Monitoring the Anesthetized Patient

Overview

• Date and Presenter: October 24, 2023, Dr. Debbie Wilson

• Focus Areas: Record keeping, equipment, common problems associated with anesthesia.

Objectives

• Review of physiology related to respiration monitoring.

• Discuss common anesthesia abnormalities and the role of capnographs.

• Introduce the anesthetic record design at MSU.

• Practice data entry and interpretation of monitored data.

Importance of Monitoring

• Enhances Outcome: Monitoring is crucial to optimize patient safety and recovery.

• Standard of Care: Adheres to guidelines set by organizations such as AAHA and ACVAA.

• Client Expectations: Veterinary practices are held accountable to clients’ concerns regarding safety and care.

Anesthesia's Impact on Respiration

• Pathologic Condition: Anesthesia can fundamentally alter respiratory functions, especially in different species (e.g., horses).

• Common Respiration Problems:

  • Strange patient positions can lead to atelectasis and ventilation-perfusion (V/Q) mismatches.

  • Anesthetic drugs can reduce respiratory drive and hypoxic response.

Monitoring Tools and Techniques

• Basic Monitoring Tools:

  • Physical Assessment: Use of hands, eyes, and ears for initial evaluations.

  • Circulation Assessment:

    • Pulse palpation at various arteries (femoral, pedal, lingual, etc.).

    • Esophageal stethoscope for heart sounds.

    • Pulse oximeter for oxygen saturation (SpO2) measurements.

    • EKG and blood pressure measurements (direct and indirect).

Practical Lung Function Assessment

• Physical Indicators:

  • Chest excursion and reservoir bag movement.

  • Mucous membrane color to assess oxygenation.

  • Use of pulse oximeter and capnograph for oxygen and CO2 levels.

  • Arterial Blood Gas (ABG) analysis for detailed respiratory assessment.

Pulse Oximetry

• SpO2 Measurement: Reflects %Hb saturation with thresholds set for normal (95-100%) to critical (<60%).

• Components of Pulse Oximeter: LED transmitter, photodiode receiver.

• Common Issues: Measurement errors due to pigmentation, motion artifacts, and poor perfusion.

Capnography in Anesthesia

• Purpose: Monitors end-tidal CO2 (ETCO2) levels, critical for assessing ventilation efficiency.

• Mainstream and Side-stream Analyzers: Types of equipment used to monitor CO2.

• Capnogram Analysis:

  • Waveform characteristics: height (ETCO2), frequency, rhythm, baseline, and shape describe respiratory status.

  • Normal capnogram shows identifiable phases and values that reflect proper ventilation.

  • Abnormal capnograms may indicate conditions such as hypoventilation or rebreathing.

Anesthesia Record-Keeping

• Importance of Documentation:

  • Serves as a standard of care and a legal document reflecting the level of care provided.

  • Tracks drug administration, dosages, physiological responses, and patient responses to interventions.

• Key Components of the Anesthesia Record:

  • Patient details (weight, age, procedure)

  • Pharmacological interventions.

  • Monitoring results (HR, BP, SpO2, ETCO2, Temp).

Common Anesthetic Problems and Responses

• Tachycardia or Tachypnea: Treatment includes assessing stimulus and administering agents to stabilize vital signs.

• Hypoventilation: Managed by adjusting anesthetic depth or supporting with mechanical ventilation.

• Hypotension: Requires evaluation of intravascular volume and possible use of inotropic agents.

• Apnea: Immediate resuscitation and identification of underlying causes are crucial.

• Esophageal Intubation: Confirm proper placement through physical cues and capnography.

Practice Scenarios and Record Exercises

• Hands-on practice in recording vital signs, interpreting scenarios, and solving abnormalities based on monitoring data.

• Education on the symbols and terminology used in the anesthesia record, enhancing understanding of patient status during procedures.

Conclusion

• Continuous Monitoring: Crucial during anesthesia with ongoing patient assessments.

• Simulation Feedback: Learn from mock cases to prepare for real-life application in anesthesia management.