| 1. |
- Zdolsek, Markus, 1989-
(författare)
-
Volume effects of albumin infusion in humans
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: The use of colloids when treating a patient for hypovolemia has been debated throughout the years. During the last decade, albumin solutions have become the colloids of choice in both operating theatres and intensive care settings when crystalloid fluids are insufficient. The volume effects of albumin infusion are explored in this thesis. Methods: Recruitment of fluid from the interstitial fluid compartment to the plasma was estimated in healthy volunteers who received 3 ml/kg of albumin 20% infusion over 30 min. The same infusion protocol was applied to burn patients to study whether significant inflammation changes the volume effect of an albumin infusion. The influence of the infusion rate of albumin 20% on plasma volume (PV) was evaluated in a crossover fashion in healthy volunteers. Additionally, two concentrations, 5% and 20%, with equivalent amounts of albumin, were given to healthy volunteers in a crossover fashion to determine if a difference in volume effect occurred. The volume effects in terms of PV expansion and capillary leakage of albumin were calculated by mass balance and volume kinetics based on repeated blood samples. Results: There was a 10–20 min delay after completion of the albumin 20% infusion until maximum PV expansion was reached. Extravascular fluid was recruited at a ratio of 3.4 times the infused albumin 20%. Both healthy volunteers and burn patients had a 15% increase in PV. Capillary leakage of albumin occurred at a similar rate in both groups. Rapid infusion resulted in a longer intravascular half-life for albumin and a larger initial PV expansion over time without long-term negative compensation. Albumin 20% increased the PV to twice the infused volume in contrast to albumin 5%, which only increased the PV by two-thirds of the infused volume. Conclusion: Albumin infusions provide long-lasting PV expansion in both burn patients and healthy volunteers. Albumin 20% induces the recruitment of extravascular fluid, amounting to three times the infused fluid volume. A rapid infusion rate is beneficial, as it results in a larger initial PV expansion over time and a longer intravascular persistence of albumin. Further, albumin 20% provides a three times more potent PV expansion than albumin 5%. The infused fluid volume of an albumin solution depends more on the amount of albumin infused than the infused volume; albumin 20% could be preferred over other fluids for its dehydrating effect in the prevention of oedema.
|
|
| 2. |
- Waldréus, Nana
(författare)
-
Thirst in Patients with Heart Failure : Description of thirst dimensions and associated factors with thirst
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Nurses and other health care professionals meet patients with heart failure (HF) who report they are thirsty. Thirst is described by the patients as a concern, and it is distressing. Currently there are no standardized procedures to identify patients with increased thirst or to help a patient to manage troublesome thirst and research in the area of thirst is scarce. In order to prevent and relieve troublesome thirst more knowledge is needed on how thirst is experienced and what factors cause increased thirst.Aim: The aim of this thesis was to describe the thirst experience of patients with HF and describe the relationship of thirst with physiologic, psychologic and situational factors. The goal was to contribute to the improvement of the care by identifying needs and possible approaches to prevent and relieve thirst in patients with HF.Methods: The studies in this thesis used a cross-sectional design (Study I) and prospective observational designs (II-IV). Studies include data from patients with HF who were admitted to the emergency department for deterioration in HF (I, IV) or visited an outpatient HF clinic for worsening of HF symptoms (III); others were patients who were following up after HF hospitalization (II), and patients with no HF diagnosis who sought care at the emergency department for other illness (I). Patients completed questionnaires on thirst intensity, thirst distress, HF self-care behaviour, feeling depressive and feeling anxious. Data on sociodemographic, clinical characteristics, pharmacological treatment and prescribed fluid restriction were retrieved from hospital medical records and by asking the patients. Data were also collected from blood, urine and saliva samples to measure biological markers of dehydration, HF severity and stress.Results: Thirst was prevalent in 1 out of 5 patients (II) and 63% of patients with worsening of HF symptoms experienced moderate to severe thirst distress at hospital admission (IV). Patients at an outpatient HF clinic who reported thirst at the first visit were more often thirsty at the follow-up visits compared to patients who did not report thirst at the first visit (II). Thirst intensity was significantly higher in patients hospitalized with decompensated HF compared to patients with no HF (median 75 vs. 25 mm, visual analogue scale [VAS] 0-100 mm; P < 0.001) (I). During optimization of pharmacological treatment of HF, thirst intensity increased in 67% of the patients. Thirst intensity increased significantly more in patients in the high thirst intensity group compared to patients in the low thirst intensity group (median +18 mm vs. -3 mm; P < 0.001) (III). Patients who were admitted to the hospital with high thirst distress continued to have high thirst distress over time (IV). A large number of patients were bothered by thirst and feeling dry in the mouth when they were thirsty (III, IV). Patients with a fluid restriction had high thirst distress over time and patients who were feeling depressed had high thirst intensity over time (IV). Thirst was associated with fluid restriction (III-IV), a higher serum urea (IIIII), and depressive symptoms (II).Conclusions: A considerable amount of patients with HF experiences thirst intensity and thirst distress. Patients who reported thirst at the first follow-up more often had thirst at the subsequent follow-ups. The most important factors related to thirst intensity or thirst distress were a fluid restriction, a higher plasma urea, and depressive symptoms. Nurses should ask patients with HF if they are thirsty and measure the thirst intensity and thirst distress, and ask if thirst is bothering them. Each patient should be critically evaluated if a fluid restriction really is needed, if the patient might be dehydrated or needs to be treated for depression.
|
|
| 3. |
- Hober, Sophia, Professor, 1965-, et al.
(författare)
-
Systematic evaluation of SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay
- 2021
-
Ingår i: Clinical & Translational Immunology. - : Wiley. - 2050-0068. ; 10:7
-
Tidskriftsartikel (refereegranskat)abstract
- Objective. The COVID-19 pandemic poses an immense need for accurate, sensitive and high-throughput clinical tests, and serological assays are needed for both overarching epidemiological studies and evaluating vaccines. Here, we present the development and validation of a high-throughput multiplex bead-based serological assay. Methods. More than 100 representations of SARS-CoV-2 proteins were included for initial evaluation, including antigens produced in bacterial and mammalian hosts as well as synthetic peptides. The five best-performing antigens, three representing the spike glycoprotein and two representing the nucleocapsid protein, were further evaluated for detection of IgG antibodies in samples from 331 COVID-19 patients and convalescents, and in 2090 negative controls sampled before 2020. Results. Three antigens were finally selected, represented by a soluble trimeric form and the S1-domain of the spike glycoprotein as well as by the C-terminal domain of the nucleocapsid. The sensitivity for these three antigens individually was found to be 99.7%, 99.1% and 99.7%, and the specificity was found to be 98.1%, 98.7% and 95.7%. The best assay performance was although achieved when utilising two antigens in combination, enabling a sensitivity of up to 99.7% combined with a specificity of 100%. Requiring any two of the three antigens resulted in a sensitivity of 99.7% and a specificity of 99.4%. Conclusion. These observations demonstrate that a serological test based on a combination of several SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay.
|
|
| 4. |
- Bahlmann, Hans, 1973-
(författare)
-
Goal-directed fluid therapy during major abdominal surgery
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Both hypo- and hypervolemia increase the risk for postoperative complications after major abdominal surgery. Fluid needs vary amongst patients depending on differences in preoperative dehydration, intraoperative physiology and surgical characteristics. Goal-directed fluid therapy (GDFT) aims to target the right amount of fluid administration in each patient by evaluating the effect of fluid boluses on haemodynamic parameters such as stroke volume. It has been shown to reduce postoperative morbidity and is generally recommended for high-risk surgery. The overall aim of this thesis was to evaluate whether more simple devices for GDFT result in clinical benefit, thus facilitating the application of GDFT in more patients.Aim: To compare performance and clinical benefit of pleth variability index (PVI), a noninvasive, easy-to-use device for GDFT, with the reference method of oesophageal Doppler; to evaluate methods for measuring preoperative dehydration and its effect on fluid handling by the body; and to confirm the expected clinical benefits of GDFT in patients undergoing oesophageal resection, a high risk procedure.Methods: In Studies I-III 150 patients scheduled for open abdominal surgery of at least 2 hrs were randomised to GDFT with either PVI or oesophageal Doppler. In the first half of the cohort, both monitors were connected to compare intraoperative performance. In 30 patients preoperative dehydration was analysed. In study IV 64 patients undergoing oesophageal resection were randomised to GDFT using pulse contour analysis or standard treatment.Results: The concordance between PVI and oesophageal Doppler for indicating the need for and effect of a fluid bolus was low, and both had only limited capacity to predict the effect of a fluid bolus. Both methods resulted in comparable amounts of fluid being administered and similar clinical outcome. Preoperative dehydration was limited but did impact on fluid handling. Patients receiving GDFT during oesophageal resection received more fluid and more dobutamine compared to controls, but this did not result in any clinical benefit.Conclusions: There are methodological issues as well as uncertainties about the clinical benefit of GDFT. We cannot recommend a strict application of any GDFT strategy, but suggest that its components should be incorporated in a more encompassing assessment of a patient’s fluid needs. The measurement, impact and treatment of preoperative dehydration need to be further clarified.
|
|
| 5. |
- Bak, Zoltan, 1950-
(författare)
-
Cardiovascular response to hyperoxemia, hemodilution and burns : a clinical and experimental study
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The last decades less invasive monitoring and analytical tools have been developed for the evaluation of myocardial mechanics in clinical praxis. In critical care, these are longed-for complements to pulmonary artery catheter monitoring, additionally offering previously inaccessible information. This work is aimed, during fluid-replacement and oxygen therapy, to determine the physiological interface of ventricular and vascular mechanical properties, which result in the transfer of blood from the heart to appropriate circulatory beds. In prospective clinical studies we investigated previously cardiovascular healthy adults during hyperoxemia, and during preoperative acute normovolemic hemodilution or early fluid resuscitation of severe burn victims. Echocardiography was used in all studies, transthoracic for healthy volunteers and transesophageal for patients. For vascular parameters and for control purposes pulmonary artery Swan-Ganz catheter, calibrated external pulse recordings, whole body impedance cardiography, and transpulmonel thermodilution method were applied.We detected no significant change in blood pressure or heart rate, the two most often used parameters for patient monitoring. During preoperative acute normovolemic hemodilution a reduction of hemoglobin to 80 g/l did not compromise systolic or diastolic myocardial function. Cardiac volumes and flow increased with a concomitant fall in systemic vascular resistance while oxygen delivery seemed maintained. Supplemental oxygen therapy resulted in a linear dose-response between arterial oxygen and cardiovascular parameters, suggesting a direct vascular effect. Cardiac flow decreased and vascular resistance increased from hyperoxemia, and a decrease of venous return implied extracardial blood-pooling. Severe burns result in hypovolemic shock if not properly treated. The commonly used Parkland fluid replacement strategy, with urinary output and mean arterial pressure as endpoints, has recently been questioned. Applying this strategy, only transient early central hypovolemia was recorded, while dimensional preload, global left ventricular systolic function and oxygen delivery or consumption remained within normal ranges during the first 36 hours after accident. Signs of restrictive left ventricular diastolic function were detected in all patients and regional unstable systolic dysfunction was recognized in every other patient, and was consistent with myocardial marker leakage. Severe burns thereby cause myocardial stiffness and systolic regional dysfunction, which may not be prevented only by central normovolemia and adequate oxygenation.
|
|
| 6. |
- Nilsson, Lena, 1956-
(författare)
-
Respiratory monitoring using reflection mode photoplethysmography : clinical and physiological aspects
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Photoplethysmography (PPG) is a non-invasive optical technique for monitoring variations in blood volume and blood flow in skin and other tissues. Light from a light-emitting diode is absorbed, scattered and reflected from the skin, and detected by a photodetector as a plethysmogram. The plethysmogram contains variations of different frequencies. The most clinically utilised is the pulse synchronous variation in the PPG application pulse oximetry, but there is also a respiratory rate synchronous variation (PPGt).The aims of this work were to evaluate PPG as a clinical method for detection of breaths during anaesthesia, postoperative and intensive care, and to investigate possible circulatory factors in the physiological background of the respiratory synchronous part of the reflection mode PPG signal.It was concluded that respiratory variations in reflection mode PPG derived from the forearm could be detected with high sensitivity and specificity. PPG, was not significantly affected by awake or anaesthetised state, though indirect signs of reduced sympathetic tone in the anaesthetic state were present, or by spontaneous or positive pressure ventilation. There were no significant differences between men and women or between young and old subjects. Circulatory pressure variations in phase with respiration were present on both the arterial and venous side and they showed the same degree of variation, as did PPG when provoking respiration. Squared coherence, cross-correlation and visual techniques for evaluating time differences were equally good.Respiratory monitoring in the clinical setting is challenging and no golden standard exists. Methods based on airflow are mostly considered advantageous in detecting apnoea, but are less well tolerated by patients. The results indicate that PPG has a potential as a tool for monitoring respiratory rate. It is non-invasive, well tolerated and can be used for continuous monitoring.
|
|
