Effect of body temperature on peripheral venous pressure measurements and its agreement with central venous pressure in neurosurgical patients

Previous studies suggest a correlation of central venous pressure (CVP) with peripheral venous pressure (PVP) in different clinical settings. The effect of body temperature on PVP and its agreement with CVP in patients under general anesthesia are investigated in this study. Fifteen American Society of Anesthesiologists I-II patients undergoing elective craniotomy were included in the study. CVP, PVP, and core (Tc) and peripheral (Tp) temperatures were monitored throughout the study. A total of 950 simultaneous measurements of CVP, PVP, Tc, and Tp from 15 subjects were recorded at 5-minute intervals. The measurements were divided into low- and high-Tc and -Tp groups by medians as cutoff points. Bland-Altman assessment for agreement was used for CVP and PVP in all groups. PVP measurements were within range of +/-2 mm Hg of CVP values in 94% of the measurements. Considering all measurements, mean bias was 0.064 mm Hg (95% confidence interval -0.018-0.146). Corrected bias for repeated measurements was 0.173 +/- 3.567 mm Hg (mean +/- SD(corrected)). All of the measurements were within mean +/- 2 SD of bias, which means that PVP and CVP are interchangeable in our setting. As all the measurements were within 1 SD of bias when Tc was > or = 35.8 degrees C, even a better agreement of PVP and CVP was evident. The effect of peripheral hypothermia was not as prominent as core hypothermia. PVP measurement may be a noninvasive alternative for estimating CVP. Body temperature affects the agreement of CVP and PVP, which deteriorates at lower temperatures.     

Peripheral venous pressure as a predictor of central venous pressure during orthotopic liver transplantation

STUDY OBJECTIVE: To assess the reliability of peripheral venous pressure (PVP) as a predictor of central venous pressure (CVP) in the setting of rapidly fluctuating hemodynamics during orthotopic liver transplant surgery. DESIGN: Prospective clinical trial. SETTING: UCLA Medical Center, main operating room-liver transplant surgery. PATIENTS: Nine adult patients with liver failure undergoing orthotopic liver transplant surgery. INTERVENTIONS: A pulmonary artery catheter and a 20-g antecubital peripheral intravenous catheter dedicated to measuring PVP were placed in all patients after standard general endotracheal anesthesia induction and institution of mechanical ventilation. MEASUREMENTS: Peripheral venous pressure and CVP were recorded every 5 minutes and/or during predetermined, well-defined surgical events (skin incision, venovenous bypass initiation, portal vein anastamosis, 5 minute post graft reperfusion, abdominal closure). Pulmonary artery pressure and cardiac output (via thermodilution) were recorded every 15 and 30 minutes, respectively. MAIN RESULTS: Peripheral venous pressure (mean +/- SD) was 11.0 +/- 4.5 mmHg vs a CVP of 9.5 +/- 5.0; the two measurements differed by an average of 1.5 +/- 1.6 mmHg. Peripheral venous pressure correlated highly with CVP in every patient, and the overall correlation among all nine patients calculated using a random-effects regression model was r = 0.95 (P < 0.0001). A Bland-Altman analysis used to determine the accuracy of PVP in comparison to CVP yielded a bias of -1.5 mmHg and a precision of +/-3.1 mm Hg. CONCLUSION: Our study confirms that PVP correlates with CVP even under adverse hemodynamic conditions in patients undergoing liver transplantation.     

Can peripheral venous pressure be an alternative to central venous pressure during right hepatectomy in living donors?

The safety of living donors is a matter of cardinal importance in addition to obtaining optimal liver grafts to be transplanted. Central venous pressure (CVP) is known to have significant correlation with the amount of bleeding during parenchymal transection and many centers have adopted CVP monitoring for right hepatectomy. However, central line cannulation can induce some serious complications. Peripheral venous pressure (PVP) has been suggested as a comparable alternative to CVP. The aim of this study was to determine whether a clinically acceptable agreement or a reliable correlation between CVP and PVP exist and if CVP can be replaced by PVP in living liver donors. A central venous catheter was placed through the right internal jugular vein and a peripheral venous catheter was inserted at antecubital fossa in the right arm. CVP and PVP were recorded in 15-minute intervals in 50 adult living donors. The paired data were divided into 3 stages: preparenchymal transection, parenchymal transection, and postparenchymal transection. A total of 1,430 simultaneous measurements of CVP and PVP were recorded. Overall, the PVP, CVP, and bias were 7.0+/-2.46, 5.9+/-2.32, and 1.16+/-1.12 mmHg, respectively. A total of 88.9% of all measurements were clinically within acceptable limits of bias (+/-2 mmHg). Regression analysis showed a high correlation coefficient between PVP and CVP (r=0.893; P<0.001) and the limits of agreement were -1.03 to 3.34 overall. In conclusion, frequencies of differences, bias, correlation coefficient, and limits of agreement between PVP and CVP remained relatively constant throughout the operation. Therefore, PVP measurement in the arm can be an alternative to predict CVP and further, obviate central venous catheter-related complications in living liver donors.     

Correlation of peripheral venous pressure and central venous pressure in surgical patients

OBJECTIVE: To determine the degree of agreement between central venous pressure (CVP) and peripheral venous pressure (PVP) in surgical patients. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Patients without cardiac dysfunction undergoing major elective noncardiac surgery (n = 150). MEASUREMENTS AND MAIN RESULTS: Simultaneous CVP and PVP measurements were obtained at random points in mechanically ventilated patients during surgery (n = 100) and in spontaneously ventilating patients in the postanesthesia care unit (n = 50). In a subset of 10 intraoperative patients, measurements were made before and after a 2-L fluid challenge. During surgery, PVP correlated highly to CVP (r = 0.86), and the bias (mean difference between CVP and PVP) was -1.6 +/- 1.7 mmHg (mean +/- SD). In the postanesthesia care unit, PVP also correlated highly to CVP (r = 0.88), and the bias was -2.2 +/- 1.9 (mean +/- SD). When adjusted by the average bias of -2, PVP predicted the observed CVP to within +/-3 mmHg in both populations of patients with 95% probability. In patients receiving a fluid challenge, PVP and CVP increased similarly from 6 +/- 2 to 11 +/- 2 mmHg and 4 +/- 2 to 9 +/- 2 mmHg. CONCLUSION: Under the conditions of this study, PVP showed a consistent and high degree of agreement with CVP in the perioperative period in patients without significant cardiac dysfunction. PVP -2 was useful in predicting CVP over common clinical ranges of CVP. PVP is a rapid noninvasive tool to estimate volume status in surgical patients.     

Peripheral venous pressure is an alternative to central venous pressure in paediatric surgery patients

BACKGROUND: Peripheral venous pressure (PVP) is easily and safely measured. In adults, PVP correlates closely with central venous pressure (CVP) during major non-cardiac surgery. The objective of this study was to evaluate the agreement between CVP and PVP in children during major surgery and during recovery. METHODS: Fifty patients aged 3-9 years, scheduled for major elective surgery, each underwent simultaneous measurements of CVP and PVP at random points during controlled ventilation intraoperatively (six readings) and during spontaneous ventilation in the post-anaesthesia care unit (three readings). In a subset of four patients, measurements were taken during periods of hypotension and subsequent fluid resuscitation (15 readings from each patient). RESULTS: Peripheral venous pressure was closely correlated to CVP intraoperatively, during controlled ventilation (r=0.93), with a bias of 1.92 (0.47) mmHg (95% confidence interval = 2.16-1.68). In the post-anaesthesia care unit, during spontaneous ventilation, PVP correlated strongly with CVP (r = 0.89), with a bias of 2.45 (0.57) mmHg (95% confidence interval = 2.73-2.17). During periods of intraoperative hypotension and fluid resuscitation, within-patient changes in PVP mirrored changes in CVP (r = 0.92). CONCLUSION: In children undergoing major surgery, PVP showed good agreement with CVP in the perioperative period. As changes in PVP parallel, in direction, changes in CVP, PVP monitoring may offer an alternative to direct CVP measurement for perioperative estimation of volume status and guiding fluid therapy.     

Correlation of peripheral venous pressure and central venous pressure in kidney recipients

BACKGROUND AND OBJECTIVE: Previous studies in adults have demonstrated a clinically useful correlation between central venous pressure (CVP) and peripheral venous pressure (PVP). The current study prospectively compared CVP measurements from a central versus a peripheral catheter in kidney recipients during renal transplantation. METHODS: With ethics committee approval and informed consent, 30 consecutive kidney recipients were included in the study. We excluded patients who had significant valvular disease or clinically apparent left ventricular failure. For each of 30 patients, CVP and PVP were measured on five different occasions. The pressure tubing of the transducer system was connected to the distal lumen of the central or to the peripheral venous catheter for measurements following induction of anesthesia, after induction, 1 hour after induction, reperfusion of the kidney, and the end of the operation, yielding 150 hemodynamic data points. Each hemodynamic measurement included heart rate, mean arterial pressure, mean CVP, and mean PVP determined at end-expiration. RESULTS: The mean PVP was 13.5 +/- 1.8 mm Hg and the mean CVP was 11.0 +/- 1.5 mm Hg during surgery. The mean difference was 2.5 +/- 0.5 (P < .01). Repeated-measures analysis of variance indicated a highly significant relationship between PVP and CVP (P < .01) with a Pearson correlation coefficient of 0.97. CONCLUSION: Under the conditions of this study, PVP showed a consistently high agreement with CVP in the perioperative period among patients without significant cardiac dysfunction.     

Peripheral venous pressure predicts central venous pressure poorly in pediatric patients

Purpose: Using peripheral venous pressure (PVP) instead of central venous pressure (CVP) as a volume monitor decreases patient risks and costs, and is convenient. This study was undertaken to determine if PVP predicts CVP in pediatric patients. METHODS: With ethical approval and informed consent, 30 pediatric patients aged neonate to 12 yr requiring a central venous line were studied prospectively in a tertiary care teaching hospital. In the supine position, PVP and CVP were simultaneously transduced. Ninety-six paired recordings of CVP and PVP were made. Correlation and Bland-Altman analysis of agreement of end-expiratory measurements were performed. RESULTS: The mean (SD; range) CVP was 10.0 mmHg (6.0; -1.0 to 27.0); the mean PVP was 13.7 mmHg (6.3; 0.0 to 33.0); offset (bias) of PVP > CVP was 3.7 mmHg with SD 2.6. The 95% confidence intervals (CI) for the bias were 3.2 to 4.1 mmHg. In the Bland-Altman analysis, lower and upper limits of agreement (LOA; CI in parentheses) were -1.5 (-2.3 to -0.7) and 8.8 (8.1 to 9.6) mmHg. Eight of 96 points were outside the limits of agreement. The correlation of PVP on CVP was r = 0.92, P < 0.0001. For a subset of ten patients (20 simultaneous recordings) with iv catheters proximal to the hand, limits of agreement were better - offset: 3.8 mmHg (+/- 1.4); lower LOA: 1.2 mmHg (0.25 to 2.1); upper LOA: 6.6 mmHg (5.7 to 7.5). CONCLUSION: Peripheral venous pressure measured from an iv catheter in the hand predicts CVP poorly in pediatric patients.     

Peripheral venous pressure as a hemodynamic variable in neurosurgical patients

Neurosurgical patients undergoing either craniotomy or complex spine surgery are subject to wide variations in blood volume and vascular tone. The ratio of these variables yields a pressure that is traditionally measured at the superior vena cava and referred to as "central venous pressure" (CVP). We have investigated an alternative to CVP by measuring peripheral venous pressure (PVP), which, in parallel animal studies, correlates highly with changes in absolute blood volume (r = 0.997). We tested the hypothesis that PVP trends parallel CVP trends and that their relationship is independent of patient position. We also tested and confirmed the hypothesis, during planned circulatory arrest, that PVP approximates mean systemic pressure (circulatory arrest pressure), which reflects volume status independent of cardiac function. PVP was compared with CVP across 1026 paired measurements in 15 patients undergoing either craniotomy (supine, n = 8) or complex spine surgery (prone, n = 7). Repeated-measures analysis of variance indicated a highly significant relationship between PVP and CVP (P < 0.001), with a Pearson correlation coefficient of 0.82. The correlation was best in cases with significant blood loss (estimated blood loss >1000 mL; r = 0.885) or hemodynamic instability (standard deviation of CVP > 2; r = 0.923). Implications: In patients undergoing either elective craniotomy or complex spine surgery, peripheral venous pressure (PVP) trends correlated with central venous pressure (CVP) trends with a mean offset of 3 mm Hg (PVP > CVP). PVP trends provided equivalent physiological information to CVP trends in this subset of patients, especially during periods of hemodynamic instability. In addition, measurements made during a planned circulatory arrest support the hypothesis that PVP approximates mean systemic pressure (systemic arrest pressure), which is a direct index of patient volume status independent of cardiac or respiratory activity.     

Intraoperative Peripherally Inserted Central Venous Catheter Central Venous Pressure Monitoring in Abdominal Aortic Aneurysm Reconstruction

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. Seventy-three 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.     

Vasotrac arterial blood pressure and direct arterial blood pressure monitoring during liver transplantation

During liver transplantation two arterial catheters are often placed. The Vasotrac is a noninvasive monitor that provides radial arterial blood pressures by a tonometric method. We investigated whether the Vasotrac would be an accurate substitute for an arterial catheter by comparing Vasotrac blood pressures with simultaneous direct radial blood pressures recorded from the contralateral arm in 14 patients undergoing liver transplantation. Correlation between the two methods was calculated and a Bland-Altman analysis performed to assess agreement. A total of 6468 simultaneous measurements were made over a duration of 1.5-7.5 h per case. For mean arterial blood pressure 57% of Vasotrac measurements were within 10% of direct arterial measurement. Correlation (r) was 0.82. Vasotrac bias was +5.4 mm Hg and limits of agreement were +/-18.6 mm Hg. For systolic arterial blood pressure 65% of Vasotrac measurements were within 10% of direct arterial measurement. Correlation was 0.78. Vasotrac bias was +7.6 mm Hg and limits of agreement +/-25 mm Hg. For diastolic arterial blood pressure 57% of Vasotrac measurements were within 10% of direct arterial measurement. Correlation was 0.82. Vasotrac bias was +3.3 mm Hg and limits of agreement +/-15 mm Hg. We conclude that the Vasotrac is not adequately accurate to substitute for direct arterial blood pressure monitoring in liver transplantation.     

Usefulness of a central venous catheter during hepatic surgery

Aim: Central venous catheter (CVC) is often inserted during liver resection because a low central venous pressure (CVP) reduces blood loss and the procedure may be associated with circulatory impairment. The aim of the study was to evaluate the usefulness of a CVC besides the measurements of CVP, and whether peripheral venous pressure (PVP) measurement could be used reliably in place of CVP.
Methods: We conducted an observational study during a 16-month period. Number of CVC inserted, expected surgical difficulties, and intraoperative complications which could lead to treatment involving a CVC were prospectively recorded and analysed. Measurements of CVP and PVP were simultaneously obtained at different times during surgery. Bias and limits of agreement with their 95% confidence interval (95% CI) were calculated.
Results: Of the 101 patients included, 28 had expected surgical difficulties. Of the 75 CVCs inserted, only six (8%) were used for another purpose that CVP measurement in patients with expected surgical difficulties. A total of 124 measurements in 23 patients were recorded. Mean CVP was 4.8 ± 2.9 mmHg and mean PVP was 6.9 ± 3.1 mmHg ( P <0.0001). The bias was −2.1 ± 1.1 mmHg (95% CI: −2.3 to −1.9). When adjusted by the average bias of −2 mmHg, PVP predicted a CVP≤5 mmHg with a sensitivity and a specificity of 93% and 87%, respectively.
Conclusion: Routine insertion of a CVC should be discussed in patients without expected surgical difficulties. Thus, PVP monitoring may suffice to estimate CVP in uncomplicated cases.     

Cuff-occluded rate of rise of peripheral venous pressure: a new, highly sensitive technique for monitoring blood volume status during hemorrhage and resuscitation

We investigated the cuff-occluded rate of rise of peripheral venous pressure (CORRP)--a new, nearly noninvasive peripheral hemodynamic monitoring parameter--in dogs subjected to hemorrhage and resuscitation. Twelve adult mongrel dogs under general anesthesia were subjected to hemorrhage of 30% of their estimated total blood volume (TBV) for 30 minutes; after this time the extracted blood was reinfused. Arterial pressure (AP), central venous pressure (CVP), pulmonary arterial pressure (PAP), cardiac output (CO), pulmonary venous pressure (PWP), heart rate, and CORRP were continuously monitored. A "clinically significant change" (CSC) in CORRP and CO was defined as a change that exceeded two standard deviations from the mean of five baseline measurements made before the onset of hemorrhage, whereas a CSC in PWP or CVP was conservatively defined as a change that exceeded 2 mm Hg from the average of five baseline measurements, and a CSC in PAP and AP was defined as a change that exceeded 3 mm Hg and 5 mm Hg, respectively from the average of the baseline measurements. There was no consistent change in heart rate during hemorrhage. Thus defined, a CSC in CORRP occurred after an average extraction of 9.2% +/- 4.7% TBV, whereas a CSC was not seen until an average loss of 16.5% +/- 8.1% TBV for AP, 21% +/- 13% TBV for PWP, 15.5% +/- 7% TBV for PAP, and 35% +/- 3% TBV for CVP. These average blood losses are all significantly different from the average blood loss required to effect a CSC in CORRP. The blood loss required to effect a CSC in CO averaged 9.7% +/- 6%. We conclude that in these anesthetized dogs, CORRP detected blood loss earlier than other commonly used hemodynamic parameters, including several invasive parameters such as CVP, PAP, and PWP; CORRP and CO were equivalent in their ability to detect early stages of blood loss.     

An alternative to left ventricular volume reduction.

BACKGROUND: Left ventricular (LV) remodeling leading to ventricular dilatation is ultimately a maladaptative process according to the law of Laplace. To counteract the wall stress increase, a new concept of reducing the LV cavity radius by changing the LV globular shape to a bilobular one through the insertion of transventricular splints has emerged. This procedure is tested in a model of congestive heart failure. METHODS: A bovine model was used (n = 9). Following splint insertion through a sternotomy, boluses of 2 liters of crystalloid were injected. After every bolus, hemodynamic measurements were performed without and with the splints tightened to a 10% and 20% stress level reduction, respectively. Comparisons between the 3 measurements were performed with analysis of variance test (p < 0.05). RESULTS: Splint tightening significantly reduced right and left heart pressures for central venous pressure (CVP) >10 mm Hg (CVP: 14.7 +/- 5.2, 12.1 +/- 5, 10.6 +/- 4.7 mm Hg, p < 0.001 for baseline, 10% and 20% stress level reduction, respectively; mean pulmonary artery pressure: 33.5 +/- 4.7, 31 +/- 4.4, 29.4 +/- 5.1 mm Hg, p < 0.001; pulmonary capillary wedge pressure: 20.5 +/- 2.8, 18.9 +/- 3.3, 17.5 +/- 3.1 mm Hg, p < 0.001). The same holds true for cardiac output (6.5 +/- 1.6, 6.7 +/- 1.4, 6.8 +/- 1.7 liter/minute, p < 0.001), whereas heart rate and mean arterial pressure were not affected. The systemic and pulmonary resistances did not vary significantly throughout the procedure. Importantly, none of the hemodynamic parameters worsened at any stage with the splints. CONCLUSIONS: In this model, hemodynamic parameters are improved with the splints for higher values of CVP, supporting the concept of reshaping the remodeled LV. This technique has the potential to improve patients with congestive heart failure.     

Cardiopulmonary effects of volume loading in patients in septic shock.

The effect of volume loading in 20 patients with clinical and bacteriological evidence of generalized sepsis was studied. The patients were divided into two groups according to their response to volume loading. Group A included 9 patients in whom the initial pulmonary capillary wedge pressure (PWP)was lower than the central venous pressure (CVP). In this group the intravenous administration of 5089+/-409ml/24 hr fluids was accompanied by a significant rise in blood pressure from 94.4+/-9.3mm Hg to 118.9+/-6.3 MM Hg with no significant change in pulse rate or CVP. PWP rose from 5.7 +/- 1.8 to 10.0 +/- 1.4. The rise in cardiac output from 8.0+/-1.3 liter/min to 9.7+/-1.1 liter/min was not statistically significant. Group B included 11 patients in whom the initial PWP was higher than the CVP. In this group, signs of fluid overloading appeared after administration of 3151+/-540ml/24 hr. There was no significant change in blood pressure, pulse rate, CVP, PWP or cardiac output. Urine output was adequate in both groups. This volume load did not affect pulmonary oxygenating capacity (PaO2/F1O2) and effective lung compliance in both groups, but the maintenance of an unchanged oxygenating capacity necessitated an increase in PEEP in some patients. Thus, synchronous monitoring of PWP and CVP in septic shock is helpful in selecting patients (Group A) who will best respond to fluid loading without deterioration of pulmonary oxygenating capacity. PEEP ventilation may be necessary in some patients to maintain the favorable effect of volume loading.     

A comparison of the Vasotrac with invasive arterial blood pressure monitoring in children after pediatric cardiac surgery

The Vasotrac is a device that provides near-continuous and noninvasive arterial blood pressure monitoring and may be an alternative to direct intraarterial measurement. It has been evaluated in adult patients, but minimal information is available for pediatric patients. We evaluated agreement between measurements of arterial blood pressure and heart rate obtained from the Vasotrac versus an arterial catheter in a pediatric population. Children undergoing corrective cardiac surgery were enrolled. Simultaneous arterial blood pressure measurements were obtained postoperatively from the Vasotrac unit and an arterial catheter. Bland-Altman plots were constructed to assess agreement. Paired correlation analysis, bias, and precision calculations were performed. Sixteen patients, mean age 10.1 +/- 2.3 yr and weight 34.6 +/- 11.9 kg, were enrolled. Four-thousand-one- hundred- two paired measurements were obtained. Arterial blood pressures measured noninvasively correlated with catheter measurements with Pearson r values of 0.90, 0.80, and 0.91 for systolic, diastolic, and mean arterial blood pressures, respectively (all P < 0.001). There was excellent agreement between arterial blood pressure measurement methods. Absolute mean differences based on mixed-model regression with 95% confidence intervals were 4.0 mm Hg (3.0-5.0 mm Hg), 4.3 mm Hg (3.1-5.5 mm Hg), and 3.5 mm Hg (2.5-4.0 mm Hg) for systolic blood pressure, diastolic blood pressure, and mean blood pressure, respectively. Arterial blood pressure measurements obtained from the Vasotrac agreed well with invasive arterial monitoring in pediatric patients.     

Prediction of successful primary closure of congenital abdominal wall defects using intraoperative measurements

To determine whether intragastric pressure (IGP) and central venous pressure (CVP) would reliably predict successful primary closure of congenital abdominal wall defects (omphalocele/gastroschisis) in newborn infants, we developed the following prospective intraoperative management protocol. Following a temporary trial of fascial closure, infants who had an IGP less than 20 mm Hg or an increase in CVP of less than 4 mm Hg were primarily closed. If IGP was greater than 20 mm Hg or if CVP increased by more than 4 mm Hg, the temporary closure of the abdomen was reopened and a prosthetic silo was placed. Ten infants who were less than 24 hours old and averaged 2.7 kg (range, 1.4 to 4.2 kg) and 37-weeks gestation (range, 32 to 41 weeks) were studied. Eight infants met criteria for primary closure. Their IGP averaged 14 +/- 4 mm Hg (+/- SD) (range, 8 to 19 mm Hg), and their increase in CVP averaged 1 +/- 2 mm Hg (range, -2 to 3 mm Hg). In the two infants who required staged repair, IGP averaged 25 +/- 1 mm Hg (+/- SD) (range, 24 to 25 mm Hg), and the increase in CVP averaged 7 +/- 1 mm Hg (range, 6 to 8 mm Hg). All patients were anesthetized with fentanyl (12.5 micrograms/kg) and paralyzed with metocurine (0.3 mg/kg) intraoperatively. There were no postoperative complications in either group of patients related to increased intraabdominal pressure, and all patients were extubated within 48 hours of the initial surgery. We conclude that the intraoperative measurement of changes in IGP and CVP can serve as a guide to the operative management of congenital abdominal wall defects and can reliably predict successful outcome following repair.     

Use of photoplethysmography with calibration in vivo for assessing venous hemodynamics of the lower extremity and particularly ambulatory venous pressure and refilling time after exercise

Several invasive and non-invasive methods are used actually for the appreciation of the morphology and the function of the venous system of the lower extremity. Hemodynamic parameters like the ambulatory venous pressure and the venous refilling time can not be determined without invasive measurements. This report describes the results of a prospective comparison of the ambulatory venous pressure and the venous refilling time with the in vivo calibrated photoplethysmography and with invasive measurements. Postural changes of hydrostatic pressure permitted in vivo calibration of the photoplethysmograph. We recorded quantitative photoplethysmography (PPG) ambulatory venous pressure and venous refilling time in 20 normal subjects, 20 patients with superficial varicosis and in 20 patients with chronic venous insufficiency. Quantitative photoplethysmography correlated closely with invasive measurements of ambulatory venous pressure with respect to estimated drop in superficial venous pressure and recovery time. PPG estimates of intravenous pressure in normal patients (24 +/- 9 mm Hg), in patients with varicosis (42 +/- 7 mm Hg) and post-thrombosis patients (63 +/- 9 mm Hg) agreed with ambulatory venous pressure measurements 22 +/- 9 mm Hg, 40 +/- 6 mm Hg and 61 +/- 6 mm Hg, respectively. Non invasive, quantitative photoplethysmography may prove to be an accurate estimate of ambulatory venous pressure in patients with superficial varicosis and in patients with chronic venous insufficiency.     

Trendelenburg versus PASG application--hemodynamic response in man

Diminished venous return is the primary determinant of reduced cardiac output in hemorrhagic hypoperfusion. In this study the hemodynamic response of two therapies commonly employed to increase venous return in hemorrhagic hypoperfusion--pneumatic antishock garment (PASG) application and Trendelenburg (TREND) positioning--were compared in normovolemic man. Five patients had PASG pressure of 20 mm Hg compared with 10 degrees Trendelenburg, eight patients had 20 and 40 mm Hg PASG application compared with 10 degrees Trendelenburg. PASG application at both 20 and 40 mm Hg resulted in a significant increase in CVP (11.1 +/- 1.9 baseline to 16.0 +/- 2.7 PASG 40; p less than 0.01) left atrial pressure (LAP) (10.1 +/- 1.3 baseline to 14.4 +/- 1.8 PASG 20; p less than 0.01) pulmonary capillary wedge pressure (PCWP) (11.6 +/- 2.0 baseline to 16.8 +/- 3.4 PASG 40; p less than 0.01) and esophageal pressure (Pes) (5.0 +/- 0.8 baseline to 8.6 +/- 0.9 PASG 40; p less than 0.01). However, transmural right and left atrial pressure (RATP, LATP) and cardiac index (CI) were unchanged. Ten degrees of Trendelenburg resulted in no increase in CVP, PCWP, RATP, or LATP, but CI (2.67 +/- 0.07 baseline to 2.82 +/- 0.1 TREND; p less than 0.01) was significantly increased. Systemic vascular resistance index (570 +/- 46 TREND vs. 668 +/- 53 PASG 40; p less than 0.01) was significantly less in Trendelenburg compared to PASG at 40 mm Hg. The data demonstrate that elevation in CVP, LAP, and PCWP following PASG application is secondary to an increase in intrathoracic pressure (as measured by Pes).(ABSTRACT TRUNCATED AT 250 WORDS)     

The Association of Lung Distention, PEEP and Biventricular Failure

Although positive and expiratory pressure (PEEP) is known to depress the cardiac output, the mechanism remains debated. Two series of experiments were designed to explore this mechanism. In the first study, the application of 15 cm H(2)O of PEEP to nine anesthetized, ventilated dogs led to a reduction of cardiac index from (mean +/- one standard error of the mean) 2.71 L/min .m (2) +/- 0.35 to 2.19 L/min m(2) +/- 0.22 (p < .05) and a drop in mean arterial pressure (MAP) from 117 mm Hg +/- 8 to 91 mm Hg +/- 11 (p < .01). The mean net (vascular minus pleural pressure) pulmonary artery pressure (MPAP) rose from 15.3 mm Hg +/- 1.2 to 20.6 mm Hg +/- 1.8 (p < .02). The mean net central venous pressure (CVP) rose from 5.2 mm Hg +/- 0.9 to 8.4 mm Hg +/- 0.9 (p < .05) and the net pulmonary arterial wedge pressure (PAWP) rose from 6.7 mm Hg +/- 0.7 to 9.5 mm Hg +/- 0.9 (p < .01). There was a nonsignificant rise in the mean net left atrial pressure (LAP). As PEEP was raised in increments from 0 to 20 cm H(2)O, both LAP and PAWP increased. The rise in PAWP was always greater than the increase in LAP. The difference between PAWP and LAP was strongly correlated with the increase in MPAP (r = 0.98). This relationship was useful in correcting the PAWP during PEEP. The problem of cardiac depression was evaluated in a second series of eight dogs. These animals underwent complete chest wall excision to eliminate any possible direct effects of increased pleural pressure on the heart and great vessels. The absence of the chest wall permitted hyperexpansion of the lungs, particularly with positive end expiratory pressure. At 15 cm H(2)O of PEEP, the mean cardiac index fell in these animals from 2.36 L/min. m(2) +/- 0.26 to 1.47 L/min.m(2) +/- 0.18 (p < .01) and the MAP fell from 105 mm Hg +/- 16.2 to 68 mm Hg +/- 4.8 (p < .001). The CVP rose from a mean of 5.5 mm Hg +/- 0.4 to 8.3 mm Hg +/- 0.6 (p < .01) and the LAP rose from 6.3 mm Hg +/- 0.8 to 8.0 mm Hg +/- 1.1 (p < .05). The MPAP rose from 18.0 mm Hg +/- 0.6 to 23.3 mm Hg +/- 1.6 (p < .01). Comparison of Group I and II showed a significantly greater depression of the cardiac output and MAP in the open-chested animals. At the same time LAP was significantly higher. These data strongly suggest that PEEP and particularly pulmonary hyperinflation induce biventricular failure.     

Estimation of intra-abdominal pressure by bladder pressure measurement: validity and methodology

BACKGROUND: Increased intra-abdominal pressure (IAP) is an adverse complication seen in critically ill, injured, and postoperative patients. IAP is estimated via the measurement of bladder pressure. Few studies have been performed to establish the actual relationship between IAP and bladder pressure. The purpose of this study was to confirm the association between intravesicular pressure and IAP and to determine the bladder volume that best approximates IAP. METHODS: Thirty-seven patients undergoing laparoscopy had intravesicular pressures measured with bladder volumes of 0, 50, 100, 150, and 200 mL at directly measured intra-abdominal pressures of 0, 5, 10, 15, 20, and 25 mm Hg. Correlation coefficients and differences were then determined. RESULTS: Across the IAP range of 0 to 25 mm Hg using all of the tested bladder volumes, the difference between IAP and intravesicular pressures (bias) was -3.8 +/- 0.29 mm Hg (95% confidence interval) and measurements were well correlated (R2 = 0.68). Assessing all IAPs tested, a bladder volume of 0 mL demonstrated the lowest bias (-0.79 +/- 0.73 mm Hg). When considering only elevated IAPs (25 mm Hg), a bladder volume of 50 mL revealed the lowest bias (-1.5 +/- 1.36 mm Hg). A bladder volume of 50 mL in patients with elevated IAP resulted in an intravesicular pressure 1 to 3 mm Hg higher than IAP (95% confidence interval). CONCLUSION: Intravesicular pressure closely approximates IAP. Instillation of 50 mL of liquid into the bladder improves the accuracy of the intravesicular pressure in measuring elevated IAPs.