`6l:539-341, I984
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`CLINICAL RF.I’OR'I'S
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`339
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`Differences in Pulmonary Artery Wedge Pressures Obtained
`by Balloon Inflation versus impaction Techniques
`
`ROGER L. ROYSTER, M.D.,* _]. CARSON_]OHNSON, M.D..T DONALD S. PROUGH, M.D.,j:
`WILLIAM E. _]oHNs'roN, M.D.,1 WILSON C. BEAMER, M.D.§
`
`Pulmonary artery wedge pressures (PAWPs) fitst were
`obtained by advancing non-balloon-tipped catheters under
`fluoroscopic guidance into an “impacted wedge" (IW)
`position and more recently by advancing flow-directed.
`balloon-tipped catheters into a balloon wedge (BW) po-
`sition. Deflated balloon-tipped catlteters may migrate into
`an IW position, which protttptly should be recognized
`and the catheter repositioned until a pulmonary artery
`tracing is seen and :1 BW pressure once again can be
`obtained. We noticed in two patients, one with catheter
`migration and the other after cardiac catheterization, a
`difference between lW and BW pressures and wave forms.
`These observations prompted a prospective clinical study
`to characterize more clearly these differences.
`
`REPORT or CASES
`
`Pulirwl l: A 65-year-old man with fever. bilateral pulmonary infil-
`mttes. cardiac murmur. and suspected infective endocarditis of the
`mitral valve \vas adtnitted to tlte lCU. A 7 French balloon-tipped flow-
`directetl pultnonary artery catheter was passed into :1 BW position.
`docutnettting :t mean pressure of I2 mmHg and A and V wave am-
`plitudes above the diastolic baseline of 2 and 4 tnml-lg. respectively.
`llectuse respimtory insufficiency progressed, his trachea was intubated,
`and he was ventilated with intermittent mandatory ventilation and
`positive end expiratory pressure. The pulmonary artery catheter was
`removed. since hemodynamic compromise had not been documented.
`The patient improved rapidly. but attempts to wean him front the
`ventilator resulted in severe hypoxemia. A pulmonary :trtery catheter
`again was inserted, and similar BW pressures were obtained.
`Because the patient appeared to have clinically significant mitral
`regurgitation. cardiac catlteterimtion was performed. The right heart
`cltantbcrs were catheterlved with a No. 7 Lehman (non-balloon-tipped)
`catheter and pressures were recorded. A mean 1W pressure of 24
`ttnnHg. a post-A-wave presure of 13 mmHg. and a peak V-wave
`amplitude of 44 mmHg were demonstrated. A left ventriculogram
`confirmed signifiatnt mitral regurgitation. After the patient had been
`returned to the ICU, 2: BW pressure tracing still did not demonstrate
`
`* Asistant l’rol‘essor of /tnestltesia. Associate itt Cardiology.
`‘l’ lCU Research Fellow.
`:1: Assistant Professor of Anesthesia.
`§ instructor in Anestltesia.
`Received front the Deparunent of Ant-stltesizt. Bowman Gray School
`ol'Medicinc of Wake Forest University. Winston-Salem. North Carolina
`27103. Accepted for l)ulJllCi|lloI1 February I4.
`l984. Presented in
`part at the Ninth Annual Gttlf/Atlatttic Anesthesia Residents Cott-
`ference. Gaittesville. Florida. May I983.
`Address reprint requests to Dr. Royster.
`Key words: Eqttiptnent: catheters.
`llow-directed. Stvzttt-Gatttz”.
`Monitoring: pttlntonary artery wedge pressure.
`
`a large V-wave. so an IW pressure measurement was obtained; the
`tmcing was idctttiral to that obtained with the Lehman catheter.
`Pntipttl 2: A 56-year-old man had :1 7 French pulmonary artery
`catheter inserted for monitoring during an episode of acute respiratory
`failure. The bedside nursing personnel requested evaluation of the
`position of the catheter because they suspected that the catheter had
`migrated to an IW position. Blood obtained front the distal lunten of
`the catheter had a pH of7.6l , :1 PW, of IQ mmHg. and a P0, of 283
`ntml-lg. while systemic arterial blood had a pH of 7.48. a Pco, of 25
`mmHg. and a P0, of 151 mtnHg. A post A-wave pressure was 15
`mmHg. and A and V wave amplitudes were 5 mmHg and I5 mntHg,
`respectively.
`The catheter was withdrawn until a pulmonary artery tracing was
`obtained. Blood obtained front the distal lttmen at that time dem-
`
`onstrated a pH of7.-14, a Pm, of 3| mmHg. and a P0, of 28 mmHg.
`A BW pressure obtained with the catltcter in that position demonstrated
`a post A-wave pressure of 17 mmHg. and A and V wave amplitudes
`that both were only 3.5 mmHg.
`
`METHODS
`
`Sixty patients in the ICU who had pulmonary artery
`catheters inserted through a commercially available sterile
`shield qualified for our clinical study, which was approved
`by the Hospital Research Practices Committee. All ma-
`nipulations of the catheter were performed by members
`of the ICU physician staff. Systemic artery pressure and
`pulmonary artery pressure tracings or an electrocardio-
`gram (ECG) and pulmonary artery pressure tracings were
`recorded. The balloon was inflated and a BW wave form
`
`recorded. Then the balloon was deflated, and the catheter
`advanced into an IW position identified by the loss of
`the phasic pulmonary artery wave form and the presence
`of obvious A and V waves typical of a wedged wave form.
`Simultaneous arterial pressure or ECG and [W pressures
`again were recorded. The catheter then was withdrawn
`to the point in the pulmonary artery where inflation of
`the balloon with 1 to 1.5 ml air was necessary to obtain
`a BW pressure.
`All PAWPS were measured at end—expiration and re-
`corded. The catheter transducer system was not flushed
`once the comparison sequence was begun. The wedge
`position was documented by a shift of the peak pressure
`event in the wave form as compared with the peak event
`in the pulmonary artery wave form. The post A wave,
`peak V wave, and mean PAWPS were recorded elec-
`tronically, and differences between the BW and IW pres-
`sures were analyzed by a paired Student's I test for sig-
`nificance of!’ < 0.05.
`
`339
`
`PRAXAIR ET AL. 1013
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`
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`340
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`CLINICAL REl'0R'l‘S
`
`Aueslliuiulogy
`V til. N113. Sq: I98-I
`
`clamped BW and 1W wave forms, which made compar-
`isons impossible. Twelve of the 60 patients demonstrated
`obvious differences in wave form between the two
`
`PAWPs. The lW tracings demonstrated greater phasic
`changes in A and V wave amplitudes (fig. 1) and generally
`had higher pressures then the BW tracings (table 1).
`Among these 12 patients, eight had an IW V-wave am-
`plitude at least 5 mmHg greater than the BW V-wave
`amplitude (fig. 2). The differences in V-wave amplitude
`and post-A wave pressure obtained in the two catheter
`positions were significant (P < 0.05). The comparison of
`mean PAWPs yielded no statistically significant difference,
`which partially may be explained by the larger mean BW
`pressure (7 mmHg) in patient 1.
`
`DISCUSSION
`
`PAWP is an indirect measurement of left ventricular
`
`filling or left ventricular end-diastolic pressure. The ab-
`solute value and the wave form of the wedge pressure
`may be affected by a variety of factors, including the
`location of the catheter tip,‘ the intravascular volume,
`the natural resonant frequency and damping of the cath-
`eter-transducer system,“ and the compliance of the left
`ventricle, the left atrium, and the pulmonary artery.”
`Differences in wedge pressure wave forms obtained by
`balloon inflation and impaction techniques are relatively
`cotntnon but usually are clinically unimportant. However,
`the additional information obtained by using both tech-
`niques in certain critically ill patients may aid in diagnosis
`and treatment. Although there are recognized limitations
`to basing a definitive diagnosis of mitral regurgitation on
`the presence of V waves on a BW tracing,’ failure to
`demonstrate large V waves with bedside pulmonary artery
`catheterization in the patient I contributed to the delay
`in diagnosis of mitral regurgitation. Such a delay in the
`diagnosis of an acute hemodynamically compromising
`event may contribute to a fatal outcome.‘ Additionally,
`Moser and Spragg5 have suggested routine impaction
`wedging during catheter insertion, and Braunwald and
`C-orlin5 have shown this to be a safe procedure in a large
`series of patients.
`
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`FIG. I. Comparison of wedge pressure atml correlation with elec-
`lroutrdiogmm. A. Wedge pressure by lxilloun inllzttlotl (BW). 11. Wedge
`prcssurc by catlietcr impaction (IW). Pressures obtained a few minutes
`apart.
`
`RESU L'l'S
`
`In many patients. an lW pressure was not obtainable
`due to the limitation of catheter length available within
`the sterile shield. In addition, several patients had very
`
`'l‘Altl.l-1 l. impaction wr.m.r Balloon Wedge Pressure Measurements
`
`
`
`V-Wave Amplitude
`1W
`5W
`Mom PAWP
`
`26
`21
`
`‘W
`BW
`
`Post A-Wave Amplitude
`lW
`BW
`
`
`18
`19
`
`340
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`CLINICAL RLPOR is
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`341
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`0
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`characteristic of the inflated or overinflated balloon. The
`
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`inflating pattern of the balloon in human cadavers, as
`demonstrated radiographically with contrast media in-
`flation, varied with whether the balloon was in the mid
`or distal portion of the pulmonary artery.’ The larger
`cross-sectional area of the pulmonary vasculature distal
`to an inflated balloon may create a more compliant system
`than the smaller cross-sectional area of vessels distal to a
`catheter advanced to an impacted position. The latter,
`less compliant system might produce A and V waves of
`greater amplitude.
`In summary, there appear to be differences (20% of
`our patients) in BW and IW pressures that have not been
`described previously. Impacting the catheter with an un-
`inflated balloon may result in a better tracing of A and
`V wave forms, thus
`ivin additional information about
`8
`8
`left-sided cardiac events.
`
`Rt<.'t-‘lstu-;Nct-Ls
`
`4.
`
`l. Bell /\LL_|r. Haynes WF_]r. Sliimomura S. Dallas DP: Influence
`l‘~h---'
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`(l: 0|‘! pu Illoll lly W4. gt. |)|‘CS&IJl'(.’S
`IFL
`2. O'Quin R. Mariui_|_|: Pulmonary artery occlusion pressure: Clinical
`Pl‘Y5i°|°gl'- ""-'3‘5“"‘-"'“5'"-- '*“‘d lm-‘-‘lil-""il5“i°"' A'“ R“ Rc5l’l"
`_ Di‘ l28i3'9'325- l983_
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`3“ l'“‘-ills RM- H"“5°" RR» Yl" l'('P- B'""‘k°".l-A‘ I-'“‘“‘“‘°"5 °l
`pulmonary wedge V waves in diagnosing mitral regurgitation.
`Am J Cnrcliol 49:849-854. I982
`l-’rieclman /'\W. Stein
`I-’itl'al|s in bedside diagnosis of severe
`"C""’ ''''":‘'l rcg""g'f‘“'°"' (‘inst 78:43°'4‘.“’ [980
`5. Moser KM. bpiagg R6: Use ol the balloon-upped pulmonary
`artery catltetcr in pulmonaty disease. Ann Intern Med 98:53-
`53_ [933
`6. Braunwald E, Corlin R: Total population studied, procedures
`¢='"Pl°Y¢‘d- '~"‘d ii"-'id!="¢¢ °fC°"|Pli<3|l5°"5- C°°P°|“-"5"! 5WdY
`on Cardiac Catlieterilation. Edited by liraunwald E. Smm HJC.
`Circulation 37—38(Suppl):8—l6. I968
`l-Iardy_|-l".Morrissette M.'l'ai|lel'er_].Vauclair R:|’athopliysiology
`or.-..p..,m or u.._. P.,|...°.my -_..-.._.,y by P.,|...o..,,,y 3..-wry bat-
`loon-tipped catheters. Anestli Analg 62:925-930. l983
`
`7.
`
`5
`
`25
`15
`Balloon Peak V wave in mm Hg
`I-'I(:. 2. Comparison of impaction peak V waves with balloon peak
`V waves. Straight line equals line of identity. which sltotx-s that the
`impaction peak V waves were higher than balloon peak V waves.
`
`30
`
`perhaps the difl‘e1.em_.e in wedge pressure wave forms
`can be explained in part by variations in the diameter of
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`L 16 Pu momny ‘lnerxsystenl ‘H l’ e sue” where Bw ‘md
`lW pressure are obtained. Bell el 11!.‘ performed wedge
`pultnonary arteriograms to document the anatomy at the
`site of wedging and showed that the manner of catheter
`impaction in dmgrem areas (such as M a bifurcatiolm in
`d.'_ ed
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`vesse 5' 0' m tortuous Vesses "my
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`whether a phasic tracing or an unsatisfactory tracing is
`obtained. An additional factor may be some damping
`
`341