Cardiac Output & Work PDF

Cardiac Output (CO) ·CO= HR · x SV volume of blood ejected 5L/min in one minute ~ Tachycardia THR -> ↓ time · · · Severe tachycardia A decrease in vagal in diastole -> ↓ ventricular will tone have a would decrease increase the myocardial perfusion in co heart rate -> ↓ diasto...

Cardiac Output (CO) ·CO= HR · x SV volume of blood ejected 5L/min in one minute ~ Tachycardia THR -> ↓ time · · · Severe tachycardia A decrease in vagal in diastole -> ↓ ventricular will tone have a would decrease increase the myocardial perfusion in co heart rate -> ↓ diastolic filling time -> ↓ cr 15/09/2022, 09:38 h ://a .b cam .c m/med- ch B cam .c m Ca di l g C e: Ca diac Pa ame e l/ca di l g / ide /ca diac- a ame e - f- h i l gic-f nc i n?inde =7 f Ph i l gic F nc i n 1/1 Cardiac Work } External work ( stroke work) is work done to eject blood under pressure. stroke work= SV×P } Internal work is work done to change shape of heart for ejection. Wall stress directly proportional to internal work } Both internal work and external work consume oxygen } } Wall motion abnormalities 3 Valvular dysfunction Too MUCH O2 will lead to an consumption infarct : men Po -> HOW TO ASSESS CONTRACTILITY ? } Pressure volume loops } Noninvasive like echocardiography } Vetriculography -> graph EF = (LVEDV – LVESV)/ LVEDV NORMAL – 60 ± 6% in page 14 Methods to measure CO } Fick principal } Thermodilution } Dye dilution } Ultrasonography } Thoracic bioimpedance oxygen electrical currents uptake , co , arterial (non invasive) in chest venous Pressure Volume Loop stic value Stroke vol · ventricle is empty . Authent open LEFT VENTRICULAR PRESSURE (mmHg) LEFT VENTRICULAR PRESSURE/VOLUME P/V LOOP END OF SYSTOLE Aurtic value 120 F closes Diastole starts E D 80 Aortic value open 40 ventricle is EMPTY A 0 50 B Filling END OF DIASTOLE Process C 100 150 Atrial contraction LEFT VENTRICULAR VOLUME (ml) LEFT VENTRICULAR PRESSURE (mmHg) EFFECT OF PRELOAD ESV End Systolic Volume save of hypo 1 2 e 3 Se dio vol. Preload EDVs VOLUME (ml) End diastolic volume EFFECT OF AFTERLOAD facilita LEFT VENTRICULAR PRESSURE (mmHg) ESV ESV 1 2 ESV R V P mejor 3 reduction of baseline after load S mejoria ES sea W a pt . w value . problem EDV VOLUME (ml) Su LEFT VENTRICULAR PRESSURE (mmHg) EFFECT OF CONTRACTILITY P S E contractilityPVR 1 VR 2 ES mejora no I 2 contracti 1 contractilidad buena - - - - Se inotropica da VOLUME (ml) QUICK QUIZ PRELOAD AFTERLOAD CONTRACTILITY ignacion Cardiovascular Reflexes } } } } } } } } Cardiac Output Regulation Valsalva Maneuver Baroreceptor Reflex Oculo Cardiac Reflex Celiac Reflex anesthesia Bainbridge reflex Cushing Reflex Chemoreceptor Reflex como en ejemplnesthesia - afecta? * Clinical Correlation: Effects of volatile anesthetics, local blockade and intravenous anesthetics. * Importance in the BP management during surgery. controlled by - Response Sympathetic to System Nervous demands for oxygen D's body . - if by a pt squeezing -> bag reservoir and 40mmHg Tachycardia Supra in for of pressure ->"blow a straw" 10 HAR Sec . offerent to eNS BD L supine or . maintain verbric. , sitting um anesthesia -> Passive is under from peripheral peripheral Motor Sterent · -> alsocated w xintraabd . · pressure - A From - in kicks -Helps to keep -cause in blood volume with BP at constant HR tot When vicevers -ex Donde los esta HR BO + , -> in MAP · · · normal full in BD mesentery Mean Arterial ex -65 Pressure is average arterial pressure throught one cardiac cycle Affected by do & SVR : systole Diastole Or Trauma 20 % , muscles orbital structures eye strabismus surgery for peds : procedures , - N When traction Trauma ex levels localizado by conjunctiva - , extraocular in sensory receptores ? decrease a Is I CNS . hemorrhage : I BP to W . surgery or laparas cop insufflated thorax abdomen abd organs When gas into aba or Sinus brady i -> ↓ Sinus arrhytmia ?? Reflex -atrial - - ilicited HRT when -role to is i an w in BP blood vol. in CO match blood vol ↑ . an i dt triggered by the heart in w . Venous return ex Spinal anotheria : w levels . below T4 ICP normal 5-15 stroke - ex - : massive mass - - midline shift effect - uncal - nerniation -subfulcine Det rhage herriation worse -herniation - - Regulates Respond - -It : to ex-Propofol leading ex - & hypoxia, it & Regional RR , CO Para and hypercarbia inhibit my to chondrial can to ph in acidosis , - - respiration lactate increase metabolic blood Slow >2 acdous hypovolemia Pacoz-partial estimate pressure O2 carbon exchange dioxide Blood Pressure: Systemic and Pulmonary Hypertension To be continued - DO2 = CO x Ca02 Si Hyb 12 x 1 34 x 1 34 x 1 x . . 14 . 1 es (15at) 100 % + = 1 (Pa02x0003) Blood Pressure } Blood flow is generally equal to cardiac output } Blood flow affected by pressure and resistance } Blood pressure: the force that is exerted by blood against blood vessel walls } Resistance depends on size of blood vessel and thickness (viscosity) of blood Blood pressure } Blood pressure is highest in large arteries will rise and fall as heart pumps } } } highest with ventricular systole lowest with ventricular diastole pulse pressure is the difference between the two Pulse Pressure } Resistance E pressure is controlled arterioles in the = SBD - DBP Resistance is highest in capillaries -> because capillaries are small How you regulate BP Control Control of blood pressure ↓ } Regulation of cardiac output } } } } } } contraction strength heart rate venous return skeletal muscles breathing rate Short Action Regulation -change that regulate occur BP to Long Term Regulation } ADH (antidiuretic hormone) promotes water retention water } Angiotensin II- in response to renin } signal (renin) produced by kidney- why? } drop in blood pressure } stimulation by sympathetic nervous system } sodium levels too low G Sodium ? Ander ! Renin angiotensin aldosterone system - - Control Resistance - Es BP - Atrial Natriuretic Peptide } Produced by the 0 atria of the heart. } Stretch of atria stimulates production of ANP. } } } contraryeffect Antagonistic to aldosterone and angiotensin II. Promotes Na+ and H20 excretion in the urine by the kidney. ↳ polynria Promotes vasodilation. Systemic Hypertension } What is hypertension?______________________ } } Up to 30% of adults Essential vs Secondary ↳ Secondary to another issue that No cause to correct } -> canlmay . Variety of causes/ risk factors are known } } } } } } } Western World sedentary lifestyle prevalent Smoking Obesity diet (excess sodium; cholesterol; calories in general) Stress Arteriosclerosis genetic factors in be corrected Classification Category Normal Systolic blood pressure (mm Hg) Diastolic blood pressure (mm Hg) <120 <80 Prehypertension 120-139 80-89 Stage 1 hypertension 140-159 90-99 Stage 2 hypertension ≥160 ≥100 Effects of Hypertension } heart has to work harder; left ventricle enlarges ↳ will i } or consumption atherosclerosis may affect coronaries ↳ dilate coronaries ; will I demand +Oz consumption } arteries as well (which have to work harder anyway) } deficient blood supply to other parts of body } damage to blood vessels accumulates } heart failure Chronic Effects Management of HBP } Lifestyle modification } } } } } Quit smoking adjust diet weight loss exercise Pharmacologic therapy } Reduce heart rate } calcium channel blockers } beta blockers Management of HBP Ø Pharmacologic } } } } therapy Diuretics reduce blood volume ACE inhibitors interfere with renin-angiotensin pathway Vasodilators (such as nitroglycerin) open up blood vessels (reduce resistance) If heart is actually failing, digitalis increases efficiency of heart muscle Anti-hypertensive drugs may be taken in combination Hypertensive Crisis -> nec ex } . : agresiv Mango accompained . headache Definition } Blood Pressure higher than 180/120 } Crisis if end organ damage present ¨ ¨ Encephalopathy can be late sign In pregnancy a diastolic higher than 109 emergency - · · } } w Urgency if no end organ damage present 1801128 ↓ symptoms Management } Drug choice dependent on history and previous usage is ! Read this - not exam but know ! Hypertensive Emergency - management Cause/manifestation Primary agents Cautions Comments Encephalopathy and intracranial hypertension Nitroprusside, labetalol, fenoldopam, nicardipine Cerebral ischemia may result from lower blood pressure due Lower blood pressure may lessen bleeding in intracerebral to altered autoregulation hemorrhage Risk of cyanide toxicity with nitroprusside Elevated blood pressure often resolves spontaneously Nitroprusside increases intracranial pressure Myocardial ischemia Nitroglycerin Avoid β-blockers in acute congestive heart failure Include morphine and oxygen therapy Acute pulmonary edema Nitroglycerin, nitroprusside, fenoldopam Avoid β-blockers in acute congestive heart failure Include morphine, loop diuretic, and oxygen therapy Aortic dissection Trimethaphan, esmolol, vasodilators Vasodilators may cause reflex tachycardia and increase pulsatile force of left ventricular contraction Goal is lessening of pulsatile force of left ventricular contraction Renal insufficiency Fenoldopam, nicardipine Tachyphylaxis occurs with fenoldopam May require emergent hemodialysis Avoid ACE inhibitors and ARBs Preeclampsia and eclampsia Methyldopa, hydralazine Magnesium sulfate Labetalol, nicardipine Lupuslike syndrome with hydralazine Definitive therapy is delivery Risk of flash pulmonary edema ACE inhibitors and ARBs are contraindicated during Calcium channel blockers may reduce uterine blood flow and pregnancy due to teratogenicity inhibit labor Pheochromocytoma Phentolamine, phenoxybenzamine, propranolol Unopposed α-adrenergic stimulation following β-blockade worsens hypertension Cocaine intoxication Nitroglycerin, nitroprusside, phentolamine Unopposed α-adrenergic stimulation following β-blockade worsens hypertension Hypertensive Emergency - management } Goal decrease by 20% } Consider placement of intrarterial catheter for close Line monitoring -> } a - Most common } } } } } } Sodium Nitroprusside Nicardipine Fenoldopam Esmolol Labetalol Clevidipine (cleviprex) –calcium channel blocker - new Management in Essential Hypertension } Pre Operative Evaluation } Determine adequacy of blood pressure control } Review pharmacology of drugs being administered to control blood pressure } Evaluate for evidence of end-organ damage } Continue drugs used for control of blood pressure Only diastolic BP above 110 is considered of concern ↳ } men Preoperative Considerations } Chronic hypertension is a cardiovascular, cerebrovascular, and renal risk factor => increased surgical risk } Intraoperative hypotension is more common in the hypertensive patient give fluid -> } Previous history of myocardial infarction increases the risk of re incidence, and neurologic complications (endarterectomy) Preoperative Considerations } Presume patient has ischemic heart disease } Presence of renal insufficiency marker of chronic widespread disease. } Look for: } } } } } orthostatic hypotension (autonomic response inhibition) angina pectoris left ventricular hypertrophy congestive heart failure cerebrovascular disease, stroke, peripheral vascular disease Preoperative Considerations } Continue Current BP medications } Rebound Hypertension } happen if BP are dic β-adrenergic antagonists and clonidine alpha } can antagonist Antihypertensive agents that act independently of the autonomic nervous system, such as ACE inhibitors, are not associated with rebound hypertension ↳ ACE S ARBS Alc prior surgery because ↓ BP * } Hypokalemia (<3.5) present in the patient with chronic use of diuretic DOES NOT increase the incidence of arrhythmias. Preoperative Considerations } Angiotensin-Converting Enzyme Inhibitors examen } risk of hemodynamic instability and hypotension during anesthesia in patients receiving ACE inhibitors. } ACE inhibitors may also decrease cardiac output by attenuating the venoconstrictor effect of angiotensin on capacitance vessels. } decreased venous return. ↳* First thing } examet } } hypotension give fluids & Surgical procedures involving major fluid shifts have been associated with hypotension in patients being treated with ACE inhibitors. } ↳ you will do in Responsive to fluid infusion and administration of sympathomimetic drugs. Hypotension resistant to such measures may require administration of vasopressin or a vasopressin analogue. ? Titration of anesthetic drugs may prevent or limit the hypotension attributable to ACE inhibitors. - - Consider discontinue ACE inhibitors 24 to 48 hours preoperatively in high risk cases in which intraoperative hypovolemia and hypotension may occur. Preoperative Considerations anesthessa bloquea esto Preoperative Considerations } Angiotensin Receptor Blockers } blockade of the renin-angiotensin-aldosterone system by ARBs increases the potential for hypotension during anesthesia. } Hypotension requiring vasoconstrictor treatment occurs more often. ↳ medications } In addition, the hypotensive episodes may be refractory to management with conventional vasoconstrictors such as ephedrine and phenylephrine, which necessitates the use of vasopressin or one of its analogues. } RECOMMENDATION: ARBs be discontinued the day before surgery. Management in Essential Hypertension } Induction and Maintenance of Anesthesia } Anticipate exaggerated blood pressure response to anesthetic drugs } Limit duration of direct laryngoscopy ↳ Will cause hypertension due to intubate in less than <15 sees supraglottic stimuli } Administer a balanced anesthetic to blunt hypertensive responses } Consider placement of invasive hemodynamic monitors ↳ } Monitor for myocardial ischemia ↳ I leads a line ! Induction and Maintenance } } } Rapidly acting intravenous drugs may produce significant hypotension due to peripheral vasodilation in the presence of a decreased intravascular fluid volume (Common in the Chronic HBP patient) Hypotension more pronounced in patients continuing ACE inhibitor or ARB therapy up until the time of surgery. Direct laryngoscopy and tracheal intubation can produce significant hypertension in patients with essential hypertension, even if these patients had been rendered due to supraglottic stimuli normotensive preoperatively. -> } High risk for myocardial ischemia Induction and Maintenance } To avoid hypertension during laryngoscopy / intubation consider: } deep inhalation anesthesia } injection of an opioid, lidocaine, β-blocker or vasodilator before laryngoscopy. - - } Ensure that direct laryngoscopy does not exceed 15 seconds in duration. Induction and Maintenance } Maintenance kee Stable BP } The hemodynamic goal \minimize wide fluctuations in blood pressure. } Management of intraoperative blood pressure lability is as important as preoperative control of blood pressure in these patients. } Regional anesthesia can be used in hypertensive patients. However, a high sensory level of anesthesia with its associated sympathetic denervation can unmask unsuspected hypovolemia. Induction and Maintenance } Maintenance: Intraoperative Hypertension } Most common cause noxious stimuli (awake !!) give more anesthesiax } Volatile anesthetics produce a dose-dependent decrease in blood pressure, which reflects a decrease in systemic vascular resistance and/or myocardial depression. } A nitrous oxide–opioid technique can be used for maintenance of anesthesia, although it is likely that a volatile agent will be needed at times to control hypertension, especially during periods of abrupt change in surgical stimulation. } Antihypertensive medication administered by bolus or by continuous infusion is an alternative to the use of a volatile anesthetic for blood pressure control intraoperatively. } No specific neuromuscular blocker has been shown to be best for patients with hypertension. ~ Morphine Induction and Maintenance } Maintenance: Intraoperative Hypotension } Decrease dose of anesthesia and/or increase intravascular volume. } Administration of sympathomimetic drugs (ephedrine or phenylephrine) } Intraoperative hypotension in patients being treated with ACE inhibitors or ARBs is responsive to administration of intravenous fluids, sympathomimetic drugs, and/or vasopressin. ↳ mimic the action of stimulators } Cardiac rhythm disturbances that result in loss of sequential atrioventricular contraction, such as junctional rhythm and atrial fibrillation, can also create hypotension and must be treated promptly -> mas volumen ?? listen audio Induction and Maintenance } Monitoring } } } } Influenced by the complexity of the surgery. ECG: signs of ischemia Pulse oxymetry Invasive monitoring } } } } intraarterial catheter central venous pulmonary artery catheter Transesophageal echocardiography Management in Essential Hypertension } Post Operative Management } control pain Anticipate periods of systemic hypertension } } } } - Requires prompt assessment and treatment to decrease the risk of myocardial ischemia, cardiac dysrhythmias, congestive heart failure, stroke, and excessive bleeding. Hypertension that persists despite adequate treatment of postoperative pain may necessitate administration of an intravenous antihypertensive medication. Promote reestablish patient’s usual regimen of oral antihypertensive medication. Maintain monitoring of end-organ function Pulmonary Arterial Hypertension (PAH) } Definition } } A mean pulmonary artery pressure of more than 25 mm Hg at rest with a pulmonary capillary wedge pressure, left atrial pressure, or left ventricular end-diastolic pressure of 15 mm Hg or less, and A pulmonary vascular resistance (PVR) of more than 3 Wood units. PVR = (PAP-PAOP) x 80 CO dynes/sec/cm-5 50-150 normal PVR = mmHg/L/min <1 normal PAP-PAOP CO Sodium NS = 152 eg/L 308 osmolarity -> ↳ Na2 RL = 130 - meq/ 4Kt Plasma osmolarily ↳ = -> 2400mmolarity + Lactate 215-255 2xNa+ contraindication + RL= men N lactic acidemia Pulmonary Arterial Hypertension (PAH) } Nomenclature based on etiologies (see table 5-10) } PAH } Idiopathic most common PAH COPD } PAH due to Left heart Disease } PAH due to Lung Disiease and/or Hypoxia } Chronic Thromboembolic Pulmonary hypertension Sickle cell } anena Pulmonary Hypertension with unclear multifactorial mechanisms Pulmonary Arterial Hypertension (PAH) } Presentation } Non specific signs } } } } } } } Right sided heart failure Fatigue Breathlessness Weakness Abdominal distention ascites Left recurrent laryngeal nerve paralysis (Ortner’s Syndrome- rare) - Extensive work up to exclude reversible causes } O Idiopathic PAH has median period of survival after diagnosis of 2.8 years. ⑧ Pulmonary Arterial Hypertension (PAH) } High Perioperative risk for: } RV failure } hypoxemia and coronary ischemia } 28% for respiratory failure } 12% for cardiac dysrhythmias } 11% for congestive heart failure } 7% for overall perioperative mortality for noncardiac surgery Pulmonary Arterial Hypertension (PAH) } Pathophysiology } } } } pulmonary vasoconstriction vascular wall remodeling thrombosis in situ. Vasoconstrictor–vasodilator response imbalance and proliferation– apoptosis imbalance ↳ } no se RV Failure } } } } - revierte + no look esta up echo para aquanter presion muche RV wall stress increases RV stroke volume reduced => LV volume reduced RV Dilatation results in annular dilation of right-sided heart valves, producing tricuspid regurgitation and/or pulmonic insufficiency RV myocardial perfusion can be dramatically limited as RV wall stress increases and RV systolic pressure approaches systemic systolic blood pressure => increase of ischemia Pulmonary Arterial Hypertension (PAH) } Hypoxemia } As right-sided pressures increase, right-to-left shunting can occur through a patent foramen oval; } The presence of a relatively fixed cardiac output, the increased oxygen extraction associated with exertion produces hypoxemia; } Ventilation/perfusion mismatch can result in perfusion of poorly ventilated alveoli. } hypoxic pulmonary vasoconstriction occurs, overall pulmonary hypertension will be worsened aprender X no Pulmonary Arterial Hypertension (PAH) - Med Para HTN pulmonar no dk se med - pa tiene rebound Pulmonary Arterial Hypertension (PAH) } Anesthesia Management } Medications should be continued throughout the perioperative period. } Continuous infusions of pulmonary vasodilators should be maintained. } Diuretics may be needed to control edema. } Caution with inhalational anesthetics or sedatives: can produce reduction of systemic vascular resistance and CO. Factors to and in PAH Pt on induction } Hypoxia, hypercarbia, and acidosis must be avoided. } Maintenance of sinus rhythm is crucial. } atrial ‘kick’ Pulmonary Arterial Hypertension (PAH) } Preoperative Preparation Induction } } } } } } Reduce PAD Consider sildenafil or l-arginine "enlarge/vasodilate Continue long-term pulmonary vasodilator therapy Inhalation of NO or prostacyclin should be available. Avoid respiratory acidosis due to sedation. Hyperventilation Ketamine and etomidate should be avoided. systemic Epidural anesthesia can be used - blood vessels allowing blood to - Short term vasodilator gotothelungs ↳ AVOID ↳ } Increase resistance close attention to intravascular volume and systemic vascular resistance in these situations. Pulmonary Arterial Hypertension (PAH) } Monitoring } } } CVP recommended Pulse oxymetry Maintenance } } } } } Inhalational anesthetics, neuromuscular blockers, and opioids, Avoid histamine release medications -> cause hypotens Hypotension can be corrected with norepinephrine, phenylephrine, or fluids. A potent pulmonary vasodilator such as milrinone, nitroglycerin, NO, or prostacyclin should be available. Avoid decrease in preload (hypovolemia) ? . Pulmonary Arterial Hypertension (PAH) } Post operative period } } } } High risk of sudden death in the early postoperative period because of worsening PAH, pulmonary thromboembolism, dysrhythmias, and fluid shifts. Monitor closely for hypotension and hypoxemia. Optimal pain control is an essential component of the postoperative care of these patients. Obstetric Considerations } } Forceps delivery decrease patient effort. Nitroglycerin should be immediately available at the time of uterine involution, because the return of uterine blood to the central circulation may be poorly tolerated in a parturient with PAH. (increase venous capacitance) Summary } Hypertension is a significant risk factor for cardiovascular disease, stroke, and renal disease. abruptly Do } Goal: <140/90 mm Hg. · · not stop ACE Inh ARBS 24 Blocker B DIC his 24-48 his before . } Preoperative evaluation of a patient with essential hypertension should focus on the adequacy of blood pressure control, the antihypertensive drug regimen, and the presence of target organ damage. } Despite the prevailing desire to render patients normotensive before elective surgery, there is no evidence that the incidence of postoperative complications is increased when hypertensive patients (diastolic blood pressure as high as 110 mm Hg) undergo elective surgery. Summary } Hypertension associated with end-organ damage does increase surgical risk. } Hypotension requiring vasoconstrictor treatment occurs more often after induction of anesthesia in patients receiving treatment with ACE inhibitors and ARBs than in those in whom such treatment has been discontinued on the day before surgery. } Direct laryngoscopy and endotracheal intubation may result in a significant increase in blood pressure in patients with essential hypertension. Due to supraglotic } PAH is hemodynamically defined as a mean pulmonary artery pressure of more than 25 mm Hg at rest. 1- arginine suldenafil Avoid Ketamine - Elomidate Summary examen } Smooth muscle hyperplasia, intimal fibrosis, medial hypertrophy, obliteration of small blood vessels, and neoplastic forms of endothelial cell growth called plexiform lesions are all part of the pathophysiology of pulmonary hypertension. } NO diffuses into vascular smooth muscle, where it activates guanylate cyclase, increasing intracellular cGMP; this reduces the intracellular calcium concentration, which results in smooth muscle relaxation. Summary } Calcium channel blockers, prostacyclins, NO, endothelin receptor blockers, and phosphodiesterase inhibitors are all pulmonary vasodilators that are useful in the treatment of patients with PAH. } All long-term pulmonary vasodilator therapy must be continued throughout the perioperative period. } In the perioperative period, the risk of right-sided heart failure or sudden death is significantly increased in patients with PAH. TO Be continued next Friday …… } Ischemic Heart Disease } Valvular Heart Disease } Congenital Heart Disease calcium channel contraind . blockers Heart Failure alter In y - contrary because contractility Milumove