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The Many Disguises of PEEP: Case Presentations. Bradley J. Phillips, MD Burn-Trauma-ICU Adults & Pediatrics. PEEP. Positive End Expiratory Pressure Equilibrium pressure reached at end of expiration is some small amount of pressure greater than atmospheric
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The Many Disguises of PEEP:Case Presentations Bradley J. Phillips, MD Burn-Trauma-ICU Adults & Pediatrics
PEEP • Positive End Expiratory Pressure • Equilibrium pressure reached at end of expiration is some small amount of pressure greater than atmospheric • PEEP = 5 mmHg considered to be physiologic
Improves O2 Increases cardiac output Increases lung compliance Worsens O2 Decreases cardiac output Barotrauma Fluid retention Intracranial HTN CO2 clearance Disquises of PEEP
O2 PEEP I:E alterations Positioning * Prone/Lateral Rate Tidal volume I:E alternations Gas Exchange
Intubation Criteria • Airway protection • RR > 35-40 breaths/min • PaCO2 > 55 mmHg ( acute) • PaO2< 70 mmHg on 100% O2 nonrebreather • A-a gradient> 400 mmHg on 100% O2 FM • High spinal injury, closed head injury, ARDS, metabolic acidosis with clinical deterioration
Benefits of PEEP? There is no evidence that routine use of PEEP is beneficial in all patients!
Case #2CO2 Retention 67 yom s/p radical neck dissection for tumor of posterior pharynx PMH: COPD - steroid x 3 years CAD s/p IWMI 8yrs ago PSH: CABG x3 5 years ago SH: Beer - 4-5/day Smoker - 1.5 ppd
Case #2 Uncomplicated procedure, admitted to ICU for mechanical ventilation PE: elderly appearing, surgical wound on neck, JP x1 old scar on sternum, S2 loud breath sound quiet scaphoid abdomen LAB: WBC 14.2, Hct 25% CXR: Hyperinflated lung o/w clear
Case #2 Initial tx : ABX per ENT (clindamycin) Albuterol inhaler IV steroids POD2 : Extubated Tube feedings started POD3: Dyspnea, RR 30/min Crackles at right base, wheezing bilaterally ABG:pH 7.21, PaCO2 74, PaO2 48 @ FiO2 0.6
Case #2 ABC’s - Intubated CXR - right sided infiltrate in lower and apical fields Diagnosis: ? Initial vent setting: SIMV 12/TV 650ml/FiO2 1.0/Peep 5 Agitated, BP 220/120, HR 120, RR 40 Peak airway pressures 60 - 65 cmH2O Diagnosis and tx: ?
Case #2 Sedated with midazolam (Versed) drip 1 hr later : unresponsive rapid breathing, out of phase with ventilator PAP = 70 mmH2O Therapy : ? 1 hr later: PAP 35 cm H2O FiO2 decreased to 0.6 with O2 sats 96% ABG: 7.36/50/94
Case #2 Evening: Desats 90% Wheezing in all fields, crackles r base CXR: new left patchy infiltrate ABG: 7.34/56/68 - Vent setting changed ??? 90mins: ABG PaCO2 decreased, PaO2 increased 3 hrs later: Desat 93%, no ABG Vent setting changed ??? ABG: 7.34/58/64 Vent setting changed ??? ABG: 7.30/62/63, PAP 50 mmH2O
Case #2 Vent changed - FiO2 1.0, PEEP 20 cm H2O ABG 7.24/68/61 Vent changed- ??? Parameter BP 132/80 to 94/54 Arterial sats 80’s CXR/EKG ordered Dopamine started ABG 7.10/84/52 VT - CPR started
Case #2 Trap: PEEP applied to the ventilator auto-PEEP developed by increased RR Results: Difficulty with CO2 elimination Trick: Limit PEEP and assess for auto-PEEP Reduce RR Treat reversible component of COPD Consider I:E manipulations
PEEP effects on pulmonary physiology and gas exchange • PEEP effects on oxygenation frequently considered • PEEP effects on ventilation often neglected • Physiological dead space • Anatomic dead space • Shunt factor • V/Q mismatch • Haldane effect
PEEP effects on pulmonary physiology and gas exchange • Factors affected by acute lung injury and chronic airflow obstruction • PEEP low levels (5-10 cm) • reduces dead space by reducing shunt • PEEP high levels (=>15) • variable and unpredictable • V/Q mismatched • Ventilate high V/Q regions • Reduce CO2 elimination • Etiology ? decreased cardiac output or directcompression of alveolar capillaries
PEEP effects on pulmonary physiology and gas exchange Increased anatomic dead space Alterations of V/Q Impaired CO2 Removal Haldene effect High PEEP Impaired Oxygenation Alterations of V/Q (Direct compression)
Case #1 75 yof s/p colostomy for perforated diverticulum PMH: Asthma - inhalers Meds: Albuterol DM - 10 years Atrovent PSH: none SH: no EtOH or Tobacco use
Case #1Hypotension Transferred to ICU for sepsis and ventilator management PE: ill appearing, pale, obese female mild dyspnea T 39 HR 120, SBP 90, RR 30, sats 92%, wt 80kg Lungs: few wheezes bilateral CV: normal S1,S2 Abd: distended, open skin, mild tenderness Ext: mild edema, slight mottled distally LABS: WBC 18K, Hct 27 Na 131, K 3.1, Bun 15, Cr 1.6, BS 220
Case #1 Initial Tx (ABC’s) : Intubate Vent AC 12/800/80%/PEEP5 NPO/IVF/NGT/ABX Inhalers tx. Dopamine qtt Replete K After intubation: SBP 80’s briefly then 95 ABG: 7.32/48/70/96%
Case #1 Vent changes: Increased vent rate ABG: 7.36/42/65/94% 2 hrs later: Agitated, RR 25, sats 88% ABG 7.46/32/58 ? Vent changes or therapeutic interventions
Case #1 Vent changes: Increased PEEP 10 ABG 7.50/28/60/90% ? Vent changes or therapeutic maneuvers? 4 hrs post op : VS: HR 130’s, BP 85/60, RR30, sats 85% What’s happening???
PEEP effects on cardiovascular output • Positive pressure ventilation • increased intrathoraci pressure • reduced venous return • decreased Cardiac output (CO) • fluid resuscitation prior to intubation
PEEP effects on cardiovascular output • High PEEP • Increased intrathoracic pressure • Barotrauma - tension PTX • Auto-PEEP (Hyperinflation) • Increased FRC with or without PEEP set • Insufficient expiratory time to expel TV • Diseases @ risk • Emphysema - loss of elastic recoil • Asthma - increased airway resistance
Auto-PEEP • Measurement technique • Occlusion of expiratory port • Immediately before delivery of next breath • Any increase in airway pressure above end-expiratory level represents auto-PEEP • Timing is important, too early and falsely elevated estimate
Auto-PEEP • Treat underlying disease • Bronchospasm • Sepsis • Sedation and paralytics • Adjust ventilator mode • Consider “permissive hypercapnia”
Case #3Difficult Oxygenation 54 yom s/partial gastrectomy for adenocarcinoma PMH: HTN Meds: Cardiazem GERD Axid PSH: RIH repair Lipoma excision SH: ETOH: 1/2 case qd Smoker 1 ppd
CASE #3 POD 0: Admitted to ICU Unremarkable events Extubated POD1 and transferred to floor POD 3: Acute onset of dyspnea, RR25 Diaphoretic, mild cyanosis, tachycardia Transferred to ICU Initial work-up: ????
Case #3 Initial workup: EKG - normal CXR - RLL infilrate ABG 7.50/32/50 Intubated Vent SIMV 16/750 ml/100%/PS5 1 hr. later: Sedated, RR 16, SBP 110, HR 110 ABG 7.38/42/56/86% ?? Vent changes ??
Case #3 Vent changes: PEEP 5.0 added, no change PEEP 10, drop in CO ABG 7.32/50/58/88% What is his diagnosis? What interventions are available to improve oxgenation?
Unilateral Lung Injury • Increased PEEP • Paradoxically increased shunting • Increased V/Q ratio • increased in overdistended lung units • increased in ratio of deadspace to tidal volume
Unilateral PEEP appropriately Sedation Paralytics reduce chest wall tone reduces O2 demand Lateral position Differential lung ventilation (DVL) Bilateral (ARDS) Same as Unilateral except: Prone positioning No indication for DVL Consider Jet ventilation Consider extracorporal membrane oxygenation (ECMO) Therapeutics for Oxygenation