Perioperative management of hypertension
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  • 1. Peri-operative management of hypertension Speaker Dr. Tipu Sultan Co-ordinator Dr.Chavi Sethi(M.D.)
  • 2. Peri-operative Hypertension Hypertension occuring in the pre-operative, intra-operative or post-operative period. Importance: Increased risk of cardiovascular events,e.g. myocardial ischemia Increased post-operative morbidity and mortality Association with end-organ damage such as renal failure.
  • 3. JNC-7
  • 4. Effects of Peri-operative hypertension CVS effects:  Increased BP→ ↑ afterload & myocardial oxygen demand → myocardial oxygen supply and demand imbalance.  Chronic ↑ BP → myocardial hypertrophy → myocardial oxygen supply and demand imbalance  Hypertrophied myocardium → decreased compliance → abnormal diastolic filling  Diastolic dysfunction especially apparent during stress, important during surgery and acute recovery interval
  • 5. CNS effects: Increased risk of stroke Impaired cerebral autoregulation Especially important in neurosurgical patients Effects on renal function Effective control of BP prevents renal dysfunction Intraoperative urine output monitoring for assessment of perioperative renal function
  • 6. Pre-operative concerns Preoperative evaluation important to identify patients with hypertension appropriate therapy. and initiate When to diagnose hypertension? Single reading of elevated BP in patient with previous undiagnosed or untreated HTN not reliable, subsequent readings in non-stressful environment required. (White Coat Hypertension)
  • 7. Stage 1 or stage 2 hypertension (systolic blood pressure < 180 mm Hg and diastolic blood pressure < 110 mm Hg) not independent risks for perioperative cardiovascular complications, hence cancellation not always justified. On initial evaluation, hypertension mild or moderate & no associated metabolic or cardiovascular abnormalities, do not delay surgery.
  • 8. Stage 3 hypertension (systolic blood pressure ≥ 180 mm Hg and diastolic blood pressure ≥ 110 mm Hg) should be controlled before surgery. More prone to perioperative ischemia, arrhythmias and cardiovascular lability, but no clear cut difference that deferring and anesthesia decreases perioperative risk. Patients with newly diagnosed mild hypertension, treatment may be delayed till after surgery.
  • 9. Management of anaesthesia in hypertensive patients: Preoperative evaluationDetermine adequacy of blood pressure control Review pharmacology of drugs being administered Evaluate for evidence of end organ damage Continue drugs used for control of blood pressure The incidence of hypertension and evidence of myocardial ischemia during maintenance of anesthesia is increased in patients who are hypertensive prior to induction of anesthesia. Also the magnitude of blood pressure decreases during anesthesia is greater in hypertensive than in normotensive patients.
  • 10. Preoperative history and examination End-organ damage Associated cardiovascular pathology Current anti hypertensive medications To be continued during perioperative period  Special care regarding β-blockers and clonidine  Patients with preoperative HTN, more likely to develop intra-operative inhibitors) hypotension. (ACE
  • 11. Preoperative β blockers: Controversial Proven to be beneficial in cardiac surgeries For non-cardiac surgeries good results in high-risk patients but not in low-risk patients (NEJM 1996, 2005) Associated with lesser incidences of perioperative ischemia  Intraoperative hypotension, precipitation of asthamatic attack, major disadvantage 
  • 12. Preoperative ACE inhibitors & AT-1 antagonists: Controversy regarding exaggerated hypotension As long as euvolumia, no hypotension Pts. with preoperative BP elevations; exaggerated intraoperative BP fluctuations & ECG evidence of ischemia. Preop. Control of BP; ↓tendency to perioperative ischemia.
  • 13. Controversy over when to delay surgery and at what BP to accept the patient  Individualize the patient Anaesthesiologists perogative Hospital protocol
  • 14. Induction and maintenance of anaesthesia: Anticipate exaggerated blood pressure response to anesthetic drugs Limit duration of direct laryngoscopy Administer a balanced anesthetic to blunt hypertensive responses Consider placement of invasive hemodynamic monitors Monitor for myocardial ischemia
  • 15. Intraoperative concerns Target range for intraoperative BP control: BP days to weeks before surgery Presence of associated comorbidity Type of surgery Maintained within 20% of the preoperative level Stressful intraoperative events: Intubation Surgical incision Emergence from GA and extubation
  • 16. Other causes of intra-operative hypertension: Inadequate depth of anesthesia Pain Hypercarbia Hypoxemia Bladder distension Hypervolumia Exaggerated response in hypertensive patients Increased sympathetic tone Decreased intravascular volume
  • 17. Methods to blunt the sympathetic response: IV Esmolol (1-2mg/kg, studies with lesser dose 0.4mg/kg) IV Lignocaine( 1.5 mg/kg, 90 sec before intubation/extubation) Short acting narcotics (Fentanyl 2-3µg/kg, sufentanil 0.3-0.5µg/kg) Increased concentration of inhalational agents (MAC-ei, MAC-bar-ei) IV NTG (1-2µg/kg, just before beginning laryngoscopy) IV Labetalol (5-20 mg boluses)
  • 18. Preoperative use of β-blockers or clonidine, smoothen intraoperative blood pressure course. Choice of anesthetic techniques and medications on the basis of presence of comorbid disease and type of surgery. (avoid ketamine) Hypertensive patients treated with diuretics or having LVH more susceptible to vasodilatory effects of inhaled anesthetics & neuraxial blockade
  • 19. Intraoperative Hypertension The most likely intraoperative hypertension produced by painful stimulation, i.e., light anesthesia. the incidence of perioperative hypertensive episodes is increased in patients with essential hypertension, even if the blood pressure was controlled preoperatively  Volatile anesthetics are useful in attenuating sympathetic nervous system activity responsible for pressor responses
  • 20. Monitoring Monitoring in patients with essential hypertension is influenced by the complexity of the surgery. Electrocardiography is particularly useful in recognizing the occurrence of myocardial ischemia during periods of intense painful stimulation such as laryngoscopy and tracheal intubation.  Invasive monitoring with an intra-arterial catheter and a central venous or pulmonary artery catheter may be useful if extensive surgery is planned and there is evidence of left ventricular dysfunction or other significant end-organ damage.  Transesophageal echocardiography is an excellent monitor of left ventricular function and adequacy of intravascular volume replacement
  • 21. Postoperative concerns Postoperative Hypertension: Arbitrarily defined as SBP>190 mm Hg and/or DBP≥100 mm Hg on two consecutive readings following surgery Implications: Risk of hemorrhage Disruption of vascular or cardiac suture lines Cerebral edema ↑ myocardial wall stress and oxygen consumption→ myocardial ischemia
  • 22. Causes: Preoperative hypertension Withdrawal of antihypertensive medications Pain Emergence delerium Hypoxia Hypercarbia Hypothermia Hypervolumia Type of surgery
  • 23. Management: Aggressive pain management Correction of previously mentioned causes Antihypertensive medications Parenteral  Rapid onset  Labetalol, hydralazine  Refractory or profound hypertension  SNP or NTG
  • 24.  Risk of General Anesthesia and in Hypertensive PatientsElective Surgery  Preoperative Systemic Blood Pressure Status Incidence of Perioperative Hypertensive Episodes (%) Incidence of Postoperative Cardiac Complications (%) Normotensive 8[*] 11 Treated and rendered 27 normotensive 24 Treated but remain hypertensive 25 7 Untreated and hypertensive 20 12 In hypertensive patients who exhibit signs of target organ damage, postponement of an elective procedure is justified if that end-organ damage can be improved or if further evaluation of that damage could alter the anesthetic plan.
  • 25. Isolated Systolic Hypertension (ISH) Systolic blood pressure>140 mm Hg with a normal diastolic blood pressure Prevalent in elderly population (steady increase in systolic pressure with age) Studies have described association between ISH and cardiovascular complications in non-cardiac surgery (Aronson et al, Franklin et al) No definitive studies for non-cardiac surgery
  • 26. Recent clinical trial and observational study data show closer association of systolic BP with CAD and stroke Vs diastolic BP Recommendations for aggressive treatment of ISH, especially in pts.> 65 yrs Further studies required to assess anesthetic risk
  • 27. Acute Hypertensive Crises Hypertensive emergencies, sudden increase in systolic and diastolic blood pressure associated with end organ damage of the CNS, the heart , or the kidneys. Hypertensive urgencies, acute end-organ damage. Malignant severely elevated BP without hypertension, syndrome characterized elevated BP accompanied by encephalopathy nephropathy by or
  • 28. SBP >169 mm Hg or DBP >109 mm Hg in a pregnant woman is considered a hypertensive emergency Majority are previously diagnosed for HTN, on irregular treatment The rate of rise more important than the absolute level
  • 29. Pathophysiology: Abrupt ↑ in systemic vascular resistance (humoral vasoconstrictors) Severe elevations of BP→ endothelial injury → fibrinoid necrosis of the arterioles → deposition of platelets and fibrin → breakdown of the normal autoregulatory function.  Resulting ischemia → release of vasoactive substances
  • 30. Hypertensive crises Hypertensive encephalopathy Acute aortic dissection Acute pulmonary edema with LVF Acute myocardial infarction/unstable angina Eclampsia Acute renal failure Pheochromocytoma crisis
  • 31. Clinical features: Those of end organ damage Hypertensive encephalopathy (headache, altered consciousness, CNS dysfunction)  Retinopathy (blurring of vision)  CVS (angina, acute MI)  Cardiac decompensation  Renal (renal failure with oliguria and/or hematuria) 
  • 32. Management of Hypertensive crises Hospital Care (urgencies), ICU care (emergencies) Invasive BP monitoring for emergencies Lower the BP + stabilize and reverse the damage to target organs Sodium restriction and diuretics if fluid overload Parenteral anti-hypertensives (emergencies), oral/parenteral (urgencies)
  • 33. Drugs Dosage  Diazoxide IV injection of 1 to 3 mg/kg to maximum of 150 given over 10 to 15 min; may be repeated if inadequate response.  Enalaprilat IV injection of 1.25 mg over 5 min every 6 h, titrated by increments of 1.25 mg at 12- to 24-h intervals to a maximum of 5 mg every 6 h.  Esmolol Loading dose of 500 µg/kg over 1 min, followed an infusion at 25 to 50 µg/kg/min, which may increased by 25 µg/kg/min every 10 to 20 min the desired response to a maximum of 300µg/kg/min. mg by be until
  • 34.  Fenoldopam maximum An initial dose of 0.1 µg/kg/min, titrated by increments of 0.05 to 0.1 µg/kg/min to a of 1.6 µg/kg/min.  Labetalol Initial bolus 20 mg, followed by boluses of 20 to mg or an infusion starting at 2 mg/min; cumulative dose of 300 mg over 24 h.  Nicardipine 5 mg/h; titrate to effect by increasing 2.5 mg/h every 5 min to a maximum of 15 mg/h.  NTG Infusion @ 5 µg/min, increase by 5 µg/min 5 min 80 maximum every 3-
  • 35.  Nitroprusside 0.5 µg/kg/min; titrate as tolerated to maximum µg/kg/min.  Phentolamine 1- to 5-mg boluses; maximum dose, 15 mg. of 2  Trimethaphan 0.5 mg/min. 0.5 to 1 mg/min; titrate by increasing by mg/min as tolerated; maximum dose, 15