Nutrition Support In Mechanical Ventilated Patients Pranithi Hongsprabhas MD.

Swallowing function Oral phase Preparation &movement of food from oral cavity to pharynx Pharyngeal phase Soft palate rises to close nasal cavity Vocal cords adducts Epiglottis tilts and shields larynx Respiration is temporarily inhibited Pharynx contracts esophageal phase upper esophageal sphincter relaxes peristalsis

The most dreaded complication of tube feedings is tracheobronchial aspiration of gastric content

Tube feeding associated aspiration The most serious complication of EN Clinically unimportant to respiratory failure Clinically silent or cough, choking to ARDS

Aspiration categories Oropharygeal bacteria Inert fluid, particulate Acidified gastric contents Wynne JW et al. Ann Intern Med 1977, 87:486

Prevalence and mortality Prevalence Varies 70% in depressed consciousness 22% in ICU 50-75% in ET intubation 0-40 % EN associated Mortality 62% in witness aspiration 40% with 1-lobe, 90% with 2 or more Gastric aspiration:

Risk factors for aspiration Naso/oral enteral intubation Tracheal intubation Enteral tube feeding Increased age with physiologic insult Gastroparesis Gastroesophageal reflux (GER)

Risk factors for aspiration Decreased level of consciousness (LOC) Anesthesia Neurological disorder Seizure Supine position

Impaired level of consciousness Stroke Head injury Sedation Anesthesia  Impaired ability to protect airway Cough and gag LES GET

Regurgitation and dysphagia Increased risk of aspiration

Cough and gag reflexes Absence or presence of gag reflex: not influence the risk of aspiration Cough reflex may or may not prevent aspiration  diminished cough or gag reflexes are not reliable indicators or aspiration risk

Nasal or oral feeding tubes Increased oropharyngeal secretions Impairment of laryngeal elevation Disruption of UES, LES Increased GER (75 vs. 35%)*, aspiration *Ibanez J. et al.JPEN 1992;16:419

Gastric vs. small bowel feeding Controversy Early study : SB feeding less aspiration Later study : not confirm

ASPEN 2005 Acute brain injury Impaired gastric function: delayed GET Impaired LES: regurgitation  Post pyloric feeding: more preferred Jejunal feeding  Better tolerate  Less reflux Gleghon E. et al. Neurologic diseases in: ASPEN manual 2005:

Size of NG-NE tube Children: Less GER in Fr8 vs Fr10-12 Adult No significant different in GER, aspiration rate Ferrer M. et al.Ann Int Med 19992;130:991

Malposition of feeding tube Faulty initial placement Upward dislocation  Increased risk when tube ports in or near esophagus  Need to confirm feeding tube position

Enteral feeding schedule Bolus vs. continuous feeding Bolus: higher aspiration risk Decreased LES intragastric pressure

Intermittent vs. continuous Aspiration rate (%)

Tracheal intubation /MV Reduce upper airway defense Cough Desensitization of pharynx and larynx Laryngeal m atrophy Esophageal compression Increase abdominal pressure: GER Sedation  increased risk after 48 hr. and 1%/day in MV

Vomiting Increased risk of aspiration Forceful entry of gastric content into oropharynx Displacement of feeding tube Sedation increases risk of vomiting

Regurgitation and dysphagia Increased risk of aspiration

Cough and gag reflexes Absence or presence of gag reflex: not influence the risk of aspiration Cough reflex may or may not prevent aspiration  diminished cough or gag reflexes are not reliable indicators or aspiration risk

Body position Supine position: associated with more aspiration Less aspiration with elevation of head of bed 30-45° during EN feeding

Position and GER/aspiration Aspiration: supine vs. semirecumbent MV patients* Semirecumbent decreases GER compare to supine# *Torres A et al: Ann Int Med 1992;116:540-3 #Orozco-Levi et al. Am J Respi Crit Care 1995;152:1387

Position and Pneumonia

Recognizing patients at risk of AP Decreased LOC Tracheal intubation MV NG, NE Major abdominal and thoracic trauma/surgery DM Advance age

Gastric residual volume (GRV) History Underlying rationale Inherent flaws in the rationale Inherent flaws in the practice Clinical pattern of GRV Evidence of correlation of GRV with EN Evidence of GRV and aspiratiom

Gastric residual volume (GRV) GRV > ml Fluid in stomach: 3000/d ~125ml/hr 50 ml???? Use less GRV: receive nutrient less GRV and risk of aspiration: controversy GISecretion (ml) Saliva1000 Gastric2000 Pancreatic2000 Bile1000 Small bowel1000 Reach colon The Washington Manual of Surgery. Chapter14

Clinical pattern of GRV GRV>100GRV>150GRV>200 Normal volunteers 40% (11%)15% (2.4%)0% (0%) Critically ill NG 50% (27.4%)50% (13.1%)30% (4.3%) Critically ill PEG 25% (2.5%)0% (0%) McClave SA, et al. JPEN 1992;16:99

Correlation of GRV with ETF Change in ETF rate  change in GRV GRV increases at the initial but decreases as feeds continue Bolus generate more GRV GRV obtained from NG>gastrostomy

GRV and aspiration: Pro P=0.01 P=0.020 P=0.018

Incidence of regurgitation by range of GRV GRV 0-50 GRV GRV GRV GRV GRV GRV 400+ P- value Regurgit- tion 28.7% (439) 41.0% (39) 29.4% (17) 35.7% (14) 33.3% (9) 40.0% (5) 37.5% (8) Aspiration 22.8% ( % (38) 26.7% (15) 20.0% (10) 0.0% (10) 40.0% (5) 25.0% (8) 0.412

GRV and aspiration: Cons Paracetamol absorption test (GET): no difference in GRV McClave 2005: found no difference in aspiration (using yellow dye) in GRV 150 ml, and >400 ml GRV 0-50 GRV GRV GRV GRV GRV GRV 400+ P- value Regurgit- tion 28.7% (439) 41.0% (39) 29.4% (17) 35.7% (14) 33.3% (9) 40.0% (5) 37.5% (8) Aspiration 22.8% ( % (38) 26.7% (15) 20.0% (10) 0.0% (10) 40.0% (5) 25.0% (8) 0.412

GRV and aspiration: Cons Lukan JK. AJCN 2002;75:417S

Prevention Head of bed elevation 30-45° Verify tube placement Gastric aspirate: GRV Evaluate GI intolerance

GI intolerance Abdominal discomfort Bowel movement Abdominal distention Bowel sound GRV Trend to increased GRV Trend to increased GRV Radiography

Conclusion Identify the risk patients Prevention Verify tube placement position Position: head of bed elevation Avoid bolus feeding