Common Modes of Mechanical Ventilation

Mode Breath Type

Breath Trigger

Flow (LPM)

Wean Mode I:E NIPP

VCMV Vol. Timer Set N Full NACV Vol. Timer/Pt. Set N Full N

IMV Vol. Timer Set Y Depends on spont. pattern N

SIMV Vol. Timer/Pt. Set Y Depends on spont. pattern N

PSV Pr. Pt. Var. Y Patient set YPCV Pr. Timer/Pt. Var. N Full NBiPA

P Pr. Timer/Pt. Set N Patient set Y

Modes of Ventilation IndexCMV = Controlled Mechanical Ventilation or Continuous Mandatory Breath TriggerACV = Assist-Control Ventilation IMV = Intermittent Mandatory VentilationSIMV = Synchronized IMVPSV = Pressure Support Ventilation PCV = Pressure Control Ventilation CiPAP = Bi-level Positive Airway Pressure

*1. CPAP (continuous positive airway pressure) is an elevated baseline pressure throughout a spontaneous inspiratory and expiratory cycle that does not provide alveolar ventilation. PEEP (positive end-expiratory pressure) may be used with all vent. modes for improved oxygenation, improved lung compliance, FRC, shunt fraction and redistribution of lung water. PS (pressure support) may be added to spontaneous respiratory efforts. *2. Spontaneous breaths are patient-cycled and patient-triggered. Mandatory breaths are always machine/time cycled and/or triggered. IMV and SIMV allow unassisted spontaneous respirations. *3. Weaning modes refers to those methods that will allow patients to gradually share and to eventually assume completely, the work of breathing. May also consider progressive T-piece trials. *4. I:E = Inspiratory:Expiratory ratio - I:E range 1:5 to 5:1. I:E ratio > 1:1, requires the use of Inverse Ratio Ventilation (IRV) and may require sedation and paralysis. *5. NIPPV = Noninvasive positive pressure ventilation: Requiring the use of either nasal pillows, nasal mask or facial mask for delivery of CPAP, BiPAP, Pressure Support or Volume-cycled ventilatory support. Clinical indications may include COPD exacerbation, acute pulmonary edema, neuromuscular

disease, control of breathing disorders (OSAS, OHS…) or thoracic cage deformity. Complications of NIPPV may include leaks at interface, skin abrasion/ulceration, conjunctivitis, aerophagia with possible risk of aspiration, claustrophobia, patient intolerance, rhinitis, nasal drying and transient periods of hypoxemia with removal of nasal/facial apparatus. *6. Dynamic hyperinflation or pulmonary air trapping during mechanical ventilation occurs when there is insufficient expiratory time to allow the lungs to decompress to their FRC or relaxation volume before the next tidal volume inspiration. This alteration of normal lung mechanics may produce an auto-PEEP effect …an increased end-respiratory elastic recoil pressure. Auto-PEEP may occur with or without dynamic hyperinflation. Clinically, it may occur with COPD, asthma, or other ventilatory patterns incorporating shortened expiratory times. Corrective measures may include reduction of airflow obstruction, and/or expiratory time with flow rate. Addition of external PEEP may help ventilator

triggering in patients with dynamic hyperinflation.

Complications of Mechanical Ventilation1. Ventilator malfunction; 2. Cardiovascular: venous return, C.O., hypotension; 3. Oxygen toxicity; 4. Pulmonary barotrauma: PTX, subcutaneous emphysema, pneumopericardium - peritoneum -mediastinum, BPF, air embolism, interstitial emphysema, air cysts; Barotrauma may be minimized by keeping Plateau pressure < 35 cm H2O. 5. Pulmonary mechanics(*6): Dynamic hyperinflation, auto-PEEP; 6. Nosocomial pneumonia (see Pul. Care II); 7. Airway: sinusitis, epistaxis (traumatic), glottic-subglottic stenosis, tracheal injury (ulceration, malacia, dilatation, granulation tissue), vocal cord/s injury (edema, paralysis, phonation dysfunction); 8. Tracheostomy: Tracheal injury (ulceration, stenosis, malacia, granulation tissue), tracheo-innominate artery erosion with hemorrhage; 9. Misc: Pulmonary embolism, DVT, stress gastritis, psychological stress -anxiety -depression, sleep deprivation, ICP, patient-ventilator asynchrony, ETT misplacement, inadvertent ETT dislocation due to cuff leak, inadvertent extubation, atelectasis worsening hypoxemia, free water retenfion Na+.End-Tidal CO2 Monitoring (Capnometry)The continuous measurement of the partial pressure of PaCO2 in exhaled gas. The ETCO2 is equivalent to fhe PaCO2 in arterial, end-capillary blood of normal lungs. ETCO2 measurements may provide clinical evaluation of pulmonary gas exchange, carbon dioxide production, cardiac performance (cardiac output) and ventilator-patient management problems. ETCO2: C.O., cardiac arrest, right or left mainstem intubation, ETT obstruction, esophageal intubation, unexpected extubation, leak around ETT cuff, pt. disconnection from ventilator, general anesthesia, hypothermia, PE, ARDS ( shunt fraction), PEEP; ETCO2: Hypermetabolism (Sepsis, Hyperthermia,

Pain), rebreathing, mechanical dead space. ETCO2 monitoring may be useful when evaluating a patient with survival potential with CPR and/or assessing the weaning status during mechanical ventilation. *PaCO2 = kVCO2/VE (1 -VD/VT) or (kVCO2 / VA)

Oxygen Delivery System (FIO2)A) Nasal: 1-6 LPM (1L = 3% FIO2) B) VentiMask: 24,28,31,35,40, 50%C) Face Mask: 35-60% D) Partial Rebreather: 60-90% E) Partial Non-Rebreather: 90-100% F) Trach Colla:24,28,31,35,40,50%

Respiratory Nubulization MedicationsA) Bronchodilators (Sympathomimetic): Isoetharine (Bronkosol) Unit - Dose (0.08%, 0.1%, 0.17%, 0.25%); Metaproterenol (Alupent) Unit-Dose (0.4%, 0.6%); Albuterol Unit-Dose (0.083%) Albuterol Inhalation Solution (0.5%): 0.5 ml + 2.5 ml NS-Full strength or 0.25 ml + 2.5 ml NS -1/2 strength; Racepinephrine (Racemic Epinephrine) Solution (2.25%): 0.5 ml + 2.5 ml NS - may also be used for post-intubation stridor or croup. (Anticholinergic): lpratropium (Atrovent) Unit-Dose (0.02% - 2.5 ml); B) Mucolytics: Dornase Alfa (Pulmozyme) Unit-Dose (2.5 ml); Acetylcysteine (Mucomyst) (10%, 20%): 4 cc of Mucomyst 10% or 2cc of Mucomyst 20%; C) Asthma - Anti-inflammatory: Cromolyn (Intal) Unit-Dose (2 ml-20 mg); D) Misc.: 10% NaCl via USN for sputum induction; Xylocaine (Lidocaine) Solution (4%): 5 ml dose - may be used for local anesthesia of the upper airway.

Pulmonary Function PhysiologyPFT values vary in the population and are influenced by age, sex, wt., ht. and race. Normal values will depend upon predicted reference equations. General guidelines: Obstruction: FEV1/FVC >= 70% = N; 60-69% = Mild; 40-59% = Mod.; 30-39% = Severe; <30% = Very severe. Restriction: VC >= 80% = N; 60-79% = Mild; 50-59% = Mod.; 35- 49% = Severe; <35% = Very severe. Use TLC instead of VC if obstruction is present.

Lung VolumesNormal

Obstruction

Restriction

Spirometry