Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Carbon Monoxide Poisoning Maria Rica P. Patawaran M.D. Resident Grand Rounds May 1, 2008 Objectives 1. To discuss the clinical features, diagnosis, complications and treatment of CO poisoning 2. Hyperbaric Oxygen Treatment Case Presentation • • • • • • B.A. 26 yo female Single Roman Catholic Right-handed No known co-morbidities Case Presentation CHIEF COMPLAINT: Unresponsiveness Case Presentation 4 mos PTA • Voiced out relational problems at work • Noted to be indecisive; difficulty concentrating; more withdrawn, quiet and had negative thoughts 2 weeks PTA • More withdrawn and quiet • Still had negative thoughts • Evasive when asked about reason for being depressed Case Presentation 1 week PTA • Went to a motel alone and drank 1/8 bottle of whiskey • Advised psychiatric consult but declined 2 weeks PTA • Seen inside a their car gasping with drooling of the saliva. • Also found unburnt charcoals with thinner and chinese herbal medications for insomnia MMC ER Case Presentation REVIEW OF SYSTEMS: • No fever, no pallor • No cough or colds, dyspnea • No chestpain, orthopnea, PND • No abdominal pain, vomiting, no bowel changes • No dysuria, hematuria, oliguria • No bleeding diathesis • No polyuria, polydipsia, polyphagia • No edema, cyanosis Case Presentation • Past Medical History: Unremarkable • Family History: (+) Hypertension; Diabetes; and Heart Disease • Social History: Non-smoker and Nonalcoholic beverage drinker; Denies Illicit drug use Case Presentation PE: • Unconscious, GCS 5 (E1V2M2) • BP:90/60 CR : 125 bpm, regular RR: 16 cpm, regular T: 36.5C O2 sat 84% • Pink palpebral conjucnctivae, anicteric sclerae, (+) soot inside anterior nares • Supple neck, no palpable cervical, supraclavicular nor axillary LNs, neck veins not distended, no carotid bruit • SCE, no retractions, clear BS, no rales, no wheezes • Adynamic precordium, tachycardic, regular rhythm, AB 6th LICS, MCL, no murmurs • Flabby abdomen, normoactive bowel sounds, soft, nontender, no hepatojugular reflux • No edema, no cyanosis, full and equal pulses, (+) soot stained fingertips Case Presentation Neurologic Examination: • Mental Status: very drowsy; opens eyes to vigorous stimuli; does not follow command • Cranial Nerves: CN: I – cannot be assessed II – pupils 3-4mm ERTL III,IV,VI – horizontal eye movements V – not done VII - grimaces to pain VIII – XII – cannot be assessed Case Presentation Neurologic Examination: • Sensory: LUE localizes to pain RUE withdraws to pain Both LE withdraws to pain • Motor: moves all extremities against resistance • Pathologic Reflexes: Bilateral babinski; (+) ankle clonus (L) • Meninges: supple neck Case Presentation Neurologic Examination • Deep Tendon Reflexes L R ++ ++ +++ ++ +++ +++ ++ ++ +++ +++ Case Presentation • Salient Features: 26 yo female No known Co-morbidities (+) Behavioral Changes unresponsive charcoals, thinner and chinese herbal medications (+) soot in the nares and fingertips GCS 5 (E1V2M2) (+) Babinski sign Admitting Impression • Inhalational Injury 2 to Carbon Monoxide Poisoning • Adjustment Disorder with Depressed Features Course in the Wards At the ER • Intubated with the ff MV settings: FiO2 100% vT 400 RR 20 PEEP 5 Peakflow 40L/min • Referred to the ff services: Medico-legal and Pulmonary Medicine – Labs Requested: ABGs with CO Hb and Met Hb, CBC, PT, PTT, CXR, 12L ECG, Spec 19, CBG • IVF Started • Immediately transferred to ICU Course in the Wards At the ICU • Pulmonary Medicine: – Antibiotics started: Co-amoxyclav 1.2 gms IV q8 – Piracetam 1gm IV q8 hrs • Referred to Neurology service – Following tests requested: • CT Scan - Normal • EEG - Normal • Drug Tests – Started Citicholine 1gm IV q12 Course in the Wards 6 - 8 hours post-admission • Repeat labs requested: • • • • Electrolytes BUN and Creatinine Total CPK, CK-MB Repeat ABGs with COHb and MetHb • FiO2 decreased to 60% Course in the Wards 2nd Hospital Day: • Patient noted to be more awake and follows commands • Feeding started • Repeat CXR • Patient shifted to CPAP with PS 10, PEEP 5, FiO2 30% • Repeat labs: • Electrolytes • Total CPK and CK-MB • Repeat ABGs • Started on CoQ10 1 tab 3x a day, Abixa 1 tab daily and Clexane • Referred to Psychiatry Service Course in the Wards 3rd Hospital day • Babinski sign now absent • Mech vent settings adjusted: CPAP, PS 5, PEEP 3, FiO2 28% in-line neb via Tpiece • Repeat ABGs done Course in the Wards 4th Hospital Day • Patient extubated and shifted to nasal cannula • Feeding per orem started • Allowed to move around with assist • Started on Serraline (Zoloft) ½ tab OD Course in the Wards 5th Hospital Day • O2 and clexane discontinued • Regular diet given Course in the Wards 6th Hospital Day • Transferred out of the ICU to NP ward The rest of the hospital stay was unremarkable DISCUSSION Pathophysiology • CO is a colorless, odorless, nonirritant gas • Known as the “Silent Killer” • CO is diffusion-limited. Amount of CO absorbed is dependent on: – Level of CO in the environment – Minute ventilation – Duration of exposure Pathophysiology • Rapidly absorbed across alveolarcapillary membrane • Hemoglobin’s affinity for CO is 200 to 250 times its affinity for oxygen O2 Dissociation Curve • CO binding to hemoglobin causes allosteric modifications increasing its affinity for oxygen • Shift of O2 dissociation curve to the left • Decreased tension at which O2 is released from hemoglobin • Less O2 delivery to the cells Pathophysiology • CO exerts toxic effects by combination of tissue hypoxia and inflammatory activity • 3 mechanisms of hypoxia: • Decrease O2 capacity of Hgb • Decrease uptake of bound oxygen into tissues • Impairs mechanism of cellular respiration Pathophysiology • Other mechanisms of toxicity: – Binding to cytochrome oxidase – Lipid peroxygenation – Reperfusion injury – Binding to myoglobin Pathophysiology • CO poisoning in pregnancy – – – – endogenous fetal production fetal hemoglobin has a higher affinity for CO longer elimination half-life in fetus fetal hypoxia worsened by maternal shift of O2 dissociation curve to the left Epidemiology • Incidence is underestimated • Most common cause of poisoning death • Death rates higher in males, blacks, ages 15 to 24 and the elderly • Higher in northern and midwestern states – North Carolina 18th (‘79 to ‘88) • More common in winter months Sources of Carbon Monoxide • Tobacco smoke is the largest source of inhaled CO – independent of nicotine levels – HbCO levels chronically elevated • • • • 0.5% for nonsmokers 1.9% for one ppd 3% for two ppd other sources - 3% to 8% for “heavy smokers” Sources of Carbon Monoxide • Endogenous production • Motor vehicles produce approximately 250 million tons per year, much is converted to CO2 in the upper atmosphere • “Clean” fuels such as propane, butane, etc. can also be culprits Sources of Carbon Monoxide • Methylene chloride (CH2-Cl2) found in paint removers – absorbed through the skin or inhaled – metabolized in the liver to CO – longer half-life Diagnosis - Symptoms • Symptoms are numerous and nonspecific • Acute CO toxicity often misdiagnosed as an acute viral syndrome, in part because of increased frequency in winter months Diagnosis - Symptoms • Most common Sx from 3 case series: – – – – – – headache dizziness weakness nausea difficulty conc./confusion shortness of breath 91% 77% 53% 47% 43% 40% Diagnosis - Symptoms • Common symptoms cont. – – – – – visual changes chest pain loss of consciousness abdominal pain muscle cramping 25% 9% 6% 5% 5% Diagnosis - Symptoms • The Delayed Neuropsychiatric Syndrome – Subacute manifestation (days to months) – Occurs in spite of normal HbCO levels – Broad variety of symptoms including cognitive defects, personality changes, psychic akinesia, parkinsonism, psychotic encephalopathy, amnesia, incontinence, gait disturbances, etc. Diagnosis - Symptoms • The Delayed Neuropsychiatric Syndrome – reported incidence varies widely, est. 10-30% – can occur in initially asymptomatic patients – symptoms can be subtle, often missed • the Carbon Monoxide Neuropsychologic Screening Battery consists of six subtests, valuable for pre and post treatment and to assess for later occurring Sx. Diagnosis - Signs • Physical exam signs are also generally nonspecific • tachypnea, tachycardia, vestibular signs common • cerebral edema if poisoning severe • retinal hemorrhages uncommon but more specific Diagnosis - Signs • Signs of smoke inhalation such as singed nasal hairs, injured mucous membranes, carbonaceous mucus discharge • “Classic” findings of cherry-red lips, skin, and mucus membranes are very rare Diagnosis - Labs • Carboxyhemoglobin – measured with a co-oximeter – arterial or venous blood sampling – chronically elevated in smokers – consider time of exposure to time of sampling • Expired Carbon Monoxide – monitor that measures CO in parts per million then converts value to estimate HbCO – gives rapid results and can be used at the scene of suspected exposure Diagnosis - Other • Pulse Oximetry – notoriously poor at detecting HbCO – HbCO and HbO2 similar light absorbance, are read as the same – study of 25 CO exposed pts with measured HbCO from 2.2-44% (mean of 16.1%), all had simultaneous pulse-ox readings of 96-100% Diagnosis - Labs • Arterial Blood Gas – may show metabolic acidosis – normal to low normal PaO2 – HbO2 saturation is calculated from PaO2 • CK Levels CPK and CK-MB Levels CPK Levels CK-MB Levels Diagnosis - Other • Other labs: – – – – – CBC Electrolytes BUN, Creatinine Met-Hb Toxicology screening Diagnosis - Other • Chest X-ray abnormalities in up to 30%, all nonspecific and often related to associated exposures or conditions • Neuroimaging – typically normal after acute exposure, used to rule-out other pathology – abnormalities in DNS sometimes seen on CT, MRI, and SPECT, most often in deep white matter and / or globus pallidus Treatment • First step is to remove victim from the source of carbon monoxide • High-flow 100% FiO2 continued until HbCO levels have normalized • Admission for underlying medical conditions (cardiac pts) and assoc. injuries • Screening of other possible victims at scene Treatment • Elimination of carbon monoxide is related to minute ventilation, duration of exposure to O2, and FiO2 • Half-life of HbCO: – 4 to 6 hours breathing room air – 40 to 80 minutes breathing 100% O2 – 15 to 30 minutes breathing hyperbaric O2 Tx – Hyperbaric Oxygen • Defined as a treatment in which a patient intermittently breathes 100% oxygen • Expressed in Atmospheres (ATM) • Treatment chamber is pressurized to a pressure greater than sealevel • Multiplace chambers - pressurized with air; O2 given via face mask, hood tent, or ET tube • Monoplace chambers – pressurized with O2 Tx – Hyperbaric Oxygen • Mechanism of Action: 1. Increase Oxygen delivery – using Henry’s Law: P1/C1 = P2/C2 2. Reduction of bubble size – using Boyle’s law: PV=K, where P = pressure and V= Volume; K = constant 3. Antagonism of Carbon Monoxide. 4. Improved wound healing Tx – Hyperbaric Oxygen • Technique: – Chamber pressure - between 2.5 and 3.0 atm – DurationAcute therapy require only one or two treatments, while chronic medical conditions may warrant up to 30 or more sessions. – : 45 to 300 minutes – Pressures exceeding 2.8 to 3.0 atm - increase the risk of both neurologic and pulmonary oxygen toxicity Tx. - Hyperbaric Oxygen • Suggested Indications in CO poisoning – – – – – – – coma or any period of unconsciousness Severe metabolic acidosis (pH < 7.1) HbCO level >25 percent pregnancy and HbCO level >20% signs of cardiac ischemia or arrythmia recurrent symptoms for up to three weeks symptoms not resolved after 4-6 hr. of NBO Tx – Hyperbaric Oxygen • Contraindications: – absolute: untreated pneumothorax. – Relative contraindications: • • • • • obstructive lung disease upper respiratory or sinus infections recent ear surgery or injury fever claustrophobia Tx. - Hyperbaric Oxygen • Side effects – reversible myopia – pain in tympanic membrane (rupture), cranial sinuses, teeth, and/or lungs due to rapid changes in pressure – rarely can precipitate generalized seizures – reversible tracheobronchial Sx and decreased pulmonary function assoc. with multiple Tx. – claustrophobia Summary • CO poisoning is common and is often misdiagnosed • Toxic effects mainly cardiac and CNS • Main sources are tobacco smoke and automobile exhaust • Neuro Sx can appear late when HbCO level is normal Summary • PE, labs, CXR, pulse-ox normal or nonspecific • HbCO levels don’t correlate well with Sx • Tx with normobaric vs hyperbaric oxygen • HBO quickens elimination of HbCO and shortens acute Sx, but long-term benefits unproven and controversial • No adequate PRCT of HBO vs NBO Acknowledgements • Dr. Ruth Divinagracia • Dr. Paul Tan • Dr. Glenn Michael Ramos • Dr. Daryl De Ramos • Nel (my sweetypie!) Thank You for your kind attention Arterial Blood Gas 10/6/07 12:19 370.6 10/6/07 19:29 254.7 10/7/07 pO2 10/6/07 10:20 440.6 10/8/07 20:00 114.0 10/9/07 105.3 10/8/07 14:15 107.8 pH 7.38 7.37 7.419 7.45 7.40 7.44 7.44 pCO2 30.0 31.0 30.0 29.9 38.8 34.8 36.0 HCO3 17.7 17.6 19.0 20.6 23.9 23.4 24.1 O2 sat 99.8 99.1 99.3 98.1 98.0 98.3 98.0 B.E. -5.9 -6.1 -2.0 -0.6 +0.1 +0.5 Total CO2 18.6 21.6 25.1 24.5 25.2 CO Hb (N.V. 0 – 0.8) Met Hb (NV 0.2 – 0.6) FiO2 100% Mode AC Mode 104.8 4.4% 0.6 - - - - 0.5% 0.9 - - - - 100% 100% 30% 28% 30% 28% CPAP CPAP In-line neb via T piece In-line neb via T piece Complete Blood Count 10/6/07 Hemoglobin Hematocrit RBC WBC Segmenters Lymphocytes Monocytes Eosinophils Platelet Count 15.8 53 27,860 88% 5% 5% 2% 427,000 10/6/07 17:23 13.2 39.5 4.1 29,000 83% 10% 6% 1% 245,000 10/8/07 10.8 32.8 3.5 12,160 85% 10% 5% 198,000 10/6/08 2030 145 10/7/07 1017 143 10/7/07 2031 141 10/8/07 10/9/07 Na 10/6/07 1100 140 140 140 K 3.8 4.3 3.3 3.3 3.4 4.1 BUN 23 16 13 Crea 1.5 0.9 0.8 0.8 0.6 Glu 135 1.14 1.18 162 325 321 241 CK-MB 7.5 8.4 2.5 0.8 Mg 1.8 1.9 1.9 iCa TCPK 103 SGOT 31 SGPT 73 LDH 147 Alk Phos 70 CO2 19 TP 6.9 Albumin 3.6 Globulin 3.3 1.9 Toxicology Report Drug/Metabolit e Amphetamine/ Metamphetami ne Barbiturates Cannabinoids Cocaine Results Cut-off Level 30.88 ng/mL NEGATIVE 1000 ng/Ml 3.44 ng/mL 4.78 ng/mL 12.49 ng/mL NEGATIVE NEGATIVE NEGATIVE 200 ng/mL 50 ng/mL 300 ng/mL CXR 10/6/07 10/07/07 10/8/08 Clear lungs and Blunting of the left Mild basal normal vascular hilum pulmonary markings Heart and the rest congestion. Heart and the rest of the chest The rest of the of the chest structures are lungs are clear structures are unremarkable No other unremarkable ET is in place remarkable ET is in place findings ET still in place