Perioperative Hypertension: Evaluation and Management

1. Perioperative Hypertension:Evaluation and Management R3 이재우

2. I. Definition • Systemic Hypertension • systolic BP ≥160 mmHg diastolic BP ≥90 mmHg • Kaplan • " that level of BP at which the benefits minus the risks and costs (of action) exceed the risks and costs minus the benefits of inaction." • periop. period에는 end-organ damage의 예방에 BP control의 중점을 둬야 한다.

4. II. Incidence(1) • periop. hypertension • depends on the type of the patients studied and the operative procedure • HTN 병력이 꼭 periop. HTN이 risk factor는 아니다. • Risk factors of periop. HTN • Patients : • with poor BP control • recent development of moderate to severe HTN • treated with antiHTN drugs or other drugs(i.e. sedatives) • with certain problems(high spinal cord injury or thyrotoxicosis

5. II. Incidence(2) • OP procedure : • intracranial and spinal op • head and neck op. • major cardiovascular op • etc. • manipulation of trachea(i.e. endotracheal intubation) • inadequate or light anesthesia • hypoxia or hypercapina

6. III. Causes • idiopathic or essential HTN • 90-95% of HTN patients • secondary HTN • usually related to renal or endocrine abnormalities

8. IV. Clinical Implications (1) • Slogoff and Keats  • Pt. with a Hx. of HTN  → increased risk for myocardial events, stroke, and renal failure  • Goldman and Caldera  • the risk for hypertensive pts. who undergo anesthesia and surgical procedures.(of 431 pts.)  • normotensive preop. and not receiving any therapy   → 8% develop periop. HTN.  • no Hx. of HTN but receiving diuretics → 6%  • normotensive when taking antiHTN therapy → 27%  • hypertensive despite therapy → 25%  • untreated HTN → 20%

9. IV. Clinical Implications (2) • Charlson et al.  • mean arterial pr.가 preop. level에 비해 20% 혹은 20mmHg 이상 변화한채 지속되는 경우 complication(cardiac or renal)과 유의하게 관련이 있다.  • HTN의 병력을 가진 환자의 경우 preexisting end-organ disease를 가지고 있을 가능성이 높다.(LVH, athrosclerosis, ischemic cardiac and cerebral events, congestive heart failure, and pph. vascular insufficiency)

10. V. Monitoring Blood Pressure (1) • Noninvasive  • BP의 정확한 측정을 위해 cuff size가 적절해야 한다.  → 20% larger than limb diameter • manual measurement • using a blood pr. cuff, auscultating Korotkoff's sound.  • m/c outside the op. room • automatic measurement • oscillometric technique(the Dinamap)  • Doppler principle technique  • Finapres - infrared photoplethysmograph vol. transducer containing small finger cuff.  • risks • electric shock  • cuff deflation이 안될 경우 ischemia and nerve damage

11. V. Monitoring Blood Pressure (2) • Invasive measures  • in Pt. with cardiovascular, thoracic, neurologic, and traumatic disorders.  • labile BP or large vol. shift가 예상되는 수술의 경우.  • Cx. : hemorrhage, infection, thrombosis  • Allen's test : to confirm collateral circulation  • sites : radial and femoral (preferred)  * closer to the central circulation, the more real the BP is. 

12. VI. Therapy (1)  • General Principles  • anesthesiologist must first determine,   •  the desired level of BP  •  the urgency of Tx.  •  the presence and severity of preexisting end-organ damage  • in the preop. evaluation,   •  HTN emergency     → parenteral drug therapy와 reversible causes의 Mx.를 동시에 시행.  •  HTN urgency     → identify and treat reversible causes first. 

15. VI. Therapy (2) • essential HTN   • 대부분의 경우 diuretics와 β-blocker로 manage.    •  diuretics 사용시에는 K+store assessment monitoring 필요.  •  β-blocker   •   preop. period에 사용했던 환자의 경우 periop. period에도 지속.  •   → 중단시 periop. myocardial event risk↑  •   labetalol : excellent parenteral drug for periop. use.   * all β-blockers should be used with caution in pts. with any evidence of reactive airway disease.(d/t rare case of bronchospasm) 

16. VI. Therapy (3) • α2-agonist(clonidine)    •  monoamine oxidase inhibitors    •  calcium antagonists  • parenteral calcium antagonists(diltiazem, nicardipine) : good for periop. BP control.  •  ACE(angiotensin converting enzyme) inhibitors  •  adjuvants to control BP  •   regional anesthesia  •   analgesics  * NSAIDs  • preemptive analgesia 위해 많이 사용.  • but, ass. with intravascular pr.↑ and renal function↓

17. VI. Therapy (4) • Intraop. managements  • a calm, reassuring environment  • induction of anesthesia  • intratracheal lidocaine, nitroprusside, esmolol to attenuate the HTN response to laryngoscopy  • significant underlying diseases  • ineffective alv. ventilation, hypercarbia, triggering of malig. hyperthermia, pheochromocytoma crisis, hyperthyroid storm, hyperparathyroidism  • HTN during op.  • effective pain control이 중요.(esp. low-conc. inhalation or IV anesthesia)  • 일부 inhalation anesthetics(i.e. isoflurane, desflurane)의 경우 high conc.에서 BP↑. 

18. VII. Postoperative Concerns (1) • postop. HTN의 경우, 우선 comorbid factor를 manage한 후 안될 경우 pharmacologic Mx.   • preop. period에 사용하던 medication을 postop.에 restart.  • if NPO, control with parenteral drugs according to the level of BP.   

19. VII. Postoperative Concerns (2)

20. VIII. Conclusions (1)  • systemic HTN  • common morbid factor (present in one of five pts. coming to op. room) • HTN pt.의 경우 preop.에 end-organ dysfunction(cardiovascular, neurologic, renal)에 대한 evaluation이 꼭 필요.  • intraop. HTN 발생시 우선 hypoxia, hypercarbia, light anesthesia, comorbid factor들이 원인인지 R/O한 후 pharmacologic therapy를 고려한다. 

21. VIII. Conclusions (2) • intraop. HTN시 sodium nitroprusside, nitroglycerine, hydralazine등이 가장 많이 사용되며, β-blocker는 op.후에도 지속해서 사용 가능한 first-line drug이다.  • perianesthetic period동안 돌보는 환자들의 short-term and long-term outcome을 향상시키기 위해 마취의는 periop. HTN을 manage하기 위한 모든 Tx. modality들을 숙지하고 있어야 한다.