Effects of Different Intra-arterial Catheter Size on Frequency of Optimal Dynamic Response in Radial Arterial Waveform

Study Overview
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Brief Summary
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The aim of this study is to compare the effects of different intra-arterial catheter size on the frequency of optimal dynamic response in radial arterial waveform.

Official Title
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Effects of Different Intra-arterial Catheter Size on the Frequency of Optimal Dynamic Response in Radial Arterial Waveform

Conditions
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Catheters

Intervention / Treatment
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* Device: different intra-arterial catheter size


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patients who were scheduled for elective neurosurgery under general anesthesia patients with age of 20-79 and ASA class I-III patients who are needed to establish invasive arterial pressure monitoring Exclusion Criteria: patients who refuted to be involved in the study patients with age of <20 or >80 patients who had both arm saved patients who had a previous history of surgery on radial artery

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 79 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: 20 gauge<br> | Device: different intra-arterial catheter size<br>* in placebo group, patients were cannulated with 20 gauge intra-arterial catheter. In experiment groups, patients were cannulated with 22 gauge or 24 gauge intra-arterial catheter.<br>|
| Active Comparator: 22 gauge<br> | Device: different intra-arterial catheter size<br>* in placebo group, patients were cannulated with 20 gauge intra-arterial catheter. In experiment groups, patients were cannulated with 22 gauge or 24 gauge intra-arterial catheter.<br>|
| Active Comparator: 24 gauge<br> | Device: different intra-arterial catheter size<br>* in placebo group, patients were cannulated with 20 gauge intra-arterial catheter. In experiment groups, patients were cannulated with 22 gauge or 24 gauge intra-arterial catheter.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The frequency of adequately damped arterial waveform | The accuracy of arterial blood pressure waveform is depedent on damping coefficient (DC) and natural frequency (NF). The extent to which a monitoring system is damped is expressed by the DC, while the frequency of oscillation that a monitoring system resonates at is known as the NF. The NF and DC are required to be within certain rages for accurate blood pressure monitoring, and they can be affected by different arterial catheter size. Adequately damped arterial waveform can be defined as NF and DC being within certain ranges. For example, waveforms with DC of 0.5 at a NF of 15Hz can be regarded as adequately damped arterial waveform. However, if waveforms have DC of 0.1 at a NF of 15Hz, these can be regarded as not having optimal dynamic response. (There is a reference figure explaining these factors in detail in a previous article. Gardner RM: Direct blood pressure measurement--dynamic response requirements. Anesthesiology 1981; 54:227-3) | 1 minute after cannulation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The difference of mean blood pressure between invasive blood pressure and non-invasive blood pressure | At 1 minute after cannulating radial artery, we will obtain information about the mean blood pressure measured in both invasive blood pressure and non-invasive blood pressure. Invasive blood pressure will be measured from radial artery cannulation, and non-invasive blood pressure will be measured by blood pressure cuff at Rt. upper arm. Thereafter, the difference of mean blood pressure between two values will be used for data analysis. | 1 minute after cannulation |