ACUTE RESPIRATORY FAILURE <ul><li>EMERGENCY CONDITION </li></ul><ul><li>ALL AGES </li></ul><ul><li>MAJOR CAUSE OF DEATH </...
ARF-DEFINITION   (Campbell 1960-BRMEDJ. 19651:1451) <ul><li>1 0  FUNCTION FAILURE OF O 2  AND CO 2  EXCHANGE </li></ul><ul...
ARF-CAUSES <ul><li>ACUTE PULMONARY PROBLEMS </li></ul><ul><li>BUT ALSO IN PATIENTS WITH NORMAL LUNGS: </li></ul><ul><ul><l...
CAUSES <ul><li>PUMP </li></ul><ul><li>Respiratory center </li></ul><ul><li>Peripheral nerves </li></ul><ul><li>Respiratory...
NORMAL GAS EXCHANGE <ul><li>BRANCHING CAPILLARIES ALLOW THE DIFFUSION OF OXYGEN AND CARBON DIOXIDE BETWEEN THE ALVEOLI AND...
 
DECREASED MIXED VENOUS O 2  SATURATION (SvO 2 ) <ul><li>O2 RETURNING TO THE LUNGS FROM THE SYSTEMIC CIRCULATION </li></ul>...
MIXED VENOUS DESATURATION <ul><li>LOW VALUES OF Hg (ANEMIA) </li></ul><ul><li>LOW VALUES OF CO (CARDIAC OUTPUT) </li></ul>...
DIFFUSION <ul><li>CO2 DIFFUSES ACROSS THE CAPILLARY MEMBRANE 20X FASTER THAN O2 </li></ul><ul><li>PCO2 IS A INDICATOR OF T...
SHUNT <ul><li>VENOUS - VENOUS BLOOD GOES TO THE SYSTEMIC CIRCULATION WITHOUT OXYGENATION </li></ul><ul><li>ABNORMAL VASCUL...
V/Q MISMATCHING <ul><li>USUALLY FROM NORMAL PERFUSION OF POORLY VENTILATED LUNGS </li></ul><ul><ul><li>BRONCHOSPASM </li><...
RESPIRATORY EXCHANGE RATIO <ul><li>FOR EACH 5 ML OF O2 CONSUMED 4 ML OF CO2 IS PRODUCED. </li></ul><ul><li>4/5 = 0.8 </li>...
A-a O2 DIFFERENCE <ul><li>PAO 2  = FIO 2  X ( Pb – PHO 2 ) – PACO 2 /R </li></ul><ul><li>PAO 2 = MEAN ALVEOLAR O2 </li></u...
A-a DIFFERENCE <ul><li>[150 - (PaCO2/0.8] - PaO2  </li></ul><ul><li>WHEN A PATIENT IS ON SUPPLEMENTAL O2----- THE CALCULAT...
A-a O2 DIFFERENCE <ul><li>MOST SENSITIVE INDICATOR OF RESPIRATORY DISEASES THAT INTERFERE WITH GAS EXCHANGE </li></ul><ul>...
A-a GRADIENT <ul><li>N < 15 </li></ul><ul><li>OLDER PERSONS </li></ul><ul><ul><li>2.5 +.25*AGE </li></ul></ul><ul><ul><li>...
RESPIRATORY FAILURE <ul><li>A BLOOD GAS DIAGNOSIS </li></ul><ul><li>TWO MAJOR TYPES: </li></ul><ul><li>I) HYPOXEMIC PaO 2 ...
HYPOXEMIC RESPIRATORY FAILURE <ul><li>HYPOVENTILATION-cns </li></ul><ul><li>V/Q MISMATCH -most common </li></ul><ul><li>SH...
HYPOXEMIC RESPIRATORY FAILURE <ul><li>HEALTHY: </li></ul><ul><ul><li>SMOKE INHALATION </li></ul></ul><ul><ul><li>CO POISON...
HYPOXEMIC RESPIRATORY FAILURE <ul><li>HYPOVENTILATION: </li></ul><ul><ul><li>O 2  CONSUMPTION > REPLACEMENT BY VENTILATION...
HYPOXEMIC OR HYPERCAPNEIC (HYPERCARBIC) <ul><li>DECEASED PO 2  VS. INCREASED PCO2 </li></ul><ul><li>INCREASED P[A-a]O 2  -...
IMPAIRED DIFFUSION <ul><li>PROCESSES THAT INCREASE THE DISTANCE FROM ALVEOLI TO CAPILLARIES </li></ul><ul><ul><li>eg. IPF ...
HYPERCAPNEIC RESPIRATORY FAILURE <ul><li>IMBALANCE BETWEEN SUPPLY (STRENGTH) AND DEMAND (LOAD) </li></ul><ul><li>CLUES: </...
HYPERCAPNEIC RESPIRATORY FAILURE <ul><li>1) INSUFFICENT DRIVE:  idiopathic,  central sleep apnea, overdose, hypothyroidism...
HYPERCAPNEIC RESPIRATORY FAILURE (cont) <ul><li>Pump failure: </li></ul><ul><li>motor neurons ( spinal cord injury, tetanu...
HYPERCAPNEA WITH O2 ADMINISTRATION <ul><li>INCREASED V/Q MISMATCH </li></ul><ul><li>LOSS OF HYPOXIC VENTILATORY DRIVE </li...
HYPOXEMIC & HYPOCAPNEIC RESPIRATORY FAILURE CAN OCCUR TOGETHER <ul><li>PaCO 2  + P(A - a)O 2  ARE HIGH </li></ul><ul><li>P...
MAKING THE DX <ul><li>IDENTIFY HYPOXEMIC ARF </li></ul><ul><li>IDENTIFY CAUSE: </li></ul><ul><ul><li>? NOT APPARENT, REVIE...
ABG IMPORTANT <ul><li>WON’T BREATHE </li></ul><ul><ul><li>INSUFFICIENT DRIVE </li></ul></ul><ul><li>CAN’T BREATHE </li></u...
FACTORS AFFECTING ABG <ul><li>AGE </li></ul><ul><li>F I O 2 </li></ul><ul><li>PREVIOUS MEDICAL CONDITION </li></ul><ul><li...
RESPIRATORY FAILURE VS. RESPIRATORY INSUFFICIENCY <ul><li>FAILURE (ACUTE OR CHRONIC) </li></ul><ul><ul><li>ABNL ABG’S </li...
ARF CAN PRESENT <ul><li>ALTERED MENTAL STATUS </li></ul><ul><li>LETHARGY </li></ul><ul><li>COMA </li></ul><ul><li>UNEXPLAI...
EARLY RECOGNITION OF ARI CAN AVERT ARF <ul><li>DEVIATION OF RESPIRATORY RATE (BASELINE) </li></ul><ul><li>TRAJECTORY OF DE...
ARF-APPROACH <ul><li>DETERMINE EXTENT OF SUPPORTIVE RX REQUIRED (O 2  SUPPLEMENTATION, VENT) </li></ul><ul><li>DX UNDERLYI...
MANAGEMENT <ul><li>RECOGNIZE TYPE- hypercapneic, hypoxemic, both </li></ul><ul><li>TREAT UNDERLYING ETIOLOGY – asthma, CHF...
INDICATIONS FOR INTUBATION <ul><li>PERSISTENT HYPOXEMIA </li></ul><ul><li>PROGRESSIVE ACIDEMIA </li></ul><ul><li>PROGRESSI...
INITIAL VENT SETTINGS <ul><li>FIO2: 90-100 </li></ul><ul><li>Tidal Volume 8-10 ml/kg </li></ul><ul><li>Mode IMV or AC 8-12...
INITIAL VENT MANAGEMENT <ul><li>Examine patient carefully and see how the patient tolerates ventilation </li></ul><ul><li>...
KEY DECISION <ul><li>WHEN TO INTUBATE? </li></ul><ul><li>AVOID WHEN POSSIBLE, BUT DON,T WAIT TOO LONG IF YOU ARE GOING TO ...
EXAMPLE OF USE OF A-a GRADIENT CALCULATION <ul><li>HEROIN OVERDOSE </li></ul><ul><ul><li>RA ABG 7.08 </li></ul></ul><ul><u...
CLINICAL MODES OF VENTILATION <ul><li>Controlled </li></ul><ul><ul><li>Volume </li></ul></ul><ul><ul><li>Pressure </li></u...
TYPES OF VENTILATORS <ul><li>A) Negative pressure </li></ul><ul><ul><li>Cuirass </li></ul></ul><ul><ul><li>Tank </li></ul>...
POSITIVE PRESSURE VENTILATORS  <ul><li>Classification is based on the Mechanism of termination of inspiration: </li></ul><...
MECHANICAL VENTILATION <ul><li>1) Triggering mechanism </li></ul><ul><li>2) Cycling mechanism </li></ul>
TRIGGERING MECHANISM <ul><li>Controlled </li></ul><ul><li>Assisted </li></ul><ul><li>Assist/Control </li></ul>
PRESSURE CYCLED  <ul><li>Tidal volume is affected by the flow rate, and mechanical properties of respiratory system </li><...
COMPLIANCE <ul><li>T v /P plateau  = static effective respiratory system compliance </li></ul><ul><ul><li>~ 100 ml/cm in n...
Clinical Modes of Ventilation <ul><li>1) Controlled Ventilation </li></ul><ul><ul><li>Volume or pressure controlled </li><...
HEMODYNAMIC EFFECTS of Positive Pressure Ventilation <ul><li>Cardiac output decreased </li></ul><ul><li>Systemic blood flo...
TIDAL VOLUMES <ul><li>5-10 ml/KG </li></ul><ul><li>< T ml cause hypoventilation </li></ul><ul><li>If peak air way pressure...
ELEVATED PEAK PRESSURE <ul><li>? Air way resistance </li></ul><ul><li>? Reduced respiratory compliance </li></ul>
PLATEAU PRESSURE   (occlude expiratory port at end inspiration, relaxed PT) <ul><li>Represents the pressure required to ho...
EFFECTIVE RESPIRATORY COMPLIANCE <ul><li>T v /P L  = Static effective respiratory system compliance  </li></ul><ul><li>100...
NONINVASIVE POSITIVE PRESSURE VENTILATION <ul><li>BiPAP </li></ul><ul><li>Positive pressure ventilation delivered via tigh...
NONINVASIVE POSITIVE PRESSURE VENTILATION   (CONTINUED) <ul><li>Problems: </li></ul><ul><ul><li>Often poorly tolerated </l...
 
 
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Acute Respiratory Failure

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Acute Respiratory Failure

  1. 1. ACUTE RESPIRATORY FAILURE <ul><li>EMERGENCY CONDITION </li></ul><ul><li>ALL AGES </li></ul><ul><li>MAJOR CAUSE OF DEATH </li></ul><ul><li>SUCCESSFUL OUTCOME DEPENDS ON PROMPT RECOGNITION AND IMMEDIATE INITIATION OF SUPPORTIVE Rx </li></ul>
  2. 2. ARF-DEFINITION (Campbell 1960-BRMEDJ. 19651:1451) <ul><li>1 0 FUNCTION FAILURE OF O 2 AND CO 2 EXCHANGE </li></ul><ul><li>Pa O 2 <60 Mm Hg OR Pa CO 2 >50,WHILE BREATHING AIR @ SEA LEVEL </li></ul>
  3. 3. ARF-CAUSES <ul><li>ACUTE PULMONARY PROBLEMS </li></ul><ul><li>BUT ALSO IN PATIENTS WITH NORMAL LUNGS: </li></ul><ul><ul><li>SHOCK </li></ul></ul><ul><ul><li>MYOCARDIAL INFARCTION </li></ul></ul><ul><ul><li>BURNS </li></ul></ul>
  4. 4. CAUSES <ul><li>PUMP </li></ul><ul><li>Respiratory center </li></ul><ul><li>Peripheral nerves </li></ul><ul><li>Respiratory muscles </li></ul><ul><li>Chest wall </li></ul><ul><li>Lungs </li></ul><ul><li>Parenchyma </li></ul><ul><li>Vasculature </li></ul>
  5. 5. NORMAL GAS EXCHANGE <ul><li>BRANCHING CAPILLARIES ALLOW THE DIFFUSION OF OXYGEN AND CARBON DIOXIDE BETWEEN THE ALVEOLI AND THE BLOOD </li></ul><ul><li>OXYGEN IS REVERSIBLY BOUND TO HEMOGLOBIN </li></ul><ul><li>100 ML BLOOD NORMALLY CONTAINS 18 TO 20 ML OF OXYGEN </li></ul><ul><li>CO2 +H2O  H + + HCO3 </li></ul>
  6. 7. DECREASED MIXED VENOUS O 2 SATURATION (SvO 2 ) <ul><li>O2 RETURNING TO THE LUNGS FROM THE SYSTEMIC CIRCULATION </li></ul><ul><li>SvO2 = SaO2 - [VO2/HgBx CO] </li></ul>
  7. 8. MIXED VENOUS DESATURATION <ul><li>LOW VALUES OF Hg (ANEMIA) </li></ul><ul><li>LOW VALUES OF CO (CARDIAC OUTPUT) </li></ul><ul><ul><li>eg. CARDIOGENIC SHOCK </li></ul></ul>
  8. 9. DIFFUSION <ul><li>CO2 DIFFUSES ACROSS THE CAPILLARY MEMBRANE 20X FASTER THAN O2 </li></ul><ul><li>PCO2 IS A INDICATOR OF THE ADEQUACY OF VENTILATION </li></ul><ul><li>PO2 CAN BE AFFECTED BY BOTH VENTILATION AND DIFFUSION </li></ul><ul><li>ELEVATED PCO2=HYPOVENTILATION </li></ul><ul><li>DECREASED PCO2=HYPERVENTILATION </li></ul>
  9. 10. SHUNT <ul><li>VENOUS - VENOUS BLOOD GOES TO THE SYSTEMIC CIRCULATION WITHOUT OXYGENATION </li></ul><ul><li>ABNORMAL VASCULAR OR CARDIAC COMMUNICATIONS </li></ul><ul><li>PERFUSING COMPLETELY UNVENTILATED LUNGS </li></ul><ul><ul><li>eg. FLOODED, CONSOLIDATED </li></ul></ul><ul><li>SHUNT IS REFRACTORY TO O2 Rx </li></ul>
  10. 11. V/Q MISMATCHING <ul><li>USUALLY FROM NORMAL PERFUSION OF POORLY VENTILATED LUNGS </li></ul><ul><ul><li>BRONCHOSPASM </li></ul></ul><ul><ul><li>EDEMA </li></ul></ul><ul><ul><li>SECRETIONS </li></ul></ul><ul><li>HYPOXEMIC PULMONARY VASOCONSTRICTION IS FREQUENTLY IMPERFECT </li></ul><ul><li>UNDERPERFUSION OF NORMALLY VENTILATED LUNGS IS LESS COMMON (P.E.) </li></ul><ul><li>V/Q MISMATCHING RESPONDS TO SUPPLEMENTAL O 2 AS EVEN POORLY VENTILATED LUNGS CAN GET O 2 TO RBC’S </li></ul>
  11. 12. RESPIRATORY EXCHANGE RATIO <ul><li>FOR EACH 5 ML OF O2 CONSUMED 4 ML OF CO2 IS PRODUCED. </li></ul><ul><li>4/5 = 0.8 </li></ul><ul><li>WE CAN’T MEASURE pAO2 DIRECTLY. </li></ul><ul><li>we use the pCO 2 and the respiratory exchange ratio to estimate the alveolar pO 2 ie pAO 2 </li></ul>
  12. 13. A-a O2 DIFFERENCE <ul><li>PAO 2 = FIO 2 X ( Pb – PHO 2 ) – PACO 2 /R </li></ul><ul><li>PAO 2 = MEAN ALVEOLAR O2 </li></ul><ul><li>PHO 2 = WATER VAPOR PRESSURE </li></ul><ul><li>Pb = BAROMETRIC PRESSURE </li></ul><ul><li>R = RESPIRATORY EXCHANGE RATIO= .8 </li></ul><ul><li>PAO 2 = .21 X ( 760mm Hg - 47 mmHg ) - PaCO 2 /.8 </li></ul><ul><li>PAO 2 = 150 mm Hg – PaCO2/.8 </li></ul><ul><li>P (A - a ) O2 = 150 – ( PaO2 + PaCO2/.8 ) </li></ul>
  13. 14. A-a DIFFERENCE <ul><li>[150 - (PaCO2/0.8] - PaO2 </li></ul><ul><li>WHEN A PATIENT IS ON SUPPLEMENTAL O2----- THE CALCULATION OF O2 CONCENTRATION IS IMPRECISE. THEREFORE, CALCULATION IS ONLY REALLY GOOD FOR ROOM AIR </li></ul><ul><li>RULE OF 7: MULTIPLY F 1 O 2 BY 7 GIVES ROUGH IDEA @ BEDSIDE OF WHAT THE PaO 2 SHOULD BE </li></ul><ul><ul><li>eg. 100% = 700 </li></ul></ul><ul><ul><li>eg. 50% = 350 </li></ul></ul>
  14. 15. A-a O2 DIFFERENCE <ul><li>MOST SENSITIVE INDICATOR OF RESPIRATORY DISEASES THAT INTERFERE WITH GAS EXCHANGE </li></ul><ul><li>HELPS TO DIFFERENTIATE PULMONARY FROM EXTRAPULMONARY CAUSES OF HYPOXIA AND HYPERCAPNIA </li></ul>
  15. 16. A-a GRADIENT <ul><li>N < 15 </li></ul><ul><li>OLDER PERSONS </li></ul><ul><ul><li>2.5 +.25*AGE </li></ul></ul><ul><ul><li>eg. AGE 60, 2.5+15=17.5 </li></ul></ul><ul><ul><li>eg. AGE 80, 2.5+20=22.5 </li></ul></ul>
  16. 17. RESPIRATORY FAILURE <ul><li>A BLOOD GAS DIAGNOSIS </li></ul><ul><li>TWO MAJOR TYPES: </li></ul><ul><li>I) HYPOXEMIC PaO 2 <55-60 </li></ul><ul><li>II) HYPERCARBIC P co 2 >50 </li></ul><ul><li>not absolute values-consider the patient’s baseline: age,FIO 2, clinical condition </li></ul>
  17. 18. HYPOXEMIC RESPIRATORY FAILURE <ul><li>HYPOVENTILATION-cns </li></ul><ul><li>V/Q MISMATCH -most common </li></ul><ul><li>SHUNT- anatomic -VSD,PDA, PFA; physiologic: pneumonia,atelectasis, pulmonary edema, ARDS </li></ul><ul><li>DIFFUSION LIMITATION </li></ul><ul><li>REDUCTION IN FIO 2 </li></ul>
  18. 19. HYPOXEMIC RESPIRATORY FAILURE <ul><li>HEALTHY: </li></ul><ul><ul><li>SMOKE INHALATION </li></ul></ul><ul><ul><li>CO POISONING </li></ul></ul><ul><ul><li>TRAVEL TO HIGHER ALTITUDE </li></ul></ul><ul><li>COPD </li></ul><ul><ul><li>AIRPLANE RIDE (~6,000 TO 8,000 Ft) PaO 2 (80 TO 100 DOWN TO 60 0R 70) </li></ul></ul>
  19. 20. HYPOXEMIC RESPIRATORY FAILURE <ul><li>HYPOVENTILATION: </li></ul><ul><ul><li>O 2 CONSUMPTION > REPLACEMENT BY VENTILATION </li></ul></ul><ul><li>ROOM AIR A-a GRADIENT </li></ul><ul><ul><li>P[A-a]O 2 =[150-(Pa CO 2 /0.8)-Pa O 2 ] </li></ul></ul><ul><ul><li>eg. 5=[150-40/0.8-95] </li></ul></ul>
  20. 21. HYPOXEMIC OR HYPERCAPNEIC (HYPERCARBIC) <ul><li>DECEASED PO 2 VS. INCREASED PCO2 </li></ul><ul><li>INCREASED P[A-a]O 2 -ALVEOLAR-ARTERIAL TENSION DIFFERENCE IS COMMON WITH NL OR DECREASED pCO 2 </li></ul>
  21. 22. IMPAIRED DIFFUSION <ul><li>PROCESSES THAT INCREASE THE DISTANCE FROM ALVEOLI TO CAPILLARIES </li></ul><ul><ul><li>eg. IPF </li></ul></ul><ul><li>PROCESSES THAT LOWER O2 DIFFUSION GRADIENT </li></ul><ul><ul><li>eg. CO POISIONING </li></ul></ul><ul><ul><li>ABNL HG </li></ul></ul><ul><ul><li>ANEMIA </li></ul></ul><ul><li>IMPAIR DIFFUSION FROM ALVEOLI TO VENOUS BLOOD </li></ul>
  22. 23. HYPERCAPNEIC RESPIRATORY FAILURE <ul><li>IMBALANCE BETWEEN SUPPLY (STRENGTH) AND DEMAND (LOAD) </li></ul><ul><li>CLUES: </li></ul><ul><ul><li>UNEXPLAINED ALTERED NEURAL STATUS </li></ul></ul><ul><ul><li>HEADACHES </li></ul></ul><ul><ul><li>PAPILLEDEMA </li></ul></ul><ul><ul><li>TACHYCARDIA </li></ul></ul><ul><ul><li>HYPERTENSION </li></ul></ul><ul><ul><li>ELEVATED SERUM BICARBONATE LEVEL </li></ul></ul>
  23. 24. HYPERCAPNEIC RESPIRATORY FAILURE <ul><li>1) INSUFFICENT DRIVE: idiopathic, central sleep apnea, overdose, hypothyroidism </li></ul><ul><li>2) INCREASED VENTILATORY WORK LOAD: increased CO2 production (i.e. burns),increased dead space with wasted ventilation (e.g.massive PE ),disorders of the chest wall </li></ul>
  24. 25. HYPERCAPNEIC RESPIRATORY FAILURE (cont) <ul><li>Pump failure: </li></ul><ul><li>motor neurons ( spinal cord injury, tetanus, polio), peripheral neuropathy (Guillan Barre, polyneuropathy of critical illness) </li></ul><ul><li>Neuromuscular junctions (myasthenia gravis,et al ) </li></ul><ul><li>Respiratory muscles (muscular dystrophy, et al.) </li></ul>
  25. 26. HYPERCAPNEA WITH O2 ADMINISTRATION <ul><li>INCREASED V/Q MISMATCH </li></ul><ul><li>LOSS OF HYPOXIC VENTILATORY DRIVE </li></ul><ul><li>HALDANE EFFECT-O2 decreased CO2 bound to hemoglobin increasing PaCo2 </li></ul><ul><li>MUST BE CAREFUL WHEN ADMINISTERING O2 TO PATIENTS WITH COPD </li></ul>
  26. 27. HYPOXEMIC & HYPOCAPNEIC RESPIRATORY FAILURE CAN OCCUR TOGETHER <ul><li>PaCO 2 + P(A - a)O 2 ARE HIGH </li></ul><ul><li>PaO 2 LOW </li></ul><ul><li>V/Q MISMATCH </li></ul><ul><li>(REPIRATORY MUSCLE FATIGUE) </li></ul>
  27. 28. MAKING THE DX <ul><li>IDENTIFY HYPOXEMIC ARF </li></ul><ul><li>IDENTIFY CAUSE: </li></ul><ul><ul><li>? NOT APPARENT, REVIEW Hx & FE </li></ul></ul><ul><ul><li>? HEART DISEASE-CHF </li></ul></ul><ul><ul><li>COLLAGEN VASC.-ALVEOLAR HEMORRHAGES </li></ul></ul><ul><ul><li>NON INFECTION PN </li></ul></ul><ul><ul><li>MALIGIANCY-LYMPHAMPITIC SPREAD </li></ul></ul>
  28. 29. ABG IMPORTANT <ul><li>WON’T BREATHE </li></ul><ul><ul><li>INSUFFICIENT DRIVE </li></ul></ul><ul><li>CAN’T BREATHE </li></ul><ul><ul><li>INSUFFICIENT STRENGTH: </li></ul></ul><ul><ul><ul><li>WEAKNESS </li></ul></ul></ul><ul><ul><ul><li>TOO HIGH WORKLOAD </li></ul></ul></ul><ul><ul><ul><li>BOTH </li></ul></ul></ul>
  29. 30. FACTORS AFFECTING ABG <ul><li>AGE </li></ul><ul><li>F I O 2 </li></ul><ul><li>PREVIOUS MEDICAL CONDITION </li></ul><ul><li>METABOLIC STATE </li></ul><ul><li>PHYSICAL POSITION </li></ul><ul><li>BAROMETRIC PRESSURE </li></ul>
  30. 31. RESPIRATORY FAILURE VS. RESPIRATORY INSUFFICIENCY <ul><li>FAILURE (ACUTE OR CHRONIC) </li></ul><ul><ul><li>ABNL ABG’S </li></ul></ul><ul><li>INSUFFICIENCY </li></ul><ul><ul><li>ABG’S MAY BE NL, BUT ABNL SIGNS & SYMPTOMS USUALLY PRESENT </li></ul></ul><ul><ul><ul><li>eg. DYSPNEA, PARADOXICAL BREATHING </li></ul></ul></ul>
  31. 32. ARF CAN PRESENT <ul><li>ALTERED MENTAL STATUS </li></ul><ul><li>LETHARGY </li></ul><ul><li>COMA </li></ul><ul><li>UNEXPLAINED TACHYCARDIA </li></ul><ul><li>ABG ANALYSIS IS IMPORTANT </li></ul>
  32. 33. EARLY RECOGNITION OF ARI CAN AVERT ARF <ul><li>DEVIATION OF RESPIRATORY RATE (BASELINE) </li></ul><ul><li>TRAJECTORY OF DECLINE </li></ul><ul><li>NATURAL HX OF MOST UNDERLYING PROCESS </li></ul>
  33. 34. ARF-APPROACH <ul><li>DETERMINE EXTENT OF SUPPORTIVE RX REQUIRED (O 2 SUPPLEMENTATION, VENT) </li></ul><ul><li>DX UNDERLYING DISORDERS (IF ANY) </li></ul><ul><ul><li>Hx, PE </li></ul></ul><ul><ul><li>BEGIN SPECIFIC CONCOMITANT RX </li></ul></ul>
  34. 35. MANAGEMENT <ul><li>RECOGNIZE TYPE- hypercapneic, hypoxemic, both </li></ul><ul><li>TREAT UNDERLYING ETIOLOGY – asthma, CHF, pneumonia </li></ul><ul><li>OXYGEN – usually the most single useful treatment </li></ul>
  35. 36. INDICATIONS FOR INTUBATION <ul><li>PERSISTENT HYPOXEMIA </li></ul><ul><li>PROGRESSIVE ACIDEMIA </li></ul><ul><li>PROGRESSIVE HYPERCAPNEA </li></ul><ul><li>ALTERATION IN MENTAL STATUS </li></ul><ul><li>EVIDENCE OF RESPIRATORY MUSCLE FATIGUE </li></ul><ul><li>ETT 7.5 mm-ease of weaning, possible bronchoscopy </li></ul>
  36. 37. INITIAL VENT SETTINGS <ul><li>FIO2: 90-100 </li></ul><ul><li>Tidal Volume 8-10 ml/kg </li></ul><ul><li>Mode IMV or AC 8-12 B/min. </li></ul><ul><li>Peep: 0-5 cm water </li></ul>
  37. 38. INITIAL VENT MANAGEMENT <ul><li>Examine patient carefully and see how the patient tolerates ventilation </li></ul><ul><li>Obtain chest xray to determine ETT position </li></ul><ul><li>Obtain ABG 15- 20 mins and adjust ventilator accordingly </li></ul><ul><li>Monitor blood pressure –?auto peep </li></ul>
  38. 39. KEY DECISION <ul><li>WHEN TO INTUBATE? </li></ul><ul><li>AVOID WHEN POSSIBLE, BUT DON,T WAIT TOO LONG IF YOU ARE GOING TO DO IT </li></ul>
  39. 40. EXAMPLE OF USE OF A-a GRADIENT CALCULATION <ul><li>HEROIN OVERDOSE </li></ul><ul><ul><li>RA ABG 7.08 </li></ul></ul><ul><ul><li>PaO2 40 </li></ul></ul><ul><ul><li>PaCO2 80 </li></ul></ul><ul><ul><li>150-80/.8-40=10 </li></ul></ul><ul><ul><li>THEREFORE, HYPOVENTILATION SOLE CAUSE </li></ul></ul>
  40. 41. CLINICAL MODES OF VENTILATION <ul><li>Controlled </li></ul><ul><ul><li>Volume </li></ul></ul><ul><ul><li>Pressure </li></ul></ul><ul><li>Assisted </li></ul><ul><ul><li>IMV </li></ul></ul><ul><ul><li>SIMV </li></ul></ul><ul><ul><li>Pressure Support </li></ul></ul>Assist/Control
  41. 42. TYPES OF VENTILATORS <ul><li>A) Negative pressure </li></ul><ul><ul><li>Cuirass </li></ul></ul><ul><ul><li>Tank </li></ul></ul><ul><li>B) Positive pressure </li></ul><ul><ul><li>Pressure limited </li></ul></ul><ul><ul><li>Volume limited </li></ul></ul><ul><li>C) High frequency devices </li></ul><ul><ul><li>Jet </li></ul></ul><ul><ul><li>High frequency </li></ul></ul><ul><ul><li>Oscillators </li></ul></ul>
  42. 43. POSITIVE PRESSURE VENTILATORS <ul><li>Classification is based on the Mechanism of termination of inspiration: </li></ul><ul><ul><li>Pressure </li></ul></ul><ul><ul><li>Volume </li></ul></ul><ul><ul><li>Time </li></ul></ul><ul><ul><li>Flow (few) </li></ul></ul>
  43. 44. MECHANICAL VENTILATION <ul><li>1) Triggering mechanism </li></ul><ul><li>2) Cycling mechanism </li></ul>
  44. 45. TRIGGERING MECHANISM <ul><li>Controlled </li></ul><ul><li>Assisted </li></ul><ul><li>Assist/Control </li></ul>
  45. 46. PRESSURE CYCLED <ul><li>Tidal volume is affected by the flow rate, and mechanical properties of respiratory system </li></ul><ul><li>Therefore, increased airway resistance or decreased compliance leads to decreased tidal volume </li></ul>
  46. 47. COMPLIANCE <ul><li>T v /P plateau = static effective respiratory system compliance </li></ul><ul><ul><li>~ 100 ml/cm in normals </li></ul></ul><ul><li>T v /(P peak- Peep) = effective dynamic respiratory system compliance </li></ul>
  47. 48. Clinical Modes of Ventilation <ul><li>1) Controlled Ventilation </li></ul><ul><ul><li>Volume or pressure controlled </li></ul></ul><ul><ul><li>A preset tidal volume or pressure and rate are set and the patient is not allowed to take any spontaneous breaths. The original ventilators were volume control ventilators. Very uncomfortable because the patient can’t take a breath between ventilator breaths. Not used any more except in the operating room where patient is under general anesthesia. </li></ul></ul>
  48. 49. HEMODYNAMIC EFFECTS of Positive Pressure Ventilation <ul><li>Cardiac output decreased </li></ul><ul><li>Systemic blood flow decreased </li></ul><ul><li>Heart rate unchanged (decreased stroke vol.) </li></ul>
  49. 50. TIDAL VOLUMES <ul><li>5-10 ml/KG </li></ul><ul><li>< T ml cause hypoventilation </li></ul><ul><li>If peak air way pressure exceeds 30 cm H 2 O, there is a decrease in tidal volume </li></ul>
  50. 51. ELEVATED PEAK PRESSURE <ul><li>? Air way resistance </li></ul><ul><li>? Reduced respiratory compliance </li></ul>
  51. 52. PLATEAU PRESSURE (occlude expiratory port at end inspiration, relaxed PT) <ul><li>Represents the pressure required to hold the lungs and chest wall at the current volume (FRC + TV) </li></ul>
  52. 53. EFFECTIVE RESPIRATORY COMPLIANCE <ul><li>T v /P L = Static effective respiratory system compliance </li></ul><ul><li>100 ml/cm in Normals </li></ul>
  53. 54. NONINVASIVE POSITIVE PRESSURE VENTILATION <ul><li>BiPAP </li></ul><ul><li>Positive pressure ventilation delivered via tight fitting facial mask covering </li></ul><ul><li>Both the nose and mouth or just the nose </li></ul><ul><li>Set both an inspiratory an expiratory pressure and rate </li></ul><ul><ul><li>Assists with ventilation </li></ul></ul><ul><ul><li>May allow carefully selected group of patients to avoid intubation </li></ul></ul>
  54. 55. NONINVASIVE POSITIVE PRESSURE VENTILATION (CONTINUED) <ul><li>Problems: </li></ul><ul><ul><li>Often poorly tolerated </li></ul></ul><ul><ul><li>Air leaks around mask </li></ul></ul><ul><ul><li>Skin breakdown with prolonged use </li></ul></ul><ul><ul><li>Heavy burden on nursing and respiratory staff </li></ul></ul><ul><ul><li>Need close monitoring to avoid emergency intubation </li></ul></ul><ul><ul><li>Still needs to be better studied before routine use </li></ul></ul><ul><ul><li>Has had best results in patients with chronic respiratory failure </li></ul></ul><ul><ul><li>due to neuromuscular disease and deformities of the chest wall </li></ul></ul>
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