Intraoperative Peripherally Inserted Central Venous Catheter Central Venous Pressure Monitoring in Abdominal Aortic Aneurysm Reconstruction Elisabeth C. McLemore, MD,1 Deron J. Tessier, MD,1 Mohamed Y. Rady, MD, PhD,2 Joel S. Larson, MD,2 Jeff T. Mueller, MD,3 William M. Stone, MD,4 Richard J. Fowl, MD,4 and Bhavesh M. Patel, MD,2 Scottsdale, Arizona,

Numerous studies have found no clinically significant benefit to the perioperative use of pulmonary artery catheters (PACs), and peripherally inserted central venous catheters (PICCs) have been reported to measure central venous pressure (CVP) accurately. The objective of this study was to determine whether the dynamic shifts in preload associated with elective reconstruction of abdominal aortic aneurysms (AAAs) are accurately reflected by CVP measurements from open-ended PICCs compared to CVP measurements from concomitant indwelling PACs. This is a retrospective review of prospectively collected data. PICCs and PACs were placed preoperatively in five patients undergoing elective AAA reconstruction. CVP measurements were recorded every 15 min during the operation. Bland-Altman statistical analysis was used to determine the degree of agreement in data collected by the two measurement devices. Seventythree paired measurements of CVP from concomitant indwelling PICCs and PACs obtained from five patients undergoing elective AAA reconstruction revealed PICC measurements to be higher than PAC measurements by 0.6 mm Hg (overall correlation coefficient 0.92). The difference between the two measurement devices was expected to be <3.4 mm Hg at least 95% of the time. The findings of this pilot study indicate that PICCs are an effective method for CVP monitoring in situations of dynamic systemic compliance and preload, such as those observed during elective AAA reconstruction.

INTRODUCTION The morbidity and mortality associated with elective operations to repair abdominal aortic aneurysms (AAAs) have declined over the past 30 1

Department of Surgery, Mayo Clinic Arizona, Scottsdale, AZ, USA. Department of Critical Care Medicine, Mayo Clinic Arizona, Scottsdale, AZ, USA. 3 Department of Anesthesiology, Mayo Clinic Arizona, Scottsdale, AZ, USA. 2

4

Division of Vascular Surgery, Mayo Clinic Arizona, Scottsdale, AZ, USA. Correspondence to: Bhavesh M. Patel, MD, Mayo Clinic Hospital, Critical Care Medicine, 5777 E. Mayo Blvd., Phoenix, AZ 85054, USA, E-mail: [email protected] Ann Vasc Surg 2006; 20: 577–581 DOI: 10.1007/s10016-006-9108-x Ó Annals of Vascular Surgery Inc. Published online: July 27, 2006

years.1 The increased use of pulmonary artery catheters (PACs) during this interval may have contributed to improved outcomes.2 However, several studies have demonstrated no clinically significant benefit with the use of PACs perioperatively.2-6 Indeed, Isaacson and colleagues6 showed that the central venous pressure (CVP) measurements derived from a centrally inserted central venous catheter (CICC) were as accurate as CVP measurements derived from PACs for monitoring patients undergoing vascular reconstruction for an AAA. More recently, open-ended, peripherally inserted central venous catheters (PICCs) have been reported to measure CVP accurately in stable patients in the intensive care unit (ICU).7 PICCs are an attractive alternative to CICCs for many reasons. PICCs can be placed without the risks associated 577

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Table I. Demographic and medical data of patients undergoing elective AAA reconstruction Patient

Sex

Age (years)

AAA (cm)

ASA

CEPOD grade

EBL (mL)

Comorbid condition(s)

1 2 3 4 5

M F F M M

83 66 84 70 75

5.1 5.0 5.5 5.8 5.5

2 2 2 2 3

1 1 1 1 1

1,000 1,500 450 700 700

CAD, HTN DM2, HL, HTN, OA HTN CAD, HL, HTN A-fib, CAD, HTN, COPD, CVD

A-fib, atrial fibrillation; CAD, coronary artery disease; EBL, estimated blood loss; COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; DM2, Type 2 diabetes mellitus; HL, hyperlipidemia; HTN, hypertension; OA, osteoarthritis.

with CICCs (e.g., pneumothorax, major hemorrhage, neck hematoma, or carotid puncture).8 PICCs also have a lower rate of bloodstream infection.8 In addition, PICCs can be left in place for the duration of the patientÕs hospitalization, thereby minimizing phlebotomy and peripheral intravenous placement and infiltration. In this study, we sought to determine whether intraoperative CVP measurements derived from PICCs correlated with CVP measurements derived from CICCs in patients undergoing dynamic changes in preload and systemic vascular compliance, as can be observed during AAA reconstruction.

METHODS A pilot retrospective review of data prospectively collected during a 6-month period was conducted for all patients undergoing elective open AAA reconstruction in which both a PICC and a CICC had been placed preoperatively. Prior to the initiation of this retrospective review, investigative approval was obtained from the Mayo Foundation Institutional Review Board. Using ultrasound guidance, trained nurses or respiratory therapists placed PICCs at the bedside. A double-lumen, open-ended Arrow PICC (18gauge or 20-gauge, 5-French, 55-cm-long polyurethane catheter; Arrow International, Reading, PA) was used in all patients. Open-ended PICC placement for CVP monitoring is a standard indication for PICC placement at our institution. Patient consent was waived by the institutional review board secondary to the nontherapeutic intervention and minimal risk nature of the study. To monitor CVP, the open-ended PICCs were coupled to a low-flow (3 mL/hr or 0.05 mL/min) pressure transfusion device. After the PICCs were inserted but before they were used, all catheter tip positions were confirmed by radiography to be at the junction of the superior vena cava and the right atrium. CICCs were placed by anesthesiologists at the bedside using the Seldinger technique. An Arrow

9-French, 10-cm-long polyurethane percutaneous sheath introducer kit and an Edwards 8-French, 110-cm-long, Swan-Ganz heparin-coated polyurethane catheter (Edwards Lifesciences, Irvine, CA) were used in all patients. CVP measurements from both the PICC and the CICC were recorded every 15 min from just before the induction of anesthesia until the completion of the operation. Bland-Altman statistical analysis was used to determine the extent of agreement between the PICC CVP measurement device and the gold standard PAC CVP measurement device. Patient demographics (age, sex, medical history, American Society of Anesthesiologists [ASA] physical status class, and Confidential Enquiry into Perioperative Deaths [CEPOD] scores) were abstracted from patientsÕ medical records.9,10 Data recorded during the operation included length of the operation in minutes, time required for aortic cross-clamping and unclamping, and any intraoperative complications. Other information abstracted from the medical records included length of the patientÕs ICU stay; length of hospital stay; indwelling catheter times for the PICC, CICC, and PAC; and any postoperative complications.

RESULTS Seventy-three paired CVP measurements from concomitant indwelling PICCs and CICCs were obtained from five patients undergoing elective AAA reconstruction. Individual patient demographic and operative data are listed in Table I. The duration of use of indwelling central lines and the length of stay in the ICU and the hospital overall are listed in Table II. Paired CVP measurements are plotted against operative time and the overall correlation coefficient of 0.92 (95% confidence interval [CI] 0.19-0.99) (Fig. 1). The agreement between CVP measurements from the two devices is summarized in Table III. On average, PICC measurements were slightly higher than PAC measurements. The overall difference, or bias, between the two measurement devices was

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Table II. Duration of indwelling central line catheterization and patient length of stay Patient

PICC (days)

CICC and PAC (hr)

Length of stay ICU (hr) Hospital (days)

Central line complications

1 2 3 4 5

7 6 8 6 6

24 20 20 19 25

24 1 1 19 25

None None None None None

7 6 8 6 6

Fig. 1. CVP measurements derived from concomitant indwelling PICCs and PACs were plotted individually for each patient vs. intraoperative time and the Pearson correlation coefficient.

0.6 mm Hg (95% CI )1.5 to 2.8). The difference between the two devices was expected to be <3.4 mm Hg (95% CI )3.2 to 7.2). To determine the degree of agreement between the two devices, the

difference between the PICC CVP and the CICC and PAC CVP measurements was plotted against the averages of the two devices (Bland-Altman plot, Fig. 2).

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Table III. Agreement between CVP measured by PICCs and CICCs Time (min)

Patient (n)

Bias (mm Hg)

95% CI (both)

0 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240 Overall

5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 4 3

1.0 1.0 1.4 0.8 0.6 0.2 1.2 0.2 0.2 0.2 0.2 0.8 )0.4 0.6 1.0 0.5 2.0 0.6

)1.0 )1.0 )0.9 )1.9 )0.5 )0.4 )1.2 )0.8 )0.8 )1.6 )1.6 )1.6 )4.4 )1.8 )1.5 )3.5 )6.6 )1.5

to to to to to to to to to to to to to to to to to to

3.0 3.0 3.7 3.5 1.7 0.8 3.6 1.2 1.2 2.0 2.0 3.2 3.6 3.0 3.5 4.5 11.0 2.8

Precision (mm Hg)

95% CI (PICC)

3.1 3.1 3.6 4.2 1.8 0.9 3.8 1.6 1.6 2.9 2.9 3.8 6.3 3.8 3.9 4.9 6.8 3.4

)0.3 )0.3 )0.3 )0.4 )0.2 )0.1 )0.4 )0.2 )0.2 )0.3 )0.3 )0.4 )0.6 )0.4 )0.4 )2.0 )8.1 )0.3

to to to to to to to to to to to to to to to to to to

6.5 6.5 7.5 8.9 3.7 1.8 7.9 3.4 3.4 6.1 6.1 7.9 13.0 8.0 8.2 12.0 22.0 7.2

Correlation coefficient

95% CI (CICC and PAC)

0.91 0.93 0.93 0.92 0.98 1.0 0.93 0.99 0.99 0.99 0.97 0.97 0.76 0.75 0.81 0.87 0.85 0.92

0.15 to 0.99 0.23 to 1.0 0.27 to 1.0 0.21 to 0.99 0.78 to 1.0 0.94 to 1.0 0.25 to 1.0 0.87 to 1.0 0.91 to 1.0 0.82 to 1.0 0.59 to 1.0 0.61 to 1.0 )0.78 to 0.98 )0.39 to 0.98 )0.26 to 0.99 )0.55 to 1.0 )1.0 to 1.0 0.19 to 0.99

DISCUSSION A substantial decrease in morbidity and mortality has occurred during the past 30 years for patients undergoing AAA operations.1 This decrease has been attributed to many factors, including improved preoperative care, intraoperative monitoring, and postoperative resuscitation.4 The increased use of PACs is thought to have contributed to the improved outcomes in this patient population.2 In the past 10 years, however, several authors have challenged this hypothesis. Several recent studies have demonstrated no clinically significant benefit to the use of PACs in the perioperative period.2-6 Specifically, using PACs instead of CVP monitoring alone does not reduce patient mortality, length of ICU or hospital stay, or blood lost or transfused.2 The only documented difference between patients with or without indwelling PACs is that patients with PACs who require transfusion with colloid products tend to receive a larger volume of crystalloid compared to patients without PACs.2,3 In a randomized study of 102 patients, Isaacson and colleagues6 demonstrated that CVP measurements from a CICC were as good as those from PACs in monitoring patients during elective AAA repairs. These data suggest that CVP monitoring is adequate during elective aortic reconstruction. PICCs have been in use since 1975, primarily to provide the long-term venous access necessary for parenteral nutrition and chemotherapy. Recent studies have reported that open-ended PICCs can

Fig. 2. PICC measurements and CICC and PAC measurements of CVP were taken simultaneously in patients undergoing elective AAA reconstruction. The difference between PICC measurements and CICC and PAC measurements is plotted against the averages of the two measurement devices (Bland-Altman plot). The solid horizontal line represents the mean bias between the two devices. The two dashed horizontal lines represent the mean bias ± 1.96 times the standard deviation of the differences.

accurately measure CVP, thus creating an opportunity for safer and more cost-effective central venous access and hemodynamic monitoring.7 PICCs can be placed quickly and safely by trained practitioners at the patientÕs bedside while the patient is under local anesthetic in the ICU or non-ICU setting8,11,12 without the risk of pneumothorax, major hemorrhage, neck hematoma, or carotid puncture

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associated with CICCs.8 PICCs also have a much lower rate of bloodstream infection compared with CICCs,13 therefore decreasing the potential risk of secondary postsurgical infection and reducing the well-known morbidity and mortality from catheter-related bloodstream infections.14,15 In addition, PICCs can be left in place for the duration of a patientÕs hospitalization, which has the potential to improve both patient satisfaction and staff safety by decreasing the number of venipunctures and intravenous attempts. Compared with the PAC as a gold standard reference, the PICC accurately captured the dynamic changes in CVP (Fig. 2). The PICCÕs overestimation of CVP by 0.6 mm Hg can be attributed to the inherent resistance created by the length and diameter of the catheter, which is partially overcome using a continuous low-flow infusion pressure transducer. This inherent resistance to flow, and hence to rapid fluid boluses, has been considered a limitation to the use of PICCs in acute settings. The open-ended PICCs used in this study tolerated pump flow rates of >1,000 mL/hr. One limitation of newer PICCs is the inability to infuse at rates >5 mL/sec (3 L/hr). The resistance created by the greater length and smaller diameter of PICCs limits rapid infusion of cool viscous blood products and may fracture red blood cells. Although limited by the small number of patients studied, data from this pilot study indicate that PICCs can be used to monitor CVP in situations of dynamic vascular compliance and changing preload. While the 95% CIs do cross equivalence, or 1, the best statistical method for comparing a new measurement device with a gold standard device is by the Bland-Altman plot (Fig. 2). The Bland-Altman plot is a statistical method used to compare to measurement techniques. The differences between the two techniques are plotted against the averages of the two techniques. The overall difference, or bias, between the two measurement devices in this study was 0.6 mm Hg, with 95% CIs suggesting the potential for underestimation by 1.5 mm Hg to overestimation by 2.8 mm Hg. The range of the CIs suggests a decrease in scientific reliability but is unlikely to impact clinical practice where CVPs are managed and monitored in the context of a clinical situation. Our findings indicate that open-ended PICCs coupled to a low-flow pressure transfusion device are effective CVP monitoring devices during elective AAA reconstruction (mean bias 0.6 mm Hg). PICCs have numerous potential advantages over CICCs: no risk of pneumothorax or major hemorrhage and a lower rate of line-related bloodstream infections,

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which has the potential to reduce patient morbidity and hospital costs. Larger prospectively randomized and controlled studies are necessary to determine the safety profile and functionality of open-ended PICCs compared with CICCs in patients undergoing elective AAA reconstruction.

We appreciate the expert statistical support provided by Joseph G. Hentz, Division of Biostatistics, Mayo Clinic Arizona.

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