高血压英文ppt精品课件anesthesia for patients with cardiovascular

Anesthesia for Patients with Cardiovascular Disease Vincent Conte, MD Clinical Assistant Professor FIU College of Nursing Nurse Anesthesia Program Cardiovascular Disease Cardiovascular diseases will be the most common diseases that you will have to deal with preop in your patients 50,000,000 will have Hypertension 22,000,000 will have Angina In all 25-35% of all your patients will have some type of Cardiovascular disease as a Co-existing disease preoperatively Cardiovascular Disease The next lecture is devoted to the most common Co-existing Cardiovascular diseases: Hypertension Ischemic Heart Disease Mitral Stenosis/Regurgitation Aortic Stenosis/Regurgitation Hypertension: The Silent Killer Hypertension By far, Hypertension is the MOST common form of cardiovascular disease you will encounter It is estimated that 20-25% of the population has Hypertension and that out of that number, between 15-20% are uncontrolled or not medicated for their condition Hypertension Hypertension is THE leading cause of death and disability in most Western countries and one of the leading causes of intraop and postop morbidity AND mortality Long standing hypertension accelerates atherosclerosis and hypertensive organ damage Hypertension It is a major risk factor for cardiac, cerebral, renal, and vascular disease Complications include MI, CHF, Stroke, Renal failure, Peripheral vascular Disease and Aortic Dissection (both thoracic and abdominal) The presence of Left Ventricular Hypertrophy (LVH) is an important predictor of cardiac mortality Hypertension Studies have demonstrated a DIRECT and continuous correlation between both diastolic and systolic blood pressures and mortality rates The definition of systemic hypertension is considered to be a consistently elevated diastolic BP 90-95 mm Hg and/or a systolic pressure greater than 140-160 mm Hg Hypertension Borderline hypertension is said to exist when the diastolic pressure is 85-89 mm Hg or the systolic is 130-139 mm Hg Even patients with borderline hypertension appear to be at some increased risk for cardiac complications Accelerated, or SEVERE hypertension (stage 3) is defined as a recent, sustained and progressive increase in blood pressure, usually with diastolic pressures in excess of 110-119 mm Hg Hypertension Severe hypertension is usually associated with acute renal dysfunction Malignant Hypertension (stage 4) is a true medical emergency associated with papilledema and frequently encephalopathy (210/120 mm Hg) Hypertension The mechanisms responsible for the pathology observed in hypertensive patients remain elusive but appear to involve: Vascular hypertrophy Hyperinsulinemia Abnormal increases in intracellular sodium and calcium in vascular smooth muscle and renal tubular cells Hypertension The increased intracellular calcium results in INCREASED arteriolar tone and consequently an elevated BP The increased intracellular Na+ impairs renal excretion of Sodium Sympathetic nervous system OVERACTIVITY and ENHANCED RESPONSE to sympathetic agonists is present as well Hypertension Hypertensive patients have OVER EXAGERATED responses to exogenous catecholamines so when treating HYPOTENSION in hypertensives, GO EASY because their response to these agents will be MORE than what is expected The same goes with anti-hypertensive agents; EXPECT EXAGERATED RESPONSES either way with their BP control How much is TOO much? At what point is it unsafe to proceed with a case in a hypertensive patient? This is a question that has been cause for strong debate among practitioners The general consensus is a diastolic BP of 110 mm Hg WITHOUT any type of treatment to see if the pressure will decrease How much is TOO much? Some practitioners will see an elevated BP (diastolic 110 mm Hg resting prior to any meds) and will give some Versed and Esmolol or Labetolol and see what their responses are Based on their response, if the BP comes down below the 110 mark, they will then clear the patient and proceed with the case How much is TOO much? This is actually contradictory to the American Society of Hypertension recommendations These recommendations state that if the resting diastolic BP is 110 mm Hg in a RESTING patient PRIOR to ANY PREMEDICATION given, that this patient demonstrates a SIGNIFICANT risk for intraop and postop complications and warrants their case being cancelled and a medical workup be initiated including rapid treatment to lower their BP ASAP Hypertension To prevent severe hypertension presenting the day of surgery, ALL anti- hypertensive meds should be continued prior to surgery with sips of water EXCEPT for diuretics Diuretics may be held the AM prior to surgery although this has never been proven to change the intraop or postop course History Preop history should examine: How long has the patient been hypertensive? What meds are being taken What end organ effects have resulted from the hypertension What other symptoms may be present (chest pain/pressure, etc.) History Questions should concentrate on: Chest pain/discomfort Exercise tolerance Shortness of breath Evidence of pedal edema Postural lightheadedness Syncope Claudication PE and Labs Preop evaluation should include: Auscultation (listen for an S4 from LVH; an S3 and rales from CHF; murmurs, etc.) Measurement of BP EKG (look for signs of LVH - means is long standing HTN; look for PVCs/PACs) CXR (signs of CHF; enlarged cardiac silhouette) Labs (creatinine/BUN for renal function; K+ from chronic diuretic therapy) Premedication Reduces Preop anxiety and is very important in hypertensive Versed, 2-4 mg excellent for preop medication If BP is slightly or moderately elevated, consider Clonidine 0.2mg Clonidine augments sedation, decreases intraop anesthesia requirements and reduces periop hypertension Premedication Drawback to Clonidine; is PO; takes about 20-30 min. to work For faster drop in BP for mild to moderate elevations, combine Versed with Esmolol (5-10 mg) and this will work in a matter of minutes BUT will wear off much more quickly than Clonidine and you will need more meds to control the BP, especially intraoperatively Monitoring Most hypertensives DO NOT require special intraop monitoring except for a BP cuff In severe hypertensives for emergency surgery, an A-line should be considered An A-line should also be considered if a moderate hypertensive is undergoing an extensive procedure that may involve large amounts of blood loss and fluid resuscitation Monitoring EKGs should be constantly monitored for signs of ischemia even when the patient is normotensive and especially during any episodes of hyper or hypotension Urinary output should be monitored in hypertensive patients with signs of renal insufficiency in procedures that are going to last for more than 2 hours Induction of Anesthesia Induction of anesthesia and endotracheal intubation are often periods of hemodynamic instability in hypertensive patients Up to 25% of patients may exhibit SEVERE hypertension following endotracheal intubation regardless of premedication Induction The duration of laryngoscopy should be as short as possible Also, intubation should be performed under deep anesthesia, of course avoiding HYPOTENSION while this is accomplished One of several techniques may be used before intubation to attenuate the hypertensive response Induction These techniques are: Deepening inhalation anesthesia for 5-10 min Administer a bolus of Fentanyl (2.5- 5mcg/kg) before intubation Administer Lidocaine 1.5mg/kg IV or Intratracheally Administer Esmolol 0.3-1.5mg/kg or Labetolol, 5-20mg Induction No one agent has been shown to be any more superior to any other in hypertensive patients Propofol, barbituates, benzodiazepines, and etomidate are all equally safe KETAMINE is contraindicated UNLESS it is administered after a dose of another agent, particularly a benzo or propofol Maintenance Agents Anesthesia may be safely continued with volatile agents (+/- N2O), a balanced technique (opiods + N2O + muscle relaxants), or Total Intravenous Anesthetic techniques (TIVA) Regardless of the primary maintenance technique, addition of a volatile agent or IV vasodilator allows more satisfactory intraop BP control Muscle Relaxants Any muscle relaxant can be used routinely with the exception of large boluses of Pavulon Pavulon can exacerbate hypertension through its vagal blocking effects and release of catecholamines Hypotension following doses of Atricurium or Mivacurium may be accentuated in hypertensive patients so you may want to avoid their use Vasopressors Hypertensive patients will display exaggerated responses to both endogenous and exogenous sympathetic agonists If vasopressor therapy is necessary, a SMALL dose should be administered first to see the initial response Intraop Hypertension Intraop Hypertension NOT responding to an increase in depth of anesthesia can be treated with a variety of parenteral agents: Nipride (0.5-10mcg/kg/min) NTG (0.5-10mcg/kg/min) Esmolol (0.5mg/kg over 1 minute) Labetolol (5-20mg) Propranolol (1-3mg) Hydralazine (5-20mg; usually 10mg initial dose) Cardene (Nicardipine) (0.25-0.5mg) Nifedipine (10mg sublingual) Intraop Hypertension Readily reversible causes such as: Inadequate depth of anesthesia Hypoxemia Hypercapnea should be excluded before initiating antihypertensive therapy Selection of an appropriate agent depends on severity, acuteness, cause of hypertension, baseline ventricular function, HEART RATE, and the presence of bronchospastic disease Intraop Hypertension B-blockers are good to use with nl LVF and an elevated heart rate but are CONTAINDICATED in patients with bronchospastic disease Cardene (Nicardipine) is preferable to use in patients w/ bronchospastic disease Nipride remains the MOST rapid and effective agent for treatment of mod. to severe hypertension Intraop Hypertension Hydralazine provides good and sustained BP control but may cause a reflex tachycardia that could induce ischemia in patients with co-existing CAD Labetolol is also an excellent agent because it is a combination Alpha/Beta blocker that will cause vasodilation and prevent the reflex tachycardia seen with it Postop Management Postop hypertension is common and should be anticipated in patients who have poorly controlled hypertension Hypertension in the recovery period is often multifactorial (pain, volume overload, bladder distention) IV Labetolol is particularly useful in the immediate postop period for control of hypertension in the recovery period Ischemic Heart Disease Ischemic Heart Disease Myocardial ischemia is characterized by a metabolic O2 demand that EXCEEDS O2 supply Ischemia can therefore result from a marked increase in metabolic demand, reduction in myocardial O2 delivery, or a combination of both IHD Common causes include: Atherosclerosis Severe hypertension Tachycardia Coronary arterial vasospasm Severe hypotension Hypoxemia Anemia Severe Aortic Stenosis or Regurgitation IHD By far the most common cause of myocardial ischemia is atherosclerosis of the coronary arteries The overall incidence of CAD in surgical patients is between 5% and 10% Major risk factors include hyperlipidemia, hypertension, diabetes, smoking, increasing age, male sex, positive family history, obesity, menopause, oral contraceptive use in smokers, sedentary life style, and what is called a “coronary-prone behavior pattern” IHD By age 65, the incidence of CAD is about 37% in men and 18% in women CAD may clinically manifest with symptoms of: Myocardial necrosis (infarction) Ischemia (angina) Arrhythmias (incl. Sudden Death) Ventricular dysfunction (CHF) IHD Three major clinical syndromes are generally recognized: Myocardial Infarction Unstable Angina Stable Angina Acute Myocardial Infarction AMI is the most serious complication of CAD with an overall mortality rate of 25% More than the deaths occur within the first hour and are thought to be due to arrhythmias CHF is the leading cause of death in hospitalized patients Unstable Angina Unstable angina is defined as: An abrupt increase in severity, frequency, or duration of anginal attacks Angina at rest New onset of angina (within the past 2 months) with severe or frequent (more than three per day) episodes Stable Angina Anginal pains that are stable in frequency, occurance and severity, and are predictably treated are characteristics of Chronic Stable Angina Chronic stable angina will convert to unstable angina unless causes and risk factors of chronic stable angina are addressed and lifestyle is altered Anesthetic Management REGIONAL ANESTHESIA: Although studies that can document the superiority of regional over GA are lacking, regional anesthesia is often a good choice for procedures involving the extremities, the perineum and possibly even the lower abdomen Decreases in BP following spinal or epidural anesthesia should be treated rapidly with small doses of either neosynephrine or ephedrine depending on the heart rate Anesthetic Management REGIONAL ANESTHESIA: Marked hypotension can usually be avoided by prior volume loading (0.5-1L) Hypotension not responding to Neo or Ephedrine may be treated with Epinephrine (2- 10mcg) Conversion of a regional to a GA is appropriate if the block is patchy and/or you are requiring more and more sedation and you are experiencing BP swings from oversedation alternating with overstimulation Anesthetic Management GENERAL ANESTHESIA: The same general principles that apply to patients with hypertension also apply to most patients with IHD However, the induction of patients with mod. to severe CAD (3-vessel disease or more, L main disease, EF 40%) requires some modification Anesthetic Management GENERAL ANESTHESIA: The goal of the induction is to have minimal hemodynamic effects, produce reliable unconsciousness, and provide sufficient depth of anesthesia for a smooth intubation w/o sudden spikes in BP Regardless of the agent used, these results are most consistently achieved by a slow, controlled technique Induction Induction with small incremental doses of the selected agent usually avoids the precipitous drop in BP seen with bolus techniques Titration of the induction agent first against loss of consciousness, then to an acceptable decrease in blood pressure allows individual variable response Induction Using this technique, sufficient anesthetic depth for endotracheal intubation can be achieved with less cardiovascular depression than that caused by the bolus technique Administration of a muscle relaxant and controlled ventilation ensure adequate oxygenation throughout induction Induction Endotracheal intubation is performed once sufficient anesthetic depth is reached OR arterial BP reaches its lowest acceptable limit BP, Heart rate, EKG, O2 Sat should be repeatedly assessed with each step of induction Induction Agents Selection of a specific agent is not critical for most patients Propofol, barbituates, etomidate, benzos, opioids, and various combos of the above drugs are used Ketamine is relatively contraindicated unless used in conjunction with other agents Induction Agents The combination of Ketamine and a benzodiazepine may be MOST useful in patients with poor LVF (EF30%) In these situations, though Etomidate is probably the superior drug to use when dealing with a patient with severely compromised myocardial function Induction Agents Then there is always the time-proven method of high dose narcotics This has been shown to have the least amount of cardiac depression in patients with mild to moderate ventricular dysfunction You need to reserve this technique, though, for the patients that you plan to leave intubated as your wake-up will be VERY unpredictable if not impossible! Induction In patients with severe Left Ventricular Dysfunction, a pure opioid induction has been shown to induce significant hypotension So, you are back to the etomidate in really sick patients as this will not cause ANY cardiac depression whatsoever Anesthetic Management One of THE MOST USEFUL tools when dealing with cardiac patients is a BIS monitor This allows the careful titration of any drug that you are using and you can tell when you have reached the point of amnesia w/o sacrificing BP control When you hit 60 or below, its GO TIME and you can safely proceed with your intubation and be assured that recall will not be an issue to have to deal with post op Anesthetic Management As you become more familiar with the BIS monitor, you will be surprised just how little anesthetic is needed at times to get below a reading of 60 It can be a significant enough discovery that it can change how you operate your whole practice, NOT just your approach to heart patients Sometimes even during a heavy MAC, you can see the reading drop below 60 for significant periods of time Maintenance Agents Most cardiac patients are managed with a combination opioid-volatile anesthetic technique Patients with an EF40% may be very sensitive to the depressant effects of the potent volatile agents In these patients, favor more narcotics than inhalational agents, or even periodic boluses of etomidate (or small doses of Ketamine) titrated to a BIS monitor reading during the case Maintenance In the patients with mild to moderate ventricular dysfunction and who can tolerate inhalational agents, they ALL have a very favorable effect on myocardial oxygen balance They are ALL potent coronary artery vasodilators and improve cardiac blood flow in a dose dependent relationship Maintenance A careful balance must be found, though, between their vasodilatory effects and their myocardial depressant effects Watching your BP, EKG and BIS w