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Pneumonia

Mechanical Ventilation

Weaning from Ventilator

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Pneumonia

 

Aspiration PNA (Bacterial)

            Clindamycin 600mg IV Q8H. Than 300mg PO Q6H

            Alternatively Augmentin 875mg Q12H OR Imipenem

 

Chemical Aspiration PNA

            Tracheal suction

            Positive Pressure Ventilation

            IV high molecular weight colloids

            Nitroprusside infused into pulmonary artery

 

Community Acquired Pneumonia

            Admission to ICU ----if severe PNA is present. Severe PNA defined if any of the following is present

           

-         RR > 30 (on admission)

-         PaO2 / FiO2 < 250 (indicates severe respiratory. failure)

-         Need for mechanical ventilation

-         CXR shows bilateral ‘OR’ multilobar disease ‘OR’ increase in size of opacity by 50% within 48hrs of admission

-         Shock (SBP < 90 or DBP< 60)

-         Need for vasopressor for > 4hrs

-         Urine output < 20ml/hr ‘OR’ < 80ml in 4hrs ‘OR’ ARF requiring dialysis

 

Hospitalization

            If any of the following risk factors for inc. morbidity and mortality present

-         >65 yrs

-         Coexisting illness (COPD, DM, CRF, CHF, CLD, AMS, Aspiration, Post-splenectomy, Alcoholic, Malnourished, Past hospitalization within 1yr for CAP)

-         Physical findings (RR > 30, SBP <90, DBP <60, >101°F, Confusion, Depressed mental status, Extra-pulmonary disease like septic arthritis)

-         Labs (WBC < 4 or >30, PaO2 <60 or PaCO2 >50 on room-air, need for mechanical vent., Creatinine >1.2 or BUN >20, Hct <30, Hgb <9, metabolic acidosis, high PT or PTT, FDPs > 1:40, low platelets)

-         CXR (multilobar, bilateral, pleural effusion, cavity, rapidly progressing)

 

 

            Treatment of CAP

            Out-patient (<60yr with no comorbidity

                                    PO Azithromycin OR Clindamycin OR Doxycycline

           

            Out-patient (>60yr and/or co morbidity (CHF, COPD), nursing home)

                                    (PO cefpodoxime, cefuroxime, augmentin, amoxicillin)

                                    + (Azithromycin OR Clarithromycin OR Doxycycline)

            In-patient (not in ICU)

Ceftriaxone (ceftazidime or cefoperazone if Pseudomonas suspected) + Macrolide

OR

B-lactmaase inhibitor + macrolide

 

            In-patient in ICU

                                    Ceftazidime or cefoperazone + macrolide

                                    OR

                                    Imipenem (alone)

                                    OR

                                    Ciprifloxacin (alone)

 

                       

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Mechanical Ventilation

 

Indications:

  1. Impaired gas exchange
  2. Rapid onset respiratory. failure
  3. inadequate response to less invasive Treatment
  4. increased work of breathing & muscle fatigue

 

Guiding Parameters:

  1. RR >35
  2. Insp. Force <25 cmH2O
  3. Vital capacity <10-15
  4. PaO2 <60 (with FiO2 of >60)
  5. PaCO2 >50 (with pH of <7.35)
  6. Absent gag or cough reflex

 

Assist-Control Ventilation (ACV):

  1. gives fixed number of breaths
  2. deliver a breath for each patient-initiated effort (Assist)
  3. controlled vent-initiated breath if pt fails (Control)
  4. usually this is initial mode of vent in respiratory failure
  5. Adverse effects:
    1. Respiratory alkalosis (in tachypneic pts)
    2. Auto-PEEP from Hyperinflation (less time for exhalation), can lead to EMD

 

Intermittent-Mandatory Ventilation (IMV):

  1. gives fixed number of breaths
  2. pt-initiated breath is not assisted so no risk of Auto-PEEP
  3. additional mechanical breaths at preset rate
  4. useful in weaning (with PSV)
  5. SIMV: coordinates vent-driven breath with pt’s respiratory cycle
  6. Adverse of IMV:
    1. lower cardiac output (by dec. ventricular filling)
    2. increase work of breathing-causes respiratory. muscle fatigue & so vent dependence (PSV of 4-8 is added for this reason)

 

Pressure-Controlled Ventilation (PCV):

  1. no participation by pt
  2. completely controlled by ventilator (Controlled)
  3. best for pts with neuromuscular disease
  4. Benefits over Volume-cycled ventilation:
    1. Less risk of Barotrauma (as insp flow dec. during lung inflation)
  5. Adverse:
    1. Inflation vol. vary with changes in lung properties

 

 

Inverse Ratio Ventilation (IRV):

  1. PCV is combined with prolonged inflation time
  2. Insp : Exp ratio is 2:1, i.e., insp longer than exp (rather than standard 1:2-1:4)
  3. prevent alveolar collapse (alveolar recruitment)
  4. Major indication: ARDS
  5. Heavy sedation or muscle paralysis is needed
  6. Adverse:
    1. Auto-PEEP
    2. Decrease cardiac output

 

Pressure-Support Ventilation (PSV):

  1. breath is initiated by pt (support)
  2. augmented by pressure (5-50) as selected
  3. allows pt to dictate duration & vol of lung inflation
  4. vent doesn’t give any breath by itself
  5. Used with IMV or in Weaning trials
  6. can be used alone by face mask as a non-invasive mech vent

 

Positive End-Expiratory Pressure (PEEP):

  1. by placing a pressure-limiting valve at exp tube
  2. prevents full exp after a fixed pr
  3. also raises mean intrathoracic pr
  4. Uses:
    1. Pt. needing very high O2 (ARDS)
    2. Low-vol ventilation - a PEEP of 10 (as repeated opening and closing of alveoli increase lung injury)
    3. COPD & Asthma (prevent alveolar collapse & air-trapping)

 

Continuous Positive Airways Pressure (CPAP):

  1. pt. breaths at his own rate
  2. a positive pr is maintained throughout respiratory cycle
  3. Uses:
    1. Obstructive sleep apnea
    2. Acute COPD exacerbation
    3. To postpone intubation in acute respiratory failure

 

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Weaning from Ventilator

 

Guidelines:

Greatest Predictive Value:

  1. RR / Tidal volume (lit)  < 100
  2. Max. inspiratory pressure: - 25

Other guidelines:

  1. Awake, alert, cooperative
  2. PaO2 > 60 (with FiO2 of <50)
  3. Vital Capacity > 10
  4. Minute Ventilation < 10
  5. RR < 30
  6. Tidal volume > 5

 

Failure:

  1. Neuromuscular depressing drugs
  2. Steroids
  3. over sedation
  4. high caloric intake
  5. dehydration
  6. electrolyte imbalance (low Mg, low Ph)

 

Methods:

  1. IMV + PSV
  2. T- piece or T-tube weaning:
    1. Pt is on-off ventilator
    2. Pt intermittently breaths thru T-tube
    3. Initially 5-15min 2-4 times/day and gradually increased
    4. Addition of CPAP of 3-5 prevent atelectasis
    5. PSV of 4-8 to decrease work of breathing
    6. Extubate once pt can tolerate 30-90min
    7. It is a fast method as compared to IMV

 

Extubation:

  1. Morning
  2. Pt educated
  3. Elevation of trunk to > 30°
  4. Equipment for reintubation available
  5. Deflate cuff and remove tube
  6. High-humidity oxygen by face mask
  7. ask pt to cough & deep breaths
  8. If stridor (from glottic edema) give nebulized 2.5% racemic epinephrine (0.5 ml in 3ml NS)
  9. Reintubate if obstruction persist
  10. ENT consult – consider tracheostomy
  11. Don’t attempt to extubate within 24-72hr of reintubation

 

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Please contact Irfan A. Khan, MD for suggestions and corrections.

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