The pulmonary artery catheter

Bedside Clinician's Guide to Pulmonary Artery Catheters

BACKGROUND

Pulmonary artery catheters provide important information about cardiac function, mixed venous oxygenation, and right-sided pressures and potentially provide temporary pacing ability.

OBJECTIVE

To provide bedside clinicians with guidance for techniques to insert right heart monitors and devices, describe risk factors for difficult insertion and contraindications to placement, and provide updates on new technologies that may be encountered in the intensive care unit.

METHODS

An extensive literature review was performed. Experienced clinicians were asked to identify topics not addressed in the literature.

RESULTS

Advanced imaging techniques such as transesophageal echocardiography or fluoroscopy can supplement traditional pressure waveform-guided insertion when needed, and several other techniques can be used to facilitate passage into the pulmonary artery. Caution is warranted when attempting insertion in patients with right-sided masses or preexisting conduction abnormalities. New technologies include a pacing catheter that anchors to the right ventricle and a remote monitoring device that is implanted in the pulmonary artery.

DISCUSSION

Bedside clinicians should be aware of risk factors such as atrial fibrillation with dilated atria, decreased ventricular function, pulmonary hypertension, and right-sided structural abnormalities that can make pulmonary artery catheter insertion challenging. Clinicians should be familiar with advanced techniques and imaging options to facilitate placement.

CONCLUSION

The overall risk of serious complications with right heart catheter placement and manipulation is low and often outweighed by its benefits, specifically pressure monitoring and pacing.

Oxygen saturation in intraosseous sternal blood measured by CO-oximetry and evaluated non-invasively during hypovolaemia and hypoxia - a porcine experimental study

PURPOSE

This study intended to determine, and non-invasively evaluate, sternal intraosseous oxygen saturation (SsO₂) and study its variation during provoked hypoxia or hypovolaemia. Furthermore, the relation between SsO₂ and arterial (SaO₂) or mixed venous oxygen saturation (SvO₂) was investigated.

METHODS

Sixteen anaesthetised male pigs underwent exsanguination to a mean arterial pressure of 50 mmHg. After resuscitation and stabilisation, hypoxia was induced with hypoxic gas mixtures (air/N₂). Repeated blood samples from sternal intraosseous cannulation were compared to arterial and pulmonary artery blood samples. Reflection spectrophotometry measurements by a non-invasive sternal probe were performed continuously.

RESULTS

At baseline SaO₂ was 97.0% (IQR 0.2), SsO₂ 73.2% (IQR 19.6) and SvO₂ 52.3% (IQR 12.4). During hypovolaemia, SsO₂ and SvO₂ decreased to 58.9% (IQR 16.9) and 38.1% (IQR 12.5), respectively, p < 0.05 for both, whereas SaO₂ remained unaltered (p = 0.44). During hypoxia all saturations decreased; SaO₂ 71.5% (IQR 5.2), SsO₂ 39.0% (IQR 6.9) and SvO₂ 22.6% (IQR 11.4) (p < 0.01), respectively. For hypovolaemia, the sternal probe red/infrared absorption ratio (SQV) increased significantly from baseline (indicating a reduction in oxygen saturation) + 5.1% (IQR 7.4), p < 0.001 and for hypoxia + 19.9% (IQR 14.8), p = 0.001, respectively.

CONCLUSION

Sternal blood has an oxygen saturation suggesting a mixture of venous and arterial blood. Changes in SsO₂ relate well with changes in SvO₂ during hypovolaemia or hypoxia. Further studies on the feasibility of using non-invasive measurement of changes in SsO₂ to estimate changes in SvO₂ are warranted.

Association of low mixed venous oxygen saturations during early ICU stay with increased 30-day and 1-year mortality after cardiac surgery: a single-center retrospective study

Background

Low postoperative mixed venous oxygen saturation (SvO₂) values have been linked to poor outcomes after cardiac surgery. The present study was designed to assess whether SvO₂ values of < 60% at intensive care unit (ICU) admission and 4 h after admission are associated with increased mortality after cardiac surgery.

Methods

During the years 2007–2020, 7046 patients (74.4% male; median age, 68 years [interquartile range, 60–74]) underwent cardiac surgery at an academic medical center in Finland. All patients were monitored with a pulmonary artery catheter. SvO₂ values were obtained at ICU admission and 4 h later. Patients were divided into four groups for analyses: SvO₂ ≥ 60% at ICU admission and 4 h later; SvO₂ ≥ 60% at admission but < 60% at 4 h; SvO₂ < 60% at admission but ≥ 60% at 4 h; and SvO₂ < 60% at both ICU admission and 4 h later. Kaplan–Meier survival curves, Cox regression models, and receiver operating characteristic curve analysis were used to assess differences among groups in 30-day and 1-year mortality.

Results

In the overall cohort, 52.9% underwent coronary artery bypass grafting (CABG), 29.1% valvular surgery, 12.1% combined CABG and valvular procedures, 3.5% surgery of the ascending aorta or aortic dissection, and 2.4% other cardiac surgery. The 1-year crude mortality was 4.3%. The best outcomes were associated with SvO₂ ≥ 60% at both ICU admission and 4 h later. Hazard ratios for 1-year mortality were highest among patients with SvO₂ < 60% at both ICU admission and 4 h later, regardless of surgical subgroup.

Conclusion

SvO₂ values < 60% at ICU admission and 4 h after admission are associated with increased 30-day and 1-year mortality after cardiac surgery. Goal-directed therapy protocols targeting SvO₂ ≥ 60% may be beneficial. Prospective studies are needed to confirm these observational findings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01862-8.

Cardiac output monitoring with pulmonary versus trans-cardiopulmonary thermodilution in left ventricular assist devices: Interchangeable methods?

Cardiac output (CO) measurement is mandatory in patients with left ventricular assist devices (LVADs). Thermodilution with pulmonary artery catheter (PAC) remains the clinical gold standard to measure CO in these patients, however it is associated with several complications. Therefore, the agreement between PAC and new, minimally invasive monitoring methods in LVAD needs to be further investigated. The aim of this study was to assess the accuracy and reliability of transpulmonary thermodilution with a PiCCO2 monitor compared with pulmonary artery thermodilution with PAC in a LVAD. Continuous-flow LVADs were implanted in six mini-pigs to assist the left ventricle. We studied two methods of measuring CO—intermittent transpulmonary thermodilution (CO_TPTD) by PiCCO2 and intermittent pulmonary artery thermodilution by CAP, standard technique (CO_PTD)—obtained in four consecutive moments of the study: before starting the LVAD (basal moment), and with the LVAD started in normovolemia, hypervolemia (fluid overloading) and hypovolemia (shock hemorrhage). A total of 72 paired measurements were analysed. At the basal moment, CO_TPTD and CO_PTD were closely correlated (r² = 0.89), with a mean bias of −0.085 ± 0.245 L/min and percentage error of 16%. After 15 min of partial support LVAD, CO_TPTD and CO_PTD were closely correlated (r² = 0.79), with a mean bias of −0.040 ± 0.417 L/min and percentage error of 26%. After inducing hypervolemia, CO_TPTD and CO_PTD were closely correlated (r² = 0.78), with a mean bias of −0.093 ± 0.339 L/min and percentage error of 13%. After inducing hypovolemia, CO_TPTD and CO_PTD were closely correlated (r² = 0.76), with a mean bias of −0.045 ± 0.281 L/min and percentage error of 28%. This study demonstrates a good agreement between transpulmonary thermodilution by PiCCO monitor and pulmonary thermodilution by PAC in the intermittent measurement of CO in a porcine model with a continuous-flow LVAD.

Comparison between thermodilution and Fick methods for resting and exercise‐induced cardiac output measurement in patients with chronic dyspnea

Studies comparing thermodilution (TD) and the direct Fick method (dFM) for cardiac output (CO) measurement are rare. We compared CO measurements between TD (2–5 cold water injections), the dFM, and indirect Fick method (iFM) at rest and during exercise, and assessed the effect of averaging different numbers of TD measurements during exercise. This retrospective study included 300 patients (52.3% women, mean age 66 ± 11 years) having pulmonary hypertension (76.0%) or unexplained dyspnea. Invasive hemodynamic and gas exchange parameters were measured at rest (supine; n = 300) and during unloaded cycling (semi‐supine; n = 275) and 25‐W exercise (semi‐supine; n = 240). All three methods showed significant differences in CO measurement (ΔCO) at rest (p ≤ 0.001; ΔCO > 1 L/min: 45.0% [iFM vs. dFM], 42.0% [iFM vs. TD], and 45.7% [TD vs. dFM]). ΔCO (TD vs. dFM) was significant during unloaded cycling (p < 0.001; ΔCO > 1 L/min: 56.6%) but not during 25‐W exercise (p = 0.137; ΔCO > 1 L/min: 52.8%). ΔCO (TD vs. dFM) during 25‐W exercise was significant when using one or two (p ≤ 0.01) but not three (p = 0.06) TD measurements. Mean ΔCO (TD [≥3 measurements] vs. dFM) was −0.43 ± 1.98 and −0.06 ± 2.29 L/min during unloaded and 25‐W exercise, respectively. Thus, TD and dFM CO measurements are comparable during 25‐W exercise (averaging ≥3 TD measurements), but not during unloaded cycling or at rest. Individual ΔCOs vary substantially and require critical interpretation to avoid CO misclassification.

Clinical Application of the Fluid Challenge Approach in Goal-Directed Fluid Therapy: What Can We Learn From Human Studies?

Resuscitative fluid therapy aims to increase stroke volume (SV) and cardiac output (CO) and restore/improve tissue oxygen delivery in patients with circulatory failure. In individualized goal-directed fluid therapy (GDFT), fluids are titrated based on the assessment of responsiveness status (i.e., the ability of an individual to increase SV and CO in response to volume expansion). Fluid administration may increase venous return, SV and CO, but these effects may not be predictable in the clinical setting. The fluid challenge (FC) approach, which consists on the intravenous administration of small aliquots of fluids, over a relatively short period of time, to test if a patient has a preload reserve (i.e., the relative position on the Frank-Starling curve), has been used to guide fluid administration in critically ill humans. In responders to volume expansion (defined as individuals where SV or CO increases ≥10–15% from pre FC values), FC administration is repeated until the individual no longer presents a preload reserve (i.e., until increases in SV or CO are <10–15% from values preceding each FC) or until other signs of shock are resolved (e.g., hypotension). Even with the most recent technological developments, reliable and practical measurement of the response variable (SV or CO changes induced by a FC) has posed a challenge in GDFT. Among the methods used to evaluate fluid responsiveness in the human medical field, measurement of aortic flow velocity time integral by point-of-care echocardiography has been implemented as a surrogate of SV changes induced by a FC and seems a promising non-invasive tool to guide FC administration in animals with signs of circulatory failure. This narrative review discusses the development of GDFT based on the FC approach and the response variables used to assess fluid responsiveness status in humans and animals, aiming to open new perspectives on the application of this concept to the veterinary field.

Perioperative Hemodynamic Monitoring: An Overview of Current Methods

Perioperative hemodynamic monitoring is an essential part of anesthetic care. In this review, we aim to give an overview of methods currently used in the clinical routine and experimental methods under development. The technical aspects of the mentioned methods are discussed briefly. This review includes methods to monitor blood pressures, for example, arterial pressure, mean systemic filling pressure and central venous pressure, and volumes, for example, global end-diastolic volume (GEDV) and extravascular lung water. In addition, monitoring blood flow (cardiac output) and fluid responsiveness (preload) will be discussed.

Cephalad misplacement of a pulmonary artery catheter in a patient with a preexisting Hickman catheter

Background

Pulmonary artery catheter insertion is a routine practice in high-risk patients undergoing cardiac surgery. However, pulmonary artery catheter insertion is associated with numerous complications that can be devastating to the patient. Incorrect placement is an overlooked complication with few case reports to date.

Case presentation

An 18-year-old male patient underwent elective mitral valve replacement due to severe mitral valve regurgitation. The patient had a history of synovial sarcoma, and Hickman catheter had been inserted in the right internal jugular vein for systemic chemotherapy. We made multiple attempts to position the pulmonary artery catheter in the correct position but failed. A chest radiography revealed that the pulmonary artery catheter was bent and pointed in the cephalad direction. Removal of the pulmonary artery catheter was successful, and the patient was discharged 10 days after the surgery without complications.

Conclusions

To prevent misplacement of the PAC, clinicians should be aware of multiple risk factors in difficult PAC placement, and be prepared to utilize adjunctive methods, such as TEE and fluoroscopy.

Agreement between continuous and intermittent pulmonary artery thermodilution for cardiac output measurement in perioperative and intensive care medicine: a systematic review and meta-analysis

BACKGROUND

Pulmonary artery thermodilution is the clinical reference method for cardiac output monitoring. Because both continuous and intermittent pulmonary artery thermodilution are used in clinical practice it is important to know whether cardiac output measurements by the two methods are clinically interchangeable.

METHODS

We performed a systematic review and meta-analysis of clinical studies comparing cardiac output measurements assessed using continuous and intermittent pulmonary artery thermodilution in adult surgical and critically ill patients. 54 studies with 1522 patients were included in the analysis.

RESULTS

The heterogeneity across the studies was high. The overall random effects model-derived pooled estimate of the mean of the differences was 0.08 (95%-confidence interval 0.01 to 0.16) L/min with pooled 95%-limits of agreement of - 1.68 to 1.85 L/min and a pooled percentage error of 29.7 (95%-confidence interval 20.5 to 38.9)%.

CONCLUSION

The heterogeneity across clinical studies comparing continuous and intermittent pulmonary artery thermodilution in adult surgical and critically ill patients is high. The overall trueness/accuracy of continuous pulmonary artery thermodilution in comparison with intermittent pulmonary artery thermodilution is good (indicated by a pooled mean of the differences < 0.1 L/min). Pooled 95%-limits of agreement of - 1.68 to 1.85 L/min and a pooled percentage error of 29.7% suggest that continuous pulmonary artery thermodilution barely passes interchangeability criteria with intermittent pulmonary artery thermodilution. PROSPERO registration number CRD42020159730.

New Advances in Monitoring Cardiac Output in Circulatory Mechanical Assistance Devices. A Validation Study in a Porcine Model

Cardiac output (CO) measurement by continuous pulmonary artery thermodilution (CO_CTD) has been studied in patients with pulsatile-flow LVADs (left ventricular assist devices), confirming the clinical utility. However, it has not been validated in patients with continuous-flow LVADs. Therefore, the aim of this study was to assess the validity of CO_CTD in continuous-flow LVADs. Continuous-flow LVADs were implanted in six miniature pigs for partial assistance of the left ventricle. Both methods of measuring CO—measurement by CO_CTD and intermittent pulmonary artery thermodilution, standard technique (CO_ITD)—were used in four consecutive moments of the study: before starting the LVAD (basal moment), and with the LVAD started in normovolemia, hypervolemia (fluid overloading), and hypovolemia (shock hemorrhage). At the basal moment, CO_CTD and CO_ITD were closely correlated (r² = 0.97), with a mean bias of −0.13 ± 0.16 L/min and percentage error of 11%. After 15 min of partial support LVAD, CO_CTD and CO_ITD were closely correlated (r² = 0.91), with a mean bias of 0.31 ± 0.35 L/min and percentage error of 20%. After inducing hypervolemia, CO_CTD and CO_ITD were closely correlated (r² = 0.99), with a mean bias of 0.04 ± 0.07 L/min and percentage error of 5%. After inducing hypovolemia, CO_CTD and CO_ITD were closely correlated (r² = 0.74), with a mean bias of 0.08 ± 0.22 L/min and percentage error of 19%. This study shows that continuous pulmonary thermodilution could be an alternative method of monitoring CO in a porcine model with a continuous-flow LVAD.

Performance of Electrical Velocimetry for Noninvasive Cardiac Output Measurements in Perioperative Patients After Subarachnoid Hemorrhage

BACKGROUND

Fluid therapy guided by cardiac output measurements is of particular importance for adequate cerebral perfusion and oxygenation in neurosurgical patients. We examined the usefulness of a noninvasive electrical velocimetry (EV) device based on the thoracic bioimpedance method for perioperative hemodynamic monitoring in patients after aneurysmal subarachnoid hemorrhage.

PATIENTS AND METHODS

In total, 18 patients who underwent surgical clipping or endovascular coiling for ruptured aneurysms were examined prospectively. Simultaneous cardiac index (CI) measurements obtained with EV (CIEV) and reference transpulmonary thermodilution (CITPTD) were compared. A total of 223 pairs of data were collected.

RESULTS

A significant correlation was found between CIEV and CITPTD (r=0.86; P<0.001). Bland and Altman analysis revealed a bias between CIEV and CITPTD of -0.06 L/min/m, with limits of agreement of ±1.14 L/min/m and a percentage error of 33%. Although the percentage error for overall data was higher than the acceptable limit of 30%, subgroup analysis during the postoperative phase showed better agreement (23% vs. 42% during the intraprocedure phase). Four-quadrant plot and polar plot analyses showed fair-to-poor trending abilities (concordance rate of 90% to 91%, angular bias of +17 degrees, radial limits of agreement between ±37 and ±40 degrees, and polar concordance rate of 72% to 75%), including the subgroup analysis.

CONCLUSIONS

Absolute CI values obtained from EV and TPTD are not interchangeable with TPTD for perioperative use in subarachnoid hemorrhage patients. However, considering the moderate levels of agreement with marginal trending ability during the early postoperative phase, this user-friendly device can provide an attractive monitoring option during neurocritical care.

Best practice & research clinical anaesthesiology: Advances in haemodynamic monitoring for the perioperative patient: Perioperative cardiac output monitoring

Less invasive or even completely non-invasive haemodynamic monitoring technologies have evolved during the last decades. Even established, invasive devices such as the pulmonary artery catheter and transpulmonary thermodilution have still an evidence-based place in the perioperative setting, albeit only in special patient populations. Accumulating evidence suggests to use continuous haemodynamic monitoring, especially flow-based variables such as stroke volume or cardiac output to prevent occult hypoperfusion and, consequently, decrease morbidity and mortality perioperatively. However, there is still a substantial gap between evidence provided by randomised trials and the implementation of haemodynamic monitoring in daily clinical routine. Given the fact that perioperative morbidity and mortality are higher than anticipated and anaesthesiologists are in charge to deal with this problem, the recent advances in minimally invasive and non-invasive monitoring technologies may facilitate more widespread use in the operating theatre, as in addition to costs, the degree of invasiveness of any monitoring tool determines the frequency of its application, at least perioperatively. This review covers the currently available invasive, non-invasive and minimally invasive techniques and devices and addresses their indications and limitations.

The Variation of Hemodynamic Parameters Through PiCCO in the Early Stage After Severe Burns

To investigate early hemodynamics of severely burned patients via PiCCO and to discuss clinical significance of hemodynamic monitoring for burn shock resuscitation, 55 extensive burn patients were enrolled in this retrospective study. The fluid resuscitation was guided according to Chinese General Formula and adjusted with urinary output of 0.5-1.0 ml/h/kg as a resuscitation goal. All patients were diagnosed within a relatively stable condition during burn shock stage, and they received PiCCO monitoring within 6 hours after burn. The preload parameter intrathoracic blood volume index was low at first, then returned to normal. The flow parameter cardiac index and myocardial contractility parameter dPmax were gradually changed from low level in the early stage to high level in the fluid reabsorption stage. The afterload parameter systemic vascular resistance index had completely opposite tendency. The lung-related parameters extravascular lung water index and pulmonary vascular permeability index were roughly in the normal range. The change of cardiac index had a linear regression relationship with dPmax and systemic vascular resistance index but had no significant relationship with intrathoracic blood volume index. Under effective fluid resuscitation, the early hemodynamics after burn is still in dynamically changing status, characterized as transition from low cardiac output (CO)-high vascular resistance in early shock stage to high CO-low vascular resistance in fluid reabsorption stage. CO mainly depends on the myocardial contractility and vascular resistance, but not on the blood volume. Excessive fluid resuscitation cannot get normal CO. The normal value of hemodynamics cannot be used as end point of burn shock resuscitation. Dynamic observation of hemodynamics is of great importance.

Electrical velocimetry for noninvasive cardiac output and stroke volume variation measurements in dogs undergoing cardiovascular surgery

OBJECTIVE

To compare electrical velocimetry (EV) noninvasive measures of cardiac output (CO) and stroke volume variation (SVV) in dogs undergoing cardiovascular surgery with those obtained with the conventional thermodilution technique using a pulmonary artery catheter.

STUDY DESIGN

Prospective experimental trial.

ANIMALS

Seven adult Beagle dogs with a median weight of 13.6 kg.

METHODS

Simultaneous, coupled cardiac index (CI; CO indexed to body surface area) measurements by EV (CI_EV) and the reference pulmonary artery catheter thermodilution method (CI_PAC) were obtained in seven sevoflurane-anaesthetized, mechanically ventilated dogs undergoing experimental open-chest cardiovascular surgery for isolated right ventricular failure. Relationships between SVV or central venous pressure (CVP) and stroke volume (SV) were analysed to estimate fluid responsiveness. Haemodynamic data were recorded intraoperatively and before and after fluid challenge.

RESULTS

Bland-Altman analysis of 332 matched sets of CI data revealed an overall bias and precision of - 0.22 ± 0.52 L minute^-1 m^-2 for CI_EV and CI_PAC (percentage error: 30.4%). Trend analysis showed a concordance of 88% for CI_EV. SVV showed a significant positive correlation (r² = 0.442, p < 0.0001) with SV changes to a volume loading of 200 mL, but CVP did not (r² = 0.0002, p = 0.94). Better prediction of SV responsiveness (rise of SV index of ≥ 10%) was observed for SVV (0.74 ± 0.09; p = 0.014) with a significant area under the receiver operating characteristic curve in comparison with CVP (0.53 ± 0.98; p = 0.78), with a cut-off value of 14.5% (60% specificity and 83% sensitivity).

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs undergoing cardiovascular surgery, EV provided accurate CO measurements compared with CI_PAC, although its trending ability was poor. Further, SVV by EV, but not CVP, reliably predicted fluid responsiveness during mechanical ventilation in dogs.

Perioperative cardiovascular monitoring of high-risk patients: a consensus of 12

A significant number of surgical patients are at risk of intra- or post-operative complications or both, which are associated with increased lengths of stay, costs, and mortality. Reducing these risks is important for the individual patient but also for health-care planners and managers. Insufficient tissue perfusion and cellular oxygenation due to hypovolemia, heart dysfunction or both is one of the leading causes of perioperative complications. Adequate perioperative management guided by effective and timely hemodynamic monitoring can help reduce the risk of complications and thus potentially improve outcomes. In this review, we describe the various available hemodynamic monitoring systems and how they can best be used to guide cardiovascular and fluid management in the perioperative period in high-risk surgical patients.

B-type natriuretic peptide secretion without change in intra-cardiac pressure

OBJECTIVE

In clinical cardiology, B-type natriuretic peptide (BNP) is used as a non-invasive surrogate marker for intra-cardiac filling pressures, particularly in patients with heart failure. It is unknown whether and to what extent increase in intravascular volume and/or sympathetic tone while maintaining constant intra-cardiac pressures leads to an increase in levels of BNP in vivo.

DESIGN AND METHODS

We aimed to test this hypothesis in an experimental in vivo model of patients directly after off-pump coronary artery bypass grafting admitted to the intensive care unit. These patients require high volumes of intravenous fluids titrated to keep intra-cardiac filling pressures and arterial blood pressure in the normal range while awakening from deep general anesthesia. In 27 consecutive patients, intra-cardiac filling pressures (using a pulmonary artery catheter) and levels of BNP were measured simultaneously every 6h.

RESULTS

At 0, 6, 12, and 18h, the pulmonary capillary wedge pressure remained constant (12±4, 13±3, 12±3, and 13±3mmHg, respectively; p=0.351). Similarly, right heart filling pressures did not change during the study period. In contrast, BNP levels increased significantly during the study period: Median levels were 82 [IQR 37-162] pg/ml at 0h, 153 [92-246] pg/ml at 6h, 274 [156-392] pg/ml at 12h, and 320 [200-528] pg/ml at 18h (p<0.001). No significant correlation between BNP levels and pulmonary capillary wedge pressures was found (r=0.052; p=0.604).

CONCLUSIONS

After cardiac surgery, BNP cannot be considered a reliable non-invasive surrogate for PCWP. In vivo, substantial BNP secretion occurs independently of PCWP in a setting of increasing intravascular volume and consciousness/sympathetic tone.

Measurement of cardiac index by transpulmonary thermodilution using an implanted central venous access port: a prospective study in patients scheduled for oncologic high-risk surgery

Background

Transpulmonary thermodilution allows the measurement of cardiac index for high risk surgical patients. Oncologic patients often have a central venous access (port-a-catheter) for chronic treatment. The validity of the measurement by a port-a-catheter of the absolute cardiac index and the detection of changes in cardiac index induced by fluid challenge are unknown.

Methods

We conducted a monocentric prospective study. 27 patients were enrolled. 250 ml colloid volume expansions for fluid challenge were performed during ovarian cytoreductive surgery. The volume expansion-induced changes in cardiac index measured by transpulmonary thermodilution by a central venous access (CIcvc) and by a port-a-catheter (CIport) were recorded.

Results

23 patients were analyzed with 123 pairs of measurements. Using a Bland and Altman for repeated measurements, the bias (lower and upper limits of agreement) between CIport and CIcvc was 0.14 (−0.59 to 0.88) L/min/m². The percentage error was 22%. The concordance between the changes in CIport and CIcvc observed during volume expansion was 92% with an r = 0.7 (with exclusion zone). No complications (included sepsis) were observed during the follow up period.

Conclusions

The transpulmonary thermodilution by a port-a-catheter is reliable for absolute values estimation of cardiac index and for measurement of the variation after fluid challenge.

Trial Registration

clinicaltrials.gov NCT02063009

Validation of the vascular pedicle width as a diagnostic aid in critically ill patients with pulmonary oedema by novice non-radiology physicians-in-training

Assessing intravascular volume status in the critically ill patient remains a challenge for intensivists, and the accuracy of such estimation based on bedside examination alone is reported to be nearly a coin toss. In this retrospective study we sought to validate a previously recommended chest radiographic vascular pedicle width (VPW) ≥70 mm for identifying cardiogenic pulmonary oedema (CPO). We additionally assessed whether novice physicians-in-training can reliably measure the VPW. The study included intensive care patients with an existing pulmonary artery catheter. Three independent raters performed measurements of VPW from chest radiographs obtained within three hours of pulmonary artery occlusion pressure measurements. In 80 patients enrolled, a VPW cut-off of ≥70 mm had a 55% sensitivity, 88% specificity, 81% positive predictive value, 69% negative predictive value and 73% accuracy for identifying patients with CPO. Receiver operating characteristic curve analysis showed an area under the curve of 0.72 (95% confidence interval 0.61 to 0.84) for VPW in discriminating CPO from non-cardiogenic pulmonary oedema. Kappa statistics for inter-rater reliability showed Kappa=0.41, 0.42 and 0.85 for each pair of the three raters. In conclusion, the previously accepted VPW cut-off of ≥70 mm is reasonably accurate in discriminating CPO from non-cardiogenic pulmonary oedema. VPW can be measured by physicians-in-training with a comparable performance to previous studies utilising expert radiologists.

Brain-type natriuretic peptide and right ventricular end-diastolic volume index measurements are imprecise estimates of circulating blood volume in critically ill subjects

BACKGROUND

Surrogate indicators have often been used to estimate intravascular volume to guide fluid management. Brain-type natriuretic peptide (BNP) has been used as a noninvasive adjunct in the diagnosis of fluid overload and as a marker of response to therapy, especially in individuals with congestive heart failure. Similarly, right ventricular end-diastolic volume index (RVEDVI) measurements represent another parameter used to guide fluid resuscitation. The aim of this study was to evaluate whether BNP and RVEDVI are clinically valuable parameters that can distinguish among hypovolemia, euvolemia, and hypervolemia, as measured by blood volume (BV) analysis in critically ill surgical subjects.

METHODS

This observational study was part of a prospective, randomized controlled trial. Subjects with pulmonary artery catheters for the treatment of traumatic injuries, severe sepsis/septic shock, cardiovascular collapse, adult respiratory distress syndrome, and postsurgical care were studied. Circulating BV was measured by a radioisotope dilution technique using the BVA-100 Analyzer (Daxor Corporation, New York, NY) within the first 24 hours of acute resuscitation. BV results were reported as percent deviation from the patient's ideal BV based on height and percent deviation from optimum weight. Hypovolemia was defined as less than 0%, euvolemia was defined as 0% to +16%, and hypervolemia was defined as greater than +16% deviation from ideal BV. RVEDVI was measured by continuous cardiac output pulmonary artery catheters (Edwards Lifesciences, Irvine, CA). BNP and RVEDVI measurements obtained with BV analysis were evaluated with Fisher's exact test and regression analysis.

RESULTS

In 81 subjects, there was no difference in BV status between those with BNP of 500 pg/mL or greater and BNP of less than 500 pg/mL (p = 0.82) or in those with RVEDVI of 140 mL/m or greater and RVEDVI of less than 140 mL/m (p = 0.43). No linear relationship existed between BV and these parameters.

CONCLUSION

In critically ill surgical patients, BNP and RVEDVI were not associated with intravascular volume status, although they may be useful as indices that reflect increased cardiac preload.

LEVEL OF EVIDENCE

Diagnostic study, level III.