Ewa Mayzner-Zawadzka

Assessment of inflow and washout of indocyanine green in the adult human brain by monitoring of diffuse reflectance at large source-detector separation.

Recently, it was shown in measurements carried out on humans that time-resolved near-infrared reflectometry and fluorescence spectroscopy may allow for discrimination of information originating directly from the brain avoiding influence of contaminating signals related to the perfusion of extracerebral tissues. We report on continuation of these studies, showing that the near-infrared light can be detected noninvasively on the surface of the tissue at large interoptode distance. A multichannel time-resolved optical monitoring system was constructed for measurements of diffuse reflectance in optically turbid medium at very large source-detector separation up to 9 cm. The instrument was applied during intravenous injection of indocyanine green and the distributions of times of flight of photons were successfully acquired showing inflow and washout of the dye in the tissue. Time courses of the statistical moments of distributions of times of flight of photons are presented and compared to the results obtained simultaneously at shorter source-detector separations (3, 4, and 5 cm). We show in a series of experiments carried out on physical phantom and healthy volunteers that the time-resolved data acquisition in combination with very large source-detector separation may allow one to improve depth selectivity of perfusion assessment in the brain.

Time-resolved detection of fluorescent light during inflow of ICG to the brain?a methodological study

It was reported that time-resolved reflectance measurements carried out during inflow and washout of an optical contrast agent may provide information on the blood supply to the brain cortex of human adults. It was also shown that a measurement of fluorescence excited in the dye circulating in the brain is feasible. Unfortunately, patterns of time-resolved fluorescence signals observed during in vivo measurements are difficult to interpret. The aim of this study was to analyze the influence of several factors on the fluorescence signals measured during in vivo experiments. A laboratory instrument for recording the distributions of arrival of fluorescence photons was constructed and optimized for measurements on humans. Monte Carlo simulations and laboratory measurements on liquid phantoms as well as in vivo measurements on healthy volunteers were carried out. An influence of source-detector separation, position of the source-detector pair on the head, as well as a dose of the injected indocyanine green (ICG) on the fluorescence signals were studied in detail. It was shown that even for a small dose of ICG (0.025 mg kg(-1)) the time-resolved signals can be successfully detected on the surface of the head. Strong influence of the studied factors on the fluorescence signals was observed. It was also noted that the changes in moments of distributions of arrival times of fluorescence photons depend on the anatomical structure of the tissues located between the source and the detector.

Assessment of cerebral perfusion in post-traumatic brain injury patients with the use of ICG-bolus tracking method

The aim of this study was to verify the usefulness of the time-resolved optical method utilizing diffusely reflected photons and fluorescence signals combined with intravenous injection of indocyanine green (ICG) in the assessment of brain perfusion in post-traumatic brain injury patients. The distributions of times of flight (DTOFs) of diffusely reflected photons were acquired together with the distributions of times of arrival (DTAs) of fluorescence photons. The data analysis methodology was based on the observation of delays between the signals of statistical moments (number of photons, mean time of flight and variance) of DTOFs and DTAs related to the inflow of ICG to the extra- and intracerebral tissue compartments. Eleven patients with brain hematoma, 15 patients with brain edema and a group of 9 healthy subjects were included in this study. Statistically significant differences between parameters obtained in healthy subjects and patients with brain hematoma and brain edema were observed. The best optical parameter to differentiate patients and control group was variance of the DTOFs or DTAs. Results of the study suggest that time-resolved optical monitoring of inflow of the ICG seems to be a promising tool for detecting cerebral perfusion insufficiencies in critically ill patients.

Multiwavelength time-resolved detection of fluorescence during the inflow of indocyanine green into the adult’s brain

Optical technique based on diffuse reflectance measurement combined with indocyanine green (ICG) bolus tracking is extensively tested as a method for clinical assessment of brain perfusion in adults at the bedside. Methodology of multiwavelength and time-resolved detection of fluorescence light excited in the ICG is presented and advantages of measurements at multiple wavelengths are discussed. Measurements were carried out: 1. on a physical homogeneous phantom to study the concentration dependence of the fluorescence signal, 2. on the phantom to simulate the dynamic inflow of ICG at different depths, and 3. in vivo on surface of the human head. Pattern of inflow and washout of ICG in the head of healthy volunteers after intravenous injection of the dye was observed for the first time with time-resolved instrumentation at multiple emission wavelengths. The multiwavelength detection of fluorescence signal confirms that at longer emission wavelengths, probability of reabsorption of the fluorescence light by the dye itself is reduced. Considering different light penetration depths at different wavelengths, and the pronounced reabsorption at longer wavelengths, the time-resolved multiwavelength technique may be useful in signal decomposition, leading to evaluation of extra- and intracerebral components of the measured signals.

Results of the severe sepsis registry in intensive care units in Poland from 2003−2009

BACKGROUND Severe sepsis remains the most common cause of death in intensive care units (ICUs) according to many epidemiological studies. There are no data in Poland on the extent of severe sepsis cases treated in ICUs. The aim of the study was to analyse the course and outcome of severe sepsis patients treated in Polish ICUs. METHODS In 2003, the internet-based severe sepsis registry was created as a multicentre observational research project. An online questionnaire was made accessible to ICUs participating in the study. Questionnaires were completed after the discharge of patients and included demographic data, clinical and microbiological information about the cause, course, treatment and outcome of septic patients. All data were given voluntarily and anonymously. RESULTS During the 7-year period (2003-2009), 4999 cases of severe sepsis were registered for analysis. The mean age of septic patients was 57 years, and the majority of the patients were men (58%). The mean length of stay in the ICU was 10 days. A significant decrease in the mortality rate was observed from 54% in 2003 and 56% in 2004 to 46% in 2009 (P < 0.05). Most of the patients were admitted to the ICU for surgical reasons (56%), and intra-abdominal infections predominated (49%). Severe sepsis patients were admitted to ICUs in critical condition, and the majority of them (89%) had 3 or more organs dysfunction. The APACHE II score on admission was 26 points. Community acquired infections were the most frequent cause of severe sepsis (53%). Most of the pathogens responsible for infection were Gram-negative bacteria (58%). Gram-positive bacteria were identified in 34% of patients and fungi in 16%. A positive blood culture was detected in 41% of patients. Vasopressors were administered to most of the patients (86%). There was a marked increase in the frequency of administering noradrenaline and a decrease in administering dopamine. Renal replacement therapy was applied in 22% of the patients, and there was a marked increase in this type of therapy in the last two years of the study period. CONCLUSIONS Patients with severe sepsis involved in the 7-year registry were critically ill in half of the cases because of intra-abdominal infections, and the majority of them had multi-organ dysfunction. The mortality of registered patients was high, but it significantly decreased during the observation time. Based on the results obtained from this voluntary registry, the authors conclude that mandated sepsis registries should be established in Polish hospitals to improve the strategy of diagnosing and managing this syndrome.

Recommendations for the management of trauma or surgery-related massive blood loss.

UNLABELLED Exsanguination is an underestimated cause of treatment failures in patients with severe trauma or undergoing surgery. In some patients the primary dysfunction of blood clot formation is a direct cause of a massive blood loss. Patients without previous coagulation disorders are at risk of coagulopathy following intraoperative or post-traumatic bleeding, where the local haemostasis does not warrant bleeding cessation. THE AIM OF THE STUDY was to assess the therapeutic value of various components of a complex interdisciplinary approach, based on the opinion of the experts treating patients with massive bleeding. MATERIAL AND METHODS The study was conducted by anonymous questionnaire, using the analogue representation of the argument strength. The results were analyzed based on the techniques of descriptive statistics. The argument was considered a key parameter, when the median value of strength was located in the highest quartile. RESULTS It was found that the arguments of the highest strength for the risk of developing the posthaemorrhagic coagulation disorders are: loss of more than one third of blood volume, fluid therapy in an amount greater than 35 ml/kg, administration of more than 5 units of packed red blood cells, insufficient supply of fresh frozen plasma and platelets in proportion to packed red blood cells, severe acidosis and hypothermia. The most important tests for post-haemorrhage coagulopathy are: anatomically non-localized bleed, abnormal values of the standard coagulation parameters and fibrinogen level below 1 g/L. In the treatment of post-haemorrhagic coagulopathy the team of experts pointed out the benefits of antifibrinolytic drugs, concentrates of prothrombin complex and recombinant activated coagulation factor VII. CONCLUSIONS Multidisciplinary therapeutic management of bleeding patients is associated with employment of appropriate treatment methods to achieve the best possible outcome. Factors influencing the development of coagulopathy, the methods of diagnosis and proposed techniques of treatment may facilitate therapeutic decisions in bleeding patients requiring massive transfusion of blood components.

Multi-wavelength Time-resolved Detection of Fluorescence of Indocyanine Green Circulating in the Human Head

Multi-wavelength detection of time-resolved fluorescence signal on the surface of the human head was carried out. Pattern of inflow and washout of indocyanine green in the head after intravenous injection of the dye was analyzed.

Evaluation of the effectiveness of the Quadratus Lumborum Block type I using ropivacaine in postoperative analgesia after a cesarean section — a controlled clinical study

OBJECTIVES Quadratus Lumborum Block in contrast to Transversus Abdominis Plane Block contains a unique component which not only stops somatic pain but also inhibits visceral pain by spreading the local anesthetic to the paravertebral space. This study was designed to determine whether performing the Quadratus Lumborum Block type I in patients un-dergoing cesarean section would be associated with both decreased morphine consumption and decreased pain levels in the postoperative 48-hour period. MATERIAL AND METHODS Sixty patients undergoing caesarean section under spinal anesthesia were randomly and equally assigned to one or other of two groups: QLB I (who received Bilateral Quadratus Lumborum Block type I with the use of 24 mL 0.375% ropivacaine per side) or a Control group. In both groups, on-demand morphine analgesia was administered postoperatively within the first 48 hours. The following were measured: the morphine consumption; the time elapsed from the C-section until the first dose of morphine; and the levels of pain intensity among patients in rest (numeral pain rating scale). RESULTS There were no statistically significant demographic data differences between the QLB I and Control groups. The following significant differences were observed in the 48-hour postoperative period: morphine consumption was higher in the Control group (p = 0.000); the time elapsed from the C-section until the first dose of morphine was longer in QLB I group (p < 0.05); and the median of the pain numeric rating scale was higher in the Control group (p < 0.05). CONCLUSIONS Quadratus Lumborum Block type I significantly reduces morphine consumption and pain levels up to 48 hours postoperatively.

Multiwavelength time-resolved measurement of diffuse reflectance for brain oxygenation assessment during hypoxic challenge test

Multi-wavelength measurement of time-resolved reflectance signal on the surface of the human head was carried out. The changes of oxy- and deoxyhemoglobin concentration were obtained at 14 wavelengths during controlled hypoxic challenge test.

Brain Perfusion Assessment by Optical Contrast Tracking Using Time-Resolved Fluorescence Detection

In this paper we present methodological studies on construction and application of optical brain monitoring system utilizing time-resolved detection of fluorescence excited in the dye circulating in the human brain. Series of Monte Carlo simulations and time-resolved measurements of diffuse reflectance and fluorescence were carried out. Measurements on physical phantoms allowing for assessment of dynamic inflow of Indocyanine Green (ICG) were performed. Finally, in-vivo measurements on the healthy subjects as well as patients with brain perfusion insufficiencies were carried out during intravenous administration of ICG. Obtained results show good signal-to-noise ratio for fluorescence signals. The simulations and phantom experiments allowed to optimize conditions of the measurement - dose of the dye injected and source-detector separation used in the in-vivo experiments. Preliminary analysis of signals obtained during in-vivo measurements in patients show that the fluorescence measurements can be used to assess brain perfusion insufficiencies.