anesthesiafor)achild)with)congenital)heart disease) • milrinone)(pdi)) _ increaseof...

Anesthesia for a child with congenital heart disease

Congenital heart disease

•  CHD is the most common birth defect, occurring in approximately 1/125 births, 90% survive to adulthood.

•  Extracardiac anomalies requiring surgery withing the first year of life are present in 30% of paIents.

•  Children with CHD undergoing norcardiac surgery are at increased risk of perioperaIve morbidity and mortality compared with other children.

•  Majority of cardiac arrest occur during noncardiac surgery.

•  75% of the paIents were under two years old.

•  75% of deaths accounted for by three disInct defects: aorIc stenosis, cardiomyopathy and single ventricle lesions.

PreoperaIve evaluaIon

•  Dg: AV-‐VA discordace, PS, LPA stenosis, VSD, B-‐T shunt x 2

HOW DOES THE BLOOD FLOW?

ClassificaIon of concenital heart lesions

Classification Physiology Effect Examples Cyanotic: Normal pulmonary blood flow

Mixing of arterial and venous blood in common cardiac chambers

Cyanosis Polycythemia

Single venticles Double outlet RV TGA with ASD or VSD

Cyanotic: Decreased pulmonary blood flow

Obstruction of PBF leads to shunting at the atrial and/or ventricular level

Cyanosis+ CHF Polycythemia

TOF Severe pulmonary stenosis Pulmonary atresia

Acyanotic: Increased pulmonary blood flow

Left to right shunt at the atrial, ventricular or great vessel level leads to preferential flow to the low resistance pulmonary bed

PDA & ASD: Clinically normal AVSD / VSD: CHF if severe

ASD VSD AVSD PDA Aortopulmonary window

Acyanotic: Obstructed blood flow

No shunt, but blood flow is ostructed

CHF Mild pulmonary stenosis Aortic stenosis Coarctation of the aorta


•  Previous history

•  At what stage of correcIon the CHD is? –  Unpalliated –  ParIally palliated –  Completely palliated –  Corrected

•  CorrecIve cardiac surgery: normalized relaIonship between cardiovascular structures and normal route of blood flow

•  Pediatric cardiac surgery is merely reparaIve and residual dysfuncIon o[en occur (arrythmias, congesIve heart failure, PH, restenosis etc)


•  How does the blood flow?

•  Echocardiography –  Anatomic defects / shunts –  Ventricular funcIon –  Valve funcIon –  Doppler and colour flow imaging -‐> direcIon of flow through defect/valves, velociIes/pressure

gradients •  Latest cardiac cathethrizaIon

–  Size and locaIon of defects –  Degree of stenosis or shunt –  Pressure cradients and sat02 in each chamber and great vessels –  Mixed venous 02 saturaIon in SVC or proximal to area where shunt occurs –  Low saturaIons in LA and LV -‐> right to le[ shunt –  High saturaIons in RA and RV -‐> le[ to right shunt –  RaIo of pumonary to systemic blood flow Qp / Qs


•  FuncIonal status –  Daily acIviIes and exercise tolerance –  Tacyphnea, dyspnea, cyanosis –  Infants; respiratory distress during feeding –  Arrythmias, syncope, chest pain –  Hypertension / hypotension –  Murmurs / pulmonary auscultaIon –  InfecIon

•  12 lead EKG –  Chamber enlargement / hypertrophy –  ConducIon defects / arrythmias –  ConducIon defects –  Arrythmias –  Ischemia


•  Chest x-‐ray –  Heart size and shape –  Prominence of pulmonary vascularity –  InfecIon

•  Pulse oximetry

•  Blood tests –  Electrolyte disturbaces (diureIc therapy, renal dysfuncIon) –  Hemoglobin / hematocrit level is a good indicator of severity / chronicity of cyanosis –  CoagulaIon tests –  Arterial blood gases –  Calcium and blood glucose especially newborns/neonates/criIcally ill children


•  Drug history –  Generally all cardiac medicaIons should be given on the morning of surgery –  ACE inhibitors? –  Aspirin therapy to prevent shunt thrombosis should usually be conInued –  Children with warfarin therapy need to be admiged to hospital for anIcoagulant

monitoring and considering LMWH prior to elecIve surgery?

•  PremedicaIon –  Used to avoid distress, minimize oxygen consumpIon and maybe to reduce the amount

of inducIon agent. –  -‐> less undesirable hemodynamic and respiratory symptoms before/during inducIon –  midazolam 0.3-‐0.5 mg/kg, diazepam 0.3-‐0.5 mg/kg –  monitoring of spO2

•  EndocardiIs porphylaxis –  Follow appropriate guidelines.

IntraoperaIve monitoring

•  Depends a lot on complexity of the heart defect and surgery

•  ECG, Sp02 x 1-‐2, ETCO2, NIBP are standard

•  A-‐lines and CVP

•  TEE

•  NIRS

•  Temperature (oesophagus, rectum, bladder)

•  Diuresis

IntraoperaIve monitoring

•  PDA –  Pulse oximetry on right hand -‐> preductal saturaIon –  Pulse oximetry on lower limb -‐> postductal saturaIon

•  AorIc coarctaIon –  Pulse oximetry on right upper limb –  Arterial line on right upper limb –  (Pre-‐ and post-‐coarctaIon blood pressure measuremaents )

AnestheIc techniques

•  InducIon and maintenance

–  Dependent on age and cardiac reserve –  Cood cardiac funcIon -‐> inhalaIonal or i.v. inducIon and maintenance

–  Poor funIon / cardiac reserve -‐> slow i.v. InducIon

–  Neonates -‐> sevoflurane, S-‐ketamine, midazolame, dexmedetomidine, opiates

–  Be careful with PVR changes during inhalaIonal inducIon due to changes in PaO2, PCO2 and intrathoracic presssure

InhalaIonal agents

•  InducIon usually well toleratered

•  Sevoflurane –  Ligle effect on myocardial contracIlity or shunt fracIon –  Don’t decrease heart rate –  Decrease in SVR, decreases MAP, may improve systemic flow in L-‐>R shunts –  CardioprotecIve effect

•  Isoflurane –  High insidence of laryngospasm -‐> not good for inducIon –  Ligle effect on myocardial contacIlity or shunt fracIon –  VasodilaIon -‐> decreases MAP -‐> increases HR

•  Desflurane –  High insidence of laryngospasm –  Decreases SVR, increases HR

•  Nitrous oxide –  May enlarge intravascular air emboli and cause obstrucIon of blood flow in arteries and capillaries –  In shunts possibility for bubbles to be shunted into systemic circulaIon –  Don’t use in children with limited pulmonary blood flow or PHT –  Is there a reason to use?

IV-‐anestheIcs

•  S-‐Ketamine –  SympatomimeIc effects helps to maintain HR, contracIlity, MAP –  No effect on PAP or PVR –  Useful with unstable hemodynamics, neonates –  Well tolerated in children with pulmonary hypertension

•  Propofol –  Depress myocardial funcIon, decrease SVR, MAP –  No effect on HR, PAP, PVR –  Can be used for most paIents –  Not for very unstable paIents or neonates

•  Thiopental –  Depress myocardial funcIon, decrease SVR, MAP –  For inducIon, also for neonates, no pain –  Not for very unstbale paIents

•  Midazolam –  Ligle effect on contracIlity, SVR and MAP –  Useful for neonates and hemodynamically unstable paIents

IV-‐anestheIcs

•  Opioids –  No cardiodepressant effect if bradycardia avoided –  High dose opioid anesthesia well tolerated in unstable paIents

•  Etomidate –  Don’t depress heart contracIly or decrease SVR, MAP –  Adrenal gland depression –  Rarely used –  For inducIon of very unstable paIents?

•  Dexmedetomidine –  Hemodynamically stable anesthesia (adjuvant) –  Can cause bradycardia –  Can be useful in treaIng tachyarythmias –  Not the best choice for paIents with AV-‐nodal conducIon defects

alfa1 alfa2 beeta1 beeta2 V1 V2

epinephrine +++ +++ +++ +++

norepinephrine +++ +++ ++ +

phenylephrine ++ ++ -‐ -‐

vasopressin -‐ -‐ -‐ -‐ +++ +++

Vasopressors

•  Epinephrine –  Beeta1 dominant with small doses, alfa1 effect increases with dose –  Increases HR, coronary flow, CO, BP, oxygen consumpIon, –  Tachyarytmias, pulmonary vasoconstricIon

•  Norepinephrine –  Alfa1 dominant –  Increases SVR, weak beeta1 inotropic effect –  High doses -‐> tachyarythmias, pulmonary vasoconstricIon

•  Phenylephrine –  Increases SVR with potent alfa acIvity, virtually no beeta effect –  Primarely as a rapid bolus, bolus / infusion to decrease oullow track gradient –  No direct heart rate effect, reflectory baroreceptor mediated rensponse a[er alteraIons in MAP

•  Vasopressin –  ConstricIon of vascular smooth muscle (V1) and increased SVR, water reabsoprIon in renal

collecIng duct (V2) –  Increases vascular sensiIvity to cathecolamines, effects preserved during acidoIc condiIons

Inotropes

•  Milrinone (PDI) -‐  Increase of intracellular cAMP and calcium by inhibiIon of cAMP breakdown in cardiac myocytes and vascular smooth muscle

-‐  Inotropic, lusitropic and vasodilaIve effect -‐  Decreases PBP and SVR -‐  Basic and well tolerated intropic infusion -‐  Loading dose 50 ug/kg during 0.5-‐2h, conIniuous infusion 0.375-‐0.75 ug/kg/min -‐  Side-‐effecs hypotension, ventricular arrythmias (rare)

•  Levosimendan

–  SensiIzaIon of contracIle protein troponin C to intracellular calcium –  Openin of Kalium channels on vascular smooth muscle –  Enhances ventricular contracIlity without increasing oxygen consumpIon –  Pulmonary and systemic vasodilataIon –  Decompensated HF –  Loading dose 12-‐24 ug/kg during 10 min, conInious infusion 0.05-‐0.2 ug/kg/min during 24 hours –  Combined to low-‐dose milrinone –  Side-‐effects hypotension, tachycardia

Anesthesic management

•  Q = Blood flow

•  P = Pressure withing chamber or vessel

•  R = Vascular resistance of pulmonary or systemic vasculature

RPQ =

L -‐> R shunts (ASD,VSD,AVSD,PDA,A-‐P window)

•  Increased pulmonary blood flow

–  Increased RV workload

–  Pulmonary congesIon

–  Longstanding L-‐>R -‐> PHT

–  PVR > SVR -‐> R-‐>L shunt -‐>Sdr Eisenmenger

L -‐> R shunts (ASD,VSD,AVSD,PDA,A-‐P window)

•  Consider inotropic support to preserve RV funcIon (milrinone)

•  Consider iNo if documented PH

•  Avoid hypovolemia

R-‐>L shunts (TOF, PS, PA…)

•  Defect between R and L heart and obstrucIon of PBF -‐> hypoxemia / cyanosis

•  Blood flow may be ductus depended or not

•  Goal to improve / preserve PBF and oxygenaIon and support RV funcIon

R-‐>L shunts (TOF, PA, PS…)

–  Increased PVR -‐> decreased pulmonary blood flow

–  Avoid

•  Hypoxemia/atelectasis/high PEEP •  Acidosis/hypercapnia •  SymphateIc / noxious sImulaIon •  Hypovolemia

–  Decreased PVR / Increased SVR-‐> increased pulmonary blood flow •  Low mean airway pressure •  Blunted stress response •  Pulmonary vasodilators •  Inotropic support (milrinoni) •  Vasoconstrictors (phenylephrine) and

direct manipulaIon to increase SVR •  Propranolol / esmolol to prevent

cyanoIc spells

Complex shunts (UVH, TA, TGA, DORV…)

•  Mixing of arterial and venous blood in common cardiac chambers

•  Arterial blood saturaIon 75-‐85%

•  Blood flow may be obstructed or not

•  Blood flow can be ductus depended or not

•  Both cyanosis and CHF

Complex shunts (UVH, TGA, TA…)

•  Ductus depended flow-‐> conInue alprostadil

•  Risk of both thrombosis and bleeding

•  Increased PBF may steal blood from systemic circulaIon

•  Don’t try to ”overoxygenate” –  Doesn’t improve systemic oxygenaIon –  Causes hypotension, coronary ischemia,

ventricular dysfuncIon

•  Goal Qp / Qs = 1 –  Qp / Qs = Sa02-‐Sv02/ 98-‐Sa02 –  Sa02 75-‐85% –  PaO2 and PaCO2 5,5-‐6 kPa

•  Adjust Hb goal to preoperaIve value

Single ventricle paUent with a shunt

•  AnIcoagulant therapy should be conIuned to avoid shunt trombosis

•  During PPV the PBF during expiraIon –  I : E = 1: 3 – 1:5 –  Inspiratory Ime max 0,7 sec –  Peep with cauIon –  NormovenIlaIon and Qp : Qs =1 (0,7-‐1,5:1) –  Don`t try to ”overoxygenate”

•  Avoid hypovolemia, preserve low PVR, sr, consider inotropic support to maintain ventricular contracIlity (milrinone,levosimendan,epinephrine?)

•  Consider increasing SVR to increase PBF

•  Spontaneous breathing is preferable -‐> early ekstubaIon if possible

ObstrucUve lesions of systemic blood flow (AS, CoA)

•  Icreased workload of LV

•  Slow i.v. inducIon of anesthesia

•  In severe obstrucIon avoid high doses of inhalaIon agents to prevent too low SVR and worse gradient?

•  OpImize preload and volume status to get beger flow beyond lesion

Pulmonary arterial hypertension

•  Systolic PAP > 50% of systemic systolic arterial blood pressure

•  Pulmonary vascular remodelling, vasoconstricIon, RV hypertrophy, RA enlargement, TI, RV / biventricular heart failure

•  PAH is significant risk factor for perioperaIve mortality


•  PremedicaIon –  Useful to avoid distres –  Consider preoperaIve sildenafil

•  Slow i.v. inducIon

•  No single ideal anestheIc -‐> balanced anesthesia o[en preferred

•  InfiltraIon of local anestheIc at the surgical site can offer benefit by reducing the need of opioids/sedaIve drugs


•  Consider profylacIc inotropic support –  Milrinone -‐> inotopic effect and pulmonary vasodilaIon –  Levosimendan –  Inhaled nitrix oxide

•  SelecIve pulmonary vasodilaIon, radip onset, easy to use •  Drug of choice to decrease PVR

•  Control volume status to opImize preload and to avoid hypotension –  Norepinephrine, phenylephrine, epinephrine if needed

•  Be prepaired and have a plan to threat increasing PVR or PHT crisis


Robert et al Ped Anesth 2008

Discussion...

Koichi et al J Anesth 2011

anesthesiafor)achild)with)congenital)heart disease) • milrinone)(pdi)) _ increaseof...

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