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Anestesiologia UIS Hipoxemia perioperatoria. Dr. Raúl Vásquez. Historia. La anestesia general se asocia con hipoxemia. Fisiologia. Consumo O2 (VO2). Oxigenación. Entrega O2 (DO2). Metabolismo celular aerobico. Oxygenation and mechanisms of hypoxemia. Definicion.
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Anestesiologia UIS Hipoxemiaperioperatoria Dr. Raúl Vásquez
Historia La anestesia general se asocia con hipoxemia
Fisiologia Consumo O2 (VO2) Oxigenación Entrega O2 (DO2) • Metabolismocelularaerobico Oxygenation and mechanisms of hypoxemia
Definicion • Disminucion de la entrega de oxigeno de la atmosfera a la sangre arterial (oxigenacióninsuficiente) Hipoxemia • Disminucion de la entrega de oxigeno de la sangre arterial a los tejidos Hipoxia Monitoring Respiratory Function
Incidencia Hipoxemiaperioperatoria Can J Anesth/J Can Anesth (2010) 57:888–897 The incidence of hypoxemia during surgery: evidence from two Institutions Duration of Hypoxemic Episodes at Hospitals A & B. The incidence and maximum duration of intraoperative hypoxemic episodes. Episodes are grouped by maximum duration per patient for both hypoxemic (SpO2\90) and severely hypoxemic episodes (SpO2 B 85). The percentage of patients experiencing two consecutive minutes or longer of hypoxemia and severe hypoxemia was 6.8% and 3.5%, respectively
Incidencia Hipoxemiaperioperatoria 234 Millones Cx Año Can J Anesth/J Can Anesth (2010) 57:888–897 1 : 15 Hipoxemiapor dos minutos 1 : 64 Hipoxemia ≥ 5 minutos ˃3 millonespacienteshipoxemia≥ 5 min
EfectosDeletereos Hipoxemiaperioperatoria Altera cicatrización, integridadanatomosis y resistencia a infección Arch Surg 1997; 132: 991-6. Arch Surg 1997; 132: 997-1005. N Engl J Med 2000; 342: 161-7 Translocacionbacteriana GI – Sepsis Arch Surg 1996; 131: 57-62 Disfuncióncognitiva – delirio Am J Med 1981; 79:1247-54. Br J Anaesth1994; 72: 286-90 ↓↑GC, precipitaarritmias, hipertensión arterial, Taquicardia, isquemia Anesthesiology 1999; 91: 1246-52. Br Heart J 1993; 69: 3-5
MedidasOxigenacion Hipoxemiaperioperatoria Pulse oximetry • Examenfísico • Cianosis franca 5 g/dl deoxihemoglobinaSaO2 67% • GASA gold standard PaO2 • SaO2 “Quintosigno vital” • Proyecto global pulsooximetria OMS • 100000 pulsooximetros
Oximetría de Pulso Hipoxemiaperioperatoria Monitoring Respiratory Function
PulsoOximetria Hipoxemiaperioperatoria Pulse oximetry Depicted here is the oxyhemoglobin dissociation curve for normal adult hemoglobin (Hemoglobin A, solid line). Note that hemoglobin is 50 percent saturated with oxygen at a partial pressure of 27 mm Hg (ie, the P50 is 27 mm Hg) and is 100 percent saturated at a pO2 of approximately 100 mm Hg. Depicted here are curves that are "left-shifted" (blue line, representing increased oxygen affinity) and "right-shifted" (red line, decreased oxygen affinity). The effect of right- or left-shifting of the curve is most pronounced at low oxygen partial pressures. In the examples shown, the right-shifted curve means that hemoglobin can deliver approximately 70 percent of its attached oxygen at a pO2 of 27 mm Hg. In contrast, the left-shifted hemoglobin can deliver only about 35 percent of its attached oxygen at this pO2. A high proportion of fetal hemoglobin, which has high oxygen affinity, shifts this curve to the left in newborns.
Oximetria de Pulso Hipoxemiaperioperatoria Global Pulse Oximetry Project • Aumentadeteccionhipoxemia 20 veces • Dxtemprano • Intubaciónendobronquial • Hipoventilacion • Pacientesmonitorizado • 50% menoseventosisquemia miocárdica
Oximetría de Pulso Hipoxemiaperioperatoria Oximetría de pulso para la monitorización perioperatoria 2008 La monitorización perioperatoria con oximetría de pulso no resulta en mejores resultados, efectividad o eficacia. No reduce transferencia a UCI nimortalidad y esinciertosiexistebeneficio real en Cx Cardiotoracica
Oximetría de Pulso Mala Colocacion ArtefactoMovimiento Luz Ambiental Radiación Electromagnetica Fuentes comunes de artefacto Pulse oximetry
Oximetría de Pulso Erroresrelacionados Con el Paciente Pulse oximetry
MedidasOxigenacion Hipoxemiaperioperatoria Oxygenation and mechanisms of hypoxemia Tension arterial de O2 PaO2 GradienteAlveolo-arterial O2 Radio PaO2/FiO2 Radio OxigenoAlveolo-arterial Indice de Oxigenacion Fraccion Shunt
Gradiente A-a Hipoxemiaperioperatoria PAO2=(FiO2x[Patm-PH2O])-(PaCO2/R) Oxygenation and mechanisms of hypoxemia • Diferenciacantidadoxigeno en el alveolo PAO2 y cantidad de O2disuelto en el plasma PaO2 • Varia con la edad • Gradiente A-a= (edad/4) + 4 • 10 mmHg jovenes, 30mmHg 70 años
Gradiente A-a http://www.mdcalc.com/a-a-o2-gradient
Gradiente A-a Hipoxemiaperioperatoria Anesthesiology Clinics of North America - Volume 19, Issue 4 (December 2001)
Gradiente A-a Hipoxemiaperioperatoria Oxygenation and mechanisms of hypoxemia • ↑FiO2 = ↑PAO2 y ↑PaO2 • La PAO2↑desproporcionadamente • ˂40 años FiO2 100% 8 a 82 mmHg • ˃40 años FiO2 100% 3 a 120 mmHg
Fraccion Shunt D-I Qs/Qt=(CcO2-CaO2)/(CcO2-CvO2) CaO2=(1.34xHgbxHgbO2)+(0.003xPO2) Monitoring Respiratory Function Gold standar de oxigenacioneficiente en los pulmones Shunt 50%= Fallarespiratoriasevera Shunt 5%= Normal
MedidasOxigenacion Hipoxemiaperioperatoria Oxygen derived variables in acute respiratory failure Crit Care Med. 1983 Aug;11(8):646-9 33 pctes con SDRA Relacionaron shunt con radio O2 A/a, PaO2/FiO2, gradiente A-a, IR, radio O2 a/A PaO2/FiO2 variable mas facilquepredice con exactitud el grado de shunt en fallarespiratoria
Radio PaO2/FiO2 Hipoxemiaperioperatoria Oxygenation and mechanisms of hypoxemia Normal= 300 a 500 mmHg ˂300 mmHg= Intercambiogaseosoanormal ˂200 mmHg= Hipoxemiasevera se correlaciona con Shunt ˃20%
↓Oxígenoinspirado Hipoxemica Hipoventilación Anemica AlteraciónV/Q Circulatoria Afinidad Difusiónlimitada Histotoxica Causas . Shunt Derecha-Izquierda Hipoxia Hipoxemia Monitoring Respiratory Function Oxygenation and mechanisms of hypoxemia
Bajo PIO2 Hipoxemiaperioperatoria Anesthesiology Clinics of North America - Volume 19, Issue 4 (December 2001) PERIOPERATIVE HYPOXIA The Clinical Spectrum and Current Oxygen Monitoring Methodology Barometric pressure (PB) and inspired oxygen (O2 ) tension or partial pressure in millimeters of mercury (mm Hg) related to altitude in thousands of feet and in meters. The PB at Denver, the Mile High City, is 640 mm Hg, and the PIO2 there is 134 mm Hg in dry air. Point 1 is at 5500 meters in the Peruvian Andes, the highest point of continuous human habitation, where the PB is 380 mm Hg, and the PIO2 in dry air is 80 mm Hg. The air is not dry at the alveolus. By the time the inhaled air reaches the alveolus, it is saturated with H2 O vapor (47 mm Hg at 37°C irrespective of the elevation or PB). At 5500 meters, H2 O vapor decreases the PIO2 from 80 to 70 mm Hg). Supplemental oxygen is usually required at point 2, although Mount Everest has been climbed without O2 . Point 3 represents the highest ascent with O2 but without superatmosphericpressure.
Ecuación 1 PIO2 = FiO2 X (PB – PH20) Anesthesiology Clinics of North America - Volume 19, Issue 4 (December 2001) ↓PIO2 = ↓PAO2
Flujometros Morgan, Edward: Anestesiologiaclinica – Seccion I capitulo 3 y 4. 2007 • Guarda Hipóxica • Mecánica, neumática o electrónica • Garantiza FiO2 25% • Flujo Metabolico O2: Peso¾ x 10
Hipoventilación Hipoxemiaperioperatoria O2 CO2 CO2 O2 CO2 O2 CO2 CO2 CO2 O2 O2 O2 O2 CO2 • Hipoventilado Anesthesiology Clinics of North America - Volume 19, Issue 4 (December 2001) • Ventilaciónminutoinadecuada(↑CO2) • FR x VC Normal
Hipoventilación Oxygenation and mechanisms of hypoxemia Anesthesiology Clinics of North America - Volume 19, Issue 4 (December 2001) Corrige al ↑FiO2 Gradiente A-a normal
Imbalance V/Q V sin Q EspacioMuerto Q sin V Shunt Anesthesiology Clinics of North America - Volume 19, Issue 4 (December 2001) • El balance V/Q escomplejo • Volumen ventilatorio • Presion alveolar • Compliance pulmony cajatoracica • Resistencia de la via aerea • Gravedad • Posicion del paciente • Flujosanguineopulmonar • Modo ventilatorio
Imbalance V/Q Anesthesiology Clinics of North America - Volume 19, Issue 4 (December 2001) Enfermedadpulmonarobstructiva Enfermedad vascular pulmonar Enfermedadintersticial
Hipoxemica Aguda Hipoventilacion Alveolar Perioperatoria Aguda Hipoperfusion Shock FallaRespiratoria Tipo I Tipo IV Tipo II Critical Care. Just the Facts 2007 Tipo III Atelectasias, dolor incisional analgesia inadecuada, alteraciontos, uso de tabaco 6 semanasprecxsobrehidratación
Atelectasias Pulmonary Atelectasis A Pathogenic Perioperative Entity In contrast, with atelectasis (B), alveolar inflation and deflation may be heterogeneous, and the resulting airway stress causes epithelial injury. Because the blood vessels are compressed, perfusion may be traumatic because of flowinduced disruption of the microvascular endothelium. Both epithelial and endothelial injury may initiate or ropagate lung injury. This figure depicts the advanced stage of lung injury caused by atelectasis. The initial injury is simple collapse of alveoli. However, with time, this leads to an inflammatory reaction. As the derecruitedlungs cause epithelial injury and loss of epithelial integrity, both type I and type II alveolar cells are damaged. Injury to type II cells disrupts normal epithelial fluid transport, impairing the removal of edema fluid from the alveolar space. In dditionto collapse, derecruited lungs also become fluid filled. Neutrophils adhere to the injured capillary endothelium and migrate through the interstitium into the alveolar airspace.Inthe airspace, alveolar macrophages secrete cytokines, interleukin (IL)-1, -6, -8, and -10, and tumor necrosis factor (TNF)-, which act locally to stimulate chemotaxisand activate neutrophils. IL-1 can also stimulate the production of extracellular matrix by fibroblasts. Neutrophils can release oxidants, proteases, leukotrienes, and other proinflammatorymolecules, such as platelet-activating factor (PAF). MIF macrophage inhibitory factor. Anesthesiology, V 102, No 4, Apr 2005 In normal lungs (A), the alveolar inflation and vascular prfusion are associated with low stress and are not injurious. Two separate barriers form the alveolar– capillary barrier, the microvascular endothelium, and the alveolar epithelium. e
Shunt (Qs/Qt) Anesthesiology Clinics of North America - Volume 19, Issue 4 (December 2001) • Derecha a izquierda • Anatomico • Intracardiaco, MAV, Venasbronquiales • Transpulmonar • Area Q no V • Atelectasias • Neumonia • Edema pulmonar • Aspiracion
Etiologia y Patogenesis Atelectasias Tres sets de mecanismoscausan o contribuyen a la formacion de atelectasias Compresion Pulmonar Alteracion Surfactante Reabsorcion Gas Anesthesiology, V 102, No 4, Apr 2005
CompresionPulmonar Hagberg: Benumof's Airway Management, 2nd ed
Reabsorcion Gas Anesthesiology, V 102, No 4, Apr 2005 Oclusioncompleta de la via aerea ↑FiO2 Va/Q Bajo
Atelectasias Anesthesiology, V 102, No 4, Apr 2005
Hipoxemia Alt Compliance Pulmonar ↑RVP Lesion pulmonar Atelectasias Complicaciones VC bajo, hiperoxia (microatelectasias) Reversadaporhiperinflacion Reduccionvolumenpulmonar, macroatelectasias. Empeoraoxigenacionsistemica Vasoconstriccionhipoxicapulmonar↓ Tension Oxigeno alveolar y venosomixto Atelectasias + VC ↑ Prevenida con PEEP Anesthesiology, V 102, No 4, Apr 2005
Atelectasias Prevencion - Reversion Depende del Pulmon! • PulmonsanoHiperinsuflación • 3 sucesivas • -20 cm H2O x 10 seg • -30 cm H2O x 15 seg • -40 cm H2O x 15 seg • Nunn et al • -40 cm H2O x 40 seg • Tusman • Reclutamiento alveolar Anesthesiology, V 102, No 4, Apr 2005
Reclutamiento Alveolar Pulmón Sano Tusman G et al. Alveolar Recruitment Strategy normalizes arterial oxygenation Schematic representation of the “Alveolar Recruitment Strategy”: PEEP is incremented in 3 steps of 5 cmH2O each. The vertical rectangles represent tidal breathing with a tidal volume of 7-9 mg/kg BW at a respiratory rate of 8 bpm. At a PEEP of 15 cmH2O tidal volumes are increased until a maximum tidal volume of 18 ml/kg or a peak airway pressure of 40 cmH2O is reached. These settings are applied for 10 breaths. Thereafter, tidal volumes are reduced to the previous values. Finally, PEEP is set to a level of 5 cmH2O in two steps.
Atelectasias Prevencion - Reversion Depende del Pulmon! PulmonLesionado -Evitar↑VC, presionespicoelevadas, atelectrauma -Usar PEEP • PulmonsanoHiperinflación pasiva • 3 sucesivas • -20 cm H2O x 10 seg • -30 cm H2O x 15 seg • -40 cm H2O x 15 seg • Nunn et al • -40 cm H2O x 40 seg • Tusman • Reclutamiento alveolar Anesthesiology, V 102, No 4, Apr 2005
VentilacionMecanica Sobredistension Baro - Volotrauma - LAD VENTANA SEGURA Atelectasias Estrespordeslizamiento, alteracionporsurfactante Barboza, Miguel Fisiologia de la ventilacion Unipulmonar
Gracias! Por la Paciencia
Incidencia Anesthesiology, V 103, No 1, Jul 2005 Management of the Difficult Airway A Closed Claims Analysis * Percent of row resulting in death or brain damage (death/BD). † Bonferroni P 0.04, 1993–1999 vs. 1985–1992.