Transcript Introduction to Pharmacology
Special Procedures
Fred Hill, MA, RRT
Surfactant Replacement
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Composition
• Phospholipids (90%) • phosphatidylcholine (PC) (85%) - dipalmitoyl phosphatidylcholine (DPPC) (60%) • • Phosphatidylglycerol (PG) Phosphatidylinositol (PI) Cholesterol Proteins (5-10%): SP-A, SP-B, SP-C, SP-D
Surfactant Replacement
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Indications
Prophylactic administration (high risk for developing RDS) – <32 weeks gestational age – – – <1300 grams L/S ratio <2:1 Absence of PG Therapeutic (rescue) administration – ↑WOB (grunting, retractions, nasal flaring) – – ↑ O 2 requirements RDS on CXR
Surfactant Replacement
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Types of Surfactant
Exosurf (colfosceril palmitate): synthetic, 5 ml/kg Survanta (beractant): calf lung, 4 ml/kg Infasurf (calfactant): calf lung, 3 ml/kg Curosurf (poractant alfa): pig lung, 2.5 ml/kg
Surfactant Replacement
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Adverse Effects
Bradycardia, desaturation ETT reflux, ETT obstruction Barotrauma
Benefit
Decreased mortality rates Decreased morbidity rates, reduction in: – Severity of RDS – Pulmonary air leaks – Incidence of BPD
High –Frequency Ventilation
Introduction
• • • • Delivery of small tidal volumes at very high rates (usually >150/min.) Rates may be expressed in hertz (Hz) (1 Hz = 60/min.) Amplitude = ΔP, determines P CO 2 Mean airway pressure determines P O 2
High –Frequency Ventilation
Indications
• Respiratory failure unresponsive to conventional methods • Pulmonary air leaks • Congenital diaphragmatic hernia
High –Frequency Ventilation
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Hazards
Gas trapping & hyperinflation Necrotizing tracheobronchitis (especially with HFJV) Chest assessment is difficult Obstruction Malposition of ETT
High –Frequency Ventilation
Types
• • • High-frequency positive pressure ventilation (HFPPV) High-frequency jet ventilation (HFJV) High-frequency Oscillatory Ventilation (HFOV)
High –Frequency Ventilation
High-Frequency Positive Pressure Ventilation (HFPPV)
• • • 60 to 150 bpm Tidal volume exceeds dead space Possible advantages: – ↓ pneumothoraces – ↓ asynchrony with ventilator
High –Frequency Ventilation
High-Frequency Jet Ventilation (HFJV) Bunnell Life Pulse High Frequency Ventilator
High –Frequency Ventilation
High-Frequency Jet Ventilation (HFJV)
• • • • 240-660 bpm Passive exhalation Requires special ETT or adapter In tandem with conventional ventilator – Occasional sighs – – PEEP Continuous gas flow for entrainment
High –Frequency Ventilation
High-Frequency Oscillatory Ventilation (HFOV) Sensormedics 3100A
High –Frequency Ventilation
High-Frequency Oscillatory Ventilation (HFOV)
• • 8 to 30 HZ (480 – 1800) Active inspiration and exhalation
Inhaled Nitric Oxide
Action
• Causes smooth muscle relaxation in vascular walls of pulmonary vessels • Improves oxygen delivery due to dilation of vessels in ventilated areas of lung
Inhaled Nitric Oxide
Applications
• • • • • PPHN – most important MAS RDS Pneumonia, sepsis Congenital diaphragmatic hernia
Inhaled Nitric Oxide
Hazards
• • Nitrogen dioxide (NO 2 ) Methemoglobinemia
Inhaled Nitric Oxide
Application
• • INOvent Delivery System 8 – 20 ppm
INOvent
Extracorporeal Membrane Oxygenation (ECMO)
History
• • • 1950’s: short-term (hours) in open heart surgery 1960’s: long-term (days to weeks) 1971: first use in infants
Extracorporeal Membrane Oxygenation (ECMO)
Exclusion Crtieria
• • • • • • • • • Gestational age <35 weeks Pre-existing IVH Significant coagulopathy or uncontrollable bleeding. No major (>grade 1) intracranial hemorrhage Irreversible lung injury Major congenital/chromosomal anomalies or severe encephalopathy Major cardiac malformation Mechanical Ventilation : >7days Cardiac arrest other than immediately at birth
Extracorporeal Membrane Oxygenation (ECMO)
Inclusion Criteria
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80% mortality risk if no ECMO intervention
Oxygenation Index (OI)>40:
OI =(Mean Airway Pressure [cmH20] x FiO2 x 100) which in turn is divided by the Post ductal PaO2 [mmHg]
OI = Paw x F I O 2 PaO 2 x 100 Gestational Age >35 weeks Weight >2 kgs Reversible lung disease No major (>grade 1) intra-cranial hemorrhage No lethal congenital abnormalities
Extracorporeal Membrane Oxygenation (ECMO)
Mechanisms of Bypass
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Venoarterial: blood drawn from right atrium via right internal jugular vein, returned to the aortic arch via right common carotid artery
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Takes over function of heart and lungs Venovenous: blood drawn from right atrium via right internal jugular vein, returned to right atrium via femoral vein
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Takes over function of lungs
Extracorporeal Membrane Oxygenation (ECMO)
Extracorporeal Membrane Oxygenation (ECMO)
Advantages of Venovenous ECLS
• • • • • • • • Sparing of carotid artery Preservation of pulsatile flow Normal pulmonary blood flow Perfusion of lungs with oxygenated blood Perfusion of coronaries with oxygenated blood Avoidance of infusion of possible emboli into arterial circulation Central venous pressure accurate Selective limb perfusion does not occur
Disadvantages of Venovenous ECLS
• • • No cardiac support Lower systemic PaO Recirculation issues 2
Advantages of Venoarterial ECLS
• • • Provides cardiac support Excellent gas exchange Rapid stabilization
Disadvantages of Venoarterial ECLS
• • • • • Carotid artery ligation Nonpulsatile flow Reduced pulmonary blood flow Lower myocardial oxygen delivery Direct infusion of possible emboli into arterial circulation • Central venous pressure inaccurate
Extracorporeal Membrane Oxygenation (ECMO)
Components of ECMO Circuit
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Venous blood drainage reservoir Blood roller pump Membrane oxygenator Heat exchanger
Extracorporeal Membrane Oxygenation (ECMO)
Physiologic Complications
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Bleeding Volume problems Blood pressure problems Hematologic problems (anemia, leukopenia, thrombocytopenia) Infection
Extracorporeal Membrane Oxygenation (ECMO)
Technical Complications
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Pump failure Rupture of tubing Membrane failure Cannula problems Other mechanical failures
Extracorporeal Membrane Oxygenation (ECMO)
Overview
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Early method of rescue Less important today with advent of SRT, HFOV, and iNO
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Still an important life support option in some centers