1 DASAR VENTILASI MEKANIK ANANG ACHMADI, SpAn ICU Bedah RS Jantung Pusat Nasional Harapan Kita - Jakarta
Oct 30, 2014
DASAR VENTILASI MEKANIK
ANANG ACHMADI, SpAn ICU Bedah RS Jantung Pusat Nasional Harapan Kita - Jakarta
1
Objectives Describe types of breaths and modes of mechanical ventilation Describe interactions between ventilatory parameters and modifications needed to avoid harmful effects
Early ventilators
Ventilator ~ ventilasi Ventilasi = keluar masuknya udara dari atmosfer ke alveolus Ventilator = menghantarkan (delivery) udara/gas TEKANAN udara/gas POSITIF ke dalam paru Ventilasi semenit = TV x RR (frekuensi nafas ) (frekuensi nafas) TV = 5-7 cc/ kgBB cc/kgBB RR = 10 12 kali/ menit kali/menit
Compliance = Pengukuran dari elastisitas paru dan dinding dada Nilai compliance mengekspresikan adanya perubahan volume akibat perubahan dari tekanan (pressure) Compliance rendah = Stiff lung - edema paru, efusi pleura, paru, obstruksi, obstruksi, distensi abdomen dan pneumotoraks Compliance tinggi = penurunan elastisitas resistensi pada inspirasi dan penurunan kemampuan mengeluarkan udara waktu ekspirasi (COPD)
4
Kriteria tradisional untuk bantuan ventilasi mekanikPARAMETER Mekanik (RR) TV (cc/kg) Oksigenasi (PaO2mmHg) P(A-aDO2) mmHg Ventilasi (PaCO2mmHg) INDIKASI VENTILASI > 35x/m 60 NORMAL RANGE 10-20x/m 5-7 75-100 (air) 25-65(FiO2 1.0) 35-45
5
TUJUAN KLINIS / INDIKASI PEMAKAIAN VENTILASI MEKANIKGAGAL NAFAS HIPOKSEMIK: Reverse hypoxemia dgn pemberian PEEP dan konsentrasi O2 tinggi (ARDS,edema paru atau pneumonia akut) GAGAL NAFAS VENTILASI: Reverse acute respiratory acidosis - Koma : trauma kepala, encefalitis, overdosis, CPR - Trauma med spinalis, polio, motor neuron disease - Polineuropati, miastenia gravis - Anesthesia (relaksan u/operasi, tetanus, epilepsi) STABILISASI DINDING DADA: Flail chest MENCEGAH ATAU MENGOBATI ATELEKTASIS
6
TUJUAN FISIOLOGISMEMPERBAIKI VENTILASI ALVEOLAR MEMPERBAIKI OKSIGENASI ALVEOLAR (FiO2, FRC,V'A) MEMBERIKAN PUMP SUPPORT ( ME WOB)
Consensus conference on mechanical ventilation, Int Care Med 1994, 20:64-79
7
Indications for Mechanical Ventilation
Ventilation abnormalities Respiratory muscle dysfunction Respiratory muscle fatigue Chest wall abnormalities Neuromuscular disease
Decreased ventilatory drive Increased airway resistance and/or obstruction
Indications for Mechanical Ventilation Oxygenation abnormalities Refractory hypoxemia
Need for positive endexpiratory pressure (PEEP) Excessive work of breathing
Types of Ventilator Breaths Volume-cycled breath Volume breath Preset tidal volume
Time-cycled breath Pressure control breath Constant pressure for preset time
Flow-cycled breath Pressure support breath Constant pressure during inspiration
Modes of Mechanical Ventilation
Consider trial of NPPV Determine patient needs Goals of mechanical ventilation Adequate ventilation and oxygenation Decreased work of breathing Patient comfort and synchrony
Modes of Mechanical VentilationPoint of Reference: Spontaneous Ventilation
Continuous Positive Airway Pressure (CPAP) No machine breaths delivered
Allows spontaneous breathing at elevated baseline pressure Patient controls rate and tidal volume
Assist-Control Ventilation Volume or time-cycled breaths + minimal ventilator rate Additional breaths delivered with inspiratory effort Advantages: reduced work of breathing; allows patient to modify minute ventilation Disadvantages: potential adverse hemodynamic effects or inappropriate hyperventilation
Pressure-Support Ventilation Pressure assist during spontaneous inspiration with flow-cycled breath Pressure assist continues until inspiratory effort decreases Delivered tidal volume dependent on inspiratory effort and resistance/compliance of lung/thorax
Pressure-Support Ventilation Potential advantages Patient comfort Decreased work of breathing May enhance patient-ventilator synchrony Used with SIMV to support spontaneous breaths
Pressure-Support Ventilation Potential disadvantages Variable tidal volume if pulmonary resistance/compliance changes rapidly
If sole mode of ventilation, apnea alarm mode may be only backup Gas leak from circuit may interfere with cycling
Synchronized Intermittent Mandatory Ventilation (SIMV) Volume or time-cycled breaths at a preset rate Additional spontaneous breaths at tidal volume and rate determined by patient Used with pressure support
Synchronized Intermittent Mandatory Ventilation (SIMV) Potential advantages More comfortable for some patients Less hemodynamic effects
Potential disadvantages Increased work of breathing
Controlled Mechanical Ventilation Preset rate with volume or time-cycled breaths No patient interaction with ventilator Advantages: rests muscles of respiration Disadvantages: requires sedation/neuromuscular blockade, potential adverse hemodynamic effects
Inspiratory Plateau Pressure (IPP) Airway pressure measured at end of inspiration with no gas flow present Estimates alveolar pressure at end-inspiration Indirect indicator of alveolar distensionPIP Plateau pressure
Peak pressure
Plateau pressure
Inspiration
Expiration
Inspiratory Plateau Pressure (IPP) High inspiratory plateau pressure Barotrauma Volutrauma Decreased cardiac output
Methods to decrease IPP Decrease PEEP Decrease tidal volume
Inspiratory Time: Expiratory Time Relationship (I:E ratio) Spontaneous breathing I:E = 1:2 Inspiratory time determinants with volume breaths Tidal volume Gas flow rate Respiratory rate Inspiratory pause
Expiratory time passively determined
I:E Ratio during Mechanical Ventilation Expiratory time too short for exhalation Breath stacking Auto-PEEP
Reduce auto-PEEP by shortening inspiratory time Decrease respiratory rate Decrease tidal volume Increase gas flow rate
Permissive Hypercapnia Acceptance of an elevated PaCO2, e.g., lower tidal volume to reduce peak airway pressure
Contraindicated with increased intracranial pressure Consider in severe asthma and ARDS Critical care consultation advised
Auto-PEEP Can be measured on some ventilators Increases peak, plateau, and mean airway pressures Potential harmful physiologic effects
Auto-PEEP Can be measured on some ventilators Increases peak, plateau, and mean airway pressures Potential harmful physiologic effects
V
Pediatric Considerations Infants (< 5 kg) Time-cycled, pressure-limited ventilation
Peak inspiratory pressure initiated at 1820 cm H2O Adjust to adequate chest movement or exhaled tidal volume ~8 mL/kg Low level of PEEP (24 cm H2O) to prevent alveolar collapse
Pediatric Considerations Children SIMV mode Tidal volume 8-10 mL/kg Flow rate adjusted to yield desired inspiratory time Infants 0.50.6 secs Toddlers 0.6-0.8 secs Older 0.81.0 secs
Rate