Capnography: Is it helpful?

1
Capnography Is it helpful?

• Has been called the 15 second triage tool
• The newest vital sign?
• Value lies in very simple application
• Advanced use requires in depth understanding of
  ventilation and perfusion

2
Key Uses of Capnography

• If PetCO2 increases, ventilation is threatened
  and airway protection may be needed
• If PetCO2 suddenly falls to zero, airway is lost,
  breathing may have stopped or sensor is
  malpositioned
• Included is determining tube placement by
  detection of CO2 (ET and NG)
• If PetCO2 suddenly falls (without a change in
  Ve), the loss of cardiac output is likely

3
Methods for Measuring Exhaled CO2
ColorimetricLimited due to lack of waveform and
easy to interpret numeric value
Purple PetCO2 - lt .5 Tan PetCO2
.5-2 Yellow PetCO2 - gt 2 Normal PetCO2 gt4
4
Methods for Measuring Exhaled CO2 - Capnography
Bedside monitor mainstream capnogram
Hand held side stream capnogram
5
Capnography reflects CO2 as it is being exhaled
from the lungs
4
3
1
2

• At the end of exhalation, called the end tidal
  CO2 or PetCO2 for pressure of CO2 at end tidal
  breathing, the exhaled CO2 is reflecting alveolar
  CO2. Normally, the PetCO2 value of 1-5 mm Hg
  below the arterial (or alveolar) CO2 level.

6
Identifying Adequate CO2 Emptying Pattern
Incomplete exhaled CO2 pattern
Adequate plateau Phase indicating good Alveolar
emptying
7
Clinical Application 1 Detecting Tube placement
Endotracheal and Esophageal tubes

• Capnography detects carbon dioxide from lungs
• Endotracheal tubes placed in the esophagus do not
  produce capnography waveform
• Nasogastric tubes placed in trachea will produce
  a capnogram

8
Clinical Application Detecting airway loss and
ventilator disconnection

• Current Alarms to Identify Patient Disconnection
  from the Ventilator are Very Accurate. However,
  they are ventilator monitors, not patient
  monitors
• The capnogram is the fastest, most reliable
  method to identify if a patient has lost the
  airway or is disconnected from the mechanical
  ventilator
• When a patient loses the airway or is
  disconnected from the ventilator, the capnogram
  immediately goes flat.

9
Case study - A 21 year old female is being
transported for a CT scan. During transport, she
extubates herself. The CRNA who is present
immediately reintubates. While waiting for the CT
to be started, he extubates himself again. The
CRNA is not present. The nurse attempts to
reintubate by waiting for inspiration and then
sliding the tube back in. She hears breath
sounds and she is trying to get the CRNA or
physician to help. However, the question is,
is the endotracheal tube in the correct location?
10
Literature supporting Capnography in Endotracheal
Tube Placement

• American Heart Association. Guidelines 2000 for
  cardiopulmonary resuscitation and emergency
  cardiovascular care. Circulation 2000102 (8
  suppl) I86I89.
• American Society of Anesthesiologists. Standards
  for Basic Anesthetic Monitoring. Approved by
  House of Delegates, October 1986, amended 2005.
  http//www.asahq.org/publicationsAndServices/stand
  ards/02.pdf2
• Hogg K, Teece S. Colourimetric CO2 detector
  compared with capnography for confirming ET tube
  placement. Emerg Med J 2003202656.
• MacLeod BA, Heller MB, Gerard J, et al.
  Verification of endotracheal tube placement with
  colorimetric end-tidal CO2 detection. Ann Emerg
  Med 19912026770.
• Recommendations for Standards of Monitoring
  During Anaesthesia and Recovery. 3rd edition,
  December 2000. The Association of Anaesthetists
  of Great Britain and Ireland. www.aagbi.org/guidel
  ines.html
• OConnor RE, Swor RA. Verification of
  endotracheal tube placement following intubation.
  National Association of EMS Physicians Standards
  and Clinical Practice Committee. Prehosp Emerg
  Care 1999324850.
• Position statement number 1. Confirmation of
  endotracheal tube placement with end tidal CO2
  detection. Emerg Med J 200118329
• Repetto JE, Donohue PA-C PK, Baker SF, Kelly L,
  Nogee LM. Use of capnography in the delivery room
  for assessment of endotracheal tube placement. J
  Perinatol. 2001 Jul-Aug21(5)284-7.
• Silvestri S, Ralls GA, Krauss B, Thundiyil J,
  Rothrock SG, Senn A, Carter E, Falk J. The
  effectiveness of out-of-hospital use of
  continuous end-tidal carbon dioxide monitoring on
  the rate of unrecognized misplaced intubation
  within a regional emergency medical services
  system. Ann Emerg Med. 2005 May45(5)497-503.
• Singh S, Allen WD Jr, Venkataraman ST, Bhende MS.
  Utility of a novel quantitative handheld
  microstream capnometer during transport of
  critically ill children. Am J Emerg Med. 2006
  May24(3)302-7.
• Verification of endotracheal tube placement
  policy statement. American College of Emergency
  Physicians. www.acep.org/1,4923,0.html

11
Use in Placing NG Tubes

• When placing Nasogastric tubes, capnography can
  help identify if the NG tube is in the esophagus
  versus the lungs
• Clinical applications also include placement of
  large diameter tubes prior to gastric lavage
  during treatment of an overdose patient
• Obvious benefit is to avoid instillation of
  substances intended for the stomach (e.g. tube
  feeding, charcoal) in the lungs
• May avoid a x-ray for tube placement

12
Detecting Esophageal Intubations

• Capnography detects carbon dioxide from lungs
• Endotracheal tubes placed in the esophagus do not
  produce capnography waveform
• Slide the nasogastric tube in about 20 cm and
  pause momentarily. If no CO2 is detected, the
  tube is in the esophagus.
• Correct detection of tube placement is immediate

13
51 yr female requires NG placement. After
difficult attempt, CO2 analyzed.

• Should you instill the tube feeding or reposition
  the NG?

14
NG placement research

• Ackerman MH, Mick DJ. Technologic approaches to
  determining proper placement of enteral feeding
  tubes. AACN Adv Crit Care. 2006
  Jul-Sep17(3)246-9.
• Araujo-Preza CE, Melhado ME, Gutierrez FJ,
  Maniatis T, Castellano MA. Use of capnometry to
  verify feeding tube placement. Crit Care Med.
  2002 Oct30(10)2255-9.
• Colorimetric device
• There were no false positives or negatives the
  technique was 100 specific. One placement out of
  the 53 was found to be in the trachea.
• To verify the sensitivity, 20 placements were
  made directly into the trachea through an
  endotracheal tube. In all 20 cases, carbon
  dioxide was detected.
• No false negatives occurred, indicating 100
  sensitivity.
• D'Souza CR, Kilam SA, D'Souza U, Janzen EP, Sipos
  RA. Can J Surg. 1994 Oct 37(5) 404-8.
• Ellett ML, Woodruff KA, Stewart DL. The use of
  carbon dioxide monitoring to determine orogastric
  tube placement in premature infants a pilot
  study. Gastroenterol Nurs 2007 Nov-Dec30(6)414-7
  
• Burns SM, Carpenter R, Blevins C, Bragg S,
  Marshall M, Browne L, Perkins M, Bagby R,
  Blackstone K, Truwit JD. Detection of inadvertent
  airway intubation during gastric tube insertion
  Capnography versus a colorimetric carbon dioxide
  detector. Am J Crit Care. 2006 Mar15(2)188-95.

15
If PetCO2 increases, ventilation is threatened
and airway protection is neededCapnography is
more valuable than oximetry in assessing
ventilation
Clinical Application 2 Assessing adequacy of
ventilation
16
Ventilation Assessment

• The main reason for a PetCO2 value to increase is
  reduced alveolar ventilation
• Obtaining a blood gas can confirm this
  possibility
• During sedation, weaning from ventilation or
  managing reactive airway patients, the PetCO2 is
  the first indication of danger
• If the PetCO2 increases by 10 mm Hg, airway
  protection should be implemented
• If sedation or analgesia is being administered,
  stop the infusion until the PetCO2 returns to
  near baseline
• Monitoring patient simultaneously for comfort and
  awareness

17
Limited Role of Pulse Oximetry in Assessing
Ventilation

• Normal SaO2 determined by PaO2
• If patient hypoventilates, PaCO2 increases and
  will drive PaO2 downward in direct proportion to
  PaCO2 increase
• If PaCO2 increases by 10, PaO2 will decrease by
  10
• If PaO2 is 90, will decrease to 80 mm Hg
• SaO2 will decrease from 98 to 97.
• Oximeter is not sensitive to rises in PaCO2
• When oxygen therapy is added or increased, rise
  in PaCO2 is completely obscured

18
Case Example of Limited Role of Oximetry in
Hypoventilation
19
Case 1
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Case 2
21
Case 3
22
Case 4 A 44 yr old male admitted to MICU with
unknown fever, SOB, hypoxemia. pH 7.34, PaCO2
38, PaO2 44, SpO2 .78. He is intubated, IMV
12/44. Extubates himself, is reintubated.
Sedation is increased. RR decreases to 12. .What
is the effect of sedation on ventilation?
47
33
23
Capnography and MAC

• Anderson JL, Junkins E, Pribble C, Guenther E.
  Capnography and depth of sedation during propofol
  sedation in children. Ann Emerg Med. 2007
  Jan49(1)9-13.
• Burton JH, Harrah JD, Germann CA, Dillon DC. Does
  end-tidal carbon dioxide monitoring detect
  respiratory events prior to current sedation
  monitoring practices? Acad Emerg Med. 2006
  May13(5)500-4.
• Deitch K, Chudnofsky CR, Dominici P. The utility
  of supplemental oxygen during emergency
  department procedural sedation and analgesia with
  midazolam and fentanyl a randomized, controlled
  trial. Ann Emerg Med. 2007 Jan49(1)1-8.
• Fu ES, Downs JB, Schweiger JW, Miguel RV, Smith
  RA. Supplemental oxygen impairs detection of
  hypoventilation by pulse oximetry. Chest. 2004
  Nov126(5)1552
• Hart LS, Berns SD, Houck CS, Boenning DA. The
  value of end-tidal CO2 monitoring when comparing
  three methods of conscious sedation for children
  undergoing painful procedures in the emergency
  department. Pediatr Emerg Care. 1997
  Jun13(3)189-93.
• Lightdale JR, Goldmann DA, Feldman HA, Newburg
  AR, DiNardo JA, Fox VL. Microstream capnography
  improves patient monitoring during moderate
  sedation a randomized, controlled trial.
  Pediatrics 2006 Jun117(6)e1170-8.
• Melloni C. Anesthesia and sedation outside the
  operating room how to prevent risk and maintain
  good quality. Curr Opin Anaesthesiol. 2007
  Dec20(6)513-9.
• Miner JR, Heegaard W, Plummer D. End-tidal carbon
  dioxide monitoring during procedural sedation.
  Acad Emerg Med. 2002 Apr9(4)275-80.
• Pino RM. The nature of anesthesia and procedural
  sedation outside of the operating room. Curr Opin
  Anaesthesiol. 2007 Aug20(4)347-51.
• Soto RG, Fu ES, Vila H Jr, Miguel RV. Capnography
  accurately detects apnea during monitored
  anesthesia care. Anesth Analg. 2004
  Aug99(2)379-82.
• Tobias JD. End-tidal carbon dioxide monitoring
  during sedation with a combination of midazolam
  and ketamine for children undergoing painful,
  invasive procedures. Pediatr Emerg Care. 1999
  Jun15(3)173-5.
• Vargo JJ, Zuccaro G Jr, Dumot JA, Conwell DL,
  Morrow JB, Shay SS. Automated graphic assessment
  (capnography) of respiratory activity is superior
  to pulse oximetry and visual assessment for the
  detection of early respiratory depression during
  therapeutic upper endoscopy. Gastrointest Endosc.
  2002 Jun55(7)826-31.
• Webb RK, van der Walt JH, Runciman WB, Williamson
  JA, Cockings J, Russell WJ, Helps S. The
  Australian Incident Monitoring Study. Which
  monitor? An analysis of 2000 incident reports.
  Anaesth Intensive Care 529-42(5), 1993 Oct21

24
Application 3Capnography and Assessment of
Blood Flow

• Use in Critical Care

25
Illustration of the Formation of Deadspace in the
Lungs
Normal Ventilation Perfusion
Reduced blood flow decreases alveolar CO2 - this
decrease is detected in the exhaled breath by
capnography
26
Capnography and Deadspace

• Normally, the end portion of the capnography wave
  (end tidal PCO2 or PetCO2) is slightly lower than
  the arterial PCO2 level
• The normal PaCO2 -PetCO2 gradient is 1-5 mm Hg.
• The primary reason for the gradient to widen is
  an increase in physiologic deadspace (such as
  occurs with a change in perfusion)
• Sudden change in PetCO2 and the PaCO2-PetCO2
  gradient is usually due to sudden drop in
  pulmonary blood flow

27
CPR, Blood Flow and Outcomes

• Ahrens et al AJCC 2001
• Weil et al 1999 - CCM
• Levine, Wayne, Miller - NEJM - 1997
• Asplin White 1995 - Ann Emer Med
• Domsky et al -1995 - CCM
• Idris et al 1994 - Ann Emer Med
• White Asplin 1994 - Ann Emer Med
• Ward et al 1993 - Ann Emer Med
• Angelos et al 1992 - Resuscitation
• Isserles Breen 1991- AA
• Callaham Barton 1990 - CCM
• Gazmuri et al 1989 - CCM
• Garnett et al 1987 - JAMA
• Weil et al 1985 - CCM

• Baraka AS, Aouad MT, Jalbout MI, Kaddoum RN,
  Khatib MF, Haroun-Bizri ST. End-tidal CO2 for
  prediction of cardiac output following weaning
  from cardiopulmonary bypass. J Extra Corpor
  Technol. 2004 Sep 36(3) 255-7.
• Deakin CD, Sado DM, Coats TJ, Davies G.
  Prehospital end-tidal carbon dioxide
  concentration and outcome in major trauma. J
  Trauma 2004 Jul57(1)65-8.
• Grmec S, Krizmaric M, Mally S, Kozelj A, Spindler
  M, Lesnik B. Utstein style analysis of
  out-of-hospital cardiac arrest--bystander CPR and
  end expired carbon dioxide. Resuscitation 2007
  Mar72(3)404-14.
• Gazmuri RJ, Kube E. Capnography during cardiac
  resuscitation a clue on mechanisms and a guide
  to interventions. Crit Care. 20037(6)411-412.
  Epub 2003 Oct 06.
• Kline JA, Arunachlam M. Preliminary study of the
  capnogram waveform area to screen for pulmonary
  embolism. Ann Emerg Med. 1998 Sep32(3 Pt
  1)289-96.
• Kunkov S, Pinedo V, Silver EJ, Crain EF.
  Predicting the need for hospitalization in acute
  childhood asthma using end-tidal capnography.
  Pediatr Emerg Care. 2005 Sep21(9)574-7.
• Mallick A, Venkatanath D, Elliot SC, Hollins T,
  Nanda Kumar CG. A prospective randomised
  controlled trial of capnography vs. bronchoscopy
  for Blue Rhino percutaneous tracheostomy.
  Anaesthesia. 2003 Sep58(9)864-8.
• Pernat A, Weil MH, Sun S, Tang W. Stroke volumes
  and end-tidal carbon dioxide generated by
  precordial compression during ventricular
  fibrillation. Crit Care Med. 2003
  Jun31(6)1819-23
• Sanchez O, Wermert D, Faisy C, Revel MP, Diehl
  JL, Sors H, Meyer G. Clinical probability and
  alveolar dead space measurement for suspected
  pulmonary embolism in patients with an abnormal
  D-dimer test result. J Thromb Haemost. 2006
  Jul4(7)1517-22.
• Sehra R, Underwood K, Checchia P. End tidal CO2
  is a quantitative measure of cardiac arrest.
  Pacing Clin Electrophysiol 2003 Jan26(1 Pt
  2)515-7

28
PetCO2 levels during cardiac arrest

• PetCO2 values should rise to gt 10mm Hg during
  successful resuscitation efforts
• Prolonged PetCO2 levels lt 10 have been shown to
  correlate with low cardiac outputs and poor
  survival
• Levine RL, Wayne MA, Miller CC. End tidal carbon
  dioxide and outcome of out-of-hospital cardiac
  arrest. New England Journal of Medicine
  1997337301-6.

29
Case 1 - A 66 yr old female is brought into the
ER, CPR is in progress. She was found down in
her house by her husband. Paramedics have been
doing CPR for gt 20 minutes. Her capnography wave
shows a value of 6 mm Hg. How would you assess
the adequacy of the resuscitation effort?
30
15
10
5
0
capnography wave showing a value of about 6
31
A 73 yr old male following a CABG and valve
replacement complains of acute shortness of
breath at 0630. He has the following information
present0600 0630 BP 112/68 122/76P 92
110IMV 10/14 IMV
10/22SpO2 .97 SpO2 .95PaCO2 32
PaCO2 - 29PetCO2 - 28 PetCO2 - 7 (see waveform
below)Is this possibly an anxious reaction due
to postoperative fear or has some physiologic
problem, like a PE occurred?
20
10
0
32
Answer

• The severe drop in PetCO2 from 28 to 7 makes it
  unlikely this is anxiety. This is more likely a
  pulmonary embolism. The widened PaCO2-PetCO2
  gradient clearly indicates a worsened deadspace.
• If this was due solely to anxiety, the PaCO2
  level would be about 12 (based on the PetCO2 of
  7), a value unlikely to be achieved by the
  present respiratory rate.
• An immediate workup for a PE is necessary in this
  patient.

33
Questions

• 1) Which of the following are indicators of
  sudden loss of blood flow
• Rise of PetCO2 from 40 to lt10 mm Hg within 2
  minutes
• Rise of PaCO2 gt 10 mm Hg in 1 minute
• Decrease in PaO2 of 10 mm Hg within 30 seconds
• a, b
• a, c
• b, c
• a, b, c
• 2) Which of the following indicate an increased
  deadspace
• PaCO2 41, PetCO2 49
• PaCO2 32, PetCO2 28
• PaCO2 45, PetCO2 39
• PaCO2 39, PetCO2 21
• 3) Which of the following are consistent with a
  sudden loss of cardiac output?
• PetCO2 decrease from 30 to 10 mm Hg
• Increase in PetCO2 from 30 to 40 mm Hg
• PetCO2 of 30 with a Ve of 10 LPM
• PetCO2 of 50 with a Ve of 4.1 LPM
• 4) If the PaCO2 is 40 and the PetCO2 is 35, what
  does that reveal about deadspace?