1
|
Berger D, Werner Moller P, Bachmann KF. Cardiopulmonary interactions-which monitoring tools to use? Front Physiol 2023; 14:1234915. [PMID: 37621761 PMCID: PMC10445648 DOI: 10.3389/fphys.2023.1234915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 07/18/2023] [Indexed: 08/26/2023] Open
Abstract
Heart-lung interactions occur due to the mechanical influence of intrathoracic pressure and lung volume changes on cardiac and circulatory function. These interactions manifest as respiratory fluctuations in venous, pulmonary, and arterial pressures, potentially affecting stroke volume. In the context of functional hemodynamic monitoring, pulse or stroke volume variation (pulse pressure variation or stroke volume variability) are commonly employed to assess volume or preload responsiveness. However, correct interpretation of these parameters requires a comprehensive understanding of the physiological factors that determine pulse pressure and stroke volume. These factors include pleural pressure, venous return, pulmonary vessel function, lung mechanics, gas exchange, and specific cardiac factors. A comprehensive knowledge of heart-lung physiology is vital to avoid clinical misjudgments, particularly in cases of right ventricular (RV) failure or diastolic dysfunction. Therefore, when selecting monitoring devices or technologies, these factors must be considered. Invasive arterial pressure measurements of variations in breath-to-breath pressure swings are commonly used to monitor heart-lung interactions. Echocardiography or pulmonary artery catheters are valuable tools for differentiating preload responsiveness from right ventricular failure, while changes in diastolic function should be assessed alongside alterations in airway or pleural pressure, which can be approximated by esophageal pressure. In complex clinical scenarios like ARDS, combined forms of shock or right heart failure, additional information on gas exchange and pulmonary mechanics aids in the interpretation of heart-lung interactions. This review aims to describe monitoring techniques that provide clinicians with an integrative understanding of a patient's condition, enabling accurate assessment and patient care.
Collapse
Affiliation(s)
- David Berger
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Per Werner Moller
- Department of Anaesthesia, SV Hospital Group, Institute of Clinical Sciences at the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Kaspar F. Bachmann
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Anaesthesiology and Intensive Care, University of Tartu, Tartu, Estonia
| |
Collapse
|
2
|
Wijnberge M, Jansen JRC, Pinsky MR, Klanderman RB, Terwindt LE, Bosboom JJ, Lemmers N, Vlaar AP, Veelo DP, Geerts BF. Feasibility to estimate mean systemic filling pressure with inspiratory holds at the bedside. Front Physiol 2022; 13:1041730. [PMID: 36523553 PMCID: PMC9745184 DOI: 10.3389/fphys.2022.1041730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 10/25/2022] [Indexed: 11/30/2022] Open
Abstract
Background: A decade ago, it became possible to derive mean systemic filling pressure (MSFP) at the bedside using the inspiratory hold maneuver. MSFP has the potential to help guide hemodynamic care, but the estimation is not yet implemented in common clinical practice. In this study, we assessed the ability of MSFP, vascular compliance (Csys), and stressed volume (Vs) to track fluid boluses. Second, we assessed the feasibility of implementation of MSFP in the intensive care unit (ICU). Exploratory, a potential difference in MSFP response between colloids and crystalloids was assessed. Methods: This was a prospective cohort study in adult patients admitted to the ICU after cardiac surgery. The MSFP was determined using 3-4 inspiratory holds with incremental pressures (maximum 35 cm H2O) to construct a venous return curve. Two fluid boluses were administered: 100 and 500 ml, enabling to calculate Vs and Csys. Patients were randomized to crystalloid or colloid fluid administration. Trained ICU consultants acted as study supervisors, and protocol deviations were recorded. Results: A total of 20 patients completed the trial. MSFP was able to track the 500 ml bolus (p < 0.001). In 16 patients (80%), Vs and Csys could be determined. Vs had a median of 2029 ml (IQR 1605-3164), and Csys had a median of 73 ml mmHg-1 (IQR 56-133). A difference in response between crystalloids and colloids was present for the 100 ml fluid bolus (p = 0.019) and in a post hoc analysis, also for the 500 ml bolus (p = 0.010). Conclusion: MSFP can be measured at the bedside and provides insights into the hemodynamic status of a patient that are currently missing. The clinical feasibility of Vs and Csys was judged ambiguously based on the lack of required hemodynamic stability. Future studies should address the clinical obstacles found in this study, and less-invasive alternatives to determine MSFP should be further explored. Clinical Trial Registration: ClinicalTrials.gov Identifier NCT03139929.
Collapse
Affiliation(s)
- Marije Wijnberge
- Amsterdam UMC Location Academic Medical Center, Department of Anesthesiology, Amsterdam, Netherlands
- Amsterdam UMC Location Academic Medical Center, Department of Intensive Care Medicine, Amsterdam, Netherlands
- *Correspondence: Marije Wijnberge, Alexander P. Vlaar,
| | - Jos R. C. Jansen
- Leiden University Medical Center, Department of Intensive Care Medicine, Leiden, Netherlands
| | - Michael R. Pinsky
- Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Robert B. Klanderman
- Amsterdam UMC Location Academic Medical Center, Department of Anesthesiology, Amsterdam, Netherlands
- Amsterdam UMC Location Academic Medical Center, Department of Intensive Care Medicine, Amsterdam, Netherlands
| | - Lotte E. Terwindt
- Amsterdam UMC Location Academic Medical Center, Department of Anesthesiology, Amsterdam, Netherlands
| | - Joachim J. Bosboom
- Amsterdam UMC Location Academic Medical Center, Department of Anesthesiology, Amsterdam, Netherlands
- Amsterdam UMC Location Academic Medical Center, Department of Intensive Care Medicine, Amsterdam, Netherlands
| | - Nikki Lemmers
- Amsterdam UMC Location Academic Medical Center, Department of Anesthesiology, Amsterdam, Netherlands
| | - Alexander P. Vlaar
- Amsterdam UMC Location Academic Medical Center, Department of Intensive Care Medicine, Amsterdam, Netherlands
- *Correspondence: Marije Wijnberge, Alexander P. Vlaar,
| | - Denise P. Veelo
- Amsterdam UMC Location Academic Medical Center, Department of Anesthesiology, Amsterdam, Netherlands
| | | |
Collapse
|
3
|
De Blasi RA, Finazzi S. Validation of the mean systemic filling pressure assessment with preserved arterial blood flow by comparing two methods of calculation. Sci Rep 2021; 11:15844. [PMID: 34349219 PMCID: PMC8338930 DOI: 10.1038/s41598-021-95350-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 07/22/2021] [Indexed: 11/28/2022] Open
Abstract
We developed a method for measuring in vivo venular volumes and the mean systemic filling pressure in the limbs using near-infrared spectroscopy (NIRS). We aimed to validate the NIRS methodology by comparing two independent methods of calculation based on different physiological approaches. Pressure–volumes (P–V) curves were recorded following graded venous occlusion on the forearm. Values from a P–V curves analysis model (method 1) were compared with data derived from a resistor-capacitance calculation model (method 2) based on arterial pressure and venous compliance. We tested these methods on 10 healthy participants at rest and during exercise and on 6 severely ill patients. Results from method 1 were comparable with those calculated by method 2. Venular volumes calculated using method 1 correlated linearly with those calculated using method 2 both in participants (R2 = 0.98) and in patients (R2 = 0.94). A good agreement between methods was shown with few values out of the range of ± 1.96 standard deviation. Our findings added mathematical consistency for the NIRS methodology validation in the venular P–V assessment with no flow interruption. Further research will be required to confirm the relevance of the methodology in the clinical setting.
Collapse
Affiliation(s)
- Roberto Alberto De Blasi
- Dipartimento di Scienze Medico-Chirurgiche e Medicina Traslazionale, Università degli studi di Roma Sapienza, Via di Grottarossa 1035, 00189, Rome, Italy.
| | - Stefano Finazzi
- Laboratorio di Clinical Data Science, Dipartimento di Salute Pubblica, Istituto di Ricerche farmacologiche Mario Negri IRCCS, Ranica, BG, Italy
| |
Collapse
|
4
|
He H, Yuan S, Long Y, Liu D, Zhou X, Ince C. Effect of norepinephrine challenge on cardiovascular determinants assessed using a mathematical model in septic shock: a physiological study. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:561. [PMID: 33987259 PMCID: PMC8105783 DOI: 10.21037/atm-20-6686] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/12/2021] [Indexed: 11/06/2022]
Abstract
BACKGROUND The present study investigated the cardiovascular determinants of cardiac output (CO), mean systemic filling pressure analogue (Pmsa) derived by Geoffrey Parkin, efficiency of heart (Eh) and related parameters to a norepinephrine (NE) challenge [an increase of 10 mmHg mean arterial pressure (MAP) by NE] in septic shock patients using of a mathematical model. METHODS Twenty-seven septic shock patients with pulse index continuous cardiac output (PiCCO) monitoring were enrolled. These patients required NE to maintain an individualized MAP for organ perfusion after early fluid resuscitation based on their clinical condition. NE was decreased to obtain a decrease of 10 mmHg from base MAP (MAP-10mmHg), and the NE doses were adjusted to return MAP to baseline (MAPbase) and produce an increase of 10 mmHg from MAPbase (MAP+10mmHg). Two NE challenge episodes were analyzed for each patient: from MAP-10mmHg to MAPbase and from MAPbase to MAP+10mmHg. The Pmsa, pressure gradient for venous return (PGvr), and Eh (PGvr relative to Pmsa) were estimated using a mathematical model for the three MAP levels (MAP-10mmHg, MAPbase and MAP+10mmHg). RESULTS A total of 54 episodes of NE challenges were obtained in 27 patients. Significant and consistent increases were observed in the central venous pressure (CVP), Pmsa, and PGvr in response during the NE titration. ΔCO negatively and significantly correlated with ΔCVP (r=-0.722, P<0.0001), ΔPmsa (r=-0.549, P<0.0001), ΔResistance of venous return (Rvr) (r=-0.597, P<0.0001), and ΔResistance of systemic vascular beds (Rsys) (r=-0.597, P<0.0001). Episodes of decreasing CO/Eh were associated with a higher ΔCVP than the CO/Eh-increasing episodes. The area under the curve (AUC) of ΔCVP to predict decreased CO by the incremental NE was 0.86, and the AUC of ΔCVP to predict decreased Eh was 0.94. A cutoff of ΔCVP >1.5 mmHg for detecting decreased CO resulted in a sensitivity of 75% and a specificity of 94.1%. A cutoff of ΔCVP >1.5 mmHg for detecting decreased Eh resulted in a sensitivity of 64.3% and a specificity of 100%. CONCLUSIONS There were a highly divergent response in Eh and CO to afterload challenge episodes of an NE-induced 10mmHg increase in MAP. An increase in CVP may be an early alarm to identify the reduction in CO/Eh during an NE-induced increase of MAP.
Collapse
Affiliation(s)
- Huaiwu He
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Siyi Yuan
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Yun Long
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Dawei Liu
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Xiang Zhou
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
| | - Can Ince
- Department of Intensive Care, Erasmus MC University Hospital, Rotterdam, The Netherlands
| |
Collapse
|
5
|
Meijs LPB, van Houte J, Conjaerts BCM, Bindels AJGH, Bouwman A, Houterman S, Bakker J. Clinical validation of a computerized algorithm to determine mean systemic filling pressure. J Clin Monit Comput 2021; 36:191-198. [PMID: 33791920 PMCID: PMC8011774 DOI: 10.1007/s10877-020-00636-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 12/14/2020] [Indexed: 11/29/2022]
Abstract
Mean systemic filling pressure (Pms) is a promising parameter in determining intravascular fluid status. Pms derived from venous return curves during inspiratory holds with incremental airway pressures (Pms-Insp) estimates Pms reliably but is labor-intensive. A computerized algorithm to calculate Pms (Pmsa) at the bedside has been proposed. In previous studies Pmsa and Pms-Insp correlated well but with considerable bias. This observational study was performed to validate Pmsa with Pms-Insp in cardiac surgery patients. Cardiac output, right atrial pressure and mean arterial pressure were prospectively recorded to calculate Pmsa using a bedside monitor. Pms-Insp was calculated offline after performing inspiratory holds. Intraclass-correlation coefficient (ICC) and assessment of agreement were used to compare Pmsa with Pms-Insp. Bias, coefficient of variance (COV), precision and limits of agreement (LOA) were calculated. Proportional bias was assessed with linear regression. A high degree of inter-method reliability was found between Pmsa and Pms-Insp (ICC 0.89; 95%CI 0.72–0.96, p = 0.01) in 18 patients. Pmsa and Pms-Insp differed not significantly (11.9 mmHg, IQR 9.8–13.4 vs. 12.7 mmHg, IQR 10.5–14.4, p = 0.38). Bias was −0.502 ± 1.90 mmHg (p = 0.277). COV was 4% with LOA –4.22 − 3.22 mmHg without proportional bias. Conversion coefficient Pmsa ➔ Pms-Insp was 0.94. This assessment of agreement demonstrates that the measures Pms-Insp and the computerized Pmsa-algorithm are interchangeable (bias −0.502 ± 1.90 mmHg with conversion coefficient 0.94). The choice of Pmsa is straightforward, it is non-interventional and available continuously at the bedside in contrast to Pms-Insp which is interventional and calculated off-line. Further studies should be performed to determine the place of Pmsa in the circulatory management of critically ill patients. (www.clinicaltrials.gov; TRN NCT04202432, release date 16-12-2019; retrospectively registered). Clinical Trial Registrationwww.ClinicalTrials.gov, TRN: NCT04202432, initial release date 16-12-2019 (retrospectively registered).
Collapse
Affiliation(s)
- Loek P B Meijs
- Department of Intensive Care, Catharina Hospital, Eindhoven, The Netherlands. .,Department of Cardiology, Catharina Hospital, Eindhoven, The Netherlands.
| | - Joris van Houte
- Department of Intensive Care, Catharina Hospital, Eindhoven, The Netherlands.,Department of Anesthesiology, Catharina Hospital, Eindhoven, The Netherlands
| | - Bente C M Conjaerts
- Department of Anesthesiology, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | - Arthur Bouwman
- Department of Anesthesiology, Catharina Hospital, Eindhoven, The Netherlands
| | - Saskia Houterman
- Department of Research and Education, Catharina Hospital, Eindhoven, The Netherlands
| | - Jan Bakker
- Department of Intensive Care, Erasmus MC University Medical Centre, Rotterdam, The Netherlands.,Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University Medical Center, New York, NY, USA.,Department of Pulmonary and Critical Care, New York University, New York, NY, USA.,Department of Intensive Care, Pontificia Universidad Católica de Chile, Santiago, Chile
| |
Collapse
|
6
|
van Loon LM, van der Hoeven H, Veltink PH, Lemson J. The inspiration hold maneuver is a reliable method to assess mean systemic filling pressure but its clinical value remains unclear. ANNALS OF TRANSLATIONAL MEDICINE 2020; 8:1390. [PMID: 33313135 PMCID: PMC7723632 DOI: 10.21037/atm-20-3540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background The upstream pressure for venous return (VR) is considered to be a combined conceptual blood pressure of the systemic vessels: the mean systemic filling pressure (MSFP). The relevance of estimating the MSFP during dynamic changes of the circulation at the bedside is controversial. Herein, we studied the effect of high ventilatory pressures on the relationship between VR and central venous pressure (CVP). Methods In 9 healthy pigs under anaesthesia and mechanically ventilated, MSFP was estimated from extrapolated VR versus CVP relationships during inspiratory hold maneuvers (IHMs) with different levels of ventilatory pressure (Pvent). MSFP was measure 3 times per animal during euvolemia and hypovolemia. Hypovolemia was induced by bleeding with 10 mL/kg. The estimated MSFP values were compared to the blood pressure recording after induced ventricle fibrillation (i.e., mean circulatory filling pressure). Results Our results revealed a strong linear correlation between VR and CVP [R2 of 0.92 (range, 0.67–0.99)], during IHMs with different levels of Pvent. Volume status significantly alters the resulting MSFP, 20±1 and 16±2 mmHg for euvolemia and hypovolemia respectively. This estimation of the MSFP was strongly correlated—but not interchangeable—to the blood pressure recording after induced ventricle fibrillation (R2=0.8 and P=0.045). Conclusions In conclusion, we showed a strong linear correlation between VR and CVP—when applying IHMs with high levels of Pvent—however the clinical applicability of this method to guide volume therapy in its current form is improbable.
Collapse
Affiliation(s)
- Lex M van Loon
- Cardiovascular and Respiratory Physiology Group, Faculty of Science and Technology, Technical Medical Centre, University of Twente, Enschede, The Netherlands.,Department of Intensive Care Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Hans van der Hoeven
- Department of Intensive Care Medicine, Radboud university medical center, Nijmegen, The Netherlands.,Radboud Center for Infectious Diseases, Nijmegen, The Netherlands
| | - Peter H Veltink
- Biomedical Signals and Systems, Faculty of Electrical Engineering, Mathematics and Computer Science, Technical Medical Centre, University of Twente, Enschede, The Netherlands
| | - Joris Lemson
- Department of Intensive Care Medicine, Radboud university medical center, Nijmegen, The Netherlands
| |
Collapse
|
7
|
Werner-Moller P, Sondergaard S, Jakob SM, Takala J, Berger D. Effect of volume status on the estimation of mean systemic filling pressure. J Appl Physiol (1985) 2019; 126:1503-1513. [PMID: 30817243 DOI: 10.1152/japplphysiol.00897.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Various methods for indirect assessment of mean systemic filling pressure (MSFP) produce controversial results compared with MSFP at zero blood flow. We recently reported that the difference between MSFP at zero flow measured by right atrial balloon occlusion (MSFPRAO) and MSFP estimated using inspiratory holds depends on the volume status. We now compare three indirect estimates of MSFP with MSFPRAO in euvolemia, bleeding, and hypervolemia in a model of anesthetized pigs (n = 9) with intact circulation. MSFP was estimated using instantaneous beat-to-beat venous return during tidal ventilation (MSFPinst_VR), right atrial pressure-flow data pairs at flow nadir during inspiratory holds (MSFPnadir_hold), and a dynamic model analog adapted to pigs (MSFPa). MSFPRAO was underestimated by MSFPnadir_hold and MSFPa in all volume states. Volume status modified the difference between MSFPRAO and all indirect methods (method × volume state interaction, P ≤ 0.020). All methods tracked changes in MSFPRAO concordantly, with the lowest bias seen for MSFPa [bias (confidence interval): -0.4 (-0.7 to -0.0) mmHg]. We conclude that indirect estimates of MSFP are unreliable in this experimental setup. NEW & NOTEWORTHY For indirect estimations of MSFP using inspiratory hold maneuvers, instantaneous beat-to-beat venous return, or a dynamic model analog, the accuracy was affected by the underlying volume state. All methods investigated tracked changes in MSFPRAO concordantly.
Collapse
Affiliation(s)
- Per Werner-Moller
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern , Bern , Switzerland.,Department of Anesthesiology and Intensive Care Medicine, Institute of Clinical Sciences at the Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital Ostra, Gothenburg , Sweden
| | - Soren Sondergaard
- Centre of Elective Surgery, Silkeborg Regional Hospital , Silkeborg , Denmark
| | - Stephan M Jakob
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern , Bern , Switzerland
| | - Jukka Takala
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern , Bern , Switzerland
| | - David Berger
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern , Bern , Switzerland
| |
Collapse
|
8
|
Berger D, Takala J. Determinants of systemic venous return and the impact of positive pressure ventilation. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:350. [PMID: 30370277 PMCID: PMC6186556 DOI: 10.21037/atm.2018.05.27] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 04/14/2018] [Indexed: 12/29/2022]
Abstract
Venous return, i.e., the blood flowing back to the heart, is driven by the pressure difference between mean systemic filling pressure and right atrial pressure (RAP). Besides cardiac function, it is the major determinant of cardiac output. Mean systemic filling pressure is a function of the vascular volume. The concept of venous return has a central role for heart lung interactions and the explanation of shock states. Mechanical ventilation during anaesthesia and critical illness may severely affect venous return by different mechanisms. In the first part of the following article, we will discuss the development of the concept of venous return, its specific components mean systemic and mean circulatory filling pressure (MCFP), RAP and resistance to venous return (RVR). We show how these pressures relate to the volume state of the circulation. Various interpretations and critiques are elucidated. In the second part, we focus on the impact of positive pressure ventilation on venous return and its components, including latest results from latest research.
Collapse
Affiliation(s)
- David Berger
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Jukka Takala
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| |
Collapse
|
9
|
Wijnberge M, Sindhunata DP, Pinsky MR, Vlaar AP, Ouweneel E, Jansen JR, Veelo DP, Geerts BF. Estimating mean circulatory filling pressure in clinical practice: a systematic review comparing three bedside methods in the critically ill. Ann Intensive Care 2018; 8:73. [PMID: 29926230 PMCID: PMC6010367 DOI: 10.1186/s13613-018-0418-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 06/15/2018] [Indexed: 11/10/2022] Open
Abstract
The bedside hemodynamic assessment of the critically ill remains challenging since blood volume, arterial–venous interaction and compliance are not measured directly. Mean circulatory filling pressure (Pmcf) is the blood pressure throughout the vascular system at zero flow. Animal studies have shown Pmcf provides information on vascular compliance, volume responsiveness and enables the calculation of stressed volume. It is now possible to measure Pmcf at the bedside. We performed a systematic review of the current Pmcf measurement techniques and compared their clinical applicability, precision, accuracy and limitations. A comprehensive search strategy was performed in PubMed, Embase and the Cochrane databases. Studies measuring Pmcf in heart-beating patients at the bedside were included. Data were extracted from the articles into predefined forms. Quality assessment was based on the Newcastle–Ottawa Scale for cohort studies. A total of 17 prospective cohort studies were included. Three techniques were described: Pmcf hold, based on inspiratory hold-derived venous return curves, Pmcf arm, based on arterial and venous pressure equilibration in the arm as a model for the entire circulation, and Pmcf analogue, based on a Guytonian mathematical model of the circulation. The included studies show Pmcf to accurately follow intravascular fluid administration and vascular compliance following drug-induced hemodynamic changes. Bedside Pmcf measures allow for more direct assessment of circulating blood volume, venous return and compliance. However, studies are needed to determine normative Pmcf values and their expected changes to therapies if they are to be used to guide clinical practice.
Collapse
Affiliation(s)
- Marije Wijnberge
- Department of Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands.,Department of Intensive Care, Academic Medical Center, Amsterdam, The Netherlands.,Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Daniko P Sindhunata
- Department of Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Michael R Pinsky
- Department of Critical Care Medicine, University of Pittsburgh Medical Center, 1215.4 Lillian S. Kaufmann Bldg, 3471 Fifth Avenue, Pittsburgh, PA, 15213, USA.
| | - Alexander P Vlaar
- Department of Intensive Care, Academic Medical Center, Amsterdam, The Netherlands.,Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Else Ouweneel
- Department of Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Jos R Jansen
- Department of Intensive Care Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Denise P Veelo
- Department of Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Bart F Geerts
- Department of Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands
| |
Collapse
|
10
|
Moller PW, Winkler B, Hurni S, Heinisch PP, Bloch A, Sondergaard S, Jakob SM, Takala J, Berger D. Right atrial pressure and venous return during cardiopulmonary bypass. Am J Physiol Heart Circ Physiol 2017; 313:H408-H420. [DOI: 10.1152/ajpheart.00081.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 05/22/2017] [Accepted: 05/22/2017] [Indexed: 11/22/2022]
Abstract
The relevance of right atrial pressure (RAP) as the backpressure for venous return (QVR) and mean systemic filling pressure as upstream pressure is controversial during dynamic changes of circulation. To examine the immediate response of QVR (sum of caval vein flows) to changes in RAP and pump function, we used a closed-chest, central cannulation, heart bypass porcine preparation ( n = 10) with venoarterial extracorporeal membrane oxygenation. Mean systemic filling pressure was determined by clamping extracorporeal membrane oxygenation tubing with open or closed arteriovenous shunt at euvolemia, volume expansion (9.75 ml/kg hydroxyethyl starch), and hypovolemia (bleeding 19.5 ml/kg after volume expansion). The responses of RAP and QVR were studied using variable pump speed at constant airway pressure (PAW) and constant pump speed at variable PAW. Within each volume state, the immediate changes in QVR and RAP could be described with a single linear regression, regardless of whether RAP was altered by pump speed or PAW ( r2 = 0.586–0.984). RAP was inversely proportional to pump speed from zero to maximum flow ( r2 = 0.859–0.999). Changing PAW caused immediate, transient, directionally opposite changes in RAP and QVR (RAP: P ≤ 0.002 and QVR: P ≤ 0.001), where the initial response was proportional to the change in QVR driving pressure. Changes in PAW generated volume shifts into and out of the right atrium, but their effect on upstream pressure was negligible. Our findings support the concept that RAP acts as backpressure to QVR and that Guyton’s model of circulatory equilibrium qualitatively predicts the dynamic response from changing RAP. NEW & NOTEWORTHY Venous return responds immediately to changes in right atrial pressure. Concomitant volume shifts within the systemic circulation due to an imbalance between cardiac output and venous return have negligible effects on mean systemic filling pressure. Guyton’s model of circulatory equilibrium can qualitatively predict the resulting changes in dynamic conditions with right atrial pressure as backpressure to venous return.
Collapse
Affiliation(s)
- Per W. Moller
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Anaesthesiology and Intensive Care Medicine, Institute of Clinical Sciences at the Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Bernhard Winkler
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; and
| | - Samuel Hurni
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; and
| | - Paul Philipp Heinisch
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; and
| | - Andreas Bloch
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | | | - Stephan M. Jakob
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Jukka Takala
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - David Berger
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| |
Collapse
|
11
|
Helmerhorst HJF, de Wilde RBP, Lee DH, Palmen M, Jansen JRC, van Westerloo DJ, de Jonge E. Hemodynamic effects of short-term hyperoxia after coronary artery bypass grafting. Ann Intensive Care 2017; 7:20. [PMID: 28233196 PMCID: PMC5323416 DOI: 10.1186/s13613-017-0246-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 02/14/2017] [Indexed: 01/11/2023] Open
Abstract
Background Although oxygen is generally administered in a liberal manner in the perioperative setting, the effects of oxygen administration on dynamic cardiovascular parameters, filling status and cerebral perfusion have not been fully unraveled. Our aim was to study the acute hemodynamic and microcirculatory changes before, during and after arterial hyperoxia in mechanically ventilated patients after coronary artery bypass grafting (CABG) surgery. Methods This was a single-center physiological study in a tertiary care ICU in the Netherlands. Twenty-two patients scheduled for ICU admission after elective CABG were enrolled in the study between September 2014 and September 2015. In the ICU, patients were exposed to a fraction of inspired oxygen (FiO2) of 90% allowing a 15-min wash-in period. Various hemodynamic parameters were measured using direct pressure signals and continuous arterial waveform analysis at three sequential time points: before, during and after hyperoxia. Results During a 15-min exposure to a fraction of inspired oxygen (FiO2) of 90%, the partial pressure of arterial oxygen (PaO2) and arterial oxygen saturation (SaO2) were significantly higher. The systemic resistance increased (P < 0.0001), without altering the heart rate. Stroke volume variation and pulse pressure variation decreased slightly. The cardiac output did not significantly decrease (P = 0.08). Mean systemic filling pressure and arterial critical closing pressure increased (P < 0.01), whereas the percentage of perfused microcirculatory vessels decreased (P < 0.01). Other microcirculatory parameters and cerebral blood flow velocity showed only slight changes. Conclusions We found that short-term hyperoxia affects hemodynamics in ICU patients after CABG. This was translated in several changes in central circulatory variables, but had only slight effects on cardiac output, cerebral blood flow and the microcirculation. Clinical trial registration Netherlands Trial Register: NTR5064
Collapse
Affiliation(s)
- Hendrik J F Helmerhorst
- Department of Intensive Care Medicine, Leiden University Medical Center, Post Box 9600, Leiden, 2300 RC, The Netherlands. .,Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands. .,Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands.
| | - Rob B P de Wilde
- Department of Intensive Care Medicine, Leiden University Medical Center, Post Box 9600, Leiden, 2300 RC, The Netherlands
| | - Dae Hyun Lee
- Department of Nephrology, Einthoven Laboratory for Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Meindert Palmen
- Department of Cardiothoracic Surgery, Leiden University Medical Center, Leiden, The Netherlands
| | - Jos R C Jansen
- Department of Intensive Care Medicine, Leiden University Medical Center, Post Box 9600, Leiden, 2300 RC, The Netherlands
| | - David J van Westerloo
- Department of Intensive Care Medicine, Leiden University Medical Center, Post Box 9600, Leiden, 2300 RC, The Netherlands
| | - Evert de Jonge
- Department of Intensive Care Medicine, Leiden University Medical Center, Post Box 9600, Leiden, 2300 RC, The Netherlands
| |
Collapse
|
12
|
Abstract
PURPOSE OF REVIEW Central venous pressure (CVP) alone has so far not found a place in outcome prediction or prediction of fluid responsiveness. Improved understanding of the interaction between mean systemic pressure (Pms) and CVP has major implications for evaluating volume responsiveness, heart performance and potentially patient outcomes. RECENT FINDINGS The literature review substantiates that CVP plays a decisive role in causation of operative haemorrhage and renal failure. The review details CVP as a variable integral to cardiovascular control in its dual role of distending the diastolic right ventricle and opposing venous return. SUMMARY The implication for practice is in the regulation of the circulation. It is demonstrated that control of the blood pressure and cardiac output/venous return calls upon regulation of the volume state (Pms), the heart performance (Eh) and the systemic vascular resistance. Knowledge of the CVP is required to calculate all three.
Collapse
|
13
|
Berger D, Moller PW, Weber A, Bloch A, Bloechlinger S, Haenggi M, Sondergaard S, Jakob SM, Magder S, Takala J. Effect of PEEP, blood volume, and inspiratory hold maneuvers on venous return. Am J Physiol Heart Circ Physiol 2016; 311:H794-806. [DOI: 10.1152/ajpheart.00931.2015] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 07/13/2016] [Indexed: 11/22/2022]
Abstract
According to Guyton's model of circulation, mean systemic filling pressure (MSFP), right atrial pressure (RAP), and resistance to venous return (RVR) determine venous return. MSFP has been estimated from inspiratory hold-induced changes in RAP and blood flow. We studied the effect of positive end-expiratory pressure (PEEP) and blood volume on venous return and MSFP in pigs. MSFP was measured by balloon occlusion of the right atrium (MSFPRAO), and the MSFP obtained via extrapolation of pressure-flow relationships with airway occlusion (MSFPinsp_hold) was extrapolated from RAP/pulmonary artery flow (QPA) relationships during inspiratory holds at PEEP 5 and 10 cmH2O, after bleeding, and in hypervolemia. MSFPRAO increased with PEEP [PEEP 5, 12.9 (SD 2.5) mmHg; PEEP 10, 14.0 (SD 2.6) mmHg, P = 0.002] without change in QPA [2.75 (SD 0.43) vs. 2.56 (SD 0.45) l/min, P = 0.094]. MSFPRAO decreased after bleeding and increased in hypervolemia [10.8 (SD 2.2) and 16.4 (SD 3.0) mmHg, respectively, P < 0.001], with parallel changes in QPA. Neither PEEP nor volume state altered RVR ( P = 0.489). MSFPinsp_hold overestimated MSFPRAO [16.5 (SD 5.8) vs. 13.6 (SD 3.2) mmHg, P = 0.001; mean difference 3.0 (SD 5.1) mmHg]. Inspiratory holds shifted the RAP/QPA relationship rightward in euvolemia because inferior vena cava flow (QIVC) recovered early after an inspiratory hold nadir. The QIVC nadir was lowest after bleeding [36% (SD 24%) of preinspiratory hold at 15 cmH2O inspiratory pressure], and the QIVC recovery was most complete at the lowest inspiratory pressures independent of volume state [range from 80% (SD 7%) after bleeding to 103% (SD 8%) at PEEP 10 cmH2O of QIVC before inspiratory hold]. The QIVC recovery thus defends venous return, possibly via hepatosplanchnic vascular waterfall.
Collapse
Affiliation(s)
- David Berger
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Per W. Moller
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Anaesthesiology and Intensive Care Medicine, Institute of Clinical Sciences at the Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Alberto Weber
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Andreas Bloch
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Stefan Bloechlinger
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; and
| | - Matthias Haenggi
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Soren Sondergaard
- Department of Anaesthesiology and Intensive Care Medicine, Institute of Clinical Sciences at the Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Stephan M. Jakob
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Sheldon Magder
- Department of Critical Care, McGill University Health Centre, Montreal, Quebec, Canada
| | - Jukka Takala
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| |
Collapse
|
14
|
Guérin L, Teboul JL, Persichini R, Dres M, Richard C, Monnet X. Effects of passive leg raising and volume expansion on mean systemic pressure and venous return in shock in humans. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:411. [PMID: 26597901 PMCID: PMC4657233 DOI: 10.1186/s13054-015-1115-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 10/26/2015] [Indexed: 12/03/2022]
Abstract
Introduction The aim of this study was to assess how mean systemic pressure (Psm) and resistance to venous return (Rvr) behave during passive leg raising (PLR) in cases of fluid responsiveness and fluid unresponsiveness. Method In 30 patients with an acute circulatory failure, in order to estimate the venous return curve, we constructed the regression line between pairs of cardiac index (CI) and central venous pressure (CVP). Values were measured during end-inspiratory and end-expiratory ventilatory occlusions performed at two levels of positive end-expiratory pressure. The x-axis intercept was used to estimate Psm and the inverse of the slope to quantify Rvr. These measurements were obtained at baseline, during PLR and after fluid infusion. Patients in whom fluid infusion increased CI by more than 15 % were defined as “fluid-responders”. Results In fluid-responders (n = 15), CVP and Psm significantly increased (from 7 ± 3 to 9 ± 4 mmHg and from 25 ± 13 to 31 ± 13 mmHg, respectively) during PLR. The Psm-CVP gradient significantly increased by 20 ± 30 % while Rvr did not change significantly during PLR. In fluid-nonresponders, CVP and Psm increased significantly but the Psm-CVP gradient did not change significantly during PLR. PLR did not change the intra-abdominal pressure in the whole population (14 ± 6 mmHg before vs. 13 ± 5 mmHg during PLR, p = 0.26) and in patients with intra-abdominal hypertension at baseline (17 ± 4 mmHg before vs. 16 ± 4 mmHg during PLR, p = 0.14). In the latter group, PLR increased Psm from 22 ± 11 to 27 ± 10 mmHg (p <0.01) and did not change Rvr (5.1 ± 2.6 to 5.2 ± 3 mmHg/min/m2/mL, p = 0.71). In fluid-responders, Psm, CVP and the Psm-CVP gradient significantly increased during fluid infusion while the Rvr did not change. In fluid-nonresponders, CVP and Psm increased significantly during fluid infusion while the Psm-CVP gradient and Rvr did not change. Conclusion PLR significantly increased Psm without modifying Rvr. This was also the case in patients with intra-abdominal hypertension. In case of fluid responsiveness, PLR increased venous return by increasing Psm to a larger extent than CVP. In patients with fluid unresponsiveness, PLR increased Psm but did not change the Psm–CVP gradient. Fluid infusion induced similar effects on Psm and Rvr.
Collapse
Affiliation(s)
- Laurent Guérin
- AP-HP, Hôpitaux universitaires Paris-Sud, Hôpital de Bicêtre, service de réanimation médicale, 78, rue du Général Leclerc, Le Kremlin-Bicêtre, F-94270, France. .,Univ Paris-Sud, Faculté de médecine Paris-Sud, Inserm UMR_S 999, Le Kremlin-Bicêtre, F-94270, France.
| | - Jean-Louis Teboul
- AP-HP, Hôpitaux universitaires Paris-Sud, Hôpital de Bicêtre, service de réanimation médicale, 78, rue du Général Leclerc, Le Kremlin-Bicêtre, F-94270, France. .,Univ Paris-Sud, Faculté de médecine Paris-Sud, Inserm UMR_S 999, Le Kremlin-Bicêtre, F-94270, France.
| | - Romain Persichini
- AP-HP, Hôpitaux universitaires Paris-Sud, Hôpital de Bicêtre, service de réanimation médicale, 78, rue du Général Leclerc, Le Kremlin-Bicêtre, F-94270, France. .,Univ Paris-Sud, Faculté de médecine Paris-Sud, Inserm UMR_S 999, Le Kremlin-Bicêtre, F-94270, France.
| | - Martin Dres
- AP-HP, Hôpitaux universitaires Paris-Sud, Hôpital de Bicêtre, service de réanimation médicale, 78, rue du Général Leclerc, Le Kremlin-Bicêtre, F-94270, France. .,Univ Paris-Sud, Faculté de médecine Paris-Sud, Inserm UMR_S 999, Le Kremlin-Bicêtre, F-94270, France.
| | - Christian Richard
- AP-HP, Hôpitaux universitaires Paris-Sud, Hôpital de Bicêtre, service de réanimation médicale, 78, rue du Général Leclerc, Le Kremlin-Bicêtre, F-94270, France. .,Univ Paris-Sud, Faculté de médecine Paris-Sud, Inserm UMR_S 999, Le Kremlin-Bicêtre, F-94270, France.
| | - Xavier Monnet
- AP-HP, Hôpitaux universitaires Paris-Sud, Hôpital de Bicêtre, service de réanimation médicale, 78, rue du Général Leclerc, Le Kremlin-Bicêtre, F-94270, France. .,Univ Paris-Sud, Faculté de médecine Paris-Sud, Inserm UMR_S 999, Le Kremlin-Bicêtre, F-94270, France.
| |
Collapse
|
15
|
Persichini R, Guerin L, Monnet X. Physiopathologie du retour veineux systémique au cours de l’insuffisance circulatoire aiguë. MEDECINE INTENSIVE REANIMATION 2014. [DOI: 10.1007/s13546-014-0869-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
16
|
|
17
|
Understanding the divergent effects of norepinephrine on cardiac output: go with the flow. Crit Care Med 2013; 41:352-4. [PMID: 23269148 DOI: 10.1097/ccm.0b013e318270e67e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
18
|
Effects of norepinephrine on mean systemic pressure and venous return in human septic shock*. Crit Care Med 2012; 40:3146-53. [DOI: 10.1097/ccm.0b013e318260c6c3] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
19
|
Estimation of mean systemic filling pressure in postoperative cardiac surgery patients with three methods. Intensive Care Med 2012; 38:1452-60. [PMID: 22584797 PMCID: PMC3423572 DOI: 10.1007/s00134-012-2586-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 04/15/2012] [Indexed: 11/16/2022]
Abstract
PURPOSE To assess the level of agreement between different bedside estimates of effective circulating blood volume-mean systemic filling pressure (Pmsf), arm equilibrium pressure (Parm) and model analog (Pmsa)-in ICU patients. METHODS Eleven mechanically ventilated postoperative cardiac surgery patients were studied. Sequential measures were made in the supine position, rotating the bed to a 30° head-up tilt and after fluid loading (500 ml colloid). During each condition four inspiratory hold maneuvers were done to determine Pmsf; arm stop-flow was created by inflating a cuff around the upper arm for 30 s to measure Parm, and Pmsa was estimated from a Guytonian model of the systemic circulation. RESULTS Mean Pmsf, Parm and Pmsa across all three states were 20.9 ± 5.6, 19.8 ± 5.7 and 14.9 ± 4.0 mmHg, respectively. Bland-Altman analysis for the difference between Parm and Pmsf showed a non-significant bias of -1.0 ± 3.08 mmHg (p = 0.062), a coefficient of variation (COV) of 15 %, and limits of agreement (LOA) of -7.3 and 5.2 mmHg. For the difference between Pmsf and Pmsa we found a bias of -6.0 ± 3.1 mmHg (p < 0.001), COV 17 % and LOA -12.4 and 0.3 mmHg. Changes in Pmsf and Parm and in Pmsf and Pmsa were directionally concordant in response to head-up tilt and volume loading. CONCLUSIONS Parm and Pmsf are interchangeable in mechanically ventilated postoperative cardiac surgery patients. Changes in effective circulatory volume are tracked well by changes in Parm and Pmsa.
Collapse
|