Post on 01-Aug-2020
Amy Gnagey RN, CRNA, MNA
At the end of this presentation the participant will be able to describe the hypothalamic‐pituitary adrenal axis.At the end of this presentation the participant will be able to discuss anesthetic considerations for 5 disorders related to the hypothalamic‐pituitary adrenal axis.
ROLE:Regulate cellular and organ functions with hormone messengers that affect target cell activityClosely regulated to maintain homeostasis
Three basic components:Endocrine GlandsHormonesTarget Organ
GLANDSHypothalamusPituitaryThyroid PancreasAdrenalThymusReproductive: ovaries and testes
HormonesClassified by their chemical structure
Protein or Peptide Hormones (e.g. insulin, glucagon, ACTH)Steroid Hormones (e.g. testosterone)Amino acid derivatives (catecholamines)
Structure dictates hormone receptor locationStructure influences half‐life of hormone
Control of hormone releaseNeural ControlHormonal Control
Nutrient or Ion Control
Abnormal Endocrine functionAbnormal production of hormoneDecreased receptor number or function
Interpretation of Hormone Levels
Pituitary Hormone Level
Target Hormone Level Low Normal High
HighPrimary failure of target endocrine organ
Autonomous secretion of pituitary hormone or resistance to target hormoneaction
Normal Normal range
Low Pituitary failureAutonomous secretion by target endocrine organ
HypothalamusNew “Master” gland
Pituitary GlandDuring embryonic development, forms from a fusion of endocrine and neural tissue
Pituitary GlandAdenohypophysis – anterior pituitary
ACTH – adenocorticotropic hormone or corticotropinGH – growth hormoneTSH – thyroid stimulating hormoneFSH – follicle stimulating hormoneLH – luteinizing hormoneProlactinMSH – melanocyte stimulating hormone
Neurohypophysis – posterior pituitaryOxytocinADH – anti‐diuretic hormone
Hypothalamus
Anterior Pituitary
GnRH GHRH SSTRH DA CRH
FSH and LH
Growth Hormone
TSHProlactin ACTH
GonadsGerm Cell Secrete HormonesDevelopment Female MaleFemale Male
Estradiol, Testos‐Ovum Sperm progesterone terone
Liver andOthercells
SecreteIGF‐1
Many organs and tissuesProtein
synthesis, carb. and lipid
metabolism
ThyroidSecretes thyroxine,
triiodothyronine
BreastsBreast dev. and milk
production.In males may facilitate
reproductive function
Adrenal cortexSecretes cortisol
Located in the neck, anterior to and straddling the trachea, just below the larynxProduces hormones
Thyroxine (T4)Triiodothyronine (T3)Calcitonin
Actions of thyroid hormonesMetabolic actions
Increases metabolic rateHeat production
Permissive actionsCatecholamines
Growth and developmentProduction of growth hormoneNerve/muscle reflexesNormal cognitionFetal life – CNS development
Located at the superior pole of each kidneyContains 2 endocrine organs
Adrenal medulla ‐‐‐ “fight or flight”Secretes Catecholamines
Epinephrine NorepinephrineDopamine
Adrenal Cortex Secretes Steroid Hormones
CortisolCorticosteroneAldosteroneAndrogens
Effects of Epinephrine and Norepinephrine Metabolic effectsIncrease alertness
Epinephrine ‐ anxiety and fearIncrease secretion of insulin and glucagonMyocardial effectsNorepinephrine – vasoconstrictionEpinephrine – total PVR drops
Zona glomerulosaZona fasciculataZona reticularis
Sodium retentionPotassium secretionMaintains intravascular volumeRenin‐angiotensin‐aldosterone system
Physiologic effectsIncreased protein catabolismIncreased hepatic glycogenesis and gluconeogenesisAnti‐inflammatory actionsAnti‐immune functions
In fetal and neonatal life:Proper differentiation of tissues and glandsSurfactant production
Physiologic effectsPermissive actions
For glucagon and catecholamines to exert their calorigenic effects For catecholamines to exert their lipolytic effectsFor catecholamines to produce pressor responses and bronchodilation
Resistance to Stress
4 year old boy109 cm, 18.6 kg6 month history of diaphoresis and reddening of skin as day goes onTachypnea and tachycardiaReferred to your facilityAny guesses???
Catecholamine‐secreting tumors Arise from chromaffin cells of the sympathoadrenal system80% located in adrenal medullaPotentially lethal
Malignant hypertensionCerebrovascular accidentsMyocardial infarctions
One of the few curable causes of hypertensionMost secrete norepinephrine alone or more commonly combined with smaller amount of epinephrine – ratio of 85/15
Signs and SymptomsTriad
HypertensionHeadacheSweating
PallorPalpitationsOrthostatic hypotensionCatecholamine‐induced cardiomyopathy may occur
DiagnosisUrine testing
Anesthetic Considerations –Preoperative α – adrenergic blockade
PhenyoxybenzamineAllows re‐expansion of intravascular volume
Delay β‐blockade until α‐blockade effectiveUnopposed α stimulation
Dangerous vasoconstriction, hypertensionβ‐blockade useful to treat dysrhythmias or tachycardia
Correct hypovolemia
Anesthetic Considerations Monitoring
Standard monitorsArterial lineCVP or PACUrinary catheter
FluidsLarge positive fluid balance is usually required to keep intravascular volumes within a normal range
Anesthetic Considerations – IntraoperativeOptimal preparation essentialGoals
Avoid drugs or maneuvers that provoke catecholamine release or potentiate catecholamine actionsMaintain cardiovascular stability
Anesthetic ConsiderationsAvoidDrugs that cause histamine releaseSympathomimetic or vagolytic drugsSuccinylcholine (fasciculations stimulate tumor, may stimulate autonomic ganglia)Agents that cause an indirect increase in catecholamine levels Anything that stimulates catecholamine release: fear, stress, pain, shivering, hypoxia, and hypercarbia
Anesthetic Considerations – IntraoperativePeriods of Greatest DangerHypertension/ArrhythmiasInductionIntubationSurgical incisionTumor manipulation/ abdominal exploration
HypotensionLigation of tumor’s venous drainage
Anesthetic Considerations – IntraoperativeHypertension
Sodium NitroprussidePhentolamineNicardipine
ArrhythmiaEsmololLidocaine
Anesthetic Considerations – IntraoperativeHypotension
Volume expansionPhenylephrineDecrease anesthetic depth
HypoglycemiaOccurs in 10‐15% of patientsMay need glucose infusion
18 year old maleSkateboarding injury
Complex left closed femur fractureUrgent, not emergent repairNervous, agitated, restlessVS: 160/90, HR 130, Temp 37.6C
Past Medical HistoryPolysubstance Abuse
ETOH THCTobacco
Endocrine Range Result
TSH, Sensitive 0.3‐5.0 mlU/L 0.01
Thyroxine, Total 5.0‐12.5 ug/dL 25.3
Thyroxine, Free 0.8‐1.8 ng/dL 10.3
Triiodothyronine 80‐190 ng/dL 627
Free T3 2.0‐3.5 pg/mL 27.5
Exaggeration of hyperthyroidism symptomsUnrecognized and untreated is fatalAdult mortality ‐ 10‐20%Abrupt onset of signs of hyperthyroidism from sudden release of T4 and T3
TachycardiaHyperthermiaAgitationSkeletal muscle weaknessCHFShockAbdominal PainGoiterHepatic Failure
AnxietyDeliriumPsychosisStuporComa NauseaVomitingDiarrhea
Treatmentβ‐blockerThionamide (propylthiouracil or methimazole)Iodine solution (SSKI or Lugol’s solution)Iodinated radiocontrast agent (not available in US)GlucocorticoidsInfusion of cooled crystalloid solutionsTylenolAvoid Aspirin
Displaces thyroid hormones from thyroglobulin and could aggravate the disease
ICU care
19 year old male3 week history of:
FatigueMuscle weaknessDizziness
Fainted this am when went out to exerciseFell down stairs – fractured humerus, requires ORIF
BP 95/60, P 110Skin: cool, dry, tannedLabs: Hct 36%, glucose 62 mg/dL, Na 120 mmol/L, K 6.7 mmol/L, Cr 1.4 mg/dL, BUN 36 mg/dL
Primary Adrenal InsufficiencyDestruction of the adrenal cortex, manifested by absence of cortisol and aldosteroneSigns and Symptoms
Hyperpigmentation over palmar surfaces and pressure pointsPsychiatric symptomsArthralgiasMyalgias
Primary Adrenal Insufficiency
Aldosterone DeficiencyHyponatremiaHypovolemiaHypotensionHypokalemiaMetabolic Acidosis
Cortisol DeficiencyWeaknessFatigueHypoglycemiaHypotensionWeight loss
Signs and Symptoms
Physiology
Preoperative tests: CBC, electrolytes, and glucose levelProvide corticosteroid supplementation for those patients that have been treated with corticosteroids for more than 1 month within the 6‐12 months prior to surgeryCortisol 25 mg IV at induction, then 25 mg every 4 hoursDaily maintenance dose should be given the day of surgery
ACTH dependentLoss of glucocorticoid functionIntact mineralocorticoid functionUncommon
Caused by hypothalamic/pituitary depression or absenceMost common formGlucocorticoid deficiencyCommonly caused by use of synthetic glucocorticoidsLack cutaneous hyperpigmentationMild electrolyte abnormalitiesACTH suppression from steroid treatment leads to adrenal atrophy
SurgeryActivation depends on:
Magnitude and duration of surgeryType and depth of anesthesia
Daily secretion estimated at 5 ‐ 10 mg/m 25 to 7 mg/day of oral prednisone 20 to 30 mg/day of hydrocortisone
Cortisol synthesis can increase under conditions of stress to 100 mg/m 2/day.
Surgical Stress Corticosteroid DosageMinorInguinal Hernia RepairColonoscopy
25 mg of hydrocortisone or 5 mg of methylprednisolone IV day of procedure only
ModerateOpen cholecystectomyHemicolectomy
50‐75 mg of hydrocortisone or 10‐15 mg of methylprednisolone IV day of procedure. Taper quickly over 1‐2 days to usual dose.
SevereMajor cardiothoracic surgeryWhipple procedureLiver resection
100‐150 mg hydrocortisone or 25‐30 mg of methylprednisolone IV day of procedure. Rapid taper to usual dose over next 1‐2 days
Hallman, MR, Head, DE, Coursin, DB, Joffe, AM. (2013). Chapter 26. When and Why Should Perioperative Glucocorticoid Replacement Be Administered? In Fleischer, LA (Ed.) Evidence Based Practice of Anesthesiology, 3e.
Schroeder, E & Wang, CCL (2013). Chapter 30 Adrenal Insufficiency. In McDermott, MT (Ed.)Endocrine Secrets. 6e.
High feverApathyConfusionAnorexiaNauseaVomiting
Untreated – coma, severe hypotension, or shock unresponsive to vasopressors may rapidly lead to deathUnder anesthesia: catecholamine‐resistant hypotension
HyponatremiaHyperkalemiaLymphocytosisEosinophiliaHypoglycemia
ManagementTreat aggressivelyDexamethasone 4 m g IVEmpiric treatment with IV hydrocortisoneIV hydrationGlucose
Anesthetic ConsiderationsGlucocorticoid replacementAvoid EtomidateUntreated AI and Emergency Surgery
Invasive monitoring (arterial line, CVC or PAC)IV corticosteroidsFluid and electrolyte resuscitationMinimal doses of anesthetic agents and drugs
26 y.o. female170 cm110 kgThin limbs, truncal obesityBuffalo hump
Problem = too much cortisolTwo types
Corticotropin‐dependent Cushing’s syndromePituitary adenomas
Corticotropin‐independent Cushing’s syndromeAdrenocortical tumors
Signs and SymptomsSudden weight gainMoon faceHTNGlucose intoleranceMuscle weakness
Anesthetic ConsiderationsPreoperative
Evaluate BP, electrolytes, blood glucose Positioning: consider osteoporosisChoice of drugs or anesthetic technique is not influencedSkeletal muscle weakness
Mechanical ventilationHypokalemia – influence response to NDMRs
Continuous cortisol infusions may be initiated intraoperatively