Aspiration Pneumonitis

Aspiration of gastric contents during induction and emergence of anesthesia can lead to serious morbidity and mortality. Proper patient assessment is crucial in order to avoid aspiration. This assessment starts with a proper interview with the patient in order to assess the compliance with nothing by mouth guidelines (NPO). History and physical assessment provide a wealth of information especially in situations where the anesthesia provider cannot or is unable to conduct a proper interview. The list of the patient medication is another tool to help the anesthesia provider. This case report will focus on assessment, and physiology, in order to avoid aspiration pneumonitis.

Phares Mondo, SRNA Westminster College, Salt Lake City UT MSNA 571 Aspiration Pneumonitis. KEY WORDS: Aspiration, Cricoid Pressure, Laryngoscopy, Pneumonitis, Rapid Sequence Induction. Aspiration of gastric contents during induction and emergence of anesthesia can lead to serious morbidity and mortality. Proper patient assessment is crucial in order to avoid aspiration. This assessment starts with a proper interview with the patient in order to assess the compliance with nothing by mouth guidelines (NPO). History and physical assessment provide a wealth of information especially in situations where the anesthesia provider cannot or is unable to conduct a proper interview. The list of the patient medication is another tool to help the anesthesia provider. This case report will focus on assessment, and physiology, in order to avoid aspiration pneumonitis. Case Report. 34 year old, 89 kg, 165 cm Caucasian male presented to the hospital for Laparoscopic cholecystectomy. According to the history and physical assessment, the patient had been experiencing right-upper quadrant pain, nausea, and vomiting especially after eating greasy foods. The patient denied any past medical or surgical history, allergies, or history of alcohol or illicit drug use. An airway exam revealed Mallampati score of II with thyromental distance >6cm, no prominent overbite or underbite, and good range of motion in the neck. After the interview, the patient was pre-treated with midazolam 2mg. On arrival in the operating room (OR) suite, the patient was assisted to the OR table. 100mcg Fentanyl was administered and the patient was instructed to take deep breaths via the face mask while other monitors were applied. The patient was pretreated with 5mg of rocuronium as a defasiculating dose. The patient was induced with Lidocaine 80mg, Propofol 150mg, and Succinylcholine 100 mg. Cricoid pressure was applied before Propofol induction. Direct laryngoscopy was attempted and as soon as positive pressure was attempted, the patient vomited. The Patient was immediately turned on his side and the oropharynx was suctioned. Positive pressure ventilation was started again due to falling saturations. After the patient saturation improved, direct laryngoscopy was attempted again, with success. A 7.5mm endotracheal tube was placed and secured at 22 cm at the teeth. An attempt to suction the airway produced no aspirate. After a train of four test with a nerve stimulator, significant fade was noted, and the patient was paralyzed further with 50mg of Rocuronium. Anesthesia was maintained with Desflurane between 6-7% fraction expired. An additional 100 mg Fentanyl was administered before the incision. The Laparoscopic cholecystectomy was performed successfully, and throughout the case the patient vital signs remained stable; there were no signs or symptoms of respiratory or cardiovascular insult. The lungs were auscultated and produced clear breath sounds in all fields. After the procedure, train of four tests showed significant fade and the muscle relaxants were reversed successfully with Neostigmine and glycopyrollate. Pressure support was started and the patient appeared to initiate breaths. The pressure support was gradually decreased, and spontaneous respirations returned without ventilator assistance. The patient followed commands to open his eyes, squeeze our hands, and lift his head off the table for more than five seconds. The patient was also spontaneously breathing 450 ml of tidal volume. The patient was extubated and oxygen via face mask was applied at 8L/min. The patient was transported to post anesthesia care unit where he showed no signs or symptoms of respiratory distress. A chest X-ray was ordered to rule out aspiration. The chest X-ray results were unremarkable, and no signs of aspiration were evident. DISCUSSION Cricoid pressure, coupled with rapid sequence induction (RSI) has been the mainstay of preventing aspiration in a patient otherwise deemed to be full stomach, or at risk for aspiration during anesthesia induction. This technique consists of pre-oxygenation, cricoid pressure, and avoidance of positive pressure ventilation. In a study performed by Schlesinger and Blanchfield, cricoid pressure is a well-established practice, but not without risk to the patient; the most alarming risk is the potential inability to secure an airway or to ventilate a patient who is unconscious and apneic.1 The authors further note that potential risks include inability to ventilate leading to hypoxia and hypercarbia. RSI can lead to a difficult intubation, mainly due to the airway obstruction, pulmonary aspiration and esophageal rapture.1 Other adverse effects of cricoid pressure include bilateral subconjuctival hemorrhage from a patient coughing against cricoid pressure resulting in cricoid cartilage rapture.1 In "The Efficacy of Cricoid Pressure" study, Ewart notes that a potential rupture of esophagus is possible and has been reported following active vomiting while cricoid pressure is being applied. Because of the seriousness of this complication, the originally suggested 40 Newtons (4kg), was revised and the new recommended pressure is 20 Newtons in awake patients, then increased to 30 Newtons as the patient slips to unconsciousness.2 Nagelhout and Plaus note that aspiration pneumonitis adds an average of 15 hospital days and $22,000 to the course of care. Curtis Mendelson, as noted in Nagelhout, described aspiration pneumonitis in 1964 after he observed a number of deaths in the obstetric population. Nagelhout goes on to note that ingestion of highly acidic or particulate aspirate can cause severe respiratory damage without infectious component. Pneumonia can develop late due the severity of the lung injury and prolonged respiratory support.3 Nader and colleagues performed a study to define the role of alveolar macrophages in the pathogenesis of aspiration pneumonitis. Aspiration pneumonitis is as an acute inflammatory process that results from regurgitation of gastric contents into the lungs.4 Nader further notes that aspiration of gastric contents contributes to 20% of deaths attributed to anesthesia and occurs in approximately 1 in 2,131 anesthesia cases. In the normal lung, the alveolar-capillary wall consists of resident macrophages, type 1 epithelial cells, type II epithelial cells, and endothelial cells.4 Lung injury causes these cells to undergo morphological and physiological changes; inflammatory cytokines are released as a result of the injury, and pro-inflammatory cytokines are responsible for vascular endothelial changes and act to promote neutrophil recruitment.4 Aspiration of small food particles is associated with a robust pro-inflammatory response and activation of reactive species of nitrogen, while pure aspiration of low PH sterile solution is often self-limited and produces a neutrophil-dependent lung injury that is associated with generation of reactive species of oxygen and proteinases.4 According to Fleisher's "Evidence Based Practice of Anesthesiology", the primary treatment should be supportive and oxygen should be provided to ensure adequate oxygenation. "Routine broncho-pulmonary hygiene and other supportive measures are the only approaches that have been demonstrated to be effective and there is no data supporting empiric initiation of other therapies immediately after suspected aspiration".5 Fleisher suggests that the primary determinant in the development of aspiration pneumonitis is the PH of the aspirate. A PH of less than 2.5 in the aspirate is necessary to cause clinically significant aspiration pneumonitis.5 The volume of the aspirate also contributes to the likelihood of pneumonitis, and a volume greater than 25 milliliters is associated with increased risk of aspiration.5 This is in sharp contrast to Nagelhout, who suggests that arbitrary diagnosis on basis of PH and volume is not enough to cause aspiration pneumonitis and rather, suggests the diagnosis be individualized.3 Waybright and Colleagues evaluated literature regarding current and future treatment of clinical aspiration complications and found one retrospective study that demonstrated that antibiotics being initiated in 97% of patients with aspiration syndrome, including pneumonitis and pneumonia.6 The authors suggest a new focus that should consider etiology and setting of the event. Supportive therapy only with antibiotics should be initiated if improvement does not occur within 48 hours. Up to 78% of physicians surveyed indicated that they would prescribe antimicrobial agents in suspected aspiration pneumonia, regardless of the cause.6 Prophylactic treatment for patients otherwise deemed to be full stomach or at risk for aspirations has varied recommendations in the literature. In one particular study, Lin CJ and colleagues compared famotidine, ranitidine, omeprazole with placebo for prophylaxis against aspiration pneumonitis. In this study, a dose of ranitidine or famotidine administered three hours before surgery provided a more effective means to control and neutralize gastric secretion than omeprazole in parturients.7 Pepcid and Bicitra have also been used prophylactically to help decrease and neutralize acidity in the stomach.7 In an article written by Nagelhout in the American Association of Nurse Anesthetists (AANA) journal, about whether it is time to change current standards regarding aspiration during anesthesia, among other recommendations, the author suggests cricoid pressure is beneficial so long as it is performed properly. Patients should be ventilated during RSI since there is no evidence that controlled light ventilation increases evidence of aspiration.8 Realistic preoperative guidelines should be instituted and a rule of NPO after midnights for all patients should be modified.8 CONCLUSION. The lesson learned here is that aspiration pneumonitis can cause serious morbidity and mortality, and the patient should be thoroughly evaluated. Airway assessment is pivotal in being able to successfully secure the patient airway without aspiration. Adjunct airway equipment, like video assisted laryngoscopy, should be considered to enable the anesthesia provider the ability to quickly secure the airway. This would probably have enhanced laryngoscopy in an otherwise difficult intubation. Gastrokinetic medications should have been considered to help decrease acidity and increase gastric motility. References: 1. Schlesinger S, Blanchfield D. Modified rapid-sequence induction of anesthesia: a survey of current clinical practice. AANA J. 2001;69:291-298. 2. Ewart L. The efficacy of cricoid pressure in preventing gastro-oesophageal reflux in rapid sequence induction of anaesthesia. J Perioper Pract. 2007;17:432-436. 3. Nagelhout, J, & Plaus, K. Nurse Anesthesia (4th ed.). St. Louis, MO: Sanders Elsevier; 2010. 4. Nader ND, McQuiller PS, Raghavendran K, Spengler RN, Knight PR. The role of alveolar macrophages in the pathogenesis of aspiration pneumonitis. Immunol Invest. 2007;36:457-471. 5. Fleisher L. Evidence Based Practice of Anesthesiology. Philadelphia, PA: Saunders Elsevier;2009. 6. Waybright RA, Coolidge W, Johnson TJ. Treatment of clinical aspiration: A reappraisal. Am J Health Syst Pharm. 2013;70:1291-1300. 7. Lin CJ, Huang CL, Hsu HW, Chen TL. Prophylaxis against acid aspiration in regional anesthesia for elective cesarean section: a comparison between oral single-dose ranitidine, famotidine and omeprazole assessed with fiberoptic gastric aspiration. Acta Anaesthesiol Sin. 1996;34:179-184. 8. Nagelhout JJ. AANA journal course. Update for nurse anesthetists. Aspiration prophylaxis: is it time for changes in our practice? AANA J. 2003;71:299-303. Mentors; James Stimpson, CRNA, DNP. Kristina Dickens CRNA.