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William Cavatassi. Introduction Signs and symptoms Risk Factors Prevention Treatment. Inhalation of gastric contents into larynx and lower respiratory tracts Pneumonitis Chemical injury of sterile contents Pneumonia
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Introduction • Signs and symptoms • Risk Factors • Prevention • Treatment
Inhalation of gastric contents into larynx and lower respiratory tracts • Pneumonitis • Chemical injury of sterile contents • Pneumonia • Infectious process from colonized contents*
Reported in 1946 after observing OB pts under anesthesia • 44016 pts from 1932-1945 • 66 aspirated (1:667) • Complete recovery in 24-36hrs, except 2 pts died (1:22008)
5-15% of CAP cases (20% NH) • 10% drug overdose • Most common cause of death in pt with dysphasia from neurological d/o • VAP 26-40%of surgical ICU pts • (more likely oropharyngeal aspiration not gastric) • Complication of general anesthesia • 1/3000 operations (higher with ASA scores and emergency) • 10-30% deaths assoc with anesthesia
Abrupt onset of dyspnea • Chest Pain • Coughing • Wheezing • Tachycardia • Tachypnea • Hypotension • Fever • Cyanosis • Hypoxemia • Diffuse crackles or dec breath sounds on auscultation
ABG • Dec O2 • Nl to low CO2 (respiratory alkalosis) • PFTs • Dec compliance • Abnl ventilation-perfusion • Dec diffusing capacity
Changes (within 2 hrs) • Infiltrate in the gravity dependent portions of the lung • Upright: basal segments lower lobes • Supine: generally lower lobes, especially the superior segments of the lower lobes, also the posterior segments of the upper lobes • More often on right because of the larger caliber and straighter course of the right main bronchus
Within 3 mins (direct caustic effects of low pH): • Pulmonary edema • Atelectasis • Alveolar hemorrhage • Degeneration of bronchial epithelial cells • Within 4 hrs: • Alveolar spaces filled with PMNs and fibrin • Within 48hrs: • Hyaline membrane formation • Alveolar consolidation • Process mediated by cytokines • TNFa & IL-8
Animal studies suggest severity dependent on: • pH <2.5 • Volume >0.3ml/kg (20-25ml) • Presence of particulate matter
Up to 60% - rapid improvement • 10-30% - fulminant course and early death (ARDS) • Up to 30% - pneumonia • Uncomplicated – 5% mortality • In critically ill mortality up to 60% • Abscess, necrotizing pneumonia, empyema
Effects of pneumonitis plus response to colonization (superimposed infection) • Conditions that result in increase volume or bacterial burden with decreased defense mechanisms
Worsening cough • High grade fever • Purulent sputum • Positive culture (PAL > 10^4 cfu/ml) • Persistent or worsening infiltrates on CXR
Nocosomial • Primarily gram negative • E. Coli, Kleb • Critically ill/ long term vent • Pseudo, MRSA • Community • Oral flora -anaerobes • Strept, H. flu
Reduced consciousness / Anesthesia • Compromises swallowing/airway protection reflex and glottic closure • Dec in strength and coordination of pharyngeal muscles • Dec UES function • Dysphagia (neurologic defect) • Upper GI tract Disorders • Esophageal dz • GERD • airway/UGI surgery
Mechanical disruption to glottic closure • Trach, ETT, bronchoscopy, endoscopy, NGT • NGT impinges on integrity of UES and causes inc relaxation of LES • Pregnancy • Elderly • Diabetes • Renal Failure
Critically ill • Supine position • Decreased Defense Mechanisms • Gastroparesis • Inc gastric distention • Inc volume • Inc regurgitation • Post extubation • Residual sedation • swallowing dysfunction (in as little as 24hrs) • Dec upper airway sensitization – dec cough reflex • Glottic injury • Laryngeal muscular dysfxn • Usually resolves within 48hrs • Dysphagia studies
Increased colonization • Inc pH from antacids, histamine blockers, PPI • Gram negatives • Enteral feedings • Gastroparesis • SBO
Supine Positioning • HOB up vs supine • Aspiration significantly higher in supine vs 45deg • Gastric Residual Volume • Poorly coordinates with aspiration • GRV> 500 hold • >200 access risk at bedside, consider prokinetics, if persistently >200 consider holding • <200 generally well tolerated • Soft diet, small bites, chin tucked, head turned, repeated swallowing (but no evidence)
GI bleed 1.5-8.5% ICU pts • High Risk • Coagulopathy • Vent >48hrs • Hx of GIB past year • Brain or burn injury • Sepsis • ICU> 1 week • Steroids • PPI & H2 blockers both significantly decrease bleeding rates (PPI slight if any better than H2) • Both better than sucrafate
Pneumonia (from presumed aspiration) significant less with sucralfate vs pH raising drugs (5% vs 16% antacids vs 21% H2) • Lower median gastric pH • Less gastric colonization • C diff • Gastric acid role in protection • Acid suppression linked to inc c diff
Enteral Feedings • In animal models, feeding protects gastric mucosa from stress related damage • Source of mucosal energy, induce secretion of cytoprotective prostaglandins and mucus, & inc mucosal blood flow • Meta-analysis • In those pts receiving enteral feedings, SUP does not reduce risk of bleeding • H2 blockers may increase risk of pneumonia vs feeding alone (up to 30%) • Recommendations vary
Two Metanalysis of randomized controlled studies of gastric vs post pyloric feedings • No significant difference: • Incidence of pneumonia • Achievement caloric goal • ICU LOS • Mortality • Significant longer time to start of nutrition in gastric feeds but not total time to goal • As long as evidence of tolerance gastric feeds are acceptable • Look for other signs of intolerance such as bloating, abdominal pain, emesis, or nausea • Need to eval gastric residuals in post-pyloric as well
Cochrane review of 33 trials comparing prophylactic NG until return of bowel vs early removal (in OR, PACU, <24hrs) • Significant Increase • Pulmonary Complications (including pneumonia and therefore presumed aspiration) • Time to return of bowel function • Insignificant Decrease • Wound infection • Ventral Hernia • No difference - anastomotic leaks In those patients WITH PROPHYLACTIC NGT USE
Metanalysis of 26 trials • No difference death, aspiration, wound infection, anast. leak • Dec fever, atelectasis, pneumonia (likely includes occult aspiration), time to po without NGT • RR of NGT was 2.9 • In those studies with quality scores, no NGT did have higher abd distention and emesis • Placement required in 5.2% of early removal • Proph. needed replaced 1.8% • NNT 20 - 30 patients
Decrease volume • fasting: Clear liquids 2, breast milk 4, formula and light meals 6hrs • NGT pre-intubation: no evidence it works; suggested in bowel obstruction or ileus, may dec UES and LES pressure and make it worse • Decrease pH • No evidence it helps (may inc pneumonia risk) • Consider non-particulate antacids in high risk (full stomach, delayed emptying like diabetic, bowel obstruction)
Rapid sequence induction • Dec time between loss of airway protection and intubation • Preoxygenation (no positive pressure) • IV anesthesia • Rapid onset paralytic • Cricoid pressure • Controversy over effectiveness • Rarely compresses esophagus, can make intubation harder
Pulmonary support • +/- intubation vs pulmonary toilet • Bronchoscopy • if known foreign body or food material • Lavage does not reduce pneumonitis, may wash further down in smaller spaces harder to clear • Normal mucociliary clearance and cough are superior to suctioning so removing everything from trach as soon as possible is recommended
?Antibiotics Common practice to empirically treat any suspected/witnessed aspiration WRONG Abx shortly after aspiration on everybody with a fever, leukocytosis or pulmonary infiltrate WRONG
Empiric tx appropriate for: • Concern for gastric colonization • Increased pH • SBO • UGI surgery • Failure to resolve within 48hrs • Broad spectrum antibiotic • Gram positives/gram negatives • Anaerobic coverage generally not necessary, can be considered if recent GI surgery • MRSA coverage if high risk • If intubated PAL to target coverage, stop if negative culture • Overuse of abx leads to resistant organisms • No evidence to support corticosteroids