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Case Report/Stimulation Scenario

Keep It Flowing: A Simulation Involving Defective Anesthetic Gas Delivery Equipment

Sposito, Jennifer A. MD; Hobbs, Eugene CHT; Taekman, Jeffrey MD

Author Information
Simulation In Healthcare: The Journal of the Society for Simulation in Healthcare: December 2007 - Volume 2 - Issue 4 - p 241-245
doi: 10.1097/SIH.0b013e318156f0cf


  • Scenario Title: Keep It Flowing: A Simulation Involving Defective Anesthetic Gas Delivery Equipment (Adapted from case report: Chacon A, et al. Unusual case of breathing circuit obstruction: plastic packaging revisited. Anesthesiology 2004;100:753.)
  • Patient File Name: Standard Man Awake
  • Simulation Developer(s): Jennifer A. Sposito, MD, Eugene Hobbs, CHT, Jeffrey M. Taekman, MD
  • Simulator: Laerdal Simman, Meti Hps, Software Version
  • Date(s) of Development: February 2006 to March 2006
  • Appropriate for following learning groups: anesthesiology residents: postgraduate years 2, 3, and 4; nurse anesthesia students: years 1 and 2


Educational Rationale

In 1985, the Anesthesia Closed Claims Project was founded with the goal to “identify major areas of loss in anesthesia, patterns of injury, and strategies for prevention.”1 One important area that has been focused on by the Closed Claims Project is anesthesia equipment malfunction. Although only 2% of the claims in the Closed Claims Project database stem from gas delivery devices, there can be significant injury resulting from these malfunctions such as delayed recovery, awareness, brain injury, and even death. A 2002 study by Fasting and Gisvold examined over 83,000 anesthetic cases reporting 0.19% of cases had equipment problems.2 Of these cases, 15% were attributable to the breathing circuit.2 Although a seemingly small problem, 25% of all equipment problems were related to human error and therefore potentially preventable.2 As such, it is important to educate anesthesia providers on the topic of equipment malfunction, including prevention of equipment misuse and failure, recognition of failed or defective equipment, and reduction of injury associated with equipment malfunction.

Learning Objectives

The following learning objectives are associated with the Accreditation Council for Graduate Medical Education (ACGME) core competencies. The ACGME core competencies were developed in 1999 as part of the Outcome Project. These competencies serve as an educational assessment tool for both individual residents and residency programs.3 Specific descriptions of the core competencies can be found at: The core competencies are as follows:

  1. Patient care
  2. Medical knowledge
  3. Practice-based learning and improvement
  4. Interpersonal and communication skills
  5. Professionalism
  6. Systems-based practice
  • List methods for confirming endotracheal tube placement (2).
  • Describe changes in vital signs and monitoring parameters that could occur with a partial obstruction in the breathing circuit (1 and 2).
  • Develop a differential diagnosis of inability to ventilate an intubated patient (1 and 2).
  • Develop an algorithm of appropriate interventions to manage a patient that is difficult to ventilate (1, 2, 3).
  • Review the 1993 Food and Drug Administration (FDA) anesthesia apparatus checkout recommendations (2).
  • Review Advanced Cardiac Life Support (ACLS) algorithms for ventricular tachycardia and ventricular fibrillation (1, 2).
  • Demonstrate ability to effectively communicate with team members to resolve intraoperative issues (4, 5).

Guided Study Questions (Suggested Answers Provided)

  1. What signs and symptoms would you expect intraoperatively if an obstruction in the breathing circuit occurred?
    • Increased peak inspiratory pressure
    • Decreased lung compliance (as appreciated by hand ventilation)
    • Decreased tidal volume with no change or increased airway pressures
    • If complete obstruction, loss of end tidal carbon dioxide trace
    • Hypoxia
    • Decreased breath sounds or no breath sounds
    • Decreased chest excursion with ventilation
    • Hemodynamic changes
  2. What is the first and most important step to take if a problem with the breathing circuit is suspected?
    • Initiate an alternative form of ventilation and oxygenation, excluding any portions of the breathing circuit suspected to be defective.
  3. What is the differential diagnosis of inability to ventilate a patient with an endotracheal tube?
    • Pulmonary edema, hemorrhage
    • Pneumothorax
    • Bronchospasm
    • Anaphylaxis
    • Airway obstruction (secretions, foreign body)
    • Change in endotracheal tube position (endobronchial)
    • Occlusion of endotracheal tube
    • Occlusion of breathing circuit
    • Ventilator failure
  4. What basic systems are covered in the 1993 FDA anesthesia apparatus checkout recommendations?
    • Emergency ventilation equipment
    • High-pressure system (cylinder and pipeline supply)
    • Low-pressure system (low pressure leak check, test flowmeters)
    • Scavenging system
    • Breathing system (calibrate oxygen monitor, high pressure leak check)
    • Manual and automatic ventilation systems (check unidirectional valves, ventilator function)
    • Monitors (check, calibrate, set alarm limits)
    • Check final machine status


Refer to:

  1. Adams AP. Breathing system disconnections. Br J Anesth 1994;73:46–54.
  2. Caplan RA, et al. Adverse anesthetic outcomes arising from gas delivery equipment: a closed claims analysis. Anesthesiology 1997;87:741–748.
  3. Chacon A, et al. Unusual case of breathing circuit obstruction: plastic packaging revisited. Anesthesiology 2004;100:753.
  4. United States Food and Drug Administration. Anesthesia Apparatus Checkout Recommendations. Rockville, MD: Food and Drug Administration; 1993.

Assessment Instruments



Monitors required:

  • Noninvasive blood pressure cuff
  • Three lead electrocardiogram
  • Temperature probe
  • Pulse oximetry
  • Capnograph

Other equipment required

  • Stethoscope
  • Drug syringes
  • Albuterol meter-dose inhaler
  • Suction catheter
  • Endotracheal tube
  • Laryngeal mask airway
  • Laryngoscope
  • Face mask
  • Oxygen tubing
  • Ambu bag
  • Additional circle circuits and straight connectors
  • Breathing circuit extension tubing
  • Anesthesia machine
  • Defibrillator/code cart
  • Operating room table with ability to move 90 degrees
  • Partially occluded circuit straight connector piece*

Supporting Files


Time Duration

  • Set-up: 5 minutes
  • Preparation: 15 minutes
  • Simulation: 15 minutes
  • Debrief: 10 minutes


History of Present Illness

Samuel B. Stuffy is a 36-year-old man with a medical history significant for mild asthma and recurrent sinusitis. Mr. Stuffy initially presented to the otolaryngology clinic due to recurrent sinus infections. After further evaluation, it was recommended that he undergo endoscopic sinus surgery. He has a history of mild asthma, which has decreased in frequency of exacerbations in his adulthood. He currently only requires an albuterol inhaler, which he uses one to two times per month. He last used his inhaler 1 week ago while jogging. His asthma attacks mostly occur with exercise. He never has had an episode of status asthmaticus, required systemic steroids, or been hospitalized or intubated for reasons related to his asthma. Otherwise, Mr. Stuffy is a healthy man without any previous surgeries or anesthetic history. He is able to walk up two flights of stairs without dyspnea. He has had nothing by mouth for greater than 12 hours. He presents today for endoscopic sinus surgery.

Medical and Surgical History

  • Asthma—mild, intermittent
  • Recurrent sinus infections
  • No previous surgeries

Social History

No alcohol, tobacco, or intravenous drug use. Patient lives with his wife and works as a school teacher. He exercises by jogging three times per week.

Family History

No history of anesthetic reactions.

Review of Systems

  • Central nervous system: Headaches associated with sinus infections. Negative for seizure and stroke.
  • Cardiovascular: Negative for angina and hypertension.
  • Pulmonary: Positive for asthma. Negative for chronic obstructive pulmonary disease and cough.
  • Renal/hepatic/gastrointestinal: Negative for liver disease, kidney disease, and reflux disease.
  • Endocrine: Negative for diabetes and thyroid problems.
  • Heme: Negative for bleeding disorders, hypercoagulable states, and anemia.

Current Medications and Allergies

  • Albuterol metered dose inhaler (patient uses two puffs approximately one to two times per month as needed).
  • No known drug allergies.

Physical Examination

  • General: Slightly overweight, white male. Not in any acute distress.
  • Weight, height: 86 kg, 185cm
  • Vital signs: Heart rate 86 bpm; blood pressure 131/78 mm Hg; respiratory rate 10 breaths per minute; oxygen saturation 98% on room air.
  • Airway: Mouth opening of three finger breadths, good dentition, no loose teeth, adequate thyromental distance, cervical spine full range of motion, Mallampati class 2 airway.
  • Lungs: Clear to auscultation bilaterally without wheezes.
  • Heart: Regular rate and rhythm, no murmurs, rubs, or gallops appreciated.
  • Abdomen: Soft, nontender, nondistended.
  • Extremities: No edema, 2+ radial and dorsalis pedis pulses.

Laboratory, Radiology, and Other Relevant Studies

  • Chemistry: Within normal limits
  • Hematocrit: 42%
  • Chest x-ray: No hyperinflation, no cardiopulmonary disease identified.

You have just received a page from your anesthesia attending asking you to relieve a colleague who has just started this case. Your colleague is feeling very ill, so your attending gives you a brief report regarding the intraoperative course so far. He tells you that induction of general anesthesia was uneventful and the patient received propofol, 100 μg of fentanyl, and is paralyzed with vecuronium. He has one 18-gauge peripheral intravenous line and an 8.0 endotracheal tube. The operating room table has been rotated 90 degrees for surgical access.


In this scenario, the learner will be taking over this case already in progress. The learner will be briefed on the patient's medical and surgical history, allergies, IV access, and intraoperative course before entering the simulation. An assistant will serve as the “ill colleague” whom the learner is relieving from the case. Just before the learner entering the operating room, the assistant will place the partially occluded straight connector into the circuit. As soon as the learner is alone in the operating room, he will be unable to ventilate the patient because of this occluded connector. At this point, the learner should review the differential diagnosis of increased peak airway pressures and inability to ventilate an intubated patient. The learner should systematically eliminate various diagnoses until he identifies the obstructed straight connector. If the obstruction is not identified in a timely manner, the learner should institute an alternative mode of ventilation/oxygenation that does not include the partially obstructed connector. During this time, the learner should be communicating the status of patient with other anesthesia providers (anesthesia attending) and the surgical team. Once the obstruction is identified and connector piece replaced, the case uneventfully concludes. If the learner does not identify the circuit obstruction or institute adequate alternative oxygenation/ventilation in a timely manner (without partially occluded connector); the patient will become hemodynamically unstable requiring resuscitation.

Table 1
Table 1
Table 1
Table 1:


1. Overview of ASA Closed Claims Project. Available at: Accessed March 2006.
2. Fasting S, Gisvold SE. Equipment problems during anaesthesia—are they a quality problem? Br J Anaesth 2002;89:825–831.
3. Overview of ACGME Outcomes Project and Core Competencies. Available at: Accessed July 2007.

*This piece can be made by obtaining a straight connector piece and partially occluding the lumen with clear silicone caulk; available at major hardware stores. As the silicone is hardening, push it toward to center of the straight connector with a finger coming from each end of the connector. The goal is to create a partial occlusion as well as to conceal the silicone in the center of the piece so that it is not readily visible.
Cited Here


Anesthesia simulation; anesthetic gas delivery systems; breathing systems; breathing circulation malfunction; anesthesia equipment misuse; anesthesia equipment failure; anesthesia complications

© 2007 Society for Simulation in Healthcare