Is there an Optimal Mode of Ventilation Following Paediatric Cardiac Surgery? Dr Steve Ponde Busamed Modderfontein Hospital

Is there an Optimal Mode of Ventilation Following Paediatric Cardiac Surgery? Dr Steve Ponde Busamed Modderfontein Hospital

There have been many advances in the perioperative care of adults and children undergoing cardiac surgery Improvements in technology and techniques of surgery, Better understanding of pathophysiology postoperatively Refinements in anesthetic and ICU care. Improved outcomes and shortened hospital stays The goal remains to reduce postop resp mortality/morbidity

Effect of CPB/cardiac surgery on organ systems * Increased PVR, endothelial injury, atelectasis * Reduced lung compliance * Activation of inflammatory cascade from ischaemia and reperfusion injury * Worsens PHT * Endocrine changes * SIRS

Cardiorespiratory Interactions of a Positive-Pressure Mechanical Breath Pulmonary Ventricle Afterload Elevated Effect: RVEDp RVp Antegrade PBF PR and/or TR Preload Reduced Effect: RVEDV RAp Systemic Ventricle Reduced Effect: LVEDp LAp Pulmonary Edema Increase cardiac output Reduced Effect: LVEDV LAp

Cardiopulmonary interactions * Positive pressure ventilation may reduce work of breathing and afterload in LV failure but it may increase afterload in RV failure * In cardiac children assisted rather than controlled ventilation may be preferable * Patients with passive pulmonary blood flow, spontaneous breathing on CPAP 3-5 cmh2o, reduced FRC and increased PVR * Rapid changes in physiology

Team approach * Staffing of the surgicardiac care team * Preop: accurate diagnosis, anticipation of problems * Preop: readiness for surgery * Intraop management * Postop handover is vital * Continuous assessment for 1 st 3hours at least * Written protocols, deviations only by Snr staff

Avoid general complications of ventilation * VILI * VAP * CLD/BPD * Air leak/pie * Airway trauma

Special Problems for the Cardiac Patient * Diaphragmatic paresis * Increased airway resistance and airway injury * Postextubation stridor * Bronchospasm * Pulmonary edema, pneumonia and atelectasis * Pleural effusions and ascites * Air leak syndromes

Complications after common cardiac surgical procedures * Ligation of Patent Ductus Arteriosus * Recurrent laryngeal nerve damage * Damage to, or ligation of, surrounding vessels (left pulmonary artery, aorta) * Fontan Procedure * Large third-space fluid losses * Cyanosis * Low cardiac output * Dysrhythmias * VSD repair * Pulmonary Hypertension * Dysrhythmias junctional ectopic tachycardia, complete heart block

Non-Invasive Ventilation * Timing of NIV * Optimal interface for NIV * Dependent on local experiences and materials, full face mask, oral-nasal mask or helmet for NIV * After cardiac surgery for congenital heart disease * Status asthmaticus * Neuromuscular patients with ARF

Endotracheal tube and patient circuit * Cuffed ETT s can be safely used * Dead space apparatus * Double-limb circuits * Single-limb circuits * Manual ventilation

Setting the Ventilator * Setting the I:E ratio/inspiratory time * Maintaining spontaneous breathing * Setting the pressures * Setting tidal volume * Setting PEEP * Lung recruitment * HFOV * Negative pressure ventilation

Supportive Measures * Airway humidification * Suctioning * Chest physiotherapy * Positioning with head of the bed elevated to 30-45 unless specific disease conditions dictate otherwise

Total PICU care * Ventilation only part of the total PICU care package * Analgesia and sedation choices * Infection control and management of sepsis episodes * Nutrition * Support of the heart VAD, ECMO * Neurocritical care

Scenario Etiology Management Sa02 80% Svo2 60% Normotension Management Considerations for Patients Following a Norwood Procedure Rogers Textbook of Pediatric Intensive Care Fourth Edition Balanced Flow Qp = Qs No Intervention Sa02 >90% Hypotension Sa02 <75% Hypertension Sa02 <75% Hypotension Low Sv02 Overcirculated Qp > Qs Low PVR Large BT Shunt Residual arch obstruction Undercirculated Qp < Qs High PVR Small, kinked, thrombosed BT shunt Low cardiac output Ventricular failure Myocardial ischemia Residual arch obstruction AV valve regurgitation Raise PVR: Controlled hypoventilation Low FIO2 (0.17-0.19) Add CO2 (3%-5%) Increase systemic perfusion: Afterload reduction, vasodilation, inotropic support Surgical shunt revision Lower PVR: Controlled hyperventilation Alkalosis Sedation / Paralysis Increase cardiac output: Inotrope support Hematocrit >40% Surgical intervention Minimize stress response Inotropic support Surgical revision Consider mechanical support Consider transplantation

Closure of PDA in neonates * Burden of prematurity and timing of surgery * Pre existing multiple organ dysfuntion * Size of patients * Specific complications for neonates, prems * Brain haemorrhage, ROP, NEC, ARI, * LVOS * Pre existing PHT CCF malnutrition

Critical Care Strategies for Postoperative Treatment of Pulmonary Hypertension * Anatomic investigation * Opportunities for right-to-left shunt as pop off * Sedation/anesthesia * Moderate hyperventilation * Moderate alkalosis * Adequate inspired oxygen * Normal lung volumes * Optimal hematocrit * Inotropic support * Vasodilators

Management considerations for patients following a modified Fontan Procedure Baffle (right side) Pressure 10-15mm Hg Aim Unobstructed venous return Management Or Preload Low Intrathoracic pressure Pulmonary Circulation PVR <2 Wood units/m₂ Mean Pap <15mm Hg Unobstructed pulmonary vessels Avoid increases in PVR, such as from acidosis, hypo and hyperinflation of the lung hypothermia and excess sympathetic stimulation Early resumption of spontaneous respiration Left atrium Pressure, 5-10mm Hg Sinus rhythm Competent AV valve Ventricle: Normal diastolic function Normal systolic function No outflow obstruction Maintain sinus rhythm Or rate to increase CO Or afterload Or contractility PDE inhibitors useful because of vasodilation and inotropic and lusitropic properties

Weaning and Extubation Readiness Testing * Routine use of any extubation readiness testing that is superior to clinical judgment * Assessing daily weaning readiness may reduce duration of ventilation * No data supporting superiority of any approach such as protocolled weaning, closed-loop protocols, or nurse-led weaning * Small study suggesting that use of NIV may prevent reintubation in children

Factors that Contribute to the inability to Wean from Mechanical ventilation after Congenital Heart Surgery Residual Cardiac Defects Volume and/or pressure overload Restrictive Pulmonary Defects Pulmonary edema Airway Subglottic edema and/ or stenosis Myocardial dysfunction Pleural effusion Retained secretions Sepsis Low cardiac output state Metabolic Inadequate nutrition Atelectasis Vocal cord injury Stress response Chest wall edema Phrenic nerve injury Ascites / hepatomegaly Extrinsic bronchial compression Tracheobronchomalacia

Considerations for planned early extubation after congenital heart surgery Patient factors Anesthetic factors Surgical factors Conduct of bypass Postoperative management Risk factors associated with anatomy and planned surgery Limited cardiorespiratory reserve of the neonate and infant Pathophysiology of specific congenital heart defects Timing of surgery and preoperative management Premedication Hemodynamic stability and reserve Drug distribution and maintenance of anesthesia on bypass Postoperative analgesia Extent and complexity of surgery Residual defects Risks for bleeding and protection of suture lines Degree of hypothermia Level of hemodilution Myocardial protection Extent of the inflammatory response and reperfusion injury Myocardial function Cardiorespiratory interactions Neurologic recovery Analgesia management

Graphical Simplification of Gaps in Knowledge Regarding Pediatric Mechanical Ventilation Saudi J Anaesth. 2011 Apr-Jun 5(2): 121-122 Disease Trajectory (getting worse) Disease Trajectory (getting better) HFNC Indication? Timing? Strategy CMV Mode? Settings? Thresholds HFOV Indication? Timing? Strategy? CMV Mode? Settings? Thresholds? Weaning When to start? Strategy? Predictors? NIV after extubation Indication? Timing? Strategy? NIV Indication? Timing? Strategy CMV Spontaneous breathing ECMO Indication? Timing? Strategy? Ventilation during ECMO CMV Spontaneous Breathing? ERT When? How?

Summary * Written management plans evidence based * Local circumstances: staff, equipment, home environment * Be prepared to modify management in response to unique circumstances * Individualise * research