Presentation on theme: "Perianesthesia Nurses Association of British Columbia Cathy Hanley, RN, BSN November 6, 2010 Capnography in the PACU: Theory and Clinical Applications."— Presentation transcript:
Perianesthesia Nurses Association of British Columbia Cathy Hanley, RN, BSN November 6, 2010 Capnography in the PACU: Theory and Clinical Applications of end tidal C02 Monitoring
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
Brief History of Capnography Used in anesthesia since the 1970s Canadian Anesthesiologists’ Society requires it in the OR New recommendations and standards expanding utilization
Capnography = Solutions for all Intubated and Non-Intubated patients Capnography can be used in all areas of the hospital Peds. GI MRI Med- Surg EP/ Cath Pain Mgmt OR PACU ICU Capnography outside of the OR
Overview of Capnography Capnography is the non-invasive, continuous measurement of CO 2 concentration at the airway Capnography provides three important parameters: Respiratory rate detected from the actual airflow Waveform tracing for every breath Numeric etCO 2 value Normal range mmHg
Obtaining an Accurate Respiratory Rate
Respiratory Cycle = Oxygenation and Ventilation
The Relationship between PaCO 2 and etCO 2 etCO 2 normal range is mmHg Under normal ventilation and perfusion conditions, the PaCO 2 & etCO 2 will be very close – 2 – 5 mmHg with normal physiology 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
Ventilation-Perfusion Mismatch 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 CO 2 ) – Unventilated areas of lung are being perfused (“Shunt”) Effect on etCO 2 may be small but oxygenation may decrease greatly
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
Summary - EtCO 2 vs. PaCO 2 End tidal CO 2 (EtCO 2 ) = noninvasive measurement of CO 2 at the end of expiration EtCO 2 allows trending of PaCO 2 - a clinical estimate of the PaCO 2, when ventilation and perfusion are appropriately matched Wide gradient is diagnostic of a ventilation-perfusion mismatch EtCO 2 monitoring allows for a breath by breath assessment of ventilation.
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
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)
Case Study: Microstream Capnography in the PACU: Submitted by: Larry Myers RRT Cottonwood Hospital Murray, 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.
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
Clinical Situation At 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: 62mmHg Sp02: High 80’s Over the next 2 hours, etC02 fell to 44mmHg and Sp02 increased to 98%.
Discussion The continuous monitoring of E t CO 2 and SpO 2 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 CO 2. The probability of a PE in this case was low with a measured E t CO 2 of 62 mmHg and a correlating PaCO 2 of 64.9 mmHg. One would expect a wider gradient in the presence of significant dead space ventilation.
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
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
Capnography monitoring in patients receiving patient controlled analgesia (PCA)
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 oversedation and 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: pdf/patientSafety/qr pdf.
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
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
CO 2 production must equal CO 2 removal
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.
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
Obstructive Sleep Apnea Sleep apnea is the most widely known sleep disorder besides insomnia Believed to be under-reported 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 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
Mechanism of OSA…a vicious pattern Survival Mechanism
A more vicious pattern…with sedation Opiates & sedatives inhibit arousal mechanisms Respiratory Arrest Without Intervention
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
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
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 = mmHg
A-B: Baseline = no CO 2 in breath, end of inhalation B-C: Rapid rise in CO 2 D-E: Inhalation C-D: Alveolar plateau D D: End point of exhalation (EtCO 2 ) Anatomy of a Waveform
Sudden loss of waveform and EtCO 2 to zero or near zero / no respiration detected – Possible causes Intubated: Kinked or dislodged ETT Abnormal waveforms – No Breath loss of waveform Total airway obstruction Complete disconnect from ventilator Non-intubated: Apnea Dislodged Capnoline
Absent alveolar plateau indicates incomplete alveolar emptying or loss of airway integrity – Possible causes Abnormal waveforms Loss of alveolar plateau Intubated: Partial airway obstruction caused by secretions Leak in the airway system Bronchospasm Endotracheal tube in the hypopharynx Non-intubated: Head and neck position secretions
Gradual decrease in etCO 2 with normal waveform indicates a decreasing CO 2 production, or decreasing systemic or pulmonary perfusion Abnormal waveforms - decreased etCO 2 Hypothermia (decrease in metabolism) Hyperventilation Hypovolemia Decreasing cardiac output
Rise in baseline CO 2 indicates rebreathing of CO 2 Intubated patient – Addition of mechanical dead space to ventilator circuit – Technical errors in CO 2 analyzer Abnormal waveforms – rebreathing intubated and non-intubated Non-intubated patient Poor head & neck alignment Draping at the airway Insufficient flow to O 2 mask Shallow breathing that does not clear anatomical dead space
Abnormal Waveforms – What to do 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
Movers and Shakers / Clinical Compass
‘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
Institute for Safe Medication Practices (ISMP) “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. ISMP Medication Safety Alert, February 22, 2007, Vol. 12, Issue 4
ASA (American Society of Anesthesiologists) Practice guidelines for the perioperative management of patients with obstructive sleep apnea CO 2 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. 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):
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
Be Prepared. Be Proactive
Continuing Capnography Education Oridion Knowledge Center: Three capnography courses available: – A Guide to Capnography during Procedural Sedation – A Guide to Capnography in the Management of the Critically Ill – A Guide to Monitoring etCO 2 during Opioid Delivery