A STUDY ON THE USE OF CAPNOMETRY IN ACUTE DYSPNEIC PATIENT IN EMERGENCY DEPARTMENT

HOSPITAL UNIVERSITI SAINS MALAYSIA

12TH. INTERNATIONAL CONFERENCE ON EMERGENCY MEDICINESAN FRANCISCO, USA

3RD - 6TH APRIL 2008

AF Mamat (MD,MMed)1, R Ahmad2 (MD, Mmed)

Nik HNA Rahman3 (MBChB, MMed)

(Emergency Physicians)

1Accident & Emergency Department, Hospital Kuala Lumpur2Lecturer in Emergency Medicine, Hospital Universiti Sains Malaysia

3 Head of Department of Emergency Medicine, Hospital Universiti Sains MalaysiaHospital Universiti Sains Malaysia, Kubang Kerian, 16150, Malaysia.

Tel: 00609-766 3000, Fax: 00609-765 3370Email: nhliza@hotmail.com

INTRODUCTIONINTRODUCTION

After pain and fatigue,dyspnea is the third most common presenting symptom in internal medicine (Mahler et al., 1996).

It is important to perform a thorough examination, including objective as well as subjective measures.

Assessment of cardiopulmonary status is a must in every patient presented with dyspnea.

Monitoring and evaluation require a device that can provide information regarding the respiratory, cardiovascular and also metabolic status of patient.

INTRODUCTIONINTRODUCTION

Traditionally the pulse oxymetry and arterial blood gases is widely used to evaluate respiratory status of dyspneic patients.

But each of them has few significant disadvantages.

So in this study we were looking for an alternative method of monitoring acutely dyspnoeic patient namely capnometry.

Capnography Recording of expired (end tidal) carbon dioxide (ETCO2) concentrations plotted over time

Use to confirm and verify endotracheal tube placement, monitor ventilatory status of respiratory impaired patients, monitor ventilation of patients during sedation/analgesia, evaluate ventilator settings and circuit integrity, assess effectiveness of cardio-pulmonary resuscitation, and for

early detection of changes in airway resistance

Yaron M, Padyk P, Hutsinpiller M, Cairns CB. (1996). Utility of Expiratory Capnogram in the Assessment of Bronchospasm. Ann Emerg Med 1996; 28: 403-407

INTRODUCTIONINTRODUCTION1

INTRODUCTIONINTRODUCTION In recent years ,capnometry has emerged as a useful measure of carbon dioxide tension in intubated patients.

Capnometry provides clinicians with a noninvasive measure of several dynamic system in the body: systemic metabolism, the circulatory system (cardiac output ) and blood flow to the lung ,and the ventilatory system.

The difference between PaCO2 and ETCO2 has been shown to be only 1-2 mmHg in healthy subjects with normal lung and uncompromised pulmonary functions.

However the utility and accuracy of portable capnometers in non-intubated patient has not been fully examined.

INTRODUCTIONINTRODUCTION Patients arriving in the emergency department (ED) with acute dyspnea need rapid and reliable evaluation of their respiratory status.

Microstream (sidestream) nasal prong ETCO2 might be a non-invasive, rapid, and reliable predictor of arterial PaCO2 in non-intubated patients in respiratory distress.

Determination are rapid , inexpensive ,and noninvasive and may obviate the need for arterial blood gasses in selected groups of patients .

STUDY OBJECTIVESSTUDY OBJECTIVES

To determine correlation between ETCO2 and PaCO2 in non-intubated acute breathlessness patients.

To evaluate the correlation between ETCO2 and PaCO2 in certain acid base imbalance conditions

METHODOLOGYMETHODOLOGY A cross sectional study on acute breathlessness patients presented to Emergency Department for a period of 6 months.

The study was conducted in The Emergency Department of Hospital University Sains Malaysia (HUSM) with ethical committee approval.

Partial requirement for Master degree in Emergency Medicine.

Written & verbal (for distress/confused patient) informed consent.

METHODOLOGYMETHODOLOGYINCLUSION CRITERIA

1. Adult patients.2. Conscious, alert and well orientated patients.3. Non-intubated patient .

4. Presented with acute dyspnea .EXCLUSION CRITERIA

1. Pediatric patients.2. Patient that needed high concentration of oxygen therapy (Spo2<91% ).3. Intubated patient .4. Reduced level of consciousness (GCS <15) or unconscious patient .5. Patient with shock systolic Blood pressure <90 mmHg or diasolic<60 mmHg.6. Patients who did not require blood gas analysis

METHODOLOGYMETHODOLOGY

Patients follow the dept. protocol for triage and registration

All patients with a chief complaint of shortness of breath with other inclusion criteria would be consented.

Treatment zones according to triage findings.

Doctor and nurses performed routine investigations.

METHODOLOGYMETHODOLOGY Adult duo-port oral/nasal oxygen (O2) and CO2 sampling canulla (micostream Capnoline ) was placed in the nostrils and over the mouth.

The nasal prong was attached to Datascope® monitor combined microstream ETCO2 analyser and pulse oxymeter .

3 ETCO2 readings were recorded over duration of 3 minutes.

Arterial blood gas was taken & analyzed using Radiometer® ABL 700 series - available in the ED .

All other data related to shortness of breath was recorded (diagnosis, type of acid base imbalance)

METHODOLOGYMETHODOLOGY

METHODOLOGYMETHODOLOGY Estimation of sample size was calculated using PS software using Regression 1 –based on the study done by Christopher W Barton: n=150 (after 10% drop out) BUT this study had recruited 165 patients.

Patients were grouped as having a primary acidosis ,alkalosis or normal using acid base normogram or as hypocapnic if PaCO2 was less than 40 mmHg and hypercapneic if PaCO2 was more than 40 .

Patient was also grouped into pulmonary and non-pulmonary pathology based on diagnosis from EDHUSM .

Correlation between PaCO2 and ETCO2 was analysed using bivariate pearson’s correlation for all variables .

All the parameters were entered into the study proforma analysed using SPSS 12.0 licensed to HUSM .

RESULTS

0 10 20 30 40

10-19

20-29

30-39

40-49

50-59

60-69

70-79

80-90

Age grou

p (years)

Percentage

mean age of 54.19 and SD of 17.38 years

There were 100 males (66.7%) and 50 females (33.3%) in this study

0 20 40 60 80 100

Hypertension

Heart disease

Asthma/COAD

Diabetes mellitus

None

Typ

es of prem

orbid

cond

ition

Percentage

0

1020

30

4050

60

7080

90

Percentage

Red Yellow Green(Triage Category)

RESULTS

Other investigations done on patients

Investigations patients

(n)

Percentage (%)

Electrocardiogram

(ECG)

148 98.7

Blood tests 135 90

Chest radiograph (CXR)

146 97

Abdominal Ultrasound

18 12

Echocardiography

(ECHO)

58 39

Abdominal Radiograph (AXR)

13 8.7

Urine analysis 34 23

Treatment and therapeutic

interventions

Patients

(n)

Percentage

(%)

Oxygen(O2) 150 100

Intravenous lines/drips 150 100

Urinary catheter 89 59.3

Iv isoket 48 32

Sedative drugs 54 24.4

Diuretic drugs 62 41.3

Inotrope drugs 28 12.7

insulin 10 6.7

Steroids 27 18

Bronchodilator drugs 67 44.7

Central Venous line 24 16

Painkiller drugs 12 8

RESULTS

RESULTS

Causes of Dyspnoea Number of patients

Percentage (%)

Acute Pulmonary edema 20 13.3

Asthma 19 12.7

Acute Coronary Syndrome 38 25.3

Pneumonia 21 14

Chest trauma 6 4

Cerebrovascular accident 16 10.7

Sepsis 9 6

Diabetic ketoacidosis 4 2.7

Epilepsy 2 1.3

Hematology disorder 4 2.7

Poisoning 1 0.7

Functional (hyperventilation,anxiety) 10 6.7

Total 150 100

Diagnosis or etiology of dyspnoea in study population

RESULTS testsMetabolic

disturbances

N PCO2 ETCO2 Perason correlation

P r 2

All 150 34.3(11.4) 29.9(8.4) 0.716 0.000 0.512

Acidotic 25 40.6(21.8) 29.5(13.4) -.248 0.02 0.062

Alkalosis 28 30.2(7) 27.9(6.3) 0.171 0.037 0.029

Hypocapnia 118 29.9(5.4) 28.1(6.2) 0.738 0.000 0.544

Hypercapnia 32 50.3(13) 36.8(11.5) -.738 0.000 0.544

Pulmonary 43 40.3(16.6) 31.0(10.3) -.336 0.000 0.113

Nonpulmonary 107 31.8(7.3) 29.5(7.5) 0.336 0.000 0.113

Temperature

(febrile)

29 32.6(11.4) 30.4(6.95) 0.074 0.370 0.005

significance level of p<0.05

DISCUSSIONDISCUSSION Cardiorespiratory disease is the leading cause of death & the second cause of admission to the hospital in Malaysia

Breathlessness is probably the second most common presentation in the ED after acute pain.

Commonly the sensation of breathlessness is related to some extent to derangement of respiratory, cardiovascular & metabolic status. (80% is related to the cardiorespiratory conditions in this study)

Hence we need a method of monitoring that could assess respiratory or cardiovascular or metabolic status

DISCUSSIONDISCUSSION

Commonly the breathing difficulty is associated with altered PaCO2 (hyper or hypocapnia)- all patients in the study (78% hypo & 22% hyper)

We have attempted to use capnometry (ETCO2) to find the correlation between the ETCO2 reading & PaCO2

Overall there is a strong correlation between the PaCO2 & the ETCO2 as we hypothesised

Interestingly there is a stronger correlation between the ETCO2 & the hypocapnic state in which we postulated that the hypercapnic state is usually associated with parenchymal lung disease which interferes the capnometry function (gas exchange)

DISCUSSIONDISCUSSION Similary the ETCO2 showed a more positive correlation with non-pulmonary disease which we also postulated that the pulmonary parenchymal disease interferes with capnometry function

We also attempted to correlate the acid base status with the ETCO2

Very interestingly the acidotic state (respiratory & metabolic) showed negative correlation with ETCO2 compared to the alkalotic state.

Metabolic acidosis state i.e DKA results in hyperventilation state and hence hypocapnic condition

CONCLUSIONCONCLUSION

There is strong correlation between ETCO2 and PaCO2 in non intubated acute breathlessness patient

This study shows that ETCO2 can be used to predict PaCO2 level especially in the case of alkalotic and hypocapnic states

However the usage of ETCO2 to predict PaCO2 should be done with caution especially in cases that involve in pulmonary disorder

We could only mention that ETCO2 is applicable & has a potential as a form of non invasive cardiopulmonary monitoring in non intubated acute breathlessness patient

REFERENCESBarton C.W & Wang ESJ. (1994). Correlation of End Tidal CO2 measurements to arterial PaCO2 in non intubated patients. Annals of Emergency Medicine 23, 145

Chan KL, Chan MT & Gin T (2003). Mainstream vs. sidestream capnometry for prediction of arterial carbon dioxide tension during supine craniotomy. Anaesthesia 58, 149-155

Ferrin MS & Tino G (1997). Acute dyspnea. AACN Clin Issues 8, 398-410

G scano & Ambrosian N (2002). Pathophysiology of dyspnea. Lung 180

Ingram RH (1987). Effects of airway versus arterial CO2 changes on lung mechanics. J Appl Physiol, 603-608

Raemer D Francis D & Philip J (1983). Variation in PCO2 between arterial blood and peak expired gas during anaesthesia. Anaesth Analg 62, 1065-1069

Sanders AB (1989). Capnometry in emergency medicine. Ann Emerg Med 18, 1287-1290