SS NRAN80323_ANESTHESIAmachineHAZARDS_FALL23.pptx

ANESTHESIA MACHINE HAZARDS Gregory Collins, DNP, CRNA PHYSICAL SCIENCE IN NURSE ANESTHESIA NRAN 80323 ANESTHESIA MACHINE HAZARDS OUTLINE: HYPOXIC GAS MIXTURE HYPOVENTILATION HYPERCAPNIA CIRCUIT OBSTRUCTION EXCESSIVE AIRWAY PRESSURE ANESTHETIC AGENT ERRORS READING: NAGELHOUT / CH 16 ANESTHESIA...

ANESTHESIA MACHINE HAZARDS Gregory Collins, DNP, CRNA PHYSICAL SCIENCE IN NURSE ANESTHESIA NRAN 80323 ANESTHESIA MACHINE HAZARDS OUTLINE: HYPOXIC GAS MIXTURE HYPOVENTILATION HYPERCAPNIA CIRCUIT OBSTRUCTION EXCESSIVE AIRWAY PRESSURE ANESTHETIC AGENT ERRORS READING: NAGELHOUT / CH 16 ANESTHESIA MACHINE HAZARDS MORBIDITY & MORTALITY RELATED TO ANESTHESIA MACHINE • Closed claims evaluation from 1980-2018:  41% of all anesthesia injury/death attributable to machine dysfunction • Death or brain death in 76% of machine dysfunction claims  Almost all were PREVENTABLE! •  Proper monitoring, response could have prevented injury in 78% CASE STUDY #1 72 y/o male patient was brought to the OR from the ER at 8:00 pm for a severe lower GI hemorrhage 1) IV induction and ventilated with 100% oxygen 2) Shortly after induction he becomes hypotensive, bradycardia, and refractory to inotropic support 3) 15 minutes after induction he arrested and did not respond to resuscitation 4) An ABG drawn during the resuscitation showed a PaO2 of 8mmHg and PaCO2 of 27mmHg CASE STUDY #1 • Upon deposition the provider said, “his appearance was ashen and blue, despite delivery of 100% oxygen” • Investigation of the OR showed a cross connection of the O2 and N2O • A service technician had serviced the gas supplies late in the afternoon on the day of the event • The technician did not perform a gas analysis test because he didn’t have a functioning oxygen analyzer • End Result: Patient received 100% N2O HYPOXIC GAS MIXTURE •Incorrect Gas Supply Cylinders → Incorrect label → Pin index overridden → Cylinder contents incorrect Pipelines → Crossovers → Unexpected contents • Flow Control Valve Malfunction Wear or damage to valve • Inadvertent Flowmeter Adjustment Operator error • Inaccurate Flowmeter Stuck float • Flowmeter Leak HYPOXIC GAS MIXTURE Detection of HYPOXIC GAS MIXTURE: • Calibrated OXYGEN ANALYZER (with low limit alarm set ~30%) • End-tidal gas analysis HYPOXIC GAS MIXTURE Response to PIPELINE CROSSOVER: 1)Open oxygen cylinder, DISCONNECT PIPELINE 2)Confirm increasing FiO2 3)Switch to manual ventilation with low fresh gas flow 4)Call for help, alert other providers 5)Do not reconnect pipeline until gas supply is tested CASE STUDY #2 • 24 y/o healthy patient for an emergency appendectomy • Pre-oxygenation and rapid sequence intubation • Intubation verified, chest rise present, end tidal CO2 waveform is present, bilateral clear breath sounds are present and equal • Placed on the ventilator - Tv 700mL, rate 10, FiO2 60%, sevoflurane dialed to 3% • Initial VS - HR 95, BP 139/90, SpO2 99%, EtCO2 34, ECG NSR with PVCs • 20 minutes into case: HR 88, BP 143/99, SpO2 99%, EtCO2 58, ECG NSR with PVCs HYPOVENTILATION  Fresh Gas Supply Issue  Excessive Gas Loss • Breathing system leaks (ETT cuff, circuit tubing, etc) • Circuit disconnect • Negative pressure relief valve stuck closed • Improper APL valve adjustment  Blocked Inspiratory and/or Expiratory Pathways • Manufacturing defects • Kinked breathing tubes  Ventilator • Inappropriate settings • Leaks o Bellows o Drive gas, canister HYPOVENTILATION Detection of HYPOVENTILATION: • • • • Airway pressure gauge Low pressure alarm Apnea alarm Continuous capnography HYPOVENTILATION END-TIDAL CO2 WAVEFORMS: HYPOVENTILATION Troubleshooting HYPOVENTILATION: • Switch to manual ventilation • Provide manual ventilation and confirm breath sounds • If ventilation is difficult, check the airway device and circuit • If manual ventilation is successful, assess ventilator function • If airway is patent and manual ventilation is difficult, disconnect circuit and provide BVM HYPERCAPNIA CAUSES OF HYPERCAPNIA:  Hypoventilation  Hypermetabolic state: • Malignant Hyperthermia • Sepsis  Inadequate CO2 removal • Exhausted, desiccated absorbent  HYPERCAPNIA Detection of HYPERCAPNIA:  Continuous capnography  Properly functioning circuit flow should produce zero FiCO2 • Increasing FiCO2 indicates absorbent failure or faulty expiratory valve • Increasing EtCO2 indicates hypoventilation or hypermetabolic state HYPERCAPNIA Troubleshooting HYPERCAPNIA: • Assess ventilation status, rule out hypoventilation • Assess absorbent function, rule out exhausted absorbent • Assess the unidirectional valves for missing, sticking, or damaged discs • Increasing Fresh Gas Flow above patient minute volume will lower CO2 levels in a circle system! HYPERCAPNIA END-TIDAL CO2 WAVEFORMS: HYPERCAPNIA END-TIDAL CO2 WAVEFORMS: CASE STUDY #3 • 44 y/o female for emergency cholecystectomy • Med Hx: anxiety, obesity, asthma, and OSA • Currently uses multiple inhalers and anti-depressant • Meet the patient, review the preoperative assessment, assess • Breath sounds clear, she had a breathing treatment in pre-op holding • Pre-oxygenate and perform Rapid Sequence Intubation • Connect the circuit, the breathing bag is full, and you are unable to ventilate the patient CIRCUIT OBSTRUCTION INSPIRATORY LIMB OBSTRUCTION: • Obstruction between reservoir bag and patient • Reservoir bag filling from flowmeters and/or O2 flush valve • Obstruction prevents forward gas movement from bag to patient CIRCUIT OBSTRUCTION CIRCUIT OBSTRUCTION Response to INSPIRATORY LIMB OBSTRUCTION: 1) 2) 3) 4) Disconnect breathing circuit from the patient Ventilate with BVM Connect to an auxiliary oxygen source Continue the anesthetic with TIVA CIRCUIT OBSTRUCTION Prevention of CIRCUIT OBSTRUCTION Emergency:  MACHINE CHECK!  Minimum requirements:  Circuit leak test • Would reveal inspiratory limb obstruction  Breathing circuit flow • Confirm reservoir bag movement during preoxygenation  Assess O2 analyzer • CASE STUDY #4 • 65 y/o female undergoing right bunionectomy • Patient is intubated and you are manually ventilating with reservoir bag • Following first few ventilations, reservoir bag is empty and HIGH AIRWAY PRESSURE alarm is sounding CIRCUIT OBSTRUCTION EXPIRATORY LIMB OBSTRUCTION: • Obstruction between patient and reservoir bag • Stuck expiratory valve is most common cause • Critical emergency due to potential for HIGH AIRWAY PRESSURES • Typical response to “flat” reservoir bag is to fill circuit with O2 flush valve → DO NOT activate flush valve with HIGH AIRWAY CIRCUIT OBSTRUCTION Response to EXPIRATORY LIMB OBSTRUCTION: 1) 2) 3) 4) Disconnect breathing circuit from the patient Ventilate with BVM Connect to an auxiliary oxygen source Continue the anesthetic with TIVA EXCESSIVE AIRWAY PRESSURE Causes of EXCESSIVE AIRWAY PRESSURE: • O2 flush valve activation (35-75L/min) • Inspiratory/expiratory limb obstruction (unidirectional valves stuck) • Ventilator relief valve obstruction • APL valve obstruction (Spontaneous ventilation only) • Scavenging system obstruction Prevention and detection of EXCESSIVE AIRWAY PRESSURE: • • • • Ventilator peak airway pressure limit setting APL valve setting (manual/spontaneous ventilation) High peak airway pressure alarm High sustained airway pressure alarm CASE STUDY #5 • 36 y/o male having a knee arthroscopy • General anesthesia with an LMA, breathing spontaneously • Patient begins to move his head…surgeon says “He’s Waking Up!!!” • You turn up the anesthesia agent, & scan the monitors • You notice a large discrepancy between the vaporizer setting and the agent concentration on the anesthetic gas monitoring INADEQUATE ANESTHETIC AGENT Causes of INADEQUATE ANESTHETIC AGENT: Empty vaporizer Oxygen flush valve overuse Faulty vaporizer Incorrect agent in vaporizer → VA with lower vapor pressure in vaporizer designed for VA with higher vapor pressure (sevoflurane in isoflurane vaporizer) • Improper vaporizer mounting • Vaporizer left in off position • • • • ANESTHETIC AGENT OVERDOSE Causes of ANESTHETIC AGENT OVERDOSE: • Tipped vaporizer (mishandling) • Vaporizer inadvertently turned on • Incorrect agent in vaporizer → VA with higher vapor pressure in vaporizer designed for VA with lower vapor pressure (isoflurane in sevoflurane vaporizer) • Overfilling of the vaporizer • Vaporizer interlock failure • Incorrect vaporizer setting ANESTHETIC AGENT ERRORS Prevention and detection of ANESTHETIC AGENT ERRORS: • Typically, there are NO ALARMS TO DETECT LOW or HIGH VA LEVELS! • Inspired and expired VA level monitoring • Preanesthesia machine check – LOW PRESSURE LEAK TEST • Routinely fill vaporizers at beginning of shift and/or every case ANESTHETIC AGENT ERRORS ELECTRONIC MALFUNCTION 1) Troubleshoot the patient 2) Then the equipment 3) If all else fails: Reboot ANESTHESIA MACHINE HAZARDS PROTECT THE PATIENT FROM THE EQUIPMENT! • Stay absolutely VIGILANT • Anticipate change • Respond to change • Always begin to troubleshoot at the SUMMARY List the potential causes of hypoxic gas mixture. Describe the prevention and detection of hypoxic gas mixture. Define the correct response to pipeline crossover. List the potential causes of hypoventilation/hypercapnia. Describe the prevention and detection of hypoventilation/hypercapnia. Discuss the steps in troubleshooting hypoventilation/hypercapnia. Relate EtCO2 waveforms to common causes of hypoventilation/hypercapnia. List the potential causes of circuit obstruction. Define the correct response to inspiratory/expiratory circuit obstruction. Describe the prevention and detection of circuit obstruction. List the potential causes of excessive airway pressure.