Towards the personalization of septic shock resuscitation: the fundamentals of ANDROMEDA-SHOCK-2 trial

Septic shock is a highly lethal and prevalent disease. Progressive circulatory dysfunction leads to tissue hypoperfusion and hypoxia, eventually evolving to multiorgan dysfunction and death. Prompt resuscitation may revert these pathogenic mechanisms, restoring oxygen delivery and organ function. High heterogeneity exists among the determinants of circulatory dysfunction in septic shock, and current algorithms provide a stepwise and standardized approach to conduct resuscitation. This review provides the pathophysiological and clinical rationale behind ANDROMEDA-SHOCK-2, an ongoing multicenter randomized controlled trial that aims to compare a personalized resuscitation strategy based on clinical phenotyping and peripheral perfusion assessment, versus standard of care, in early septic shock resuscitation.

S-Nitrosylation in endothelial cells contributes to tumor cell adhesion and extravasation during breast cancer metastasis

BACKGROUND

Nitric oxide is produced by different nitric oxide synthases isoforms. NO activates two signaling pathways, one dependent on soluble guanylate cyclase and protein kinase G, and other where NO post-translationally modifies proteins through S-nitrosylation, which is the modification induced by NO in free-thiol cysteines in proteins to form S-nitrosothiols. High levels of NO have been detected in blood of breast cancer patients and increased NOS activity has been detected in invasive breast tumors compared to benign or normal breast tissue, suggesting a positive correlation between NO biosynthesis, degree of malignancy and metastasis. During metastasis, the endothelium plays a key role allowing the adhesion of tumor cells, which is the first step in the extravasation process leading to metastasis. This step shares similarities with leukocyte adhesion to the endothelium, and it is plausible that it may also share some regulatory elements. The vascular cell adhesion molecule-1 (VCAM-1) expressed on the endothelial cell surface promotes interactions between the endothelium and tumor cells, as well as leukocytes. Data show that breast tumor cells adhere to areas in the vasculature where NO production is increased, however, the mechanisms involved are unknown.

RESULTS

We report that the stimulation of endothelial cells with interleukin-8, and conditioned medium from breast tumor cells activates the S-nitrosylation pathway in the endothelium to induce leukocyte adhesion and tumor cell extravasation by a mechanism that involves an increased VCAM-1 cell surface expression in endothelial cells. We identified VCAM-1 as an S-nitrosylation target during this process. The inhibition of NO signaling and S-nitrosylation blocked the transmigration of tumor cells through endothelial monolayers. Using an in vivo model, the number of lung metastases was inhibited in the presence of the S-nitrosylation inhibitor N-acetylcysteine (NAC), which was correlated with lower levels of S-nitrosylated VCAM-1 in the metastases.

CONCLUSIONS

S-Nitrosylation in the endothelium activates pathways that enhance VCAM-1 surface localization to promote binding of leukocytes and extravasation of tumor cells leading to metastasis. NAC is positioned as an important tool that might be tested as a co-therapy against breast cancer metastasis.

Recommendations for antibiotic selection for severe nosocomial infections

Severe infection and its evolution to sepsis are becoming more prevalent every day and are among the leading causes of critical illness and mortality. Proper management is crucial to improve prognosis. This document addresses three essential points that have a significant impact on this objective: a) early recognition of patients with sepsis criteria, b) identification of those patients who suffer from an infection and have a high risk of progressing to sepsis, and c) adequate selection and optimization of the initial antimicrobial treatment.

Practical recommendations for the perioperative management of the patient with suspection or serious infection by coronavirus SARS-CoV

En diciembre del 2019, la Comisión Municipal de Salud y Sanidad de Wuhan (provincia de Hubei, China) informó de una serie de casos de neumonía de etiología desconocida. El 7 de enero del 2020, las autoridades chinas identificaron como agente causante del brote un nuevo tipo de virus de la familia Coronaviridae, denominado SARS-CoV-2. Desde entonces, se han notificado miles de casos con una diseminación global. Las infecciones en humanos provocan un amplio espectro clínico que va desde infección leve del tracto respiratorio superior, hasta síndrome de distrés respiratorio agudo grave y sepsis. No existe un tratamiento específico para SARS-CoV-2, motivo por lo que los aspectos fundamentales son establecer medidas adecuadas de prevención y el tratamiento de soporte y manejo de las complicaciones.

Method Extension Study to Validate Applicability of AOAC Official Method 997.03 Visual Immunoprecipitate Assay (VIP®) for Listeria monocytogenes and Related Listeria spp. from Environmental Surfaces: Collaborative Study

Test portions from 3 environmental surface types, representative of typical surfaces found in a food production facility, were analyzed by the Visual Immunoprecipitate assay (VIP®) and the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) culture method for Listeria monocytogenes and related Listeria species. In all cases, naturally contaminated environmental test samples were collected from an actual food production facility by sponge or swab. Test samples from concrete surfaces were collected by both swab and sponge; sponge test samples were collected from rubber surfaces, and swabs were used to sample steel surfaces. Test portions from each surface type were simultaneously analyzed by both methods. A total of 27 laboratories, representing government agencies as well as private industry in both the United States and Canada, participated in the study. During this study, a total of 615 test portions and controls was analyzed and confirmed, of which 227 were positive and 378 were negative by both methods. Nine test portions were positive by culture, but negative by the VIP. Five test portions were negative by culture, but positive by the VIP. Four test portions were negative by VIP and by culture, but confirmed positive when VIP enrichment broths were subcultured to selective agars. The data reported here indicate that the VIP method and the USDA/FSIS culture method are statistically equivalent for detection of L. monocytogenes and related Listeria species from environmental surfaces taken by sponges or swabs.

Individualized lung recruitment maneuver guided by pulse-oximetry in anesthetized patients undergoing laparoscopy: a feasibility study

BACKGROUND

We conducted this study to test whether pulse-oximetry hemoglobin saturation (SpO₂ ) can personalize the implementation of an open-lung approach during laparoscopy. Thirty patients with SpO₂  ≥ 97% on room-air before anesthesia were studied. After anesthesia and capnoperitoneum the FIO₂ was reduced to 0.21. Those patients whose SpO₂ decreased below 97% - an indication of shunt related to atelectasis - completed the following phases: (1) First recruitment maneuver (RM), until reaching lung's opening pressure, defined as the inspiratory pressure level yielding a SpO₂ ≥ 97%; (2) decremental positive end-expiratory (PEEP) titration trial until reaching lung's closing pressure defined as the PEEP level yielding a SpO₂  < 97%; (3) second RM and, (4) ongoing ventilation with PEEP adjusted above the detected closing pressure.

RESULTS

When breathing air, in 24 of 30 patients SpO₂ was < 97%, PaO₂ /FIO₂  ˂ 53.3 kPa and negative end-expiratory transpulmonary pressure (P_TP-EE ). The mean (SD) opening pressures were found at 40 (5) and 33 (4) cmH₂ O during the first and second RM, respectively (P < 0.001; 95% CI: 3.2-7.7). The closing pressure was found at 11 (5) cmH₂ O. This SpO₂ -guided approach increased P_TP-EE (from -6.4 to 1.2 cmH₂ O, P < 0.001) and PaO₂ /FIO₂ (from 30.3 to 58.1 kPa, P < 0.001) while decreased driving pressure (from 18 to 10 cmH₂ O, P < 0.001). SpO₂ discriminated the lung's opening and closing pressures with accuracy taking the reference parameter P_TP-EE (area under the receiver-operating-curve of 0.89, 95% CI: 0.80-0.99).

CONCLUSION

The non-invasive SpO₂ monitoring can help to individualize an open-lung approach, including all involved steps, from the identification of those patients who can benefit from recruitment, the identification of opening and closing pressures to the subsequent monitoring of an open-lung condition.

Controllable direction of liquid jets generated by thermocavitation within a droplet

A high-velocity fluid stream ejected from an orifice or nozzle is a common mechanism to produce liquid jets in inkjet printers or to produce sprays among other applications. In the present research, we show the generation of liquid jets of controllable direction produced within a sessile water droplet by thermocavitation. The jets are driven by an acoustic shock wave emitted by the collapse of a hemispherical vapor bubble at the liquid-solid/substrate interface. The generated shock wave is reflected at the liquid-air interface due to acoustic impedance mismatch generating multiple reflections inside the droplet. During each reflection, a force is exerted on the interface driving the jets. Depending on the position of the generation of the bubble within the droplet, the mechanical energy of the shock wave is focused on different regions at the liquid-air interface, ejecting cylindrical liquid jets at different angles. The ejected jet angle dependence is explained by a simple ray tracing model of the propagation of the acoustic shock wave inside the droplet.

Evaluation of Bone Mineral Density in Patients with Type 1 Gaucher Disease in Argentina

The purpose of this study was to evaluate the frequency of osteoporosis (OP) in patients with Gaucher disease (GD) in Argentina. GD patients from 28 centers were consecutively included from April 2012 to 2014. Bone mineral density (BMD) was determined by dual X-ray absorptiometry in the lumbar spine and the femoral neck or the total proximal femur for patients ≥20 yr of age, and by whole-body scan in the lumbar spine in patients <20 yr of age. In children, mineral density was calculated using the chronological age and Z height. OP diagnosis was determined following adult and pediatric official position of the International Society for Clinical Densitometry. A total of 116 patients were included, of which 62 (53.5%) were women. The median age was 25.8 yr. All patients received enzyme replacement therapy, with a median time of 9.4 yr. Normal BMD was found in 89 patients (76.7%), whereas low bone mass (LBM) or osteopenia was found in 15 patients (13%) and OP in 12 patients (10.3%). The analysis of the pediatric population revealed that 4 patients (9.3%) had LBM and 3 (7%) had OP (Z-score ≤ -2 + fractures height-adjusted by Z), whereas in the adult population (n = 73), 11 patients (15%) had LBM or osteopenia and 9 (12.3%) had OP. Bone marrow infiltration and the presence of fractures were significantly correlated with the presence of OP (p = 0.04 and <0.001, respectively). This is the first study in Argentina and in the region describing the frequency of OP or LBM in GD patients treated with imiglucerase using the official position of the International Society for Clinical Densitometry.

[Intracranial hypertension related to sedation with sevoflurane using the AnaConDa(®) device in a patient with severe traumatic brain injury]

Sedation in neurocritical patients remains a challenge as there is no drug that meets all the requirements. Since the appearance of the AnaConDa(®) device, and according to the latest recommendations, sevoflurane has become an alternative for patients with brain injury. The use of AnaConDa(®) produces an increase in the anatomical dead space that leads to a decrease in alveolar ventilation. If the decrease in the alveolar ventilation is not offset by an increase in minute volume, there will be an increase in PaCO2. We report the case of a patient with severe traumatic brain injury who suffered an increase in intracranial pressure as a result of increased PaCO2 after starting sedation with the AnaConDa(®) device.

The identification of two subgroups of obese women with differing endometrial proliferation levels: potential consequences in the development of endometrial cancer

Enhanced endometrial proliferation correlates obesity to type-I (estrogen-dependent) endometrial cancer (EC). Our aim was to distinguish obese women (without EC) with differing endometrial proliferation. Endometrial and blood samples were obtained from normal-weight and obese women without EC. Type-I EC samples were obtained from obese patients. On measuring endometrial proliferation (Ki67 and phosphorylated histone H3 (p-H3)), two groups of obese women without EC were identified: obese(High Proliferating) (O(HP)) and obese(Low Proliferating) (O(LP)). Increased Ki67 (88.5%, P<0.001), p-H3 (62.6%, P<0.01), 17β-estradiol/progesterone ratio (46.3%, P<0.01) and endometrial estrogen receptor alpha (ERα) (82.2%, P<0.001) were observed in O(HP) compared with O(LP) patients. ECs possessed similar ERα and enhanced proliferation as O(HP), suggesting that O(HP) women are at higher risk of type-I EC. O(LP) women were indistinguishable from normal-weight women regarding these determinants of endometrial proliferation, ERα and 17β-estradiol/progesterone ratio. Our data may further define the obesity phenotype in regards to type-I EC risk and may help identify obese women more susceptible to develop type-I EC, allowing early intervention and a potential reduction in mortality.

Microcystin-LR detection in water by the Fabry-Pérot interferometer using an optical fibre coated with a sol-gel imprinted sensing membrane

Cyanobacteria deteriorate the water quality and are responsible for emerging outbreaks and epidemics causing harmful diseases in Humans and animals because of their toxins. Microcystin-LR (MCT) is one of the most relevant cyanotoxin, being the most widely studied hepatotoxin. For safety purposes, the World Health Organization recommends a maximum value of 1 μg L(-1) of MCT in drinking water. Therefore, there is a great demand for remote and real-time sensing techniques to detect and quantify MCT. In this work a Fabry-Pérot sensing probe based on an optical fibre tip coated with a MCT selective thin film is presented. The membranes were developed by imprinting MCT in a sol-gel matrix that was applied over the tip of the fibre by dip coating. The imprinting effect was obtained by curing the sol-gel membrane, prepared with (3-aminopropyl) trimethoxysilane (APTMS), diphenyl-dimethoxysilane (DPDMS), tetraethoxysilane (TEOS), in the presence of MCT. The imprinting effect was tested by preparing a similar membrane without template. In general, the fibre Fabry-Pérot with a Molecular Imprinted Polymer (MIP) sensor showed low thermal effect, thus avoiding the need of temperature control in field applications. It presented a linear response to MCT concentration within 0.3-1.4 μg L(-1) with a sensitivity of -12.4±0.7 nm L μg(-1). The corresponding Non-Imprinted Polymer (NIP) displayed linear behaviour for the same MCT concentration range, but with much less sensitivity, of -5.9±0.2 nm L μg(-1). The method shows excellent selectivity for MCT against other species co-existing with the analyte in environmental waters. It was successfully applied to the determination of MCT in contaminated samples. The main advantages of the proposed optical sensor include high sensitivity and specificity, low-cost, robustness, easy preparation and preservation.

[Clinical validation of minimally invasive evaluation of systolic function]

BACKGROUND AND OBJECTIVE

Pulse contour continuous cardiac output (PiCCO) monitoring by means of transpulmonary thermodilution provides 2 indices of systolic function: the cardiac function index and the global ejection fraction. Our aim was to compare these 2 PiCCO indices to the left-ventricular ejection fraction obtained by transthoracic echocardiography.

MATERIAL AND METHODS

This was a prospective clinical study of 35 adult patients in the critical care unit of a university hospital. Each patient provided his or her own control data. Patients with marked changes in regional segment contractility or nonsinus rhythm were excluded. We collected patient variables, reason for admission to the critical care unit, the Acute Physiology and Chronic Health Evaluation II score, the reason for hemodynamic monitoring, and the infusion of vasoactive drugs at the time of the procedure.

RESULTS

Statistically significant correlations were found between the left-ventricular ejection fraction and the global ejection fraction (r=0.79, P<.001) and the cardiac function index (r=0.66, P<.001). The mean (SD) difference between the left-ventricular ejection fraction and the global ejection fraction and the cardiac function index were 1.05% (10.2%) (range, 19.0% to 29.1%) and 0.001% (12.4%) (range, -24.3% to 24.3%), respectively. For predicting a left-ventricular ejection fraction of less than 40%, the area under the curve was 0.879 for the global ejection fraction and 0.805 for the cardiac function index of A global ejection fraction less than 13.5% and a cardiac function index less than 3.15 min(-1) predicted a left-ventricular ejection fraction less than 40% with sensitivities of 97% and 96% and specificities of 85% and 77%, respectively.

CONCLUSIONS

In patients without marked changes in regional segment contractility, the global ejection fraction and the cardiac function index calculated by the PiCCO monitor offer a reliable and simple way to assess left-ventricular systolic function. Low values for these indicators suggest the need for echocardiographic assessment of left- and right-ventricular function.

Phase II study of sunitinib as first-line treatment of urothelial cancer patients ineligible to receive cisplatin-based chemotherapy: baseline interleukin-8 and tumor contrast enhancement as potential predictive factors of activity

BACKGROUND

A strong rationale supports the role of antiangiogenic drugs in urothelial cancer. This trial was designed to assess the activity of sunitinib as first-line treatment in patients with metastatic urothelial cancer ineligible for cisplatin and to explore molecular and imaging variables predictive of clinical benefit.

PATIENTS AND METHODS

This was a multicenter phase II trial with sunitinib 50 mg daily in 4/2-week schedule. Eligibility criteria were as follows: creatinine clearance 30-60 ml/min, Eastern Cooperative Oncology Group Pperformance Sstatus of one or less, and adequate hepatic and hematologic function. Twelve circulating cytokines were evaluated at baseline and sequentially using Luminex xMAP(®) (Austin, TX). Baseline and treatment-related changes in perfusion were evaluated in a patient subgroup using contrast-enhanced computed tomography.

RESULTS

On intention-to-treat analysis, 38 patients showed 3 (8%) partial responses (PRs) and 19 (50%) presented with stable disease (SD), 17 (45%) of them ≥3 months. Clinical benefit (PR + SD) was 58%. Median time to progression (TTP) was 4.8 months and median overall survival 8.1 months. Toxicity was consistent with previous reports for sunitinib. Low interleukin-8 (IL-8) baseline levels were significantly associated with increased TTP. Baseline tumor contrast enhancement with >40 Hounsfield units was associated with clinical benefit.

CONCLUSIONS

This study highlights the potential role of the angiogenic pathway as a therapy target in urothelial cancer. Baseline IL-8 serum levels and contrast enhancement of lesions warrant further study.

Complications related to less-invasive haemodynamic monitoring

BACKGROUND

The aim of this study was to evaluate the type and incidence of complications during insertion, maintenance, and withdrawal of central arterial catheters used for transpulmonary thermodilution haemodynamic monitoring (PiCCO™).

METHODS

We conducted a prospective, observational, multicentre study in 14 European intensive care units (six countries). A total of 514 consecutive patients in whom haemodynamic monitoring by PiCCO™ was indicated were studied.

RESULTS

Five hundred and fourteen PiCCO catheters (475 in femoral, 26 in radial, nine in axillary, and four in brachial arteries) were inserted. Arterial access was obtained on the first attempt in 86.4% of the patients. Minor problems such as oozing after insertion (3.3%) or removal of the catheter (3.5%) were observed, but no episodes of serious bleeding (more than 50 ml) were recorded. Small local haematomas were observed after insertion (4.5%) and after removal (1.2%) of the catheter. These complications were not more frequent in patients with coagulation abnormalities. The incidence of site inflammation and catheter-related infection was 2% and 0.78%, respectively. Other complications such as ischaemia (0.4%), pulse loss (0.4%), or femoral artery thrombosis (0.2%) were rare, transient, and all resolved with catheter removal or embolectomy, respectively.

CONCLUSIONS

In this series of patients, central arterial catheters used for PiCCO™ monitoring were demonstrated to be a safe alternative for advanced haemodynamic monitoring.

Pump-probe imaging of nanosecond laser-induced bubbles in agar gel

In this paper we show results of Nd:YAG laser-induced bubbles formed in a one millimeter thick agar gel slab. The nine nanosecond duration pulse with a wave length of 532 nm was tightly focused inside the bulk of the gel sample. We present for the first time a pump-probe laser-flash shadowgraphy system that uses two electronically delayed Nd:YAG lasers to image the the bubble formation and shock wave fronts with nanosecond temporal resolution and up to nine seconds of temporal range. The shock waves generated by the laser are shown to begin at an earlier times within the laser pulse as the pulse energy increases. The shock wave velocity is used to infer a shocked to unshocked material pressure difference of up to 500 MPa. The bubble created settles to a quasi-stable size that has a linear relation to the maximum bubble size. The energy stored in the bubble is shown to increase nonlinearly with applied laser energy, and corresponds in form to the energy transmission in the agar gel. We show that the interaction is highly nonlinear, and most likely is plasma-mediated.

Effects of prone position on alveolar dead space and gas exchange during general anaesthesia in surgery of long duration

BACKGROUND AND OBJECTIVE

We investigated the effects of prone position on respiratory dead space and gas exchange in 14 anaesthetized healthy patients undergoing elective posterior spinal surgery of more than 3 h of duration.

METHODS

The patients received a total intravenous anaesthetic with propofol/remifentanil/cisatracurium. They were ventilated at a tidal volume of 8-10 mL kg(-1), zero positive end-expiratory pressure and an inspired oxygen fraction of 0.4. Physiological, airway and alveolar dead spaces were calculated by analysis of the volumetric capnography waveform. Measurements were made in supine position (20 min after the beginning of mechanical ventilation) and 30, 120 and 180 min after turning to prone position.

RESULTS

We found that the alveolar dead space/tidal volume ratio did not change. PaO(2)/F(i)O(2) increased, although not statistically significantly. Dynamic compliance was reduced due to a reduction in tidal volume and an increase in plateau pressure.

CONCLUSIONS

Patients undergoing surgery in prone position for a duration of 3 h under general anaesthesia including muscle relaxation and mechanical ventilation without positive end-expiratory pressure have stable haemodynamics and no significant changes in the alveolar dead space to tidal volume ratio. Oxygenation tended to improve.

Comparison of the EEG-based SNAP index and the Bispectral (BIS) index during sevoflurane-nitrous oxide anaesthesia

The BIS monitor (Aspect Medical Inc, Newton, USA) was the first electroencephalogram (EEG)-based monitor of the hypnotic effect reflected by a dimensionless figure ranging from 100 (awake state) to 0 (flat line EEG). Its widespread use makes it the most-studied and the best-known among same intended devices. Its algorithm processes low-frequency EEG oscillations in order to provide the Bispectral index. A BIS index ranging from 40 to 60 has been established as the proper for surgical performance. The BIS monitor permits a closer approach to the hypnotic component of anaesthesia beyond clinical signs and may reduce the probability of intraoperative awareness; therefore, it has become a recommended monitoring tool in routine practice. The SNAP monitor (Nicolet Biomedical, Madison WI, USA) is also intended for monitoring the hypnotic effect of anaesthetics, which is in turn displayed as an index ranging from 100 to 0, with 100 meaning a fully awake state and 0 meaning no brain activity. The algorithm of the SNAP monitor is featured by its additional processing of ultra-high EEG frequencies, which seem to be involved in the formation of consciousness. The use of these frequencies would theoretically improve responsiveness during increased brain activity. We studied its behaviour patterns and capability to monitor the hypnotic effect induced by sevoflurane-nitrous oxide by comparison with the BIS index. Seventy patients ASA I-III were induced with propofol, fentanyl and rocuronium, and maintained with sevoflurane-N(2)O. BIS and SNAP indices were simultaneously recorded before induction, after intubation, after incision, at the following 10, 30 and 50 minutes, awakening and extubation time points, together with heart rate and blood pressure. The Pearson correlation was R(2) = 0.68 (p < .05). The Bland and Altman test showed a bias of 14.3 for SNAP index values with respect to BIS index values. We concluded that the SNAP index correlates with variations in the hypnotic effect induced by sevoflurane-nitrous oxide anaesthesia when compared with the BIS index. In this context, a SNAP index ranging from 58 to 70 would be equivalent to the BIS index range 40 to 60 and, therefore, the accurate for surgical performance.

[Measurement of cardiac output after cardiac surgery: validation of a partial carbon dioxide rebreathing (NICO) system in comparison with continuous thermodilution with a pulmonary artery catheter]

Cardiac output is usually monitored with a pulmonary artery catheter. However, because that method is not free of risk, devices have been designed in recent years to measure cardiac output in a way that is minimally invasive or fully noninvasive. Among such devices is the NICO monitor, which is based on a modified Fick equation (partial CO2 rebreathing).

OBJECTIVE

To compare the accuracy of cardiac output measurements from the NICO monitor to measurements obtained by continuous thermodilution with a pulmonary artery catheter.

MATERIAL AND METHODS

A nonprobabilistic, consecutive sample of 20 patients was enrolled in the early postoperative period after elective cardiac surgery (coronary or valve procedures) in the recovery ward. Seven measurements of cardiac output were taken simultaneously with each method in each patient.

RESULTS AND CONCLUSIONS

Cardiac output estimated by the partial CO2 rebreathing method was lower than the measurement obtained by the pulmonary artery catheter. The percentage error between the 2 methods was 37%, indicating that the NICO monitor can not substitute for the traditional method. The better correlation found between normal-to-low cardiac output values and the absence of side effects of using the NICO method suggest that it might be indicated for detecting low cardiac output after cardiac surgery, especially when the risk-benefit ratio does not favor using a pulmonary artery catheter.

Closed-system anaesthesia for laparoscopic surgery: is there a risk for carbon monoxide intoxication?

BACKGROUND AND OBJECTIVE

One of the complications of laparoscopic surgery is carbon monoxide production during electrocautery. The aim of our study was to ascertain the relationship between intraperitoneal and alveolar concentrations of carbon monoxide and systemic carboxyhaemoglobin in patients undergoing laparoscopic cholecystectomy and anaesthetized with a closed system, where the carbon monoxide excreted through the lungs is accumulated in the circuit and thus re-inhaled.

METHODS

Nine consecutive patients undergoing laparoscopic cholecystectomy were studied. Patients' lungs were ventilated with a closed anaesthesia breathing system (Physioflex). Measurements were taken after establishing pneumoperitoneum (baseline) and at 5, 15 and 30 min after starting electrocautery.

RESULTS

Mean duration of pneumoperitoneum was 42 +/- 13 min with cumulative electrocautery time of 2.4 +/- 1.8 min. Intraperitoneal carbon monoxide concentrations increased significantly at 5, 15 and 30 min reaching peak values of 481 +/- 151 ppm at 15 min. No significant differences were found in alveolar carbon monoxide and carboxyhaemoglobin concentrations with respect to baseline.

CONCLUSIONS

No significant increase in carboxyhaemoglobin is produced during laparoscopic surgery, even under closed-system anaesthesia without pulmonary carbon monoxide elimination. This is most likely due to a low peritoneal absorption of carbon monoxide. We conclude that in adult patients, no carbon monoxide intoxication is caused if reasonable periods of electrocautery are used and the intraperitoneal gas is regularly renewed.

[Ventilatory management of the severely brain-injured patient]

Mechanical ventilation is necessary for treating patients with severe brain injury because it guarantees the airway (through endotracheal intubation), permits sedation (and even curarization), and prevents hypoxemia and/or hypercapnia. Hyperventilation continues to be a focus of debate in the current literature. Nevertheless, the weight of scientific evidence to date suggests that it should not be applied prophylactically during the first 24 hours and that patients should not be hyperventilated for prolonged periods in the absence of intracranial hypertension. Acute lung injury and respiratory distress are among the most frequent and serious complications related to severe brain injury that benefit from the use of positive end-expiratory pressure (PEEP) and ventilation to protect the lung. Gas insufflation through the trachea is a promising therapeutic option for correcting hypercapnia secondary to ventilation for lung protection in such patients. Finally, multimodal monitoring (intracranial pressure, central venous pressure, oxygen saturation detected in the jugular bulb, cerebral oxygen pressure) is recommended for adjusting PEEP and controlling hyperventilation.

Cooling efficiency of cryogen spray during laser therapy of skin

BACKGROUND AND OBJECTIVES

Cryogen spray cooling (CSC) is used extensively for epidermal protection during laser-induced photothermolysis of port wine stains and other vascular skin lesions. The efficacy of CSC depends critically on the heat transfer coefficient (H) at the skin surface for which, however, no reliable values exist. Reported values for H, based on tissue phantoms, vary from 1,600 to 60,000 W/m(2) K.

STUDY DESIGN/MATERIALS AND METHODS

A simple experimental model was designed and constructed, consisting of a pure silver-measuring disk (diameter 10 mm, thickness approximately 1 mm), embedded in a thermal insulator. The disk was covered with a 10 microm thick stratum corneum layer, detached from in vivo human skin. The heat transfer coefficient of the stratum corneum/cryogen interface was measured during CSC with short spurts of atomized tetrafluoroethane.

RESULTS

H was found to be dependent on the specific design of the cryogen valve and nozzle. With nozzles used in typical clinical settings, H was 11,500 W/m(2) K, when averaged over a 100 ms spurt, and 8,000 W/m(2) K when averaged over a 200 ms spurt.

CONCLUSIONS

The presented model enables accurate prediction of H and thus improve control over temperature depth profile and cooling efficiency during laser therapy. Thereby, it may contribute to improvement of therapeutic outcome.

Phobic anxiety in 11 nations. Part I: Dimensional constancy of the five-factor model

The Fear Survey Schedule-III (FSS-III) was administered to a total of 5491 students in Australia, East Germany, Great Britain, Greece, Guatemala, Hungary, Italy, Japan, Spain, Sweden, and Venezuela, and submitted to the multiple group method of confirmatory analysis (MGM) in order to determine the cross-national dimensional constancy of the five-factor model of self-assessed fears originally established in Dutch, British, and Canadian samples. The model comprises fears of bodily injury-illness-death, agoraphobic fears, social fears, fears of sexual and aggressive scenes, and harmless animals fears. Close correspondence between the factors was demonstrated across national samples. In each country, the corresponding scales were internally consistent, were intercorrelated at magnitudes comparable to those yielded in the original samples, and yielded (in 93% of the total number of 55 comparisons) sex differences in line with the usual finding (higher scores for females). In each country, the relatively largest sex differences were obtained on harmless animals fears. The organization of self-assessed fears is sufficiently similar across nations to warrant the use of the same weight matrix (scoring key) for the FSS-III in the different countries and to make cross-national comparisons feasible. This opens the way to further studies that attempt to predict (on an a priori basis) cross-national variations in fear levels with dimensions of national cultures.

Rapid purification and biochemical characterization of glucose kinase from Streptomyces peucetius var. caesius

Glucose kinase catalyzes the ATP-dependent phosphorylation of glucose. Streptomyces peucetius var. caesius glucose kinase was purified 292-fold to homogeneity. The enzyme has cytosolic localization and is composed of four identical subunits, each of 31 kDa. The purified enzyme easily dissociates into dimers. However, in the presence of 100 mM glucose the enzyme maintains its tetrameric form. Maximum activity was found at 42 degrees C and pH 7.5. Isoelectric focusing of the enzyme showed a pl of 8.4. The N- and C-terminal amino acid sequences were MGLTIGVD and VYFAREPDPIM, respectively. The kinetic mechanism of S. peucetius var. caesius glucose kinase appears to be a rapid equilibrium ordered type, i.e., ordered addition of substrates to the enzyme, where the first substrate is d-glucose. The K(m) values for d-glucose and MgATP(2-) were 1.6 +/- 0.2 and 0.8 +/- 0.1 mM, respectively. Mg(2+) in excess of 10 mM inhibits enzyme activity.

Cryogen spray cooling in laser dermatology: effects of ambient humidity and frost formation

BACKGROUND AND OBJECTIVE

Dynamics of cryogen spray deposition, water condensation and frost formation is studied in relationship to cooling rate and efficiency of cryogen spray cooling (CSC) in combination with laser dermatologic surgery.

STUDY DESIGN/MATERIALS AND METHODS

A high-speed video camera was used to image the surface of human skin during and after CSC using a commercial device. The influence of ambient humidity on heat extraction dynamics was measured in an atmosphere-controlled chamber using an epoxy block with embedded thermocouples.

RESULTS

A layer of liquid cryogen may remain on the skin after the spurt termination and prolong the cooling time well beyond that selected by the user. A layer of frost starts forming only after the liquid cryogen retracts. Condensation of ambient water vapor and subsequent frost formation deposit latent heat to the target site and may significantly impair the CSC cooling rate.

CONCLUSIONS

Frost formation following CSC does not usually affect laser dosage delivered for therapy of subsurface targets. Moreover, frost formation may reduce the risk of cryo-injury associated with prolonged cooling. The epidermal protection during CSC assisted laser dermatologic surgery can be further improved by eliminating the adverse influence of ambient humidity.