MORBIDITY AND MORTALITY PULMONARY ASPIRATION

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MORBIDITY AND MORTALITYPULMONARY ASPIRATION

• DENNIS STEVENS CRNA, MSN, ARNP
• FEBRUARY 2006
• FLORIDA INTERNATIONAL UNIVERSITY
• PRINCIPLES ANESTHESIOLOGY NURSING II
• NGR 6093

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OBJECTIVES

• Discuss incidence and predisposing risk factors
  associated with pulmonary aspiration in the
  parturient.
• Explain pathophysiology leading to morbidity and
  mortality due to aspiration in the obstetrical
  population.
• Describe clinical presentation and diagnostic
  findings in patients whom aspiration has
  occurred.
• Discuss preventative measures to avoid
  aspiration, including strategies to protect the
  airway in the parturient.
• Describe management of pulmonary aspiration,
  including outcome for the obstetric patient.

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REFERENCES

• Chestnut, D. H. (1999). Obstetric Anesthesia (2nd
  ed.).
• St. Louis, MO Mosby.
• Morgan, G.E., Mikhail, M.S., Murray, M.J.
  (2002). Clinical Anesthesiology (3rd ed.). New
  York, NY McGraw-Hill.

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INTRODUCTION

• All patients in the OB unit potentially require
  anesthesia
• All OB patients are considered to have a full
  stomach
• Contributing factors exist that increase the risk
  of pulmonary aspiration
• Small amount of clear fluid permissible during
  labor
• Minimum NPO status for elective c-section is 6
  hours
• Pulmonary aspiration is largely preventable,
  anesthetist can take measures to minimize the
  occurrence of this condition
• Contributes significantly to MM in OB patient
• Leading cause of maternal death under general
  anesthesia

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INCIDENCE

• Incidence of pulmonary aspiration in the general
  population undergoing elective surgery is
  12131 to 13216
• Occurs more frequently in patients having
  emergency surgery 1895
• Incidence of pulmonary aspiration in OB patient
  presenting for c-section under general anesthesia
  is 1661
• There has been a progressive decline in the rate
  of pulmonary aspiration as a cause of maternal
  death

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PREDISPOSING FACTORS

• Three components must be present together
  presence of an at risk stomach, reflux of
  gastric contents into oropharnyx, and inhalation
  of these contents into lungs
• As pregnancy progresses intragastric pressure is
  increased and lower esophageal sphincter pressure
  is decreased
• Gastric emptying is delayed in pregnancy
• Mendelsons syndrome increased risk for
  aspiration pneumonitis
• Term parturient at higher risk for difficult
  intubation

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PATHOPHYSIOLOGY

• Injury due to pulmonary aspiration is dependent
  on pH of gastric contents and presence of solids
  or liquids
• Histologic findings show damage to alveolar and
  endothelial cells
• Differentiation between aspiration of solids and
  liquids
• Hypoxia occurs rapidly after aspiration of
  gastric contents and is related to the degree of
  lung damage
• Pulmonary aspiration causes an acute chemical
  pneumonitis
• Pulmonary compliance is eventually reduced

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CLINICAL PRESENTATION

• Aspiration likely to occur in an unfasted
  parturient having emergency c-section under
  general anesthesia
• Risk is increased in association with difficult
  intubation, eclamptic patient, or obtunded
  patient
• Gastric contents may be seen in airway during
  intubation, most frequently a presumptive
  diagnosis is made
• Aspiration of large particulate matter may lead
  to partial or complete airway obstruction
• Shock complicates the course in 20-30 of
  patients

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CLINICAL PRESENTATION

• Initial chest x-ray findings are extremely
  variable and noncharacteristic. Infiltrates are
  mainly seen
• Immediately, chest films may not reveal any
  abnormalities, but all show some abnormality
  within 24-36 hours
• Majority of patients show rapid clinical
  improvement and recovery
• 10-15 rapidly deteriorate and die within 24
  hours due to respiratory failure. Remainder
  develop various complications
• Hospitalization is prolonged by an average of
  8-21 days

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PREVENTION

• Strategies applied to reduce the at risk
  stomach contents
• Emptying stomach contents with nasogastric tube
• Medication administration
• Antacids
• H2 Receptor Blockers
• Metoclopramide
• Omeprazole
• Strategies to prevent regurgitation
• Strategies to protect the airway

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MANAGEMENT

• Suction
• Bronchoscopy
• Improving lung function
• Ventilation
• Fluid therapy
• Steroid administration
• Antibiotic administration

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SUMMARY

• Pulmonary aspiration is a potential threat to
  every parturient
• Failed intubation and aspiration continue to
  cause morbidity and mortality
• Aspiration most often occurs during emergency
  cesarean section under general anesthesia in
  which difficult or failed intubation is
  encountered
• Measures for preventing aspiration focus on
  reducing the use of general anesthesia,
  administration of a clear antacid, and
  restricting oral intake during labor