Capnography in the PACU: Clinical Applications of End-Tidal CO2 Monitoring

1. Capnography in the PACU: Theory and Clinical Applications of end tidal C02 Monitoring Perianesthesia Nurses Association of British ColumbiaCathy Hanley, RN, BSNNovember 6, 2010

2. Objectives • Review of physiology, ventilation vs oxygenation • Identify normal and abnormal etC02 values and waveforms and appropriate clinical interventions • Discuss current applications of capnography in the PACU and beyond • Discuss current standards and recommendations • Review of capnography case studies

3. Brief History of Capnography • Used in anesthesia since the 1970s • Canadian Anesthesiologists’ Society requires it in the OR • New recommendations and standards expanding utilization

4. PACU ICU OR Med- Surg Peds. EP/ Cath MRI Pain Mgmt GI Capnography outside of the OR • Capnography = Solutions for all Intubated andNon-Intubated patients • Capnography can be used in all areas of the hospital

5. Overview of Capnography • Capnographyis the non-invasive, continuous measurement of CO2concentration at the airway • Capnography provides three important parameters: • Respiratory ratedetected from the actual airflow • NumericetCO2 value • Normal range 35-45 mmHg • Waveformtracing for every breath

6. Obtaining an Accurate Respiratory Rate

7. Respiratory Cycle = Oxygenation and Ventilation

8. Important Measurements http://www.covidien.com

9. etCO2 normal range is 35 - 45 mmHg Under normal ventilation and perfusion conditions, the PaCO2 & etCO2 will be very close 2 – 5 mmHg with normal physiology The Relationship between PaCO2 and etCO2 Ideally, every alveolus is involved in air exchange (ventilation) and has blood flowing past it (perfusion), but in reality, ventilation and perfusion are never fully matched, even in the normal lung

10. There is inappropriate matching of ventilation and perfusion when: “Dead space” is being ventilated with no perfusion Since no gas exchange occurs, air coming out is the same as air going in (no CO2) Unventilated areas of lung are being perfused (“Shunt”) Effect on etCO2 may be small but oxygenation may decrease greatly Ventilation-Perfusion Mismatch

11. Dead Space Ventilation • Physiologic • conducting airways and unperfused alveoli • Mechanical • breathing circuits • Disease states leading to this include: • Severe hypotension • Pulmonary embolism • Emphysema • Bronchopulmonary dysplasia • Cardiac arrest

12. Ventilation-perfusion mismatch • Bronchial intubation • Increased secretions • Mucus plugging • Bronchospasm • Atelectasis

13. Summary -EtCO2 vs. PaCO2 • End tidal CO2 (EtCO2) = noninvasive measurement of CO2 at the end of expiration • EtCO2 allows trending of PaCO2 - a clinical estimate of the PaCO2, when ventilation and perfusion are appropriately matched • Wide gradient is diagnostic of a ventilation-perfusion mismatch • EtCO2 monitoring allows for a breath by breath assessment of ventilation.

14. Why use etC02 in the PACU? • Accurately monitors effective ventilation, giving a true airway respiratory rate • Early warning of : • Hypoventilation • Apnea • Obstruction Provides easy and accurate airway monitoring for intubated or non-intubated patients • Promotes better ventilation assessment resulting in timely interventions • Titrate sedation and pain medication

15. Why use etC02 in the PACU? • Indicator of Malignant Hyperthermia • Use with patient with history of respiratory compromise, such as asthma or COPD to monitor trend and need for breathing treatments and response to treatment • Endotracheal tube placement • Monitoring during weaning • Decrease frequency of arterial blood gases • Use with non-invasive ventilation (NIV)

16. Case Study: Microstream Capnography in the PACU:Submitted by: Larry Myers RRTCottonwood HospitalMurray, Utah • Profile • A 31-year-old female s/p abdominal hysterectomy 6 months prior to admission is admitted with right lower quadrant pain. The patient underwent a bilateral salpingo-oophorectomy and lysis of adhesions on this admission. On post-op day one she became hypotensive and had a substantial decrease in her hematocrit. The patient was returned to the OR for an exploratory laparotomy.

17. Case Study in PACU Clinical Situation: When the patient was returned to the PACU, she was extubated and became acutely hypoxic on a non-rebreather mask. The patient was in profound distress, drowsy, lethargic, but arousable and able to converse with c/o severe abdominal and chest pain. Sp02: 82% pH: 7.22 PaC02: 64.9mmHg HCO3: 25.5mEq/L Pa02: 53mmHg Sa02: 81% RR: 40bpm HR: 130bpm BP: 107/48

18. Clinical SituationAt this point anesthesia was preparing to reintubate. A suggestion was made to use etC02 with an oral/nasal cannula and place the patient on a high flow 02 delivery system with an Fi02 of 1.0 and monitor the patient closely. The patient was rushed to the Radiology Department for a CT angiogram where a pulmonary embolus was ruled out.Initial values:etC02: 62mmHgSp02: High 80’sOver the next 2 hours, etC02 fell to 44mmHg and Sp02 increased to 98%.

19. DiscussionThe continuous monitoring of EtCO2 and SpO2 when measured in concert but evaluated independently allowed this patient to be safely observed and avoid reintubation and mechanical ventilation. It is also interesting to note, retrospectively, an expensive procedure to rule out PE may have been avoided with a better understanding of the relationship between arterial and end-tidal CO2. The probability of a PE in this case was low with a measured EtCO2 of 62 mmHg and a correlating PaCO2 of 64.9 mmHg. One would expect a wider gradient in the presence of significant dead space ventilation.

20. PACU, Post-op PCA, Med/Surg Floors • Post operative patients on Patient Controlled Analgesia (PCA) - often starts in PACU • Bariatric Patients/Obstructive Sleep Apnea(OSA) high risk patients • Awareness building regarding the need for monitoring ventilation/breathing on general floors • Patient sentinel events/deaths • Recent professional statements (APSF, ISMP) • Great need for more education on Oxygenation vs. Ventilation for nurses in non-acute areas

21. Compelling Recent Research “During analgesia and anesthesia, cases of respiratory depression were 28 times as likely to be detected if they were monitored by capnography as those that were not” University of Alabama – Birmingham, Waugh, Epps, Khodneva - meta-analysis presented at the Society of Technology in Anesthesia International Congress, January, 2008

22. Capnography monitoring in patients receiving patient controlled analgesia (PCA)

24. Patient safety with Patient Controlled Analgesia (PCA) • Patient Controlled Analgesia (PCA) aids patients in balancing effective pain control with sedation • The risk of patient harm due to medication errors with PCA pumps is 3.5-times the risk of harm to a patient from any other type of medication administration error • 2004 more deaths with PCA than with all other IV infusions combined • Due to oversedationand respiratory depression with PCA delivery Sullivan M, Phillips MS, Schneider P. Patient-controlled analgesia pumps. USP Quality Review 2004;81:1-3. Available on the web at: http://www.usp.org/ pdf/patientSafety/qr812004-09-01.pdf.

25. PCA Issues List • PCA by proxy • Drug product mix-ups • Device design flaws • Inadequate patient/family education • Practice issues including pump misprogramming • Inadequate monitoring ISMP Medication Safety Newsletter, July 10, 2003 Vol 8, no.14

26. Currently, no monitoring during PCA therapy at most hospitals • Post operative surgical units where there is no centralized monitoring • Large units making proximity to patient impossible • Vital signs are typically every 4 hours • Sometimes spot checking with pulse oximetry • Nurse to patient ratio can be 1:6 – 1:10

27. CO2 production must equal CO2 removal

28. Case scenario • 16 yr-old Billy falls off his skateboard and sustains a left femur fracture. He is now post-op from ORIF and is in the PACU extubated. He rates his pain at a 10 on 0-10 scale and has been given multiple doses of IV Morphine and is now on a PCA pump for pain.

29. Case scenario • Later that evening on the med-surg floor, after hours of poor pain control, Billy falls asleep • Afraid Billy will soon wake up and again be in severe pain, Billy’s mother repeatedly presses his morphine PCA button while he is asleep • He subsequently stops breathing and is resuscitated, but suffers hypoxic brain injury

30. Sleep apnea is the most widely known sleep disorder besides insomnia Believed to be under-reported 18-40 million people have sleep apnea Effects 2% of middle-aged females Effects 4% of middle-aged males More common in men It is estimated that nearly 80% of men and 93% of women with moderate to severe sleep apnea are undiagnosed Obstructive Sleep Apnea Practice Guidelines for the Perioperative Management of Patients with Obstructive Sleep Apnea, Anesthesiology 2006; 104:1081–93 Sleep Diagnosis and Therapy ♦ Vol 3 No 5 September-October 2008

31. Mechanism of OSA…a vicious pattern Survival Mechanism

32. Respiratory Arrest Without Intervention A more vicious pattern…with sedation Opiates & sedatives inhibit arousal mechanisms

33. PCA Case Scenario #2 • 60 year old female with morbid obesity and history of intractable low back pain • X-rays demonstrated severe bone-on-bone changes in both knee and hip areas • Placed on PCA continuous infusion with PCA demand dose • Placed on continuous SpO2 and EtCO2 monitoring

34. PCA Case Scenario #2 cont. • Soon after starting PCA, patient desaturated to SpO2 = 85% • Patient placed on 60% O2 aerosol mask and EtCO2 monitoring discontinued • PCA continuous discontinued, PCA demand dose continued

35. PCA Case Study #2 cont. • Following morning, patient appeared very lethargic and difficult to arouse • SpO2 in high 90s • EtCO2 monitor reapplied on patient with readings of 74 mmHg* indicating elevated CO2 level • Patient was transferred to ICU with diagnosis of obstructive sleep apnea complicated by obesity and PCA *Normal EtCO2 = 35-45 mmHg

36. Normal Waveform

37. D A-B: Baseline = no CO2 in breath, end of inhalation B-C: Rapid rise in CO2 C-D: Alveolar plateau D: End point of exhalation (EtCO2) D-E:Inhalation Anatomy of a Waveform

38. Abnormal waveforms – No Breath loss of waveform Sudden loss of waveform and EtCO2 to zero or near zero / no respiration detected • Possible causes • Intubated: • Kinked or dislodged ETT • Total airway obstruction • Complete disconnect from ventilator • Non-intubated: • Apnea • Dislodged Capnoline

39. Abnormal waveforms Loss of alveolar plateau Absent alveolar plateau indicates incomplete alveolar emptying or loss of airway integrity • Possible causes • Intubated: • Partial airway obstruction caused by secretions • Leak in the airway system • Bronchospasm • Endotrachealtube in the hypopharynx • Non-intubated: • Head and neck position • secretions

40. Classic Hypoventilation

41. Classic Hyperventilation

42. Abnormal waveforms - decreased etCO2 Gradual decrease in etCO2 with normal waveform indicates a decreasing CO2 production, or decreasing systemic or pulmonary perfusion • Hypothermia (decrease in metabolism) • Hyperventilation • Hypovolemia • Decreasing cardiac output

43. Capnography in Obstructive Lung Disease • Waveform shape detects presence of bronchospasm • etCO2 trends assess disease severity (e.g., asthma, emphysema) • etCO2 trends gauge response to treatment (e.g., asthma, emphysema

44. Abnormal waveforms – rebreathing intubated and non-intubated Rise in baseline CO2 indicates rebreathing of CO2 • Intubated patient • Addition of mechanical dead space to ventilator circuit • Technical errors in CO2 analyzer • Non-intubated patient • Poor head & neck alignment • Draping at the airway • Insufficient flow to O2 mask • Shallow breathing that does not clear anatomical dead space

45. Assess patient Check sample line position – reposition or check ET tube position Check head/neck alignment, and open airway, suction if needed Instruct patient to take a deep breath If patient is not breathing and not responding, follow airway protocol Abnormal Waveforms – What to do

46. Movers and Shakers / Clinical Compass

47. ‘The monitoring used in the PACU should be appropriate to the patient’s condition and a full range of monitoring devices should be available’.Canadian Anesthesiologists’ Society, R. Merchant, et al Revised edition 2010

48.  “Do not rely on pulse oximetry readings alone to detect opiate toxicity. Use capnography to detect respiratory changes caused by opiates, especially for patients who are at high risk (e.g., patients with sleep apnea, obese patients).” Establish guidelines for appropriate monitoring of patients who are receiving opiates, including frequent assessment of the quality of respirations (not just respiratory rate) and specific signs of oversedation. Institute for Safe Medication Practices (ISMP) ISMP Medication Safety Alert, February 22, 2007, Vol. 12, Issue 4

49. Practice guidelines for the perioperative management of patients with obstructive sleep apnea CO2 monitoring should be used during moderate or deep sedation for patients with OSA. If moderate sedation is used, ventilation should be continuously monitored by capnography or another automated method if feasible because of the increased risk of undetected airway obstruction in these patients.       Postoperative Management:OSA patients should be monitored for a median of 3 hours longer than the non-OSA counterparts before discharge.  Monitoring of OSA patients should continue for a median of 7 hours after the last episode of airway obstruction or hypoxemia. ASA (American Society of Anesthesiologists) Practice guidelines for the perioperative management of patients with obstructive sleep apnea: a report by the American Society of Anesthesiologists Task Force on Perioperative Management of Patients with Obstructive Sleep Apnea. Anesthesiology 2006 May;104(5):1081-93

50. Conclusion • Capnography for sedation/analgesia/postoperative monitoring: • Accurately monitors RR • Monitors adequate ventilation • Monitors hypoventilation due to over-sedation more effectively than pulse oximetry • Earliest indicator of apnea and obstruction • Adds additional level of safety providing caregiver with objective information to make accurate assessments and timely interventions