Pre-Hospital Capnography The ventilation vital sign

Carbon dioxide Physiology A Capnograph will show you second by second where you are with the patient by showing you The CO2 reading The CO2 waveform The Respiratory rate The Oxygen saturation The pulse rate Metabolism/Perfusion/Ventilation

Capnography An EtCO2 value of e.g..38mm/Hg with a trace 5 4 3 2 1 is as diagnostic as an ECG

► Application in clinical practice Objectives ► How it works ► The physiology involved ► Application in clinical practice

►How it works

►CO2 monitoring technology Capnometry: the measurement and numerical display of the CO2 level appearing in the airway Capnograpahy: the measurement and graphical display of the CO2 level appearing in the airway

►CO2 monitoring technology Infrared spectroscopy Compares the amount of infrared light absorbed by a sample of expired CO2 to a chamber with no CO2

► The physiology involved Physiology of Respiration Physiology of Metabolism

Physiology of metabolism Homeostasis. The body tries to maintain a state of equilibrium despite everything we throw at it. Body pH range 7.1-7.8, homeostasis is about 7.35 -7.45 A body pH of 7.2 called acidaemia A body pH of 7.5 called alkalaemia An acidoisis makes the pH more acidic than usual An alkalosis makes the pH more alkaline than usual

Physiology of metabolism There are a number of acids in the body CO2 Lactic acid from cell activity if starved of oxygen. Complex chemical interactions that keep these in balance. These dangerous acids need to be removed Buffers: immediate CO2 production: minutes Renal excretion/Liver breakdown: days

Physiology of metabolism A balance exists ACID CO2 Tissues Lungs By looking at what goes into the body via the lungs (Oxygen) and what comes out (Carbon dioxide) you get a picture as to how damaged or ill the body is

Physiology of respiration Carbon dioxide a natural waste product of cellular activity

Oxygenation Versus Ventilation Physiology of respiration Oxygenation Versus Ventilation Oxygenation is how we get oxygen to the tissue. Oxygen is inhaled into the lungs where gas exchange occurs at the capillary-alveolar membrane. Oxygen is transported to the tissues through the blood stream. Pulse oximetry measures oxygenation. Ventilation (the movement of air) is how we get rid of carbon dioxide. Carbon dioxide is carried back through the blood and exhaled by the lungs through the alveoli. Capnography measures ventilation

Physiology of respiration Oxygen/Carbon dioxide interaction: Metabolism Oxygen -> lungs -> alveoli -> blood Oxygen breath CO2 produced by cellular metabolism diffuses across the cell membrane into the circulating blood. CO2 muscles + organs lungs 5-10% carried in solution 20-30% bound to haemoglobin 60-70% carried as bicarbonate in the red blood cell Oxygen CO2 cells energy blood Oxygen + Glucose CO2

Ventilation Perfusion Physiology of respiration Oxygen/Carbon dioxide interaction: Perfusion and Ventilation Ventilation O2 CO2 CO2 CO2 O2 Perfusion

Ventilation Perfusion Physiology of respiration Oxygenation = oxygen → lungs→ alveoli→ blood Metabolism = oxygen is converted to energy + CO2 CO2 elimination = CO2 → blood→ lungs→ exhalation Perfusion

METABOLISM PERFUSION VENTILATION Physiology So CO2 levels provide evidence of three parameters going on the body METABOLISM PERFUSION VENTILATION What's happening at the cellular level How well the circulation is performing How well the lungs are working

METABOLISM VENTILATION PERFUSION Physiology If metabolism fails, acid forms (metabolic acid). With severe shock, the patient becomes very “acidic” and very ill This may be tolerated if circulation and oxygenation are maintained. The acid is converted to CO2 and this is blown off by the lungs Metabolic acidosis

METABOLISM VENTILATION PERFUSION Physiology If the circulation is failing, this “acid” cannot be transported to the lungs and the patient becomes more ill CO2 cannot be removed from the lungs as it cannot get there. Your only hope is to get the circulation working more effectively Metabolic acidosis

Carbon dioxide METABOLISM VENTILATION PERFUSION Physiology If the breathing is inadequate, CO2 accumulates in the blood and is converted to acid By ventilating the patient, we can get rid of the excessive CO2 and thereby reduce the damage the “acid” in the blood is doing to the tissues Respiratory acidosis

Physiology Metabolic acidosis Acid builds up (anaerobic metabolism) Tissue hypoxia (anaemia, shock, severe infection, diabetic ketoacidosis) Renal failure Loss of body salts (severe diarrhea) Respiratory acidosis Hypoventilation: CO2 builds up Airway obstruction Central neuro: brain injury, stroke, opiates Periph neuro: spinal cord injury Chest wall disease (muscle, flail chest, trauma, pneumothorax COPD Pneumonia, Respiratory alkalosis Hyperventilation: CO2 blown off Anxiety states Asthma - low O2, low CO2 PE - low O2, low CO2 BUT as exhaustion sets in -low O2 with rising CO2 Metabolic alkalosis Acid is lost Severe vomiting (acid lost from stomach)

Capnography measurements

The waveform Capnography measurements I just want you to look at the display first for a minute and then I will break the wave down into its constituent parts Normal waveform:

The waveform Capnography measurements The lungs are composed of tissue involved in gas exchange (alveoli) and tubes connecting them to the outside world (bronchi, trachea). These tubes ARE NOT involved in gas exchange and is called dead space.

The waveform Capnography measurements Phase I Represents the CO2-free gas from the airways (anatomical and apparatus dead space).

The waveform Capnography measurements Phase II Consists of a rapid upswing on the tracing (due to mixing of dead space gas with alveolar gas).

The waveform Capnography measurements Phase III Consists of an alveolar plateau representing CO2-rich gas from the alveoli. It almost always has a positive slope, indicating a rising PCO2

The waveform Capnography measurements Phase 0 Is the inspiratory phase where normal air is breathed in. There is only 0.36mmHg of CO2 in the air compared to 40mmHg in expired air

Capnography measurements The waveform

Capnography measurements The waveform Normal waveform:

EtCO2 Values Normal 35 – 45 mmHg Hypoventilation > 45 mmHg Hyperventilation < 35 mmHg

Physiology Relationship between CO2 and RR RR  CO2 Hyperventilation  RR   CO2 Hypoventilation There is an inverse relationship between your respiratory rate and your CO2 level. As you breath faster your RR goes up, your body is unable to hold onto CO2 and therefore blows it off faster so those levels go down. As you breath more slowly, your RR goes down, your body is holding more CO2 due to the lack of breaths taken and the CO2 level goes up. It is important to keep a healthy balance.

Capnography Values ETCO2 = 35-45 mm Hg 45 35 Square waveforms 50 40 30 50 40 10 20 30 45 35 Square waveforms Capnography Values The term used to describe the amount of carbon dioxide that is being eliminated with each breath is referred to as expired end-tidal carbon dioxide. It is abbreviated as ETCO2. In normal situations, the concentration of carbon dioxide in a sample of expired air is about 5%. At sea level, this would translate to a reading of 38 torr or 38 mmHg. We consider a reading between 35 and 45 mmHg to be within the normal range.

Capnography Values High Carbon Dioxide Low Carbon Dioxide 45 35 50 40 50 40 10 20 30 45 35 Low Carbon Dioxide Capnography Values Any ETCO2 below 35 mm Hg is low carbon dioxide. Any ETCO2 value above 45 mm Hg is elevated carbon dioxide. This correlates with the arterial blood oxygen levels (PaO2) of 35-45 torr. This is directly opposite of the ph scale which is 7.35-7.45.

Causes for a rise in end tidal CO2 Increased CO2 output Increased Pulmonary perfusion Reduced Alveolar Ventilation Technical errors Machine faults Increased cardiac output Increased blood pressure Inadequate fresh gas flows Poor ventilation by airway person Faulty valves Fever Hypercatabolic states Hypoventilation by patient Bronchial intubation (reduces the dead space) Rebreathing

Causes for a fall in end tidal CO2 Reduced CO2 output Reduced Pulmonary perfusion Increased Alveolar Ventilation Technical errors Machine faults Hypothermia Hypocatabolic state (eg gross myxoedema) Reduced cardiac output Hypotension Hypovolaemia Pulmonary embolism Cardiac arrest Hyperventilation Apnea Airway blocked: obstruction, ET tube extubated Circuit disconnection Sampling tube leak

Waveform analysis Look for five characteristics of the waves, Height (normal = 38mmHg. Tall = high CO2, small = low CO2) Rate Rhythm (regular, getting bigger (or smaller) Base line (how wide it is) Shape of the wave

Waveform analysis Hyperventilation Baseline at zero, but height is reduced gradually Hypoventilation Base line at zero, but height is increased gradually

Abnormal Capnogram Patterns If the waveform is abnormal, there usually IS an airway problem.

What is Wrong Here? 50 40 10 20 30 What is Wrong Here?

Rising Baseline 50 40 30 20 10 Rising Baseline 50 40 10 20 30 Rising Baseline In a normal situation, the baseline value will be zero. If the baseline is rising, it suggests that carbon dioxide is passing by the sidestream sampler on the way out and on the way in.

Rebreathing CO2 50 40 30 20 10 Rebreathing CO2 50 40 10 20 30 Rebreathing CO2 A rising baseline could only happen if the patient was rebreathing carbon dioxide. This would require an evaluation of the breathing circuit to locate the source of the carbon dioxide. If we are trying to give the patient supplemental oxygen but discover that he is rebreathing carbon dioxide, we are not meeting our goal. Common reasons for carbon dioxide rebreathing would be an inadequate oxygen flow into an oxygen mask or faulty one-way valves on non-rebreather masks or bag-valve-mask respirators.

80 Rising Baseline 01:27 Possible Causes: Treatment: Rebreathing CO2 Mark Event X 28 Apr 2009 15:44 A B CO2 Needs Calibration ↑ Adult Non-Paced Possible Causes: Rebreathing CO2 Treatment: Increase Oxygen on NRB (bag inflated?) If intubated allow exhale time 80 HR Pulse bpm 01:27 120 80 ∆ X bpm 50 II SpO2 % EtCO2 mmHg AwRR rpm 94 100 90 40 50 20 20 ∆ ∆ X CO2 60 Possible causes of a rising baseline and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 30 Pleth Start NBP 12-Lead MENU

What is Wrong Here? 50 40 10 20 30 What is Wrong Here?

Delayed Upstroke 50 40 30 20 10 Delayed Upstroke 50 40 10 20 30 Delayed Upstroke In phase II, if the upstroke of the wave form is slow, it suggests that the carbon dioxide is being delayed from getting to the sampler. When the movie is over, we would expect a trickle of people leaving the theater initially, but then more and more people would make it to the door. If you were waiting and waiting and did not see an increase in the number of people, you might wonder what is causing their delay.

Bronchoconstriction 50 40 30 20 10 Delayed Upstroke 50 40 10 20 30 Delayed Upstroke This type of waveform may indicate bronchoconstriction in your Asthma or COPD patient.

148 Bronchoconstriction 11:34 Possible Causes: Treatment: Asthma COPD Mark Event X 28 Apr 2009 15:44 A B TACHYCARDIA Adult Non-Paced Possible Causes: Asthma COPD Treatment: Bronchodilators Albuterol Atrovent Terbutaline CPAP/BiPAP ? 148 HR Pulse bpm 11:34 120 148 ∆ X bpm 50 II SpO2 % EtCO2 mmHg AwRR rpm 92 100 90 60 50 20 38 ∆ ∆ X CO2 60 Possible causes of a bronchoconstriction waveform and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 30 Pleth Start NBP 12-Lead MENU

What is Wrong Here? 50 40 10 20 30 What is Wrong Here?

Prolonged Phase IV 50 40 30 20 10 Prolonged Phase IV 50 40 10 20 30 Prolonged Phase IV If the drop in phase IV is prolonged, it suggests that fresh air is not efficiently clearing the area near the sampler. Since phase IV occurs during inspiration, it suggests that air entering the trachea is using a different entrance other than the one being monitored.

Deflated ETT Cuff or (in peds) ETT too Small 50 40 10 20 30 Deflated Tracheal Tube Cuff or Uncuffed Tube That is Too Small In intubated patients, this can only happen if the patient is breathing around the endotracheal tube instead of through it. You might see this if the cuff on the tube was deflated or in tubes without cuffs that are too small for the patient.

80 Prolonged Phase IV 01:27 Possible Causes: Treatment: Mark Event X 28 Apr 2009 15:44 A B CO2 Needs Calibration ↑ Adult Non-Paced 80 HR Pulse bpm 01:27 Possible Causes: Deflated ETT cuff Small ineffective ETT in pediatric Treatment: Increase the amount of air in the ETT cuff Increase the size of the ETT in the pediatric 120 80 ∆ X bpm 50 II SpO2 % EtCO2 mmHg AwRR rpm 94 100 90 40 50 20 10 ∆ X ∆ CO2 60 Possible causes of a prolonged phase IV and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 30 Pleth Start NBP 12-Lead MENU

What is Wrong Here? 50 40 10 20 30 What is Wrong Here?

Notched Alveolar Plateau “Curare Cleft” 50 40 10 20 30 Notched Alveolar Plateau In intubated patients that have been paralyzed and an advanced airway placed, the waveform should be normal shape. If the paralytic begins to wear off, the diaphram will begin to contract again. This creates a notching or Curare Cleft in the alveolar plateau.

Paralytic Medication Wearing Off 50 40 10 20 30 Some publications also state that a pulmonary embolism may cause this type of notching. If paralytics have been administered, then this identifies that you should administer additional paralytic medication and sedatives.

Notched Alveolar Plateau Mark Event X 28 Apr 2009 15:44 A B CO2 Needs Calibration ↑ Adult Non-Paced 80 Possible Causes: Paralytic efficiency decreasing Treatment: Administer additional paralytic medication Consider administering additional sedatives HR Pulse bpm 01:27 120 80 ∆ X bpm 50 II SpO2 % EtCO2 mmHg AwRR rpm 94 100 90 40 50 20 16 ∆ ∆ X CO2 60 Possible causes of a notched alveolar plateau and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 30 Pleth Start NBP 12-Lead MENU

What is Wrong Here? 50 40 10 20 30 What is wrong with this waveform.

Stair Step Alveolar Plateau 50 40 10 20 30 Stair step alveolar plateau The Phase 3 will drop significantly in the last half of the alveolar plateau.

Pressure of Expelled Air Decreasing, Allowing Oxygen to Dilute the Sample 50 40 10 20 30 Stair step alveolar plateau This may be caused by the pressure of the patient’s expelled air decreases causing oxygen to dilute the air sample. The outcome is to decrease the alveolar plateau at the end of the Phase IV. This may also occur if your patient is becoming exhausted moving into respiratory failure. This may be an indication that you should perform advanced airway management such as utilizing a BVM, RSI/PAI, etc.

Stair step Alveolar Plateau Mark Event X 28 Apr 2009 15:44 A B TACHYCARDIA Adult Non-Paced 148 HR Pulse bpm 11:34 120 148 ∆ X Possible Causes: CPAP Patient is exhausted Respiratory Failure Treatment: Monitor CPAP BVM Advanced Airway Management bpm 50 II SpO2 % EtCO2 mmHg AwRR rpm 92 100 90 44 50 20 38 ∆ X ∆ CO2 60 Possible causes of a stair step alveolar plateau and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 30 Pleth Start NBP 12-Lead MENU

Normal Waveform, but........... Normal Waveform, but....

What is Wrong Here? Respiratory Rate is 6 bpm 100 80 60 40 20 100 80 20 40 60 What is Wrong Here? Respiratory Rate is 6 bpm

Hypoventilation or Increased Metabolic Rate 100 80 20 40 60 Hypoventilation Assuming a normal waveform, a gradual increase in ETCO2 levels indicates hypoventilation (you are not diluting the carbon dioxide in the alveoli with enough fresh air) or an increased metabolic rate. Rising body temperature, or partial obstruction can also present this way.

120 Increasing CO2 05:41 Possible Causes: Treatment: Mark Event X 28 Apr 2009 15:44 A B TACHYCARDIA Increasing CO2 Adult Non-Paced 120 HR Pulse bpm 05:41 120 120 X ∆ bpm 50 Possible Causes: Increased metabolic rate Hypoventilation Treatment: Oxygen BVM II SpO2 % EtCO2 mmHg AwRR rpm 88 100 90 80 50 20 6 ∆ X ∆ CO2 100 Possible causes an increased level of carbon dioxide and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 50 Pleth Start NBP 12-Lead MENU

What is Wrong Here? Respiratory Rate is 40 bpm 50 40 30 20 10 50 40 10 20 30 What is Wrong Here? Respiratory Rate is 40 bpm

Hyperventilation or Decreased Metabolic Rate 50 40 10 20 30 Hyperventilation Assuming a normal waveform, gradual decreases in ETCO2 suggest hyperventilation or a decreased metabolic rate.

120 Decreasing CO2 05:41 Possible Causes: Treatment: Mark Event X 28 Apr 2009 15:44 A B TACHYCARDIA Decreasing CO2 Adult Non-Paced 120 HR Pulse bpm 05:41 120 120 X ∆ bpm 50 Possible Causes: Decreased metabolic rate Hyperventilation Treatment: Oxygen BVM Calming techniques Sedatives II SpO2 % EtCO2 mmHg AwRR rpm 88 100 90 20 50 20 30 ∆ X ∆ CO2 100 Possible causes of decreasing carbon dioxide and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 50 Pleth Start NBP 12-Lead MENU

What is Wrong Here? 50 40 10 20 30 What is Wrong Here?

Sudden Drop in Cardiac Output 50 40 10 20 30 Sudden Severe Hypotension Sudden drops in previously normal ETCO2 readings indicate that something is keeping the carbon dioxide from crossing into the alveoli from the blood. This could be caused by sudden severe hypotension, or a life-threatening arrhythmia that has produced cardiogenic shock.

120 Decreased CO2 05:41 Possible Causes: Treatment: Mark Event X Decreased CO2 28 Apr 2009 15:44 A B TACHYCARDIA Adult Non-Paced 120 HR Pulse bpm 05:41 Possible Causes: Sudden drop in cardiac output Treatment: Check a pulse CPR Oxygen Shock treatment IV fluid Vasopressors 120 120 ∆ X bpm 50 II SpO2 % EtCO2 mmHg AwRR rpm 88 100 90 40 50 20 16 ∆ X ∆ CO2 60 Possible causes of decreased level of carbon dioxide and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 30 Pleth Start NBP 12-Lead MENU

What is Wrong Here? 50 40 10 20 30 What is Wrong Here?

Apnea or ETT Dislodged YIKES! 50 40 30 20 10 50 40 10 20 30 Esophageal Intubation or Dislodged Tracheal Tube A sudden decrease in CO2 to zero or near zero with no waveform should alert the clinician to a catastrophic event such as esophageal intubation, dislodged ETT, ventilator disconnection, or obstructed ETT.

Capnography in ETT Placement The presence of a capnography waveform suggests endotracheal rather than esophageal intubation. 50 40 10 20 30 Capnography and ETT Placement Besides visualization of the ETT passing between the vocal cords, ETCO2 measurement has been found to be the most reliable method of confirming ETT position. Because CO2 is exhaled through the trachea and not usually from the esophagus, the presence of a capnometry waveform suggests endotracheal rather than esophageal intubation.

Absent CO2 05:41 Possible Causes: Treatment: Apnea Dislodged ETT Mark Event X 28 Apr 2009 15:44 A B TACHYCARDIA Absent CO2 Adult Non-Paced HR Pulse bpm 05:41 120 X ∆ bpm 50 Possible Causes: Apnea Dislodged ETT Disconnected tubing Treatment: BVM Advanced Airway Management Reconnect tubing II SpO2 % EtCO2 mmHg AwRR rpm 88 100 90 50 20 ∆ X ∆ CO2 60 Possible causes of absent carbon dioxide and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 30 Pleth Start NBP 12-Lead MENU

What does This Indicate? 50 40 10 20 30 What does this indicate?

Return of Spontaneous Circulation 50 40 10 20 30 This would indicate that the patient had a return of spontaneous circulation (ROSC). The carbon dioxide level was low and then immediately increased in one waveform.

You Need to Check a Pulse 50 40 10 20 30 Since this may be ROSC, you should immediately reassess your patient by checking for a pulse. The heart began beating again but since the vessels are dilated from the full arrest, the patient may not be able to generate a systolic blood pressure high enough to generate a palpated pulse. This would be PEA.

50 Sudden Increase in CO2 19:34 Possible Causes: Treatment: ROSC Mark Event X 28 Apr 2009 15:44 A B VTACH VTACH Adult Non-Paced 50 HR Pulse bpm 19:34 Possible Causes: ROSC Treatment: Check a pulse CPR Oxygen ACLS IV fluid Vasopressors Atropine 50 -?- X ∆ bpm 50 II SpO2 % EtCO2 mmHg AwRR rpm -?- 100 90 98 50 20 12 X ∆ ∆ CO2 100 Possible causes of a sudden increase in carbon dioxide and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 50 Pleth Start NBP 12-Lead MENU

Determination of Death If capnography is 10 mm Hg or less for a period of 20 min (as long as YOU are not hyperventilating them ) the patient has no chance of successful resuscitation. 50 40 10 20 30 Determination of Death. It has been observed that non-survivors had lower ETCO2 levels than survivors and no patient with ETCO2 <10 mmHg could be successfully resuscitated. You now have a reliable tool than establishes death. ETCO2 of 10 mm Hg or less at 20 minutes suggests death and the obvious conclusion is that CPR can reasonably be terminated in those patients.

Low CO2 Level 23:34 Possible Causes: Treatment: Over Ventilation Death Mark Event X 28 Apr 2009 15:44 A B ASYSTOLE ASYSTOLE Low CO2 Level Adult Non-Paced HR Pulse bpm 23:34 120 -?- X ∆ bpm 50 Possible Causes: Over Ventilation Death Treatment: CPR ACLS Termination of resuscitative efforts II SpO2 % EtCO2 mmHg AwRR rpm -?- 100 90 8 50 20 12 X ∆ ∆ CO2 30 Possible causes of a low carbon dioxide level and standard treatment options. You must follow your specific Medical Director’s protocols for treatment options. 15 Pleth Start NBP 12-Lead MENU

Clinical applications

Applications Intubated patients

Applications Intubated patients Intubation Verification of tube placement and monitoring ET placement during transport AND its dynamic. 5-20% of tubes are misplaced either at the time of intubation or during transfer.

PEA – an ECG with no endtidal CO2. Applications Intubated patients Cardiac arrest CO2 is a a measure of cardiac output. Because CO2 tracks cardiac output, capnography can show you how effective CPR is. It is the earliest sign of a returning circulation. It is even more effective than a pulse check PEA – an ECG with no endtidal CO2.

Applications Intubated patients Cardiac arrest and CPR

Non-intubated patients Applications Non-intubated patients

Chest pain: MI or not an MI Applications Non-intubated patients Chest pain: MI or not an MI Chest pain + tachyarrhythmia with normal capnogrpahy: Pt stable Chest pain + tachyarrhytmia with CO2 at 10mmHg is about to have a cardiac arrest on you

3 patients who are short of breath Applications 3 patients who are short of breath Who has asthma, who has COPD and who has CHF?

Bronchospasm/Airway Obstruction Applications Asthma 3 patients short of breath Waveform diagnostic of asthma/COPD. It indicates bronchospasm/airway obstruction Normal Bronchospasm/Airway Obstruction The reason for the shark fin shape is due to the increased dead space present

Asthma Applications The shape is a shark fin Width of the shape gets smaller as the patient gets worse

This patient needs ventilatory assistance Applications Asthma 3 patients short of breath Worsening asthma Note the narrow base and tachypnea and rising CO2 This patient needs ventilatory assistance

Response to treatment with Albuterol. Applications Asthma 3 patients short of breath Response to treatment with Albuterol. Indices return to normal. This patient has asthma: Diagnosis.

Applications COPD Hypoxic drive: rare phenomenon that affects only a very small percentage of patients who have the most chronic forms of pulmonary disease (COPD) When a patient has chronic hypoventilation, bicarbonate ions migrate into the cerebrospinal fluid; the primary stimulus to breathe comes from decreased levels of oxygen, not increased levels of carbon dioxide.

It is estimated that 5%-20% of COPD pt have a hypoxic drive Applications COPD Hypoxic Drive It is estimated that 5%-20% of COPD pt have a hypoxic drive Capnography will show the hypoxic drive in COPD "retainers." ETCO2 readings will steadily rise, alerting you to cut back on the oxygen before the patient becomes obtunded.

Shark fin shaped waveform appearance showing airway obstruction. Applications COPD 3 patients short of breath Shark fin shaped waveform appearance showing airway obstruction. Wide base ( asthma which was narrow) Elevated ETCO2 level 50mmHg Pt has COPD In contrast with asthma

Applications Monitoring capnography will allow you to maintain sufficient oxygen levels in the majority of tachypneic COPD pt without worry that they will hypo-ventilate.

The low waveform height shows a low CO2 level. Applications CHF 3 patients short of breath The low waveform height shows a low CO2 level. It is not shark fin in shape so not COPD/asthma. The low CO2 level indicates poor perfusion. This is a poor circulation that could go with CHF. The heart is not pumping as well as it should

The unconscious patient Applications The unconscious patient

Applications The unconscious patient Look for hypoventilation i.e. a high endtidal CO2 reading And a low respiratory rate

Applications The unconscious patient Sedation: Alcohol: a drunk with a normal CO2 is stable. A drunk who is hypoventilating is at risk Drug ingestion:

Applications Metabolic states

Applications Metabolic states With acidosis, the respiratory rate increases (e.g. diabetic ketoacidosis)

METABOLISM VENTILATION PERFUSION Physiology reminder If the circulation is failing, this “acid” cannot be transported to the lungs and the patient becomes more ill CO2 cannot be removed from the lungs as it cannot get there. Your only hope is to get the circulation working more effectively Metabolic acidosis

Applications Metabolic states: a tale of two patient both with diabetic ketoacidosis Who is the sickest of the two? Patient A Endtidal CO2 30mmHg SpO2 100 RR 30 Pulse 120 Patient B SpO2 99 RR 10

Applications Metabolic states A diabetic with a normal ETCO2 is not sick A diabetic with a low ETCO2 is a sick person. An ETCO2 of 6mmHg is bordering on a cardiac arrest

The head injured patient Applications The head injured patient

Applications The head injured patient Capnography can help avoid hyperventilation in intubated head injured patients. Evidence suggests hyperventilation leads to ischemia almost immediately

Optimize Ventilation Carbon dioxide affects cerebral blood flow (CBF) Hypercapnia causes cerebral vasodilation ↑ CBF ↑ICP Hypocapnia causes cerebral vasoconstricion ↓ CBF ↓ICP = ISCHEMIA Hypercapnia causes cerebral vasodilation, which causes increased CBF, and further elevates ICP. Hypocapnia causes cerebral vasoconstriction, reduce ICP. Resulting in hypoperfusion. MAP-ICP=CPP

Assist ventilation to maintain homeostasis A target value ETc02: Applications The head injured patient Hyperventilation decreases intracranial pressure by decreasing intracranial blood flow. The decreased cerebral blood flow may result in cerebral ischemia. Assist ventilation to maintain homeostasis A target value ETc02: 35 mmHg is recommended

Applications The head injured patient Traumatic brain injury requiring intubation: ETCO2 should be in the lo normal range 35-40 mm hg Signs of herniation( blown pupil or pupils or posturing) give“mild hyperventillation” 30-35 mm hg

Why is Pre-Hospital Capnography important

Hyperventilation Kills

Why is Pre-Hospital Capnography important We cannot do anything about those who are going to die whatever we do. However, we should be able to recognise and prevent those who would otherwise die needlessly.

Why is Pre-Hospital Capnography important Preventable needless deaths occur Immediately at the time of injury Hypoxia and Airway obstruction Later following their injury Hypercarbia (too much CO2 ) Acidaemia Cerebral vasodilation Hypoxia (not enough O2 ) Hypoxic encephalopathy Cardiac arrest

Why is Pre-Hospital Capnography important Time is important. For every minute of “no pre-hospital resuscitation”, the risk of dying increases by 4.3%

Why is Pre-Hospital Capnography important Patient Management Airway Breathing Circulation

Why is Pre-Hospital Capnography important Patient Management Airway Breathing Circulation Just because they are BREATHING, does NOT mean they are oxygenating and ventilating properly

Why is Pre-Hospital Capnography important Patient Management Airway Breathing Circulation and just because they have a CIRCULATION doesn’t mean the blood’s going to the right places or may even be going in the wrong direction.

Why is Pre-Hospital Capnography important Patient Management Airway Breathing Circulation Here is an broader concept

Why is Pre-Hospital Capnography important Scene Management Airway Breathing Circulation Ventilation Perfusion Capnography

Why is Pre-Hospital Capnography important Severe trauma management is not ABC Airway Ventilation Haemorrhage control Assisting the circulation Airway Ventilation Perfusion

Final Thought ! Beware……………….. The patient with the low CO2 and the low respiratory rate Could be about to die on you