Correlation between centrally versus peripherally transduced venous pressure in prone patients undergoing posterior spine surgery

Association Between the Liver Fibrosis Markers and Scores, and Hemodynamic Congestion Assessed by Peripheral Venous Pressure in Patients With Acute Heart Failure

Background Peripheral venous pressure (PVP) has been shown to be a reliable surrogate for right atrial pressure in assessing congestion in patients with heart failure (HF). Liver fibrosis markers and scores can be useful in assessing organ injury in patients with acute HF. This study aimed to investigate the association of liver fibrosis markers and scores with PVP in patients with acute HF. Methods and Results The 7S domain of the collagen type IV N-terminal propeptide (P4NP 7S), aspartate aminotransferase-to-platelet ratio index, fibrosis-4, and nonalcoholic fatty liver disease fibrosis score were determined along with PVP measurements before discharge in 229 patients with acute HF. The strongest correlation with PVP was found for P4NP 7S (Pearson r=0.40). Patients with high P4NP 7S levels (≥median [6.2 ng/mL]) had an increased risk of cardiovascular death or HF hospitalization (adjusted hazard ratio [HR], 1.80 [95% CI, 1.09-3.04], P=0.02). The concomitant high PVP (≥mean [8 mm Hg])/high P4NP 7S group, in contrast to the high PVP/low P4NP 7S or low PVP/high P4NP 7S group, had a significant risk relative to the low PVP/low P4NP 7S group for cardiovascular death or HF hospitalization (adjusted HR, 2.63 [95% CI, 1.43-5.05], P=0.002). A sustained elevation in PVP for 1 month postdischarge was associated with a persistent increase in P4NP 7S. Conclusions The study demonstrated the relationship between the liver fibrosis marker P4NP 7S and congestion. PVP and P4NP 7S could be useful for assessing congestion-related organ injury and predicting prognosis in patients with acute HF.

Relation of Peripheral Venous Pressure to Central Venous Pressure in Patients With Heart Failure, Heart Transplant, and Left Ventricular Assist Device

Peripheral venous pressure (PVP) monitoring is a noninvasive method to assess volume status. We investigated the correlation between PVP and central venous pressure (CVP) in heart failure (HF), heart transplant (HTx), and left ventricular assist device (LVAD) patients undergoing right heart catheterization (RHC). A prospective, cross-sectional study examining PVP in 100 patients from October 2018 to January 2020 was conducted. The analysis included patients undergoing RHC admitted for HF, post-HTx monitoring, or LVAD hemodynamic testing. Sixty percent of patients had HF, 30% were HTx patients, and 10% were LVAD patients. The mean PVP was 9.4 ± 5.3 mm Hg, and the mean CVP was 9.2 ± 5.8 mm Hg. The PVP and CVP were found to be highly correlated (r = 0.93, p < 0.00001). High correlation was also noted when broken down by HF (r = 0.93, p < 0.00001), HTx (r = 0.93, p < 0.00001), and LVAD groups (r = 0.94, p < 0.00005). In conclusion, there is a high degree of correlation between PVP and CVP in HF, HTx, and LVAD patients. PVP measurements can be used as a rapid, reliable, noninvasive estimate of volume status in these patient populations.

Validation of Peripherally Inserted Central Catheter-Derived Fick Cardiac Outputs in Patients with Heart Failure

The pulmonary artery catheter (PAC) remains the gold standard to calculate Fick cardiac outputs (FCOs) in patients with heart failure admitted to the intensive care unit (ICU). The peripherally inserted central catheter (PICC) provides long-term intravenous access and is used outside the ICU; however, there is scant literature validating venous oxygen saturations (VOSs) from PICC lines. Heart failure patients in the ICU with an existing PAC requiring a PICC line to transition were enrolled. Three blood samples were taken per person (1 at PICC, 1 at central venous pressure [CVP], and 1 at distal PAC). We performed repeated measures analysis of variance, as well as reliability analysis on 31 subjects (77% male, 71% Caucasian, mean ± standard deviation age 60 ± 8 years, 80% on inotropes). The average VOSs were 62 ± 11%, 62 ± 12%, and 61 ± 9% for the PICC line, CVP, and distal port, respectively (p = 0.66); there was excellent reliability (0.79). The median FCOs were 5 [4, 6], 5 [4, 6], and 5 [4, 6] L/min at the PICC, CVP, and distal port, respectively (p = 0.91); there was fair-to-good reliability (0.67). In conclusion, VOS and FCO did not differ by location, on average. Reliable data may be obtained through the PICC line, after evaluation from the PAC. The PICC may provide longer-term hemodynamic assessment while improving patient comfort.

Analysis of central venous pressure (CVP) signals using mathematical methods

Central venous pressure (CVP) is an important clinical parameter for physicians but only the absolute CVP value is typically monitored in the intensive care unit (ICU). In this study, we propose a novel mathematical method to present and analyze CVP signals. A total of 44 suitable samples were chosen from a total of 65 collected in an ICU. Pre-processing of the samples included rate reduction and digital filtering. The statistical features of time and frequency domain, wavelet, and empirical mode decomposition of these signals were extracted. We found no significant difference among the CVP signals regarding sex, smoking, coronary disease, and respiration mode of the samples.

Prediction of blood loss during surgery on the lumbar spine with the patient supported prone on the Jackson table

BACKGROUND CONTEXT

To date, many studies have examined the effects of one or several factors on blood loss during lumbar spine surgery. The nature and extent of the operation, patient position, blood pressure, and a variety of factors related to patient size have been touted as predictors of blood loss.

PURPOSE

To measure multiple factors implicated as determinants of blood loss and develop a multivariable statistical model capable of predicting blood loss.

STUDY DESIGN

An observational study of patients undergoing lumbar spine surgery in the prone position on the Jackson table.

PATIENT SAMPLE

A total of 71 healthy adult men and women undergoing lumbar spine surgery in a university hospital setting.

OUTCOME MEASURE

Blood loss during surgery.

METHODS

We observed 35 surgeries and recorded demographic and body habitus data on each patient as well as surgical variables, blood pressure, and peripheral venous pressure. We measured bladder pressure intermittently as a surrogate for intra-abdominal pressure. We constructed a statistical model with the results and validated that model in a separate set of 36 subjects.

RESULTS

The Jackson table supported all our patients regardless of body dimensions without causing an increase in bladder pressure. Blood loss during surgery averaged 1,167±998 mL (mean±1 standard deviation, range 32-3,745). The statistical model was able to account for about 75% of the variability in blood loss using four variables: the number of laminectomies, whether bone was harvested from the iliac crest, experience of the surgeon doing the initial exposure and closure, and distension of the epidural veins. Data on these variables that were collected in the validation study found a multiple correlation coefficient (R(2)) of 0.66 between predicted and observed blood loss.

CONCLUSIONS

This is the first study to build a successful multivariable predictive model of blood loss during spine surgery. The Jackson table was effective in supporting patients with different body sizes and shapes, thus removing raised intra-abdominal pressure as an important factor.

Comparative utility of centrally versus peripherally transduced venous pressure monitoring in the perioperative period in spine surgery patients

STUDY OBJECTIVE

To compare central venous pressure (CVP) with peripheral venous pressure (PVP) monitoring during the intraoperative and postoperative periods in patients undergoing spine surgery.

DESIGN

Prospective observational study.

SETTING

University-affiliated teaching hospital.

PATIENTS

35 ASA physical status 1, 2, and 3 patients.

INTERVENTIONS

A peripheral catheter in the forearm or hand and a central catheter into the internal jugular vein were placed for PVP and CVP monitoring, respectively.

MEASUREMENTS

CVP and PVP values were collected simultaneously and recorded electronically at 5-minute intervals throughout surgery and in the recovery room. The number of attempts for catheter placement, ease of use, maintenance, and interpretation were recorded. Patient comfort, frequency of complications, and cost were analyzed.

MAIN RESULTS

The correlation coefficient between CVP and PVP was 0.650 in the operating room (P < 0.0001) and 0.388 in the recovery room (P < 0.0001). There was no difference between groups in number of attempts to place either catheter, maintenance, and interpretation with respect to PVP and CVP monitoring in the operating room. In the recovery room, the nurses reported a higher level of difficulty in interpretation of PVP than CVP, but no differences were noted in ease of maintenance. There were no complications related to either central or peripheral catheter placement. Patient comfort and cost efficiency were higher with a peripheral than a central catheter.

CONCLUSION

During clinically relevant conditions, there was limited correlation between PVP and CVP in the prone position during surgery and postoperatively in the recovery room.

Perioperative comparative effectiveness research

The goal of comparative effectiveness research (CER) is to improve effectiveness, efficacy and efficiency in health care. While CER seems to present a major opportunity to introduce accountability into health care by identifying and promoting best practices in medicine, many issues surrounding CER remain poorly understood by clinicians and researchers, including what study designs are most appropriate for such research and what analytic tools are most helpful. The goal of this review is therefore to provide background and definitions of what constitutes CER and to discuss the various study designs and their strengths and weaknesses in achieving the stated goals of CER, while relating them to examples relevant to perioperative research. We provide a brief outline of the types of analytic methods particularly useful for CER and connect the reader to references for their practice. Finally, we assess the role of CER in perioperative research and provide some thoughts on future paths.

Peripheral venous pressure as an alternative to central venous pressure in patients undergoing laparoscopic colorectal surgery

BACKGROUND

Peripheral venous pressure (PVP) is strongly correlated with central venous pressure (CVP) during various surgeries. Laparoscopic surgery in the Trendelenburg position with pneumoperitoneum typically increases CVP. To determine whether PVP convincingly reflects changes in CVP, we evaluated the correlation between PVP and CVP in patients undergoing laparoscopic colorectal surgery.

METHODS

Both CVP and PVP were measured simultaneously at predetermined time intervals during elective laparoscopic colorectal surgery in 42 patients without cardiac disease. The pairs of venous pressure measurements were analysed for correlation, and the Bland-Altman plots of repeated measures were used to evaluate the agreement between CVP and PVP.

RESULTS

A total of 420 data pairs were obtained. The overall mean CVP was 11.3 (sd 4.5) mm Hg, which was significantly lower than the measured PVP of mean 12.1 (4.5) mm Hg (P=0.005). There was a strong positive correlation between overall CVP and PVP (correlation coefficient=0.96, P<0.0001). The mean bias (PVP-CVP) corrected for repeated measurements using random-effects modelling was 0.9 mm Hg [95% confidence interval (CI) 0.54-1.19 mm Hg] with 95% limits of agreement of -1.2 mm Hg (95% CI -1.75 to -0.62 mm Hg) to 2.9 mm Hg (95% CI 2.35-3.48 mm Hg).

CONCLUSIONS

PVP displays a strong correlation and agreement with CVP under the increased intrathoracic pressure of pneumoperitoneum in the Trendelenburg position and may be used as an alternative to CVP in patients without cardiac disease undergoing laparoscopic colorectal surgery.

Influence of tissue pressure on central venous pressure/peripheral venous pressure correlation: An experimental report

BACKGROUND

Peripheral venous pressure (PVP) has been shown to correlate with central venous pressure (CVP) in a number of reports. Few studies, however, have explored the relationship between tissue pressure (TP) and PVP/CVP correlation.

METHODS

PVP and CVP were simultaneously recorded in a bench-top model of the venous circulation of the upper limb and in a single human volunteer after undergoing graded manipulation of tissue pressure surrounding the intervening venous conduit. Measures of correlation were determined below and above a point wherein absolute CVP exceeded TP.

RESULTS

Greater correlation was observed between PVP and CVP when CVP exceeded TP in both models. Linear regression slope was 0.975 (95% CI: 0.959-0.990); r (2) 0.998 above tissue pressure 10 cmH2O vs. 0.393 (95% CI: 0.360-0.426); and r (2) 0.972 below 10 cmH2O at a flow rate of 2000 mL/h in the in vitro model. Linear regression slope was 0.839 (95% CI: 0.754-0.925); r (2) 0.933 above tissue pressure 10 mmHg vs. slope 0.238 (95% CI: -0.052-0.528); and r (2) 0.276 in the en vivo model.

CONCLUSION

PVP more accurately reflects CVP when absolute CVP values exceed tissue pressure.

Application of positive end-expiratory pressure in a case with large laceration on the superior vena cava

Iatrogenic injury is a difficult situation for a surgeon. Being successful in saving a patient at risk is the major concern in this situation. Once an iatrogenic injury to the superior vena cava (SVC) is found, increasing the intrathoracic pressure is theoretically able to overcome the venous pressure and to alleviate or even stop bleeding from injury. A 76-year-old female patient, who had suffered from end-stage diabetic nephropathy, developed tension hemothorax during insertion of the cuffed hemodialysis catheter. The successful course of resuscitation without emergent operation or endovascular repair is presented here.