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Direct venous pressure determinations by use of a new instrument
DIRECT
VENOUS PRESSURE DETERMINATIONS BY USE OF A NEW INSTRUMENT WILLIAM
A. SODEMAN, M.D.
NEW ORLEANS,LA.
I
N RECENT years a number of instruments have been introduced for the direct determination of venous pressure. Of these, that’ used for determination of tissue pressure has certain advantages, including the employment of a small needle which makes it possible to enter and record pressure in small veins. Recently, this instrument has been modified2 by the replacement of the U-tube water manometer with a bellows system. This change made the instrument more compact and portable. The present report records some experiences with a further modification* whereby an important and novel change in the bellows system not only eliminates the necessity for an additional recorder but also simplifies the readings and manipulations. THE INSTRUMENT The essential change in the instrument consists of a drastic reduction in the total dead air space to such a degree that one turn through 360 degrees of a screw compressing the bellows permits a range of pressure from 0 to 600 mm. of water. For this reason a dial securely fastened to the screw compressing the bellows may be calibrated through the 360 degrees in millimeters of water and so marked that immediate direct readings of the pressure may be made upon it. In essence, the instrument (Fig. 1) consists of a glass adapter approximately 10.0 cm. in length with a bore of 1.0 mm. Transverse scratch marks are made on the adapter at 1 .O mm. levels to aid in the location of movements of a meniscus. A metal frame, or holder, facilitates the attachment to one end of the adapter of a 24- to 27-gauge needle of the type commonly used for subcutaneous injections and, to the other end, of a rubber or plastic tubing which leads through a valve (Fig. 1, l’) to a bellows system in which the air pressure may be raised or lowered by turning the screw (Fig. 1, S) mentioned above, and the pressure in the system determined by reading directly the value on the previously calibrated dial. The valve, Ir, is so arranged that a turn in one direction opens the system to atmospheric pressure and a turn in the opposite direction closes this opening and creates a single air system opening to the atmosphere only through the attached needle. From the Department of Tropical Medicine and Public University of Louisiana. Received for publication Jan. 4, 1952. *The instrument was designed by Mr. G. Morgavi. Jr. 687
Health,
School
of Medicine,
The
Tulane
638
AMERICAN
HEART
JOURNAL
TECHNIQUE
A sterile glass adapter and needle are prepared. The valve, V, is closed, creating a single air system completely closed to the atmosphere down to the needle The adjustment screw, S, of the bellows is turned counterclockwise as opening. far as it will go. This increases the air space in the system to a maximum and shows on the dial a pressure reading of zero. The point of the needle is then placed, with sterile precautions, into a solution of sterile normal saline or 2 per cent sodium citrate solution and the screw of the bellows turned until a series of bubbles, produced by air being displaced from the closed system through the needle, emerge from the end of the needle. The screw, S, is then reversed, still keeping the needle point below the surface of the solution. The negative pressure thus produced by increasing the dead space in the bellows causes the solution When the meniscus to be drawn up into the needle and into the glass adapter.
Fig
L-Photograph
of instrument
prepared for use. Size of instrument adapter. which is 10 cm. in length.
may be judged
from
the
is about one-third of the way up the adapter, the valve, V, is opened and the needle removed from the solution. Atmospheric pressure is thus introduced above the meniscus and the screw, S, may then be turned to read zero (atmospheric) pressure. The valve, V, is then again closed. At this point the exact location of the meniscus must be noted by sighting it off against the transverse scratches on the adapter, for when the reading is finally made the meniscus must be brought back to this exact point or there will be an error in the determination. Then in the usual fashion the skin over the vein is prepared for venipuncture and the site of puncture brought to proper level for the determination. The instru-
SODEMAN
:
NEW
INSTRUMENT:
DIRECT
VENOUS
PRESSURE
DETERMINATIONS
689
ment itself need not be at this level, only the needle penetrating the vein. Upon insertion of the needle into the vein, the meniscus in the adapter will immediately and rather rapidly begin to rise as venous blood enters the needle. The screw, S, is then promptly turned clockwise, not only until the meniscus ceases to move but until there is no movement of the meniscus when it is brought to the exact location in the adapter that it occupied just before venipuncture was made. Fine adjustments are made at this precise point until the menisclrs is j&t at right angles to the wall of the adapter rather than having its usual U-shaped surface. At this point the pressure may be read directly from the dial and taken as the venous pressure. Since the meniscus is not in motion when the determination is made, the small bore of the needle does not interfere with the determination. The needle may then be removed from the vein. Because of the positive pressure in the closed system, the fluid, partially blood tinged, will escape from the end of the needle. The screw may be turned farther to facilitate emptying of the adapter and needle, both of which are then detached and resterilized for future use. By keeping on hand a number of such sterile needles and adapters, along with sterile saline or citrate solution, the physician may take repeated venous pressures on different subjects without the necessity for a sterilizer at the time. The absence of a water manometer makes the instrument easily portable and it may be stored, together with the sterile equipment, in a small space in a physician’s bag for use outside the hospital or office. Two final words about technique are necessary. First, the capillarity in the glass adapter is slightly under 2 cm. of water. This error is corrected by holding the level of the meniscus about 2 cm. above the vein during the determination. Second, the fluid in the adapter should never be permitted to go above the adapter into the tubing. If this occurs, the tubing must be heat-sterilized to prevent the possible transmission of serum hepatitis and other infections. After several manipulations, one becomes adept at increasing the pressure in the system as the vein is entered so that the meniscus does not go above the upper one-third of the adapter. RESULTS
The author has tested the apparatus against varying levels of water in an upright glass tube turned at right angles near its lower end and capped at the lower opening with a rubber diaphragm. By inserting the needle into the rubber diaphragm, the pressure may be taken just as the venous pressure is determined. In repeated tests over several months at pressure levels from 30 to 300 mm. of water, errors of 2 to 5 mm. of water were observed, and included the errors of the entire procedure, those of the instrument, readings of the meniscus, and all personal factors. In ten patients with various venous pressures, the technique has been compared with direct determinations made with a saline manometer and syringe. Results are shown in Table I. It may be seen that agreement was satisfactory and that differences to 16 mm. of water occurred. These errors, of course, represent those of both techniques as well as some possible slight variation in the relationship of the veins-to-heart level between determinations.
690
AMERICAN
TABLE
I.
HEART
JOURNAL
ESTIMATION OF VENOUS PRESSURE IN SAME PATIENTS BY PRESENT METHOD AND BY SALINE MANOMETER VEFOUS PRESSURE ANTECIJBITAL VEIN,
AT SAME TIME
(mm. H.20) HEART
LEVEL
SUB-
JECT
DIAGNOSIS
PRESENT METHOD
DIFFERENCE BETWEEN 1DETERMINATIONS
SALINE MANOMETER _-
Normal
W. T. J. D. J. M. B. H. R. H.
::::it Constrictive pericarditis Decompensated arteriosclerotic heart disease Decompensated arteriosclerotic heart disease Decompensated arteriosclerotic heart disease Decompensated rheumatic heart disease Aortic aneurysm Decompensated hypertensive heart disease
92 78
101 74
9 4
22 172
2;: 168
1: 4
140
148
160
160
134
140
176 198
170 192
-
-
DISCUSSION
The notable advantages of the instrument are the facility with which it may be used on small veins, the immediately apparent readings, and the simplicity of storing, transporting, and reusing the apparatus. There are certain minor disadvantages observed by the operator when he first uses it. These are easily overcome by a few trials of the instrument. The small dead air space, which is the heart of the instrument in that it permits complete readings on the partial single turn of a dial, makes it necessary that (1) the meniscus be brought back exactly to the starting position and “flattened out,” and (2) a deft maneuver, to stop the rise of the meniscus above the upper third of the adapter, be carried out to prevent possible contamination of the plastic tubing. However, after a few trials, the operator should have no difficulty. Obviously, too, the instrument may be adapted for measurement of other pressures
(tissue,
spinal
fluid). SUMMARY
The use of an apparatus for direct determination of venous pressure is described. Its advantages include: 1. The facility with which it may be used on small veins. 2. The easewith which it may be stored and transported. 3. The easewith which results are read. 4. Opportunity for frequent reuse in the absence of a sterilizer. Comparison of this technique with a standard technique for direct determination of venous pressure showed satisfactory results. REFERENCES
1. Burch, G. E., and Sodeman, W. A.: A Direct Method for the Determination of Venous Pressure; Relationship of Tissue Pressure to Venous Pressure, J. Clin. Investigation 18:31, 1939. 2. Burch, G. E., and Winsor, T.: The Phlebomanometer: A New Apparatus for Direct Measurement of Venous Pressure in Large and Small Veins, J. A. M. A. 123:91, 1943.
VENOUS PRESSURE DETERMINATIONS BY USE OF A NEW INSTRUMENT WILLIAM
A. SODEMAN, M.D.
NEW ORLEANS,LA.
I
N RECENT years a number of instruments have been introduced for the direct determination of venous pressure. Of these, that’ used for determination of tissue pressure has certain advantages, including the employment of a small needle which makes it possible to enter and record pressure in small veins. Recently, this instrument has been modified2 by the replacement of the U-tube water manometer with a bellows system. This change made the instrument more compact and portable. The present report records some experiences with a further modification* whereby an important and novel change in the bellows system not only eliminates the necessity for an additional recorder but also simplifies the readings and manipulations. THE INSTRUMENT The essential change in the instrument consists of a drastic reduction in the total dead air space to such a degree that one turn through 360 degrees of a screw compressing the bellows permits a range of pressure from 0 to 600 mm. of water. For this reason a dial securely fastened to the screw compressing the bellows may be calibrated through the 360 degrees in millimeters of water and so marked that immediate direct readings of the pressure may be made upon it. In essence, the instrument (Fig. 1) consists of a glass adapter approximately 10.0 cm. in length with a bore of 1.0 mm. Transverse scratch marks are made on the adapter at 1 .O mm. levels to aid in the location of movements of a meniscus. A metal frame, or holder, facilitates the attachment to one end of the adapter of a 24- to 27-gauge needle of the type commonly used for subcutaneous injections and, to the other end, of a rubber or plastic tubing which leads through a valve (Fig. 1, l’) to a bellows system in which the air pressure may be raised or lowered by turning the screw (Fig. 1, S) mentioned above, and the pressure in the system determined by reading directly the value on the previously calibrated dial. The valve, Ir, is so arranged that a turn in one direction opens the system to atmospheric pressure and a turn in the opposite direction closes this opening and creates a single air system opening to the atmosphere only through the attached needle. From the Department of Tropical Medicine and Public University of Louisiana. Received for publication Jan. 4, 1952. *The instrument was designed by Mr. G. Morgavi. Jr. 687
Health,
School
of Medicine,
The
Tulane
638
AMERICAN
HEART
JOURNAL
TECHNIQUE
A sterile glass adapter and needle are prepared. The valve, V, is closed, creating a single air system completely closed to the atmosphere down to the needle The adjustment screw, S, of the bellows is turned counterclockwise as opening. far as it will go. This increases the air space in the system to a maximum and shows on the dial a pressure reading of zero. The point of the needle is then placed, with sterile precautions, into a solution of sterile normal saline or 2 per cent sodium citrate solution and the screw of the bellows turned until a series of bubbles, produced by air being displaced from the closed system through the needle, emerge from the end of the needle. The screw, S, is then reversed, still keeping the needle point below the surface of the solution. The negative pressure thus produced by increasing the dead space in the bellows causes the solution When the meniscus to be drawn up into the needle and into the glass adapter.
Fig
L-Photograph
of instrument
prepared for use. Size of instrument adapter. which is 10 cm. in length.
may be judged
from
the
is about one-third of the way up the adapter, the valve, V, is opened and the needle removed from the solution. Atmospheric pressure is thus introduced above the meniscus and the screw, S, may then be turned to read zero (atmospheric) pressure. The valve, V, is then again closed. At this point the exact location of the meniscus must be noted by sighting it off against the transverse scratches on the adapter, for when the reading is finally made the meniscus must be brought back to this exact point or there will be an error in the determination. Then in the usual fashion the skin over the vein is prepared for venipuncture and the site of puncture brought to proper level for the determination. The instru-
SODEMAN
:
NEW
INSTRUMENT:
DIRECT
VENOUS
PRESSURE
DETERMINATIONS
689
ment itself need not be at this level, only the needle penetrating the vein. Upon insertion of the needle into the vein, the meniscus in the adapter will immediately and rather rapidly begin to rise as venous blood enters the needle. The screw, S, is then promptly turned clockwise, not only until the meniscus ceases to move but until there is no movement of the meniscus when it is brought to the exact location in the adapter that it occupied just before venipuncture was made. Fine adjustments are made at this precise point until the menisclrs is j&t at right angles to the wall of the adapter rather than having its usual U-shaped surface. At this point the pressure may be read directly from the dial and taken as the venous pressure. Since the meniscus is not in motion when the determination is made, the small bore of the needle does not interfere with the determination. The needle may then be removed from the vein. Because of the positive pressure in the closed system, the fluid, partially blood tinged, will escape from the end of the needle. The screw may be turned farther to facilitate emptying of the adapter and needle, both of which are then detached and resterilized for future use. By keeping on hand a number of such sterile needles and adapters, along with sterile saline or citrate solution, the physician may take repeated venous pressures on different subjects without the necessity for a sterilizer at the time. The absence of a water manometer makes the instrument easily portable and it may be stored, together with the sterile equipment, in a small space in a physician’s bag for use outside the hospital or office. Two final words about technique are necessary. First, the capillarity in the glass adapter is slightly under 2 cm. of water. This error is corrected by holding the level of the meniscus about 2 cm. above the vein during the determination. Second, the fluid in the adapter should never be permitted to go above the adapter into the tubing. If this occurs, the tubing must be heat-sterilized to prevent the possible transmission of serum hepatitis and other infections. After several manipulations, one becomes adept at increasing the pressure in the system as the vein is entered so that the meniscus does not go above the upper one-third of the adapter. RESULTS
The author has tested the apparatus against varying levels of water in an upright glass tube turned at right angles near its lower end and capped at the lower opening with a rubber diaphragm. By inserting the needle into the rubber diaphragm, the pressure may be taken just as the venous pressure is determined. In repeated tests over several months at pressure levels from 30 to 300 mm. of water, errors of 2 to 5 mm. of water were observed, and included the errors of the entire procedure, those of the instrument, readings of the meniscus, and all personal factors. In ten patients with various venous pressures, the technique has been compared with direct determinations made with a saline manometer and syringe. Results are shown in Table I. It may be seen that agreement was satisfactory and that differences to 16 mm. of water occurred. These errors, of course, represent those of both techniques as well as some possible slight variation in the relationship of the veins-to-heart level between determinations.
690
AMERICAN
TABLE
I.
HEART
JOURNAL
ESTIMATION OF VENOUS PRESSURE IN SAME PATIENTS BY PRESENT METHOD AND BY SALINE MANOMETER VEFOUS PRESSURE ANTECIJBITAL VEIN,
AT SAME TIME
(mm. H.20) HEART
LEVEL
SUB-
JECT
DIAGNOSIS
PRESENT METHOD
DIFFERENCE BETWEEN 1DETERMINATIONS
SALINE MANOMETER _-
Normal
W. T. J. D. J. M. B. H. R. H.
::::it Constrictive pericarditis Decompensated arteriosclerotic heart disease Decompensated arteriosclerotic heart disease Decompensated arteriosclerotic heart disease Decompensated rheumatic heart disease Aortic aneurysm Decompensated hypertensive heart disease
92 78
101 74
9 4
22 172
2;: 168
1: 4
140
148
160
160
134
140
176 198
170 192
-
-
DISCUSSION
The notable advantages of the instrument are the facility with which it may be used on small veins, the immediately apparent readings, and the simplicity of storing, transporting, and reusing the apparatus. There are certain minor disadvantages observed by the operator when he first uses it. These are easily overcome by a few trials of the instrument. The small dead air space, which is the heart of the instrument in that it permits complete readings on the partial single turn of a dial, makes it necessary that (1) the meniscus be brought back exactly to the starting position and “flattened out,” and (2) a deft maneuver, to stop the rise of the meniscus above the upper third of the adapter, be carried out to prevent possible contamination of the plastic tubing. However, after a few trials, the operator should have no difficulty. Obviously, too, the instrument may be adapted for measurement of other pressures
(tissue,
spinal
fluid). SUMMARY
The use of an apparatus for direct determination of venous pressure is described. Its advantages include: 1. The facility with which it may be used on small veins. 2. The easewith which it may be stored and transported. 3. The easewith which results are read. 4. Opportunity for frequent reuse in the absence of a sterilizer. Comparison of this technique with a standard technique for direct determination of venous pressure showed satisfactory results. REFERENCES
1. Burch, G. E., and Sodeman, W. A.: A Direct Method for the Determination of Venous Pressure; Relationship of Tissue Pressure to Venous Pressure, J. Clin. Investigation 18:31, 1939. 2. Burch, G. E., and Winsor, T.: The Phlebomanometer: A New Apparatus for Direct Measurement of Venous Pressure in Large and Small Veins, J. A. M. A. 123:91, 1943.