Predictors of treatment limitations in Finnish intensive care units

BACKGROUND

Few studies have examined the factors that predict the limitations of life-sustaining treatment (LST) to patients in intensive care units (ICUs). We aimed to identify variables associated with the decision of withholding of life support (WHLS) at admission, WHLS during ICU stay and the withdrawal of ongoing life support (WDLS).

METHODS

This retrospective observational study comprised 17,772 adult ICU patients who were included in the nationwide Finnish ICU Registry in 2016. Factors associated with LST limitations were identified using hierarchical logistic regression.

RESULTS

The decision of WHLS at admission was made for 822 (4.6%) patients, WHLS during ICU stay for 949 (5.3%) patients, and WDLS for 669 (3.8%) patients. Factors strongly predicting WHLS at admission included old age (adjusted odds ratio [OR] for patients aged 90 years or older in reference to those younger than 40 years was 95.6; 95% confidence interval [CI], 47.2-193.5), dependence on help for activities of daily living (OR, 3.55; 95% CI, 3.01-4.2), and metastatic cancer (OR, 4.34; 95% CI, 3.16-5.95). A high severity of illness predicted later decisions to limit LST. Diagnoses strongly associated with WHLS at admission were cardiac arrest, hepatic failure and chronic obstructive pulmonary disease. Later decisions were strongly associated with cardiac arrest, hepatic failure, non-traumatic intracranial hemorrhage, head trauma and stroke.

CONCLUSION

Early decisions to limit LST were typically associated with old age and chronic poor health whereas later decisions were related to the severity of illness. Limitations are common for certain diagnoses, particularly cardiac arrest and hepatic failure.

Bowel Perforation During Haemophagocytic Lymphohistiocytosis Treatment with Corticosteroids and Anakinra

We report the use of anakinra to treat a case of a 64-year-old man diagnosed with haemophagocytic lymphohistiocytosis (HLH) with neurological involvement. After the administration of intravenous pulse corticosteroid therapy, immunoglobulin and anakinra the patient showed neurological recovery. However, the recovery was complicated by the perforation of a pre-existing bowel diverticulum. The effect of anakinra on bowel inflammation has not yet been clearly established. It can potentially augment bowel inflammation and contribute to the risk of bowel perforation associated with the concomitant use of corticosteroids.

LEARNING POINTS

Anakinra can potentially augment bowel inflammation.The concomitant use of anakinra and corticosteroids may increase the risk of bowel perforation.Use of anakinra and corticosteroids in patients with pre-existing gastrointestinal diseases requires vigilant observation for abdominal symptoms.

Modulation of the prefrontal blood oxygenation response to intermittent theta-burst stimulation in depression: A sham-controlled study with functional near-infrared spectroscopy

OBJECTIVE

To better understand the neural mechanisms behind the effect of intermittent theta-burst stimulation (iTBS), we investigated how the prefrontal blood oxygenation response measured by changes in oxygenated haemoglobin (oxy-Hb) was modulated during a sham-controlled iTBS treatment course, and whether this was related to depressive symptom change.

METHODS

In this randomised, double-blind study, patients with ongoing treatment-resistant depression received either active (n = 18) or sham (n = 21) iTBS over the dorsomedial prefrontal cortex for ten to fifteen days with two sessions daily. Event-related functional near-infrared spectroscopy (fNIRS) was measured during each iTBS train, and resting-state oxy-Hb was compared before and after each iTBS session at the first, fifth, and last treatment day.

RESULTS

Patients receiving active iTBS had an increase of the event-related oxy-Hb response compared to the sham group on the fifth (bilateral prefrontal cortices p < .001) and last (left prefrontal p = .007, right prefrontal p = .025) treatment day. Resting-state analysis showed suppressed oxy-Hb change in active iTBS compared to sham iTBS on the last treatment day (p = .024). Oxy-Hb change was unrelated to depressive symptom change (p = .474).

CONCLUSIONS

This study describes a modulation of the blood oxygenation response over the prefrontal cortex that was built up during the course of active iTBS treatment in depression.

Unchanged Cognitive Performance and Concurrent Prefrontal Blood Oxygenation After Accelerated Intermittent Theta-Burst Stimulation in Depression: A Sham-Controlled Study

Aim: Intermittent theta-burst stimulation (iTBS) delivered over the dorsomedial prefrontal cortex (DMPFC) has shown promise as a treatment for anhedonia and amotivation in patients with depression. Here, we investigated whether this protocol modulates cognitive performance and concurrent prefrontal blood oxygenation. We also examined whether depressed patients exhibit cognitive dysfunction and prefrontal hypoactivity at baseline compared to healthy controls. Methods: This sham-controlled study comprises 52 patients randomized to either active or sham accelerated iTBS over the DMPFC (applied twice daily) for 10 consecutive treatment days, and 55 healthy controls. Cognitive performance was assessed at baseline and once again 4 weeks later using a cognitive test battery targeting attention, inhibitory control, and numerical, verbal, and visual working memory. Concurrent prefrontal oxygenated hemoglobin (oxy-Hb) was captured with functional near-infrared spectroscopy. Results: Active iTBS over DMPFC did not affect cognitive performance or concurrent oxy-Hb change compared to sham iTBS in patients with depression. Compared to controls, patients at baseline showed impaired performance in the Trail Making Test, the Rey Auditory Verbal Learning Test, the Animal Naming Test, and the Digit Symbol Substitution Test, however no difference in prefrontal oxy-Hb was observed. Conclusion: Patients with treatment-resistant depression displayed cognitive deficits, however without prefrontal hypoactivity, compared to healthy controls at baseline. iTBS treatment did not alter cognitive performance, nor concurrent prefrontal blood oxygenation, in patients. Taken together, iTBS can likely be considered a cognitively safe treatment option in this sample of patients.

Intensive care patient survival after limiting life-sustaining treatment-The FINNEOL* national cohort study

BACKGROUND

Few studies have examined survival in intensive care unit (ICU) patients after the restriction of life-sustaining treatment (LST). We aimed to analyse independent factors associated with hospital and 12-month survival rates in ICU patients after treatment restrictions.

METHODS

This retrospective observational study examined all patients treated in adult ICUs from 1 January 2016 until 31 December 2016 included in the Finnish ICU Registry. Multivariable logistic regression analysis was performed to explain the effect on survival.

RESULTS

Decisions to limit LST were made for 2444 patients (13.7%; 95% CI 13.2-14.2). ICU, hospital, and 12-month survival rates were 71% (95% CI 69-73), 49% (95% CI 47-51), and 24% (95% CI 22-26), respectively. In patients for whom life support was withheld, increased 12-month survival rates were associated with admission from the operating theatre (OR 1.9, 95% CI 1.1-3.4), good pre-hospital physical fitness (OR 4.7, 95% Cl 1.2-16.8) and being housed at home (OR 2.0, 95% Cl 1.4-2.8). Decreased survival rates were associated with admission from a hospital ward (OR 0.67, 95% Cl 0.5-0.9), higher comorbidity (OR 0.6, 95% Cl 0.4-0.9), cancer (OR 0.4, 95%CI 0.2-0.9), greater illness severity (SAPS II; OR 0.98, 95% Cl 0.98-0.99), and higher care intensity (TISS-76; OR 0.93, 95% Cl 0.92-0.95).

CONCLUSION

Survival among ICU patients with limited treatment was higher than expected. Advanced age was not associated with higher mortality, potentially because treatment restrictions may be set more easily for older patients.

Frequency analysis of oscillations in cerebral hemodynamics measured by time domain near infrared spectroscopy

In this paper, we propose the application of time-domain near-infrared spectroscopy to the assessment of oscillations in cerebral hemodynamics. These oscillations were observed in the statistical moments of the distributions of time of flight of photons (DTOFs) measured on the head. We analyzed the zeroth and second centralized moments of DTOFs (total number of photons and variance) to obtain their spectra to provide parameters for the frequency components of microcirculation, which differ between the extracerebral and intracerebral layers of the head. Analysis of these moments revealed statistically significant differences between a control group of healthy subjects and a group of patients with severe neurovascular disorders, which is a promising result for the assessment of cerebral microcirculation and cerebral autoregulation mechanisms.

Multiwavelength time-resolved near-infrared spectroscopy of the adult head: assessment of intracerebral and extracerebral absorption changes

An optical technique based on diffuse reflectance measurement combined with indocyanine green (ICG) bolus tracking is extensively tested as a method for the clinical assessment of brain perfusion at the bedside. We report on multiwavelength time-resolved diffuse reflectance spectroscopy measurements carried out on the head of a healthy adult during the intravenous administration of a bolus of ICG. Intracerebral and extracerebral changes in absorption were estimated from an analysis of changes in statistical moments (total number of photons, mean time of flight and variance) of the distributions of times of flight (DTOF) of photons recorded simultaneously at 16 wavelengths from the range of 650-850 nm using sensitivity factors estimated by diffusion approximation based on a layered model of the studied medium. We validated the proposed method in a series of phantom experiments and in-vivo measurements. The results obtained show that changes in the concentration of the ICG can be assessed as a function of time of the experiment and depth in the tissue. Thus, the separation of changes in ICG concentration appearing in intra- and extracerebral tissues can be estimated from optical data acquired at a single source-detector pair of fibers/fiber bundles positioned on the surface of the head.

The roles of mid-myocardial and epicardial cells in T-wave alternans development: a simulation study

Background

The occurrence of T-wave alternans in electrocardiographic signals was recently linked to susceptibility to ventricular arrhythmias and sudden cardiac death. Thus, by detecting and comprehending the origins of T-wave alternans, it might be possible to prevent such events.

Results

Here, we simulated T-wave alternans in a computer-generated human heart model by modulating the action potential duration and amplitude during the first part of the repolarization phase. We hypothesized that changes in the intracardiac alternans patterns of action potential properties would differentially influence T-wave alternans measurements at the body surface. Specifically, changes were simulated globally in the whole left and right ventricles to simulate concordant T-wave alternans, and locally in selected regions to simulate discordant and regional discordant, hereinafter referred to as “regional”, T-wave alternans. Body surface potential maps and 12-lead electrocardiographic signals were then computed. In depth discrimination, the influence of epicardial layers on T-wave alternans development was significantly higher than that of mid-myocardial cells. Meanwhile, spatial discrimination revealed that discordant and regional action potential property changes had a higher influence on T-wave alternans amplitude than concordant changes. Notably, varying T-wave alternans sources yielded distinct body surface potential map patterns for T-wave alternans amplitude, which can be used for location of regions within hearts exhibiting impaired repolarization. The highest ability for T-wave alternans detection was achieved in lead V1. Ultimately, we proposed new parameters Vector Magnitude Alternans and Vector Angle Alternans, with higher ability for T-wave alternans detection when using multi-lead electrocardiographic signals processing than for single leads. Finally, QT alternans was found to be associated with the process of T-wave alternans generation.

Conclusions

The distributions of the body surface T-wave alternans amplitude have been shown to have unique patterns depending on the type of alternans (concordant, discordant or regional) and the location of the disturbance in the heart. The influence of epicardial cells on T-wave alternans development is significantly higher than that of mid-myocardial cells, among which the sub-endocardial layer exerted the highest influence. QT interval alternans is identified as a phenomenon that correlate with T-wave alternans.

Routine Treatment-Resistant Clostridium difficile Infection during Recovery from Myxedema

Development of the extreme form of hypothyroidism defined as myxedema is very rare. Acute symptoms and their management have been described in detail previously. However, not much attention has been devoted to therapeutic challenges that are faced in the recovery phase of the treatment, especially pertaining to the gastrointestinal system. The link between myxedema and the appearance of severe Clostridium difficile infection (CDI) has not been established so far. A 61-year-old woman with no significant medical record was admitted to hospital because of infected heel pressure and thyroid dysfunction. A week later, due to hypothermia, hypotension, and unconsciousness, she was transferred to the intensive care unit. The clinical picture and the results of laboratory tests confirmed diagnosis of myxedema. After the introduction of resuscitative measures and hormonal substitution, patient's condition stabilized within 10 days. Due to concomitant sepsis, initially piperacillin/tazobactam and later cefuroxime were administered. After 20 days of antibiotic therapy, the patient developed CDI that was resistant to the routine mode of treatment. The clinical recovery was achieved only after a fecal microbiota transplantation procedure. The function of the digestive tract in myxedema is disturbed by gastric achlorydia and reduced peristalsis, which in turn can predispose the small intestine to overgrowth of bacteria. The use of antibiotics can additionally decrease the intestinal bacterial diversity, favoring the overgrowth of Clostridium difficile. The authors conclude that myxedema may increase the likelihood of a treatment-resistant form of CDI that requires the implementation of fecal microbiota transplantation.

Perioperative analgesia after intrathecal fentanyl and morphine or morphine alone for cesarean section: A randomized controlled study

OBJECTIVES

Intrathecal morphine is used in the postoperative management of pain after caesarean section (CS), but might not be optimal for intraoperative analgesia. We hypothesized that intrathecal fentanyl could supplement intraoperative analgesia when added to a local anesthetic and morphine without affecting management of postoperative pain.

METHODS

This prospective, randomized, double-blind, parallel-group study included 60 parturients scheduled for elective CS. Spinal anesthesia consisted of bupivacaine with either morphine 100 μg (M group), or fentanyl 25 μg and morphine 100 μg (FM group). The frequency of intraoperative pain and pethidine consumption in the 24 hours postoperatively was recorded.

RESULTS

Fewer patients in the FM group required additional intraoperative analgesia (P < .01, relative risk 0.06, 95% confidence interval [CI] 0.004-1.04). The FM group was noninferior to the M group for 24-hour opioid consumption (95% CI -10.0 mg to 45.7 mg, which was below the prespecified boundary of 50 mg). Pethidine consumption in postoperative hours 1 to 12 was significantly higher in the FM group (P = .02). Postoperative nausea and vomiting (PONV) were more common in the FM group (P = .01). Visual analog scale scores, effective analgesia, Apgar scores, and rates of pruritus and respiratory depression were similar between the groups.

CONCLUSIONS

Intrathecal combination of fentanyl and morphine may provide better perioperative analgesia than morphine alone in CS and could be useful when the time from anesthesia to skin incision is short. However, an increase in PONV and possible acute spinal opioid tolerance after addition of intrathecal fentanyl warrants further investigation using lower doses of fentanyl.

Human skull translucency: post mortem studies

Measurements of optical translucency of human skulls were carried out. An incandescent light source and a CCD camera were used to measure the distribution of light transmitted through the skull in 10 subjects post-mortem. We noticed that intra-individual differences in optical translucency may be up to 100 times but inter-individual translucency differences across the skull reach 10⁵ times. Based on the measurement results, a "theoretical" experiment was simulated. Monte-Carlo calculations were used in order to evaluate the influence of the differences in optical translucency of the skull on results of NIRS measurements. In these calculations a functional stimulation was done, in which the oxyhemoglobin and deoxyhemoglobin concentrations in the brain cortex change by 5μM and -5μM respectively. The maximal discrepancies between assumed hemoglobin concentration changes and hemoglobin concentration changes estimated with Monte-Carlo simulation may reach 50% depending of the translucency of the skull.

Application of optical methods in the monitoring of traumatic brain injury: A review

We present an overview of the wide range of potential applications of optical methods for monitoring traumatic brain injury. The MEDLINE database was electronically searched with the following search terms: "traumatic brain injury," "head injury," or "head trauma," and "optical methods," "NIRS," "near-infrared spectroscopy," "cerebral oxygenation," or "cerebral oximetry." Original reports concerning human subjects published from January 1980 to June 2015 in English were analyzed. Fifty-four studies met our inclusion criteria. Optical methods have been tested for detection of intracranial lesions, monitoring brain oxygenation, assessment of brain perfusion, and evaluation of cerebral autoregulation or intracellular metabolic processes in the brain. Some studies have also examined the applicability of optical methods during the recovery phase of traumatic brain injury . The limitations of currently available optical methods and promising directions of future development are described in this review. Considering the outstanding technical challenges, the limited number of patients studied, and the mixed results and opinions gathered from other reviews on this subject, we believe that optical methods must remain primarily research tools for the present. More studies are needed to gain confidence in the use of these techniques for neuromonitoring of traumatic brain injury patients.

Prospective assessment of standardized mortality ratio (SMR) as a measure of quality of care in intensive care unit--a single-centre study

BACKGROUND

The standardized mortality ratio (SMR) is a recognized indicator of critical care quality. This ratio is used to compare actual hospital mortality of all patients treated in a Intensive Care Unit (ICU) with predicted mortality. The aim of the study was prospective analysis of SMR as a measure of quality of care in single ICU.

METHOD

Prospective study was performed during the period of 12 months in ICU of Czerniakowski Hospital in Warsaw. Predicted hospital mortality was calculated using the SAPS 3 model. The value of SMR was evaluated in the three risk groups (low, moderate, high risk) and included patients surgical status (nonoperative, after elective and emergency surgery).

RESULTS

A total of 341 patients were included. SMR in general population was 0,98 (95% CI 0,74-1,28). In the low and high-risk groups the value of SMR did not differ significantly from 1. In the average risk group as well as patients undergoing elective surgery, the value of SMR tended to exceed 1.

CONCLUSIONS

In groups of patients with low and high risk the values of SMR indicated favourable quality of care. Study results should prompt to carry out detailed analysis of the course of treatment of patients at average risk of death. Analysis of the course of treatment and qualification criteria for surgery in patients undergoing elective surgery is also indicated.

Analgesic efficacy of intrathecal fentanyl during the period of highest analgesic demand after cesarean section: A randomized controlled study

Cesarean section (CS) is one of the most common surgical procedures in female patients. We aimed to evaluate the postoperative analgesic efficacy of intrathecal fentanyl during the period of greatest postoperative analgesic demand after CS. This period was defined by detailed analysis of patient-controlled analgesia (PCA) usage.This double-blind, placebo-controlled, parallel-group randomized trial included 60 parturients who were scheduled for elective CS. Participants received spinal anesthesia with bupivacaine supplemented with normal saline (control group) or with fentanyl 25 μg (fentanyl group). To evaluate primary endpoints, we measured total pethidine consumption over the period of greatest PCA pethidine requirement. For verification of secondary endpoints, we recorded intravenous PCA requirement in other time windows, duration of effective analgesia, pain scores assessed by visual analog scale, opioid side effects, hemodynamic changes, neonatal Apgar scores, and intraoperative pain.Detailed analysis of hour-by-hour PCA opioid requirements showed that the greatest demand for analgesics among patients in the control group occurred during the first 12 hours after surgery. Patients in the fentanyl group had significantly reduced opioid consumption compared with the controls during this period and had a prolonged duration of effective analgesia. The groups were similar in visual analog scale, incidence of analgesia-related side effects (nausea/vomiting, pruritus, oversedation, and respiratory depression), and neonatal Apgar scores. Mild respiratory depression occurred in 1 patient in each group. Fewer patients experienced intraoperative pain in the fentanyl group (3% vs 23%; relative risk 6.8, 95% confidence interval 0.9-51.6).The requirement for postoperative analgesics is greatest during the first 12 hours after induction of anesthesia in patients undergoing CS. The addition of intrathecal fentanyl to spinal anesthesia is effective for intraoperative analgesia and decreases opioid consumption during the period of the highest analgesic demand after CS, without an increase in maternal or neonatal side effects. We recommend using intrathecal fentanyl for CS in medical centers not using morphine or other opioids intrathecally at present.

Optimization of the method for assessment of brain perfusion in humans using contrast-enhanced reflectometry: multidistance time-resolved measurements

The aim of the study was to determine optimal measurement conditions for assessment of brain perfusion with the use of optical contrast agent and time-resolved diffuse reflectometry in the near-infrared wavelength range. The source-detector separation at which the distribution of time of flights (DTOF) of photons provided useful information on the inflow of the contrast agent to the intracerebral brain tissue compartments was determined. Series of Monte Carlo simulations was performed in which the inflow and washout of the dye in extra- and intracerebral tissue compartments was modeled and the DTOFs were obtained at different source-detector separations. Furthermore, tests on diffuse phantoms were carried out using a time-resolved setup allowing the measurement of DTOFs at 16 source-detector separations. Finally, the setup was applied in experiments carried out on the heads of adult volunteers during intravenous injection of indocyanine green. Analysis of statistical moments of the measured DTOFs showed that the source-detector separation of 6 cm is recommended for monitoring of inflow of optical contrast to the intracerebral brain tissue compartments with the use of continuous wave reflectometry, whereas the separation of 4 cm is enough when the higher-order moments of DTOFs are available.

Fluorescence-based method for assessment of blood-brain barrier disruption

We report on a fluorescence-based optical method for assessment of blood-brain barrier in humans. The technique is based on monitoring of fluorescence light excited in the dye circulating in the brain. Measurements were carried out in healthy volunteers and in patients with disruption of the blood-brain barrier with the use of time-resolved method during inflow and washout of indocyanine green after its intravenous injection. We show large differences in the fluorescence signals - in healthy subjects a fast washout of the dye can be observed whereas in patients the washout is significantly prolonged. We conclude that the monitoring of the fluorescence signals during injection of exogenous optical contrast agent can be used for the assessment of the condition of blood-brain barrier at the bedside. The technique may be of benefit for diagnosis of the patients suffering from damage of the blood-brain barrier and in monitoring of therapies used in such patients.

The differences between two selected intensive care units located in central and northern Europe - preliminary observation

BACKGROUND

The aim of this study was to evaluate possible differences in the functioning of two selected intensive care units in Poland and Finland. The activity of the units was analysed over a period of one year.

METHODS

The following parameters were compared: demography of treated populations, site of admission, category of illness, severity of illness (APACHE-II scale), mean length of stay, demanded workload (TISS-28 scale), mortality (both ICU and hospital) and standardized mortality ratio (SMR).

RESULTS

The results of this study indicated that most of the patients in the Polish ICU, regardless of age, diagnosis and APACHE II score, presented significantly longer lengths of stay (14.65 ± 13.6 vs 4.1 ± 4.7 days, P = 0.0001), higher mean TISS-28 score (38.9 ± 9.1 vs 31.2 ± 6.1, P = 0.0001) and higher ICU and hospital mortality (41.5% vs 10.2% and 44.7% vs 21.8%, respectively, P = 0.0001). The values of SMR were 0.9 and 0.85 for the Finnish and Polish ICUs, respectively.

CONCLUSION

The collected data indicate huge differences in the utilisation of critical care resources. Treatment in Polish ICU is concentrated on much more severely ill patients which might be sometimes accompanied by futility of care. In order to verify and correctly interpret the presented phenomena, further studies are needed.

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.

Variance of time-of-flight distribution is sensitive to cerebral blood flow as demonstrated by ICG bolus-tracking measurements in adult pigs

Variance of time-of-flight distributions have been shown to be more sensitive to cerebral blood flow (CBF) during dynamic-contrast enhanced monitoring of neurotrauma patients than attenuation. What is unknown is the degree to which variance is affected by changes in extracerebral blood flow. Furthermore, the importance of acquiring the arterial input function (AIF) on quantitative analysis of the data is not yet clear. This animal study confirms that variance is both sensitive and specific to changes occurring in the brain when measurements are acquired on the surface of the scalp. Furthermore, when the variance data along with the measured AIF is analyzed using a nonparametric deconvolution method, the recovered change in CBF is in good agreement with CT perfusion values.

Modern methods of assessment of lung aeration during mechanical ventilation

Despite the fact that several modes of ventilation are being used, it is not always possible to maintain adequate parameters of gas exchange. In order to provide proper ventilation, it is necessary to assess the lung function. The aim of this article is presentation of different methods of assesment of lung aerations including its advantages, disadvantages and possibilities for implementation in clinical practice. Computed tomography provides information regarding morphology and aeration of lung tissue, but has several limitations: necessity of patients transportation, it cannot be performed in a continuous manner, a quantitative assessment of picture seems to be rather complicated. Ultrasonography is widely used in intensive care and is a noninvasive and bedside method. It gives the opportunity to assess an investigated organ in real time. Its clinical utility in patients with ARDS was proved by Lichtenstein et al. Another technology which has been implemented for the purpose of lungs visualization is electrobioimpedancy (EIT). This new method consists of continuous monitoring of chest electrobioimpedancy changes due to its air content. Unlike to techniques mentioned above, lung images generated with EIT do not provide any information about morphology of affected tissue. The method which indirectly describes the sum of lung interactions is the assessment of quasi-static P/V curve. This method provides information allowing to draw conclusions regarding the usefulness of recruitment maneuvers, but does not provide information regarding the nature of morphologic changes and their location. In the search for the ideal method of lung aeration assessment, it is necessary to define its characteristics, such as noninvasiveness, availability and visualization of tissue morphologic changes in real time.

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.

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.

Optical system based on time-gated, intensified charge-coupled device camera for brain imaging studies

An imaging system for brain oxygenation based on a time-gated, intensified charge-coupled device camera was developed. It allows one to image diffusely reflected light from an investigated medium at defined time windows delayed with respect to the laser pulse. Applying a fast optomechanical switch to deliver the light at a wavelength of 780 nm to nine source fibers allowed one to acquire images in times as short as 4 s. Thus, the system can be applied in in vivo studies. The system was validated in phantom experiments, in which absorbing inclusions were localized at different depths and different lateral positions. Then, the decrease in absorption of the brain tissue related to increase in oxygenation was visualized in the motor cortex area during finger tapping by a healthy volunteer.

Time-resolved diffuse reflectance measurement carried out on the head of an adult at large source-detector separation

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 system is based on femtosecond TiSa laser and sensitive photomultiplier tube detector. The laser light of 300mW of power was delivered to the surface of the head with the use of an optical fiber. A beam expander was applied in order to distribute the laser light on a large spot which allowed to avoid energetic stimulation of the tissue. The photomultiplier tube detector was positioned directly on the surface of the medium at the distance of 9cm from the center of the source position. In this paper we report results of an in-vivo experiment carried out on the head of an adult healthy volunteer. The time-resolved system was applied during intravenous injection of an optical contrast agent (indocyanine green - ICG) and the distributions of times of flight of photons were successfully acquired showing inflow and washout of the dye to the tissue. Time-courses of the moments of distributions of times of flight of photons are presented and compared with the results obtained simultaneously at shorter source-detector separations (3 cm, 4 cm and 5 cm).

[The influence of epidural analgesia on the course of labor]

OBJECTIVE

The aim of the study was to analyze the influence of epidural analgesia (EA) on the course of labor.

MATERIAL AND METHODS

The study group consisted of 191 women with EA ("walking anesthesia"). 209 women without EA were chosen for controls. All the patients delivered at the 1st Dept of Obstetrics and Gynecology Medical University of Warsaw, Poland. T-test and chi2 test were used for statistical analysis and p < 0.05 was considered statistically significant.

RESULTS

There were no significant differences between the groups regarding age, parity weight, average birth weight of newborns and the rate of preterm deliveries. The first and second stage of labor were significantly longer in EA group (p < 0.01). The velocity of dilatation was significantly slower in the study group until 3-5cm (0.87 vs. 1.34 cm/h). After EA was applied, the acceleration of dilatation was, however significantly greater than among controls (4.27 times vs. 3.2 times). The rate of CS was similar in both groups, however the indications for it differed significantly: fetal asphyxia 22% vs. 50% (p = 0.04), occiput posterior 22% vs. 4% (p = 0.009) in EA vs. controls, respectively. There were no differences between the groups regarding the general condition of the newborns.

CONCLUSIONS

The overall longer first stage of labor in patients from the study group can result from the characteristics of women more than from EA itself, as EA seems to accelerate the dilatation of the cervix. EA does not affect the incidence of operative delivery however it may change the indications to cesarean section. EA has no impact on the condition of the newborns.

[Comparative study of postoperative analgesia after intrathecal administration of bupivacaine with fentanyl or morphine for elective Caesarean section]

BACKGROUND

Various opioids have been recommended for spinal anaesthesia during Caesarean section. The aim of this prospective randomized, double-blind study was to compare the quality of postoperative analgesia and adverse effects after intrathecal administration of 0.5% hyperbaric bupivacaine (HB) combined with either morphine or fentanyl.

METHODS

Sixty parturients were randomly allocated to receive intrathecally, 7.5-15 mg of HB with either 25 microg fentanyl (group F), or 100 microg morphine (group M). All women received 100 mg ketoprofen at 2 and 14 h after surgery, and 1.0 g paracetamol at 2, 8, 14 and 20 h after surgery. Additionally, meperidine was offered as a rescue analgesic via patient-controlled analgesia (PCA). During the first 24 h after surgery, pain intensity was evaluated using a VAS score, meperidine consumption was noted, and possible side effects were assessed.

RESULTS

Mean PCA meperidine consumption was 47 mg and 130 mg, for groups M and F, respectively. Intrathecal morphine significantly prolonged the time to first PCA use, when compared to fentanyl. The mean VAS score was lower in group M. Pruritus was more frequently observed in group M. There was no significant difference in the incidence of postoperative nausea and vomiting between both groups.

CONCLUSIONS

Both intrathecal morphine and fentanyl significantly reduced the intensity of postoperative pain. Morphine increased the duration of postoperative analgesia and reduced the demand for rescue meperidine.