's return to a normal life after discharge includes incorporation of MCS self-care (eg, changing power sources) into his or her daily routines. Family caregiver support is an important component of self-care. Family caregivers who are also trained to assist with troubleshooting alarms typically change driveline exit dressings and address potential equipment malfunctions.After discharge, patients with MCS adjust to performing activities of daily living (eg, bathing, dressing, sleeping, home management, and work) and engaging in leisure activities. Most patients identify bathing as a key component of normalcy. Submersion in a bathtub and swimming are prohibited with these electrically powered devices; however, the manufacturers have developed accessories that allow patients to shower once the driveline site has healed adequately. Sleeping requires planning so that equipment is set up in the bedroom and allows nighttime trips to the bathroom. Patients adapt to sleeping with the controller and finding comfortable positions for sleep, given the presence of the pump and drive line. In addition, resumption of work, more strenuous activities (including leisure activities), and sexual intimacy may be challenging.5,7Driving is also an important activity for many patients who undergo device implantation because it promotes independence, reduces caregiver burden, and facilitates social interaction. Patients cite the ability to drive as a major contributor to improved quality of life.8 Eligibility for driving should be determined by the individual center, taking into consideration the patient's recovery from debility and local laws. Factors to be considered are the potential impact of the sudden deployment of a supplemental restraint system (airbag) against a passenger or driver with an implanted device9 and the presence of an implantable cardiac defibrillator (ICD). Furthermore, the potential for sudden pump malfunction, change in level of consciousness, and driver distraction by alarms may pose a risk to the patient who is driving, passengers in the vehicle, and others on the road.AnticoagulationAnticoagulation with warfarin is required for all continuous-flow devices; however, the level of anticoagulation may vary by center, practice, and device type.10,11 Antiplatelet therapy with aspirin and often a second antiplatelet agent is necessary because of the threat of stasis, thrombosis, shear-induced platelet dysfunction, and hemolysis. Upregulation of platelet function is described with MCS and may contribute to long-term risk of thromboembolic events.12,13 In the case of subtherapeutic international normalized ratio, the necessity of bridging is patient specific and should be guided by the implanting center.Hypertension and HypotensionTitration of medical therapy to maintain a mean arterial blood pressure in the normal range is imperative to optimize forward flow and to prevent adverse events.6,8,14 Hypertension after ventricular assist device (VAD) implantation is common, and an increase in diastolic pressure with a continuous-flow device may exacerbate or lead to hypertension.15 Increased afterload decreases pump flow and increases the risk of neurological events and end-organ damage.6,8,14 Neurohormone-modifying agents such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-blockers, and mineralocorticoid receptor antagonists are used to decrease afterload, to improve pump function, and to potentially contribute to ventricular recovery. Diuretics are frequently prescribed to manage symptoms of right ventricular (RV) failure and fluid retention. Hydralazine/nitrates and phosphodiesterase type 5 inhibitors such as sildenafil and tadalafil may also be used for RV failure and pulmonary hypertension.16Renal FailureRenal insufficiency is common in end-stage heart failure. After MCS implantation, 67% of patients have been reported to experience improved renal function.17 Hemodialysis is complicated yet occasionally possible with special consideration of hemodynamics, anticoagulation, and volume assessment. Continuous veno-venous hemodialysis and inpatient intermittent hemodialysis are relatively common in the early postoperative recovery period. Similar outcomes in bridge-to-transplantation patients with a left VAD requiring hemodialysis and those not needing renal replacement therapy have been reported.18 The availability of outpatient hemodialysis centers with the capacity of offering outpatient therapy is essential for the patient with MCS to achieve hospital discharge after surgery, and renal failure requiring dialysis is often an impediment to hospital discharge. Successful peritoneal dialysis is reported but at this time is not routine practice.19Diabetes MellitusClose serum glucose control is essential to reduce postoperative infection and progressive diabetes mellitus-related end-organ dysfunction. Insulin requirements may change significantly when the patient develops increased functional capacity, appetite, and nutrient absorption. Poor glucose control influences a patient's transplantation candidacy.20Psychosocial, Behavioral, and Cognitive ProblemsPatients may be evaluated for MCS implantation as an outpatient or while hospitalized. Evaluation includes a rigorous clinical and psychosocial/behavioral assessment. Patients also learn more about their diagnosis and prognosis, MCS risks (eg, adverse events) and benefits (eg, lengthening life and improving quality of life), and reasonable alternatives and their associated risks and benefits. Patients, in turn, share their preferences for care, goals in life, and what they hope to gain from MCS therapy with their families and clinicians. The intention of informed consent is to document shared decision making.Debilitating psychiatric morbidity may be a contraindication to MCS. Patients with psychosocial, behavioral, cognitive, or other mental disorders who undergo MCS implantation may require referral for psychiatric medication management, counseling, or cognitive behavioral therapy.21Whether patients with MCS have psychosocial or behavioral comorbidities, they experience psychosocial challenges related to MCS self-care and returning home.7 Modifications to activities of daily living are required. Patients and caregivers can experience significant stress.22,23 Early after implantation, patients are often grateful for the device, but they may experience anxiety related to learning and implementing self-care and adapting to lifestyle changes after discharge.5 Over time, patients and caregivers gain confidence in their ability to perform MCS self-care and to incorporate lifestyle modifications into daily living.5 However, frustration and depression may occur, related to discomfort with carrying equipment, body image issues, loss of independence, and symptoms (eg, ongoing right-sided heart failure or new MCS-related symptoms). Caregivers may also feel burdened by the time and effort needed to assist patients with MCS with device-related care on a daily basis. A multidisciplinary plan involving medical and psychosocial care, including psychopharmacology and counseling, may contribute to positive outcomes for both patients and caregivers.Cardiac-related cognitive dysfunction often resolves after MCS, which may significantly improve the quality of life for the patient and family. In elderly destination therapy patients, dementia can become an issue, and follow-up cognitive assessment and treatment may be needed.24 If post-MCS cognitive dysfunction increases, patients may be at risk for dementia-related adverse events and poor outcomes, and caregivers may incur significant personal and financial burden (eg, placement of the elderly patient with MCS in a memory care unit).25Management of Chronic ComplicationsRV FailureDuring the investigation of decompensated MCS, RV failure must be in the differential because it remains the Achilles heel of LV mechanical support. The relationships of LV and RV geometry and LV-to-RV transit are important concepts in the MCS physiological system. RV failure may follow a variety of physiological conditions.First, elevated preload from volume overload or blood resuscitation, for example, increases wall stress and can lead to RV dilation and functional tricuspid regurgitation. Second, high device speeds can lead to high CO, which may cause increased venous return to the failing RV. Third, an underfilled LV may allow shifting or suction of the interventricular septum. In this case, the loss of septal contribution to RV contractility can lead to RV failure. Finally, increased RV afterload attributable to pulmonary hypertension and elevated transpulmonary gradient is a common cause of RV failure.25aProgressive RV failure is associated with tricuspid regurgitation, hepatic congestion, and peripheral edema. Transthoracic echocardiography may demonstrate RV dilation, hypocontractility, and septal shifting toward the LV. Inotropes to support RV function, pulmonary vasodilators to decrease transpulmonary gradient, or diuresis can be used in the short term to help the impaired and failing RV. If increased LV filling pressures are suspected (findings of hypertension or pulmonary edema), afterload reduction may improve RV function by augmenting forward flow. Phosphodiesterase type 5 inhibitors can be used in this setting to reduce pulmonary hypertension and to support the RV.26 In general, consultation with an MCS center is crucial in the assessment and treatment of RV failure in the patient with MCS.Aortic InsufficiencyAortic insufficiency is known to complicate ≈25% of patients with nonpulsatile MCS.27,28 The understanding of aortic insufficiency after MCS is evolving; however, continuous closure of the aortic valve is thought to be a central factor. Careful attention to outflow cannula orientation to prevent direct flow toward the aortic valve can minimize stress on the valve. For patients requiring long duration of support, aortic insufficiency may become a serious morbidity. Management of hypertension and intravascular volume optimization is important. If aortic insufficiency persists when these factors are controlled, further evaluation by the MCS center is necessary.BleedingWith continuous-flow devices, bleeding complications appear to be associated with additional factors beyond the level of anticoagulation.29–31 Factors contributing to bleeding include platelet dysfunction,32 acquired von Willebrand syndrome,33 and gastrointestinal bleeding related to arteriovenous malformations.30 Events most commonly seen are gastrointestinal bleeds and epistaxis.AnemiaAnemia, regardless of the cause, is associated with significant morbidity and mortality in patients with MCS.34 Transfusion of red blood cells can be detrimental for the bridge-to-transplantation patient, increasing anti-HLA antibodies and complicating eventual donor matching. Transfusion should be targeted to symptomatic patients only. Iron replacement can be done safely when indicated. Caution is suggested with the use of erythropoietin-stimulating agents because of their potential to promote thrombosis.HemolysisA baseline level of hemolysis occurs in patients with MCS and may be monitored by periodic laboratory studies (eg, urinalysis, plasma free hemoglobin, haptoglobin, and lactate dehydrogenase analysis).35 Baseline and serial measurements are helpful after changes in clinical status when obstruction or thrombosis is considered. Elevation of lactate dehydrogenase above the patient's baseline or 2.5 times the upper level of normal requires evaluation at an MCS center.36Pump ThrombosisThrombosis is a relatively frequent adverse event,37 with a reported incidence of 5.5% to 12.2% in patients with MCS.38–40 Thrombosis is associated with significant morbidity because device exchange is typically necessary. INTERMACS data indicate that 2-year survival after pump exchange or no history of thrombus is 56% and 69%, respectively.39 Factors that may contribute to thrombus formation are subtherapeutic anticoagulation, low pump speed, and elevated blood pressure.40 Elevation of lactate dehydrogenase can occur up to 3 months before clinically significant pump thrombosis. It is helpful to obtain a lactate dehydrogenase level during the evaluation of patient with MCS.38 When thrombus is suspected, management should always be coordinated with the MCS center.Neurological EventsStroke is a relatively frequent adverse event of MCS. Among all devices, an incidence of 11% is observed at 1 year and of 17% at 2 years.3 Risk factors for stroke in patients on left VAD support remain poorly defined. Because hypertension is a known major risk factor for ischemic and hemorrhagic stroke, postimplantation hypertension should be avoided (Table 4).Table 4. Stroke in Patients With a VADEvaluation of StrokeAssessmentPurposePT/PTT, INRGuide management of anticoagulationHead CT scanAssess severity and type of stroke (hemorrhagic vs ischemic)Doppler blood pressureManage hypertensionCTA of the neck and/or carotid Doppler (if not completed before LVAD insertion)Assess for alternative causes of strokeCT of the chest and CXRAssess device positioning (look for kinking of cannula or device obstruction)Neurology and/or neurosurgical consultationMake recommendations for stroke management (BP guidelines, surgical intervention if hemorrhagic, etc)BP indicates blood pressure; CT, computed tomography; CTA, computed tomography angiography; CXR, chest x-ray; INR, international normalized ratio; LVAD, left ventricular assist device; PT, prothrombin time; PTT, partial thromboplastin time; and VAD, ventricular assist device.Arrhythmia and Heart Rhythm ManagementVentricular ArrhythmiasVentricular arrhythmias occur in up to one third of patients with MCS.41,42 Although ventricular arrhythmias are generally well tolerated, prolonged ventricular tachycardia can contribute to low flow and ultimately end-organ dysfunction with increased mortality.41 The majority of patients with MCS have ICDs at the time of implantation, and appropriate ICD intervention occurs in up to 34% of supported patients.43,44 In this population, arrhythmias may be precipitated by ventricular collapse related to "suction events." After ICD discharge, assessment for a correctable problem (eg, hypovolemia, excess pump speed, electrolyte abnormality) can reduce the risk of recurrent shocks. Antiarrhythmic agents may be useful in decreasing arrhythmias and subsequent ICD firings, which have a significant impact on quality of life.45 Catheter ablation of unstable ventricular tachycardia has been successfully performed in patients on MCS.46Device InterrogationDevice (ICD and cardiac resynchronization therapy) function should be assessed postoperatively because displacement of the generator and leads during the surgery has been described.47,48 Electromagnetic interference is reported with some ICDs and implantable pacemakers, and telemetry function may be lost; however, the device continues to function normally.48 Most defibrillators and pacemakers do not interact and are safe to use after MCS. It is generally recommended that patients who have incompatible devices undergo implantation with an alternative compatible device.8,44 Successful ICD programming with an incompatible device has been described by shielding the ICD programmer or extension cable with aluminum or steel and by using a programming wand during interrogation.49 Because of the risk of ventricular arrhythmias after MCS therapy and the unique circumstances of the patient on MCS, multidisciplinary management including electrophysiology is important.InfectionInfection remains one of the most common causes of morbidity and mortality during VAD support. Currently, the incidence of device infection is roughly 30% at 3 years.3 The percutaneous lead exit site through the skin poses risk for infection; trauma is the leading cause because a break in the healing seal formed at the driveline exit site provides a portal for infection. Patients and their families are trained in the immobilization of the percutaneous lead, meticulous exit-site care, and the prevention of pulling or dropping the external device components to minimize device infections.8,50 Abdominal binders, additional gauze and tape, stoma-adhesive transparent dressings,8 and other securing devices are essential to reduce traction and infection of the driveline exit site. Exit-site dressing protocol and frequency vary from center to center.Emergency Patient AssessmentWhen a patients on MCS is unstable, the MCS center should be contacted immediately. Patients are issued center contact information and basic emergency protocols to assist first responders in rapid assessment and stabilization. Because family caregivers are knowledgeable about device function and emergency protocols, they should assist in emergency management until communication is established with the MCS center. The initial survey of an unstable patient should ignore the presence of MCS and begin with consideration of conditions such as arrhythmias, infection, or hypovolemia (Table 5).2 In addition, bleeding or thromboembolic complications need to be considered because patients with MCS are typically on anticoagulation.Table 5. Recommended Diagnostics for Assessment of Patients on Mechanical Circulatory SupportChemistriesCBCUrine analysisLDHPT/INRECGChest x-rayConsider pacemaker interrogationCBC indicated complete blood count; INR, international normalized ratio; LDH, lactate dehydrogenase; and PT, prothrombin time.Initial AssessmentDespite fixed revolutions per minute, the nature of the blood flow may be pulsatile or nonpulsatile, depending on the contractile reserve of the heart. Individual patients have a variable contribution to CO from the native heart and the device. This may change as a natural response to dynamic physiological conditions such as heart rate, circulatory volume, or vasodilation. If the device provides the majority of the CO, the aortic valve may open intermittently or not at all. No aortic valve opening is seen with severe LV dysfunction or high pump speed. In this circumstance, the arterial pulse pressure will be low, and the patient may not have a palpable pulse. Alternatively, with substantial native heart function or lower pump speeds, LV ejection will occur through the aortic valve. In this scenario, regular aortic valve opening and higher arterial pulse pressures are seen.A unique approach is necessary when a clinical assessment is performed. Because patients may not have a palpable pulse, standard assessment of vital signs such as blood pressure, heart rate, and pulse oximetry may be unreliable. Initially, an attempt should be made to measure the blood pressure with an automated sphygmomanometer. This will be possible ≈50% of the time51 because Korotkoff sounds may not be detectable because of low pulse pressure. Manual assessment with a Doppler ultrasound sphygmomanometer may be necessary to determine the pressure at which brachial artery blood flow resumes. Using Doppler requires special expertise and produces a single measurement that may represent the systolic blood pressure or mean arterial pressure (in situations when the pulse pressure is low). Current guidelines recommend maintenance of a mean systemic BP of <80 mm Hg (Class IIb, Level of Evidence C).52 For more acutely ill patients, telemetry and invasive hemodynamic moni
Referência(s)