HYPERTENSION GENERAL MANAGEMENT AND ANAESTHESIA

MANAGEMENT

“A man is as old as his arteries”

BY ABAYNEH BELIHU GELETA AKSUM UNIVERESITY

OUTLINES

Pertinent Complications General overview of the

managementAnesthesia management

Preoperative htn & managementIntraoperative htn & managementSelection of drugs Intraoperative monitoringPostoperative htn & management

TREATMENT

1.Lifestyle modification2.Pharmacological treatment

1. Life style modification

Weight reduction Maintain normal body weightAdopt DASH eating plan Consume a diet rich in

fruits, vegetables, and low fat dairy products with a reduced content of saturated and total fat.

Dietary Na reduction Physical activity Engage in regular aerobic PA

such as brisk walking (at least 30 min per day, most days of the week).

Moderation of alcohol Limit

Cont…

MODIFICATION APPROX. SBP REDUCTION

Weight reduction 5 – 20 mm of hg /10 kg weight loss

Adopt DASH eating plan 8 – 14 mm of hg

Dietary sodium reduction 2 – 8 mm of hg

Physical activity 4 – 9 mm of hg

Moderation of alcohol consumption 2 – 4 mm of hg

2. PHARMACOLOGIC THERAPY

GOALS OF THERAPY• Reduce CVD & renal morbidity & mortality• Treat to BP <140/90 mmHg or BP<130/80

mmHg in pt. with diabetes or chr. Kidney ds.• Achieve SBP goal especially in persons > or

equal 50 yr. of age

PHARMA CONT…

Drug therapy has been shown to reduce the progression of htn, and the incidence of stroke, CHF, CAD, and renal damage + reversal of concomitant pathphyl ∆ , such as LVH and altered CAR.

Most patients with mild htn require only single-drug therapy, which may consist of a thiazide diuretic, ACEI, ARB, ßAB, or CCB.

Cont…

The Joint National Committee on Hypertension (USA) recommends low doses of a thiazide diuretic for most patients.

However, concomitant illnesses should influence drug selection.

-AP-D+BB+ACEI+CCB -DM-D+BB+ACEI+ARB+CCB -RS-D+ACEI -HF=D+BB+ACEI+ARB+ARA -PMI=BB+ACEI+ARA -CRD=ACEI+ARB

CONT… ACEI is considered an optimal first-line

choice for patients with LVD or HF, whereas an ACEI or ARB is considered an optimal initial single agent in the setting of hyperlipidemia, CRD, or DM (particularly with nephropathy).

BB or, less commonly, CCB is used as a first-line agent for patients with CAD.

ACEIs, ARBs, and ßAB are generally less effective than diuretics and CCB in black patients.

Cont…. Treatment guidelines recommend a diuretic

with or without -adrenergic blockade or CCB alone for elderly patients.

Patients with moderate to severe hypertension require a second or third drug.

Diuretics are often used to supplement ßAB and ACEIs when single-drug therapy is ineffective.

ACEIs have been shown to prolong survival in patients with CHF or left ventricular dysfunction.

Cont…

In addition, these agents appear to preserve renal function in patients with diabetes or with underlying renal disease.

Familiarity with the names and mechanisms of action of commonly used antihypertensive agents is important for anesthetists.

HYPERTENSIVE EMERGENCY & PARENTRAL DRUGS

Hypertensive encephalopathy Nitroprusside,nicardipine,labetalol,

Malignant HTn Labetalol , nicardipine,nitroprusside,enalaprilat

stroke Nicardipin,labetalol,nitroprusside

MI/unstable angina Nitroglycerin,nicardipine labetalol,esmolol

Acute left ventricular failure Nitroglycerin,enalaprilat,loop diuretic

Aortic dissection Nitroprusside, esmolol, labetalol

Adrenergic crisis Phentolamine, nitroprusside

Postoperative HTn Nitroglycerin, nitroprusside,labetalol,nicardipine

Preeclampsia/ eclampsia Hydralazine,labetalol,nicardipine

ANAESTHESIA MX

WHY HEADACHE?• Common disorder• High risk factor for CVD• End organ damage – Heart, Brain &

Kidney• Alteration in cerebral & renal blood

flow

GOALS

• Preanesthetic evaluation• Perioperative risk reduction• Premedication• Balanced anesthesia• Proper monitoring• Parenteral medications

Preoperative Considerations

Htn is a leading cause of death and disability in most Western societies and the most frequent preoperative abnormality in surgical patients, with an overall prevalence of 20–25%.

The presence of LVH in htnsive patients may be an important predictor of cardiac mortality.

Increased cardiac mortality has also been reported in patients with carotid bruits—even in the absence of symptoms.

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Perioperative risk reduction

• Effective control of blood pressure

• Anti Hypertensive drug therapy

• Hydration

• Choice of anesthetic agent

• Adequate analgesia

• Miscellaneous

Cont…

Surgical Risk for Hypertensive Patients Fortunately, data available indicate that at least

patients presenting with mild or moderate hypertension can safely undergo surgical procedures.

In a landmark study of 1,001 patients undergoing non cardiac operations, preoperative evaluation detected 280 with current or past elevated blood pressures (Goldman L,Caldera DL,Nussbaum SR,et al: Multifactorial index of cardiac risk in non cardiac surgical procedures. NEnglJ Med1977;297:845-850)

Although several other criteria predicted a perioperative cardiac event, in multivariate analysis, hypertension did not.

Cancelectomy vs proceedectomy • Drug-controlled htn is not a contraindication

to GA. • Medication should be maintained throughout

the operative period as there is a risk of rebound htn causing a cerebrovascular accident.

• Also, a sustained rise in EDP reduces the inflow of blood to the myocardium during diastole.

• Untreated htn discovered at the preop anaesthetic asst necessitates a systematic approach.

Cont…

The following algorithm is one possibility. Three diastolic blood pressure readings are taken.

If the average value is: 1.>120mmHg:

• cancel the operation.• Admit, investigate ,and treat the htn .• reschedule once the BP is controlled for 4-6

weeks time. 2.105-115mmHg with signs of end-organ

damage: follow the same course as for BP>120mmHg

CONT…3.105-115mmHg without signs of end-organ

damage:– continue with operative plan– Consider preop Rx with an oral ßAB, e.g. atenolol, or alpha-2-agonist, e.g.

clonidine• A BP of, for example, 240/80 mmHg in an

elderly patient may be due to arteriosclerosis.

• It is important to avoid perioperative hypotension in these patients as they need an elevated BP to maintain tissue perfusion.

Physiology: Perioperative HTN

• Increase SVR , increase preload• Rapid intravascular volume shifts• Renin angiotensin activation• Adrenergic stimulation (cardiac &

neural)• Serotonergic overproduction• Baroreceptor denervation• Altered cardiac reflexes• Depth anesthesia inadequate• Cross clamp

Preoperative htn

Assess BP & review the patient's medical records

Patients may be anxious, fearful, in pain, all of which can induce a "physiologic" increase in BP not representing true htn.

put the patient at ease With reassurance and a calm environment, relieving pain if it exists, then repeating the BP measurement.

The basic principles of BP msmt, such as the use of a proper sized cuff, must not be forgotten.

Cont… Transient htn only on admission may not need

specific antihtnsive therapy, this finding alone does indicate a propensity to become htnsive during anesthesia and surgical therapy and should alert those caring for the patient to be prepared for the possible need to treat excessive rises in BP.

Particularly for patients undergoing a serious surgical procedure, BP is often monitored directly through an intra-arterial catheter beginning immediately before anesthesia and continuing into the early postop course.

Cont…

• Rapid ∆BP are detected and obviates the possibility of inaccurate cuff msmts due to Body habitus or upper extremity vascular rigidity.

• ßAB in those expected to tolerate such therapy Well may offer a particular advantage in smoothing Intraoperative hemodynamics.(Bedford RF, Feinstein B: Hospital admission blood pressure: A predictor for hypertension following endotracheal intubation.Anesth Analg1980;59:367-370)

Etiology

• Intubation htn• Inadequate anesthesia• Hypercapnia• Hypoxemia• Pharmacological adjuvants• Phaeochromocytoma• Surgical procedures• Bladder distension• Extubation htn• PIH

Intubation hypertension

• Laryngoscopy & intubation are known causes of htn.

• It is severe if laryngoscopy is prolonged.(3rd year)

• Can be minimized by pre administration of lignocaine.

Inadequate anaesthesia

• Stimulation during inadequate ansth.

• The depth of anaesthesia can be monitored by BIS

• Tachycardia, sweating, grimacing, tears and movement indicate inadequate anesthesia

• Beware of empty vaporizers.

Hypercapnia• Increased sympathetic stimulation causes htn• Watch out for: Inadequate TV Depleted soda lime Disconnection of circuits Inadequate fresh gas flow• Malignant hyperthermia and thyrotoxicosis• Exogenous admn of CO2 during laproscopic

procedures

Hypoxemia

• Hypoxia increases CO• In severe hypoxia the SBP is raised• Severe systolic htn is a very late

sign of hypoxemia and indicate complete circulatory collapse.

Pharmacological adjuvants

• Inotropic & vasoconstrictor agents• LA containing adrenaline if injected

IV.• Nasal packing• Medication errors

Surgical procedures• Aortic cross clamping• Aortic valve replacement• Carotid endarterectomy• PDA ligation

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Plan of anesthesia

• to maintain an appropriate stable BP range

• Those with long standing or poorly controlled BP have altered CAR; higher than normal mean BP may be required to maintain adequate CBF

• Arterial BP should generally be kept within 20% of preop level

premedication

• Premedication reduces preoperative anxiety & is highly desirable in hypertensive pt.

• Mild to moderate HT often resolve following administration of anxiolytic agent

• Preoperative antihtnsive agent should be continued, can given with small sip of water

• Central alpha 2 adrenergic agonist (clonidine 0.2 mg)can be useful adjuncts for premedication

MONITORING

• Most htnsive pts do not require any special intraop monitors

• Invasive BP monitoring should be reserved for pt. with wide swing in BP & for those undergoing major surgical procedure associated with rapid or marked change in cardiac pre & after load.

• ECG monitoring should focus on detecting signs of ischemia

• UOP with indwelling catheter in pt. with renal impairment or duration of surgery is >2 hr.

induction

• Indcn & intn are often period of hemodynamic instability for htnsive pt.

• Many htnsive pt. display an accentuated hnsive response indcn of anesthesia, followed by exaggerated htnsive response to intbtn

• The laryngoscopy, should be short , smooth & gentle.

• Intubation should be performed under deep anesthesia.

Cont…

• Attenuate hypertensive response b4 intn by;

-deepening anesthesia with potent VAA. -opioid (fentanyl 2.5-5mmg/kg; alfentanyl

15-25 mmg/kg; sufentanyl o.25-0.5 mmg/kg ; or ramifentanyl 0.5-1mmg/kg)

-lidocaine 1.5 mg/kg IV OR intratracheally

-Achieving ßAB with esmolol 0.3-1.5 mg/kg; propranolol 1-3 mg; or labetalol 5-10 mg

-Using topical airway anesthesia.

Cont…

• Induction agentspropofol , barbiturates,

benzodiazepines and etomidates are equally safe for induction of GA in htnsive pt.

ketamine may be use in htnsive by blunting its sympathetic stimulation activity by other agents.

Maintenance

may be safely continued with VAAa balanced technique( opioids +

nitrous oxide + muscle relaxant)TIVAOpioids esp.sufentanyl may provide

greater autonomic suppression & control over BP

Muscle relaxation

• any NMBA can be used except panc.• hypotension following large doses of

tubocurarine ,metocurine,atracurium or mivacurium may be accentuated in htnsive pt.

Vasopressor

• if use is necessary direct acting agent (phenylephrine 25-50mmg) may be preferable to indirect acting agent

• Small dose of ephedrine (5-10 mg) are more appropriate when vagal tone is high.

POSTOP HTN

Although patients with htn engender the Concern already discussed of ischemia during a surgical procedure, it is during the hours and first few days after an operation that most episodes of surgically related MI occur.

Several factors may contribute to this risk, including oxygenation problems, tachycardia, and altered thrombotic potential, but prominent is htn.

Htn directly raises the myocardial oxygen demand. In the presence of CAD, this demand may not be able

to be met. Postop htn may also cause a ventricle With systolic

dysfunction-for which chronic hypertension is a risk factor to fail and result in PE.

Cont… Diastolic dysfunction from a "stiff,“ often

hypertrophied, ventricle resulting from chronic htn may lead to intolerance of tachycardia, often seen postop coz of inadequate ventricular filling time, resulting in HN and inadequate CO.

postop control of the BP is almost always feasible i.e careful and frequent monitoring after a surgical procedure, often using an intra-arterial catheter for direct and continuous monitoring and evaluating the patient for possibly reversible contributing causes of the htn.

CONT… pain and other discomfort, anxiety and fear,

hypercarbia, and volume overload. Newer approaches toward pain management, such

as epidural narcotic infusion, may be useful in patients with postoperative pain.

If these factors are corrected as much as possible and the patient remains HTNsive, additional pharmacologic intervention will almost certainly achieve normotension.

Medical antihtnsive therapy is especially likely to be needed for patients who are Htnsive preop, whether or not the htn had been controlled.

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