HTNPART- II

DR HITESH MOTWANI

DEPT OF ORAL & MAXILLOFACIAL SURGERY

What happens physiologically in a ptn. Sitting on a operating chair just prior to surgery

▪ Psychogenic factors, such as fright, anxiety, emotional stress, and receipt of unwelcome news.

▪ Two other factors are pain- sply. Sudden and unexpected pain and the sight of blood or surgical/dental instrument.

▪ These factors lead to the development of “fright or flight” response.

+ (vasopressin)

Activation of SNSActivation of HPA

axis

How to know whether the ptn is hypertensive or not

1. Symptoms

2. History : a. family history

b. drug history

c. social history

3. Physical examination : a. general

b. cardiovascular

c. fundus

Cause Examples

Drug causing Na+ retention indomethacine

Corticosteroids

Drug causing increased sympathetic

activity

Ephidrine

Drugs containing oestrogen Oral contraceptives

Drug interaction with antiHTN drugs indomethacine

▪ Investigations are needed in all ptn with HTN to detect any underlying cause, assess for the consequences of HTN, and test for other cardiovascular risk factor.

1. Urinalysis

2. Biochemistry: a. serum level of K+ ( 3.5-5.2 mEq/L)

b. level of Na+ ( 135-147 mEq/L)

c. level of urea and creatine ( 20-40 mg/dL) ( 0.5-1.4 mg/dL)

3. Lipids ( LDL= 100-160 mg/dL) (HDL >= 40 mg/dL)

4. ECG

How to know whether the ptn is hypertensive or not

Sokolow-Lyon criteria

How it affects US ( OMFS )

▪ The primary concern is that during the course of treatment, a sudden, acute elevation in blood pressure might occur, potentially leading to a serious outcome such as stroke or MI

▪ Two important questions should be answered before dental treatment is provided for a patient with hypertension:

1. What are the associated risks of treatment in this patient?

2. At what level of blood pressure is treatment unsafe for the patient?

▪ The American College of Cardiology and the American Heart Association have jointly published practice guidelines for the perioperative evaluation of patients with cardiovascular disease for whom noncardiac surgery of various types is planned.

▪ determination of risk includes the evaluation of three factors:

(1) The risk Imposed by The patient’s Cardiovascular disease,

(2) The risk imposed by the surgery or procedure, and

(3) The risk imposed by the functional reserve or capacity of the patient.

How it affects US ( OMFS )

▪ The ACC/AHA guideline recommendation are classified as follows:

▪ Class I: Benefits >> risk

▪ Class II: Benefits >= risk, and scientific evidence incomplete

▪ Class III: Risks >>benefits

Class I recommendations are as follows:

• Patients who have a need for emergency noncardiac surgery should proceed to the

operating room

• Patients with active cardiac conditions should be evaluated by a cardiologist and treated

according to ACC/AHA guidelines

• Patients undergoing low-risk procedures should proceed to surgery

• Patients with poor exercise tolerance (<4 metabolic equivalents [METs]) and no known

risk factors should proceed to surgery

Class II recommendations are as follows:

• Patients with a functional capacity >4 METs and without symptoms should proceed

to surgery

• Patients with a functional capacity <4 METs or those with an unknown functional

capacity scheduled for intermediate-risk surgery should proceed to surgery with heart

rate control

• Patients with a functional capacity <4 METs or those with an unknown functional

capacity who are scheduled for vascular surgery should proceed to surgery with heart

rate control

How it affects US ( OMFS )

Dental Management and Follow-up Recommendations Based on Blood Pressure

* Little and Falace’s Dental Management of the Medically Compromised Patient, 8th Edition

How it affects US ( OMFS )Drug Vasoconstictor interaction Oral manifestation Other considerations

Thiazide Diuretics None Dry mouth, lichenoid

reactions

Orthostatic hypotension; avoid

prolonged use of NSAIDs—

may reduce antihypertensive

effects

Nonselective Beta Blocker potential increase in blood

pressure (use maximum of

0.036 mg epinephrine)

Taste changes,

lichenoid reactions

Avoid prolonged use of

NSAIDs— may reduce

antihypertensive Effects

Combined Alpha and Beta

Blockers

Because both B1 - and B2 -

adrenergic receptor sites are

blocked, the potential for an

adverse interaction is present;

however, it is unlikely to occur

because of compensatory a-

adrenergic receptor blockade

Orthostatic hypotension; avoid

prolonged use of NSAIDs—

may reduce antihypertensive

effects

Angiotensin-Converting Enzyme

(ACE) Inhibitors

None Angioedema of lips,

face, tongue; taste

changes; oral

Burning

-- “--

a1-Adrenergic Blockers None Dry mouth -- “--

Direct Vasodilators None -- “--

Central a2 -Adrenergic Agonists None Dry mouth Orthostatic hypotension

Calcium Channel Blockers None Gingival hyperplasia

Choice of LA with/without vasoconstrictor

▪ Epinephrine has both beta 1 and beta 2 activity, it does not tend to dynamically increase blood pressure owing in part to beta 2 vasodilation.

▪ The hemodynamic alterations epinephrine very short duration less than 1 minute.

▪ Multiple studies with regard to local anesthesia and epinephrine confirmed that even though blood pressure and heart rate may have changed significantly, the mean arterial blood pressure (MAP) is unchanged.

▪ In evaluating the relationship between systemic resistance, blood flow, and pressure, it is the MAP that is important and not the diastolic or systolic blood pressure values.

▪ Epinephrine usually increases HR , Stroke Vol. , SBP , myocardial oxygen consumption, and cardiac automaticity but reduces DBP. Therefore, the MAP is relatively unchanged.

▪ There is a theoretical increased risk of LA toxicity because beta blockers can retard the hepatic oxidation of the local anesthetic by inhibiting hepatic enzyme activity. But, this noted drug interaction involves only the local anesthetic and not epinephrine.

▪ Niwa et al, demonstrated that infiltration anesthesia with epinephrine (45 ugepinephrine) and lidocaine can be carried out safely on patients with an exercise capacity of more than 4 MET.

Choice of LA with/without vasoconstrictor

▪ From the preceding studies, 3.6 - 5.4 ml of 2% lidocaine with 1:100,000 epinephrine (36 to 54 ug of epinephrine) appears to be tolerated in most patients with hypertension or other cardiovascular disease, and the benefits of the vasoconstrictor appear to outweigh potential disadvantages or risks.

▪ Conclusion: recommended maximum dosage of epinephrine in normotensive ptn.= 0.2 mg and in htn (<=180/110 mm hg) = 0.04 mg.

▪ In ptn. With severe form of htn (> 180/110 mm hg) use of LA with vasoconstrictorshould be avoided.

Choice of LA with/without vasoconstrictor

Epinephrine conc. Conc./ ml Max. does in ptn with CVD Max. does in normal ptn

1:80,000 0.0125 mg epinephrine/ml 3.2 ml 16ml

1:10,00,00 0.01 mg epinephrine/ml 4 ml 20ml

1:20,00,00 0.005 mg epinephrine/ml 8 ml 40ml

NB: max permissible dose of lidocaine with vasoconstrictor should not exceed 500 mg and without vasoconstrictor

not more than 300 mg

Management of emergency cases

▪ In diagnosed htn cases:

▪ Relative complication: M.I., stroke, increased blood loss

▪ Under LA: postural hypotension, incr. blood loss controlled by local methods

▪ Under GA: use of HYPOTENSIVE ANESTHESIA and other drugs to control htn and increased blood loss

▪ In undiagnosed case:

▪ Relative comp: M.I., stroke, increased blood loss via the surgical field

▪ If proper precautions are not taken while injecting la, may lead to inc. in BP, HR, due to the stimulation of beta receptors by the vasoconstrictor. Also at toxic levels of lidocaine, there is marked cvs depression and vasodilatation

Management of emergency cases

▪ Management of lidocaine toxicity :

▪ Most local anesthetic overdose self-limiting

▪ rarely any drugs other than oxygen be necessary to terminate a local anesthetic overdose.

▪ Management of epinephrine overdose

▪ Most instances of epinephrine overdose are of short duration little or no formal management is necessary.

▪ Terminate the Procedure If possible, remove the source of epinephrine. Stopping the injection does not remove epinephrine that has been deposited; however, release of anxiety induced endogenous epinephrine and norepinephrine is lessened

▪ Oxygen may be administered if necessary. The patient may complain of difficulty breathing. An apprehensive patient may hyperventilate. Oxygen is not indicated in the management of hyperventilation because it can exacerbate symptoms, possibly leading to carpopedal tetany

Management of emergency cases

Preferred Parenteral Drugs for Selected Hypertensive Emergencies

Stroke Nicardipine, labetalol, nitroprusside

Myocardial infarction/unstable angina Nitroglycerin, nicardipine, labetalol, esmolol

Acute left ventricular failure Nitroglycerin, enalaprilat, loop diuretics

Postoperative hypertension Nitroglycerin, nitroprusside, labetalol, nicardipine

Antihypetensive agent Intravenous Dose

Nitroprusside Initial 0.3 (ug/kg)/min; usual 2–4 ( ug/kg)/min;

maximum 10 ( ug/kg)/min for 10 min

Nicardipine Initial 5 mg/h; titrate by 2.5 mg/h at 5–15 min

intervals; max 15 mg/h

Labetalol 2 mg/min up to 300 mg or 20 mg over 2 min, then 40–

80 mg at 10-min intervals up to 300 mg total

Esmolol Initial 80–500 ug/kg over 1 min, then 50–

300(ug/kg)/min

Nitroglycerin Initial 5 ug/min, then titrate by 5 ug/min at 3–5-min

intervals; if no response is seen at 20 ug/min,

incremental increases of 10–20 ug/min may be used