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Respiratory Dysfunction

Respiratory Dysfunction. Naisan Garraway Najib Ayas. The Case.

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Respiratory Dysfunction

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  1. Respiratory Dysfunction Naisan Garraway Najib Ayas

  2. The Case • 69 yr old male with a 3-day history of worsening SOB and increase use of his puffers. He denies chest pain. He also describes a productive cough with green sputum. He has a known history of COPD and quit smoking 1 month ago but had a 40-pack year history. He has had multiple admissions for COPD exacerbations but never intubated.

  3. The case • His past history is significant for Type II DM diet controlled, HTN, anterior resection 5 yrs ago for diverticulitis and a large incisional hernia, which he is booked for repair in 2 months

  4. The case • His meds include: Atrovent 4 puffs QID, Ventolin 2 puffs QID, Cipro (he bought in Mexico) prn, ECASA 81 mg, Ramipril 5 mg OD, Cold-FX (during the winter months) • He is allergic to Penicillin (anaphylaxis)

  5. The Case • He lives with his wife and has a son in Medical School in Scotland. He quit smoking 1 month ago and drinks 1-2 beer a week.

  6. In the ER • He was seen by the ER doc and was noted to be alert, SOB with a RR of 20 but could speak 3-5 word sentences, audible wheezes bilaterally, no peripheral edema, unable to see JVP, no abdominal pain, obvious reducible incisional hernia. BP 150/90, HR 120, and temp 37.5

  7. In the ER • showed WBC 14.8, Hb 140, Plts 400 normal coags. Lytes were Na 138, K 3.5, Cl 100, CO2 35, Creat 160, and BUN 12. • An ECG showed sinus tachy with poor R wave progression in the lateral leads. A CXR showed hyperinflation with possible “streaking” in the RLL

  8. CXR

  9. In ER • An IV was started and he was given nebs of Atrovent and Ventolin. 100 mg hydrocortisone was given IV. The CTU Snr was consulted and said would be right there but was dealing with a septic patient on the ward.

  10. Later that day • 2 hours later the patient was assessed by CTU and was found to be obtunded but would rouse to a loud voices. His BP was 140/81, HR 130 regular, RR 10, temp 37.8, and a sat of 88% • An ABG was done stat: 7.15/75/104.8/36. • You get the call just having resuscitated a septic CTU patient on the ward, to get down to the ER ASAP

  11. Assessment • As you get there your keen Jr resident has arrived first and tells you the story. • 1. What is the differential diagnosis? Gord

  12. Hypercapnic Respiratory Failure • Chronic obstructive pulmonary disease • Emphysema • Chronic bronchitis • Neuromuscular disorders • Amyotrophic lateral sclerosis • Muscular dystrophy • Diaphragm paralysis • Guillain-Barré syndrome • Myasthenia gravis

  13. Hypercapnic Respiratory Failure • Chest wall deformities • Kyphoscoliosis • Fibrothorax • Thoracoplasty • Central respiratory drive depression • Drugs - Narcotics, benzodiazepines, barbiturates • Neurologic disorders - Encephalitis, brainstem disease, trauma • Primary alveolar hypoventilation • Obesity hypoventilation syndrome

  14. MI/CHF • PE Pulmonary Embolism in Patients with Chronic Obstructive Pulmonary Disease Ann Intern Med. 2006;144:390-396. • Showed a 25% prevalence of PE in patients with COPD hospitalized for severe exacerbation of unknown origin. • Clinical factors associated with PE were previous thromboembolic disease, malignancy, and decrease in PaCO2 of at least 5 mm Hg

  15. BiPAP • You notice the RT is preparing the BiPAP ventilator. • 2. What is the role of BiPAP in COPD exacerbation/acute respiratory failure? Gord

  16. NIPPV • Two meta-analysis found that patients randomized to receive NIPPV had a statistically significant decrease in the need for invasive mechanical ventilation and in the risk of death • Keenan SP, et al: Effect of noninvasive positive pressure ventilation on mortality in patients admitted with acute respiratory failure: a meta-analysis. Crit Care Med 1997. • Thys F, et al: Noninvasive ventilation for acute respiratory failure: a prospective randomized placebo-controlled trial. Eur Respir J 2002

  17. NIPPV • Exacerbations of COPD with rapid clinical deterioration should be considered candidates for NIPPV • International consensus conferences in intensive care medicine: noninvasive positive pressure ventilation in acute respiratory failure. Am J Respir Crit Care Med 2001, 163:283–291.

  18. NIPPV Noninvasive ventilation in acute respiratory failure Nicholas S. Hill, et al; Crit Care Med 2007 Vol. 35, • Review of the literature supports that an initial trial with NIV is not deleterious, even in severely ill COPD patients ( eg pH <7.2) (Conti et al 2002, Squadrone et al 2004) • The “scant & conflicting data” suggests a cautious trial of NIV in COPD pts with severe pneumonia is warranted.

  19. Predict failure?

  20. Review by Peñuelas et al.CMAJ 2007;177(10):1211-8 Sinuff et all Chest2003;123:2062-73

  21. Obtunded Patient • 3. Is there a role for NIPPV in the obtunded hypercarbic COPD patient? Gord

  22. Noninvasive Positive-PressureVentilation To Treat Hypercapnic ComaSecondary to Respiratory FailureGumersindo Go´nzalez Dý´az,et al CHEST 2005; 127:952–960 • The randomized studies excluded pts with decreased LOC • Concern of aspiration risk • International consensus conference considered GCS <10 as contraindication • Never evaluated prospectively

  23. Decreased LOC • Prospective, observational study between January 1, 1997, and May 31, 2002 • Patients with GCS score <8 and CO2 retention formed one group, and those without coma served as a comparison group. • Excluded if another cause for LOC was found

  24. Decreased LOC • Total of 958 pts started NIPPV • 95 (10.1%) had GCS scores on admission <8 • NIPPV success was similar in both groups • hospital mortality was not significantly different

  25. Outcomes

  26. Conclusions for Coma • Coma should no longer be considered a contraindication to NPPV therapy.

  27. NIPPV in Patients With Acute Exacerbations of COPD and Varying Levels of ConsciousnessScala, et al; CHEST 2005; 128:1657–1666 • A 5-year case-control study with a prospective data collection. • Study confirms that NPPV may be successfully applied to patients experiencing COPD exacerbations with milder ALCs, the rate of failure in patients with severely ALCs (ie, Kelly score > 3) is higher, though better than expected, so that an initial attempt with NPPV may be performed

  28. Ventilation • You decide to intubate the patient instead and it goes ahead smoothly. Your medical student said he had heard these patients can get auto peep and that it can be BAD! • 4. What would be your initial ventilator settings including what measures can be done to minimize auto peep in the ventilated COPD patient? Yoan

  29. Goals for COPD patients • Adequate patient monitoring • Optimize ventilator settings to minimize excessive work of breathing • Assure Synchrony • Detect auto-PEEP and prevent barotrauma • Prevent further respiratory muscle atrophy • Intubate using the widest diameter ET tube possible (R = 8nl / πr 4)

  30. Mechanical Ventilation • Mode? • Volumes/Pressures? • Flow Rate? • RR? • pH? • I:E ratio? • PEEP? • FiO2

  31. Auto-PEEP • When the expiratory time is not long enough to allow exhalation of all tidal volume auto-PEEP is generated.

  32. Airway Pressures

  33. PEEPi + PEEPe Ranieri et al Eur Respir J, 1996, 9, 1283–1292

  34. The Unit • The patient is brought up to “The Unit” and your Jr has finished the admission orders and wants to review them with you. • 5. What treatments do you want to ensure the patient receives? Yoan

  35. Orders • Sedation? • Bronchodilators? • Steroids? • Antibiotics? • Nutrition? • Insulin? • Heliox? • Further investigations?

  36. Weaning • After a few days, some improvement is seen. His FiO2 requirements are 30% and his lungs sound much clearer. He has also been weaned down to pressure support. The RT mentioned the weaning indices for the day with a PO2/FiO2=300, RSBI of 120. Your medical student looks confused and asks: • 6. What are weaning indices and what is the evidence for their use? Yoan

  37. RSBI • This is f/VT • Yang, KL, Tobin, MJ (1991) A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. N Engl J Med324,1445-1430 • Shown to be predictive of extubation if <105

  38. RSBI Risk Factors for Extubation Failure in Patients Following a Successful Spontaneous Breathing Trial Frutos-Vivar, et al 2006;130;1664-1671 Chest

  39. Spontaneous Breathing Trial ELY et al; N Engl J Med 1996;335:1864-9.) • RCT of 300 vented pts in ICU&CSICU • All pts screened daily for PaO2/FiO2>200, PEEP<5, f/Vt <105, good cough, no pressors

  40. SBT • Intervention group then underwent SBT for 2 hours that morning • If passed a note was left on the chart • Controls only had the daily assessment

  41. SBT results

  42. Asynchrony • Five days later, your patient is still requiring a PSV of 10 and PEEP 5. The RT notes some asynchrony as well. The bright Jr resident pipes up and says he heard about a different form of ventilation called PAV that might help with this. • 7. What is PAV and how does it work? Steve

  43. PAV (Proportional Assist Ventilation) • ventilator amplifies the patient'sinspiratory effort without any preselected target volume orpressure • Aim is to allow the patient to attain their own ventilation and breathing pattern • Younes M. Proportional assist ventilation, a new approach to ventilatory support. Am Rev Respir Dis 1992;145:114–20

  44. PSV vs PAV • Varelmann, et al; Crit Care Med 2005; 33:1968 –1975) • 12 pts in randomized clinical crossover • Increasing vent demand by adding dead space • Cardiorespiratory, ventilatory, and work of breathing variables were assessed

  45. Results • No major differences in cardiorespiratory function between dynamic and constant inspiratory pressure assistance.

  46. PAV • 8. Is there evidence it helps with patient vent asynchrony? Steve

  47. Giannouli, et al. Response of ventilator dependent patients to different levels of pressure support and proportional assist. Am J Respir Crit Care Med. 1999;159:1716 –1725. • found lower rates of ineffective triggering with PAV than with PSV, because tidal volume was smaller at high levels of assistance and because ventilator insufflation time was limited

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