Heart Rate Response to Atropine Doses Less Than 0.1mg IV to Anesthetized Infants
| Status: | Completed |
|---|---|
| Conditions: | Cardiology |
| Therapuetic Areas: | Cardiology / Vascular Diseases |
| Healthy: | No |
| Age Range: | Any - 2 |
| Updated: | 10/14/2017 |
| Start Date: | February 2013 |
| End Date: | July 2013 |
Do Small Doses of Atropine Cause Bradycardia in Young Children
An infants heart rate is very important because it ensures that blood is pumped to all organs
in the body. Heart rate may decrease during anesthesia and surgery, and this is why the
anesthesiologist will often give a medication to prevent this from happening. The most common
drug for this purpose is called atropine. The dose of most drugs given to babies is based
upon the baby's weight, but some believe that the dose of atropine should not be less than
0.1mg. However there is no evidence to support this minimum dose. A larger dose of atropine
may cause a very fast heart rate instead. Anesthesiologists routinely dose the atropine based
upon the baby's weight without regard for a minimum dose.
The purpose of the present study is to measure the heart rate after doses of atropine in
neonates and infants who receive less than 0.1 mg.
in the body. Heart rate may decrease during anesthesia and surgery, and this is why the
anesthesiologist will often give a medication to prevent this from happening. The most common
drug for this purpose is called atropine. The dose of most drugs given to babies is based
upon the baby's weight, but some believe that the dose of atropine should not be less than
0.1mg. However there is no evidence to support this minimum dose. A larger dose of atropine
may cause a very fast heart rate instead. Anesthesiologists routinely dose the atropine based
upon the baby's weight without regard for a minimum dose.
The purpose of the present study is to measure the heart rate after doses of atropine in
neonates and infants who receive less than 0.1 mg.
60 neonates and infants, ASA physical status I and II, undergoing elective surgical
procedures will be enrolled after signed informed parental consent.
All children will be fasted according to institutional guidelines and unpremedicated. After
arriving in the operating room, EKG, pulse oximeter and blood pressure monitors will be
applied (Datex-Ohmeda Aisys).
Anesthesia will be induced with 66% N2O in O2 and 8% sevoflurane. Respiration will be
supported by a properly sized face mask through which he/she is allowed to breath
spontaneously. Respiration will continue spontaneously through a facemask at 2 MAC
sevoflurane in 66% N2O.
All children will be positioned supine, warmed with a forced air warmer and given 20 ml/kg IV
balanced salt solution over 30 minutes after the IV has been established. The end-tidal pCO2
will maintained 35-45 mmHg and oxygen saturation >96%.
After a 22 or 24G IV cannula is inserted, 0.005 mg/kg atropine will be administered
intravenously over 5 seconds through a fast-flowing IV and followed by 5 ml of normal saline
to flush it in through the IV deadspace. The study (ECG recording) period will extend from 30
seconds before atropine administration to 5 minutes after injection. During this time the
heart rate and rhythm (through lead II) will be monitored and recorded continuously using an
analogue interface system. EKG will be recorded on paper continuously for the 330 seconds of
the study.
The recording will be analyzed for the heart rate (based on the R-R interval) and arrhythmias
by a physician blinded to the study. Blinding means that the individual is unaware of the
hypothesis of the study and what medication was administered to account for any changes in
heart rate. Bradycardia is defined as a 20% reduction from baseline heart rate while
tachycardia is a heart rate > 160 beats/minute(6). Any heart rate < 100/minute will be
considered a bradycardia in this age group. Arrhythmia is any disorder of rhythm or rate
observed. These will be summarized for each child.
All heart rate responses will be recorded and reviewed. The time to record the heart rate
after atropine, which will occur before surgery, will add less than 5 additional minutes to
the anesthetic since it will overlap the time taken for other surgical preparatory events.
The blood pressure will be monitored non-invasively immediately before receiving atropine and
at one and five minutes after it is given.
The primary outcome is the incidence of bradycardia during the first 5 minutes after atropine
will be determined by reviewing the electrocardiogram. All continuous data will be reported
as means +/- standard deviation.
procedures will be enrolled after signed informed parental consent.
All children will be fasted according to institutional guidelines and unpremedicated. After
arriving in the operating room, EKG, pulse oximeter and blood pressure monitors will be
applied (Datex-Ohmeda Aisys).
Anesthesia will be induced with 66% N2O in O2 and 8% sevoflurane. Respiration will be
supported by a properly sized face mask through which he/she is allowed to breath
spontaneously. Respiration will continue spontaneously through a facemask at 2 MAC
sevoflurane in 66% N2O.
All children will be positioned supine, warmed with a forced air warmer and given 20 ml/kg IV
balanced salt solution over 30 minutes after the IV has been established. The end-tidal pCO2
will maintained 35-45 mmHg and oxygen saturation >96%.
After a 22 or 24G IV cannula is inserted, 0.005 mg/kg atropine will be administered
intravenously over 5 seconds through a fast-flowing IV and followed by 5 ml of normal saline
to flush it in through the IV deadspace. The study (ECG recording) period will extend from 30
seconds before atropine administration to 5 minutes after injection. During this time the
heart rate and rhythm (through lead II) will be monitored and recorded continuously using an
analogue interface system. EKG will be recorded on paper continuously for the 330 seconds of
the study.
The recording will be analyzed for the heart rate (based on the R-R interval) and arrhythmias
by a physician blinded to the study. Blinding means that the individual is unaware of the
hypothesis of the study and what medication was administered to account for any changes in
heart rate. Bradycardia is defined as a 20% reduction from baseline heart rate while
tachycardia is a heart rate > 160 beats/minute(6). Any heart rate < 100/minute will be
considered a bradycardia in this age group. Arrhythmia is any disorder of rhythm or rate
observed. These will be summarized for each child.
All heart rate responses will be recorded and reviewed. The time to record the heart rate
after atropine, which will occur before surgery, will add less than 5 additional minutes to
the anesthetic since it will overlap the time taken for other surgical preparatory events.
The blood pressure will be monitored non-invasively immediately before receiving atropine and
at one and five minutes after it is given.
The primary outcome is the incidence of bradycardia during the first 5 minutes after atropine
will be determined by reviewing the electrocardiogram. All continuous data will be reported
as means +/- standard deviation.
Inclusion Criteria:
1. Age : 0-2 years old
2. Weight : less than the 95th percentile for age and height ( no more than 15kg )
3. ASA classification : I-II
4. Meets the hospital and department of anesthesiology guidelines with respect to
peri-operative care
Exclusion Criteria:
1. History of heart disease
2. Any condition predisposing to arrhythmia
3. Any medication known to influence the heart rate
4. Child taking anti-cholinergic medication routinely
5. The use of succinylcholine anticipated (will cause bradycardia)
6. Rapid sequence intubation is required (due to aspiration risk)
7. Known difficult airway (may be difficult to bag mask ventilate)
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