Combination of serum and peritoneal 1.3-beta-D-glucan can rule out intra-abdominal candidiasis in surgical critically ill patients: a multicenter prospective study

BACKGROUND

Intra-abdominal candidiasis (IAC) is difficult to predict in critically ill patients with intra-abdominal infection, leading to the overuse of antifungal treatments. Serum and peritoneal 1.3-beta-D-glucan (sBDG and pBDG) have been proposed to confirm or invalidate the diagnosis of IAC, but clinical studies have reported inconsistent results, notably because of heterogeneous populations with a low IAC prevalence. This study aimed to identify a high-risk IAC population and evaluate pBDG and sBDG in diagnosing IAC.

METHODS

This prospective multicenter noninterventional French study included consecutive critically ill patients undergoing abdominal surgery for abdominal sepsis. The primary objective was to establish the IAC prevalence. The secondary objective was to explore whether sBDG and pBDG could be used to diagnose IAC. Wako® beta-glucan test (WT, Fujifilm Wako Chemicals Europe, Neuss, Germany) was used for pBDG measurements. WT and Fungitell® beta-D-glucan assay (FA, Associate of Cape Cod, East Falmouth, USA) were used for sBDG measurements.

RESULTS

Between 1 January 2020 and 31 December 2022, 199 patients were included. Patients were predominantly male (63%), with a median age of 66 [54-72] years. The IAC prevalence was 44% (87/199). The main IAC type was secondary peritonitis. Septic shock occurred in 63% of cases. After multivariate analysis, a nosocomial origin was associated with more IAC cases (P = 0.0399). The median pBDG level was significantly elevated in IAC (448 [107.5-1578.0] pg/ml) compared to non-IAC patients (133 [16.0-831.0] pg/ml), P = 0.0021. For a pBDG threshold of 45 pg/ml, the negative predictive value in assessing IAC was 82.3%. The median sBDG level with WT (n = 42) at day 1 was higher in IAC (5 [3.0-9.0] pg/ml) than in non-IAC patients (3 [3.0-3.0] pg/ml), P = 0.012. Similarly, median sBDG level with FA (n = 140) at day 1 was higher in IAC (104 [38.0-211.0] pg/ml) than in non-IAC patients (50 [23.0-141.0] pg/ml), P = 0.009. Combining a peritonitis score < 3, sBDG < 3.3 pg/ml (WT) and pBDG < 45 pg/ml (WT) yielded a negative predictive value of 100%.

CONCLUSION

In critically ill patients with intra-abdominal infection requiring surgery, the IAC prevalence was 44%. Combining low sBDG and pBDG with a low peritonitis score effectively excluded IAC and could limit unnecessary antifungal agent exposure.

TRIAL REGISTRATION

The study was registered with ClinicalTrials.gov (ID number 03997929, first registered on June 24, 2019).

Expiratory abdominal muscle thickness, a new point of care ultrasound measure for respiratory muscle mass in the intensive care unit: a prospective observational cohort study

BACKGROUND

Even if expiratory muscles are key muscles in intensive care unit (ICU) patients, the association between their thickness and mortality has never been assessed. This study aimed to determine whether expiratory abdominal muscle thickness assessed by ultrasonography (US) was associated with 28-day mortality in ICU patients.

BASIC PROCEDURES

US expiratory abdominal muscle thickness was measured within the first 12 h after ICU admission. The primary endpoint was 28-day mortality.

MAIN FINDINGS

In 310 analyzed patients, a thinner total abdominal expiratory muscle thickness at admission was associated with 28-day mortality (median value with interquartile range: 10.8 [10; 14.6] versus 16.5 [13.4; 20.7] mm). Total abdominal expiratory muscle thickness had an area under the curve of 0.78 [0.71;0.86] to discriminate 28-day mortality.

CONCLUSIONS

US expiratory abdominal muscle thickness was associated with 28-day mortality, supporting its use in predicting ICU patient outcome.

Arterial Load and Norepinephrine Are Associated With the Response of the Cardiovascular System to Fluid Expansion

Background

Fluid responsiveness has been extensively studied by using the preload prism. The arterial load might be a factor modulating the fluid responsiveness. The norepinephrine (NE) administration increases the arterial load and modifies the vascular properties. The objective of the present study was to determine the relationship between fluid responsiveness, preload, arterial load, and NE use. We hypothesized that as a preload/arterial load, NE use may affect fluid responsiveness.

Methods

The retrospective multicentered analysis of the pooled data from 446 patients monitored using the transpulmonary thermodilution before and after fluid expansion (FE) was performed. FE was standardized between intensive care units (ICUs). The comparison of patients with and without NE at the time of fluid infusion was performed. Stroke volume (SV) responsiveness was defined as an increase of more than 15% of SV following the FE. Pressure responsiveness was defined as an increase of more than 15% of mean arterial pressure (MAP) following the FE. Arterial elastance was used as a surrogate for the arterial load.

Results

A total of 244 patients were treated with NE and 202 were not treated with NE. By using the univariate analysis, arterial elastance was correlated to SV variations with FE. However, the SV variations were not associated with NE administration (26 [15; 46]% vs. 23 [10; 37]%, p = 0.12). By using the multivariate analysis, high arterial load and NE administration were associated with fluid responsiveness. The association between arterial elastance and fluid responsiveness was less important in patients treated with NE. Arterial compliance increased in the absence of NE, but it did not change in patients treated with NE (6 [−8; 19]% vs. 0 [−13; 15]%, p = 0.03). The changes in total peripheral and arterial elastance were less important in patients treated with NE (−8 [−17; 1]% vs. −11 [−20; 0]%, p < 0.05 and −10 [−19; 0]% vs. −16 [−24; 0]%, p = 0.01).

Conclusion

The arterial load and NE administration were associated with fluid responsiveness. A high arterial load was associated with fluid responsiveness. In patients treated with NE, this association was lower, and the changes of arterial load following FE seemed to be driven mainly by its resistive component.

Mental health and stress among ICU healthcare professionals in France according to intensity of the COVID-19 epidemic

BACKGROUND

We investigated the impact of the COVID-19 crisis on mental health of professionals working in the intensive care unit (ICU) according to the intensity of the epidemic in France.

METHODS

This cross-sectional survey was conducted in 77 French hospitals from April 22 to May 13 2020. All ICU frontline healthcare workers were eligible. The primary endpoint was the mental health, assessed using the 12-item General Health Questionnaire. Sources of stress during the crisis were assessed using the Perceived Stressors in Intensive Care Units (PS-ICU) scale. Epidemic intensity was defined as high or low for each region based on publicly available data from Santé Publique France. Effects were assessed using linear mixed models, moderation and mediation analyses.

RESULTS

In total, 2643 health professionals participated; 64.36% in high-intensity zones. Professionals in areas with greater epidemic intensity were at higher risk of mental health issues (p < 0.001), and higher levels of overall perceived stress (p < 0.001), compared to low-intensity zones. Factors associated with higher overall perceived stress were female sex (B = 0.13; 95% confidence interval [CI] = 0.08-0.17), having a relative at risk of COVID-19 (B = 0.14; 95%-CI = 0.09-0.18) and working in high-intensity zones (B = 0.11; 95%-CI = 0.02-0.20). Perceived stress mediated the impact of the crisis context on mental health (B = 0.23, 95%-CI = 0.05, 0.41) and the impact of stress on mental health was moderated by positive thinking, b = - 0.32, 95% CI = - 0.54, - 0.11.

CONCLUSION

COVID-19 negatively impacted the mental health of ICU professionals. Professionals working in zones where the epidemic was of high intensity were significantly more affected, with higher levels of perceived stress. This study is supported by a grant from the French Ministry of Health (PHRC-COVID 2020).

High plasma concentration of non-esterified polyunsaturated fatty acids is a specific feature of severe COVID-19 pneumonia

COVID-19 pneumonia has specific features and outcomes that suggests a unique immunopathogenesis. Severe forms of COVID-19 appear to be more frequent in obese patients, but an association with metabolic disorders is not established. Here, we focused on lipoprotein metabolism in patients hospitalized for severe pneumonia, depending on COVID-19 status. Thirty-four non-COVID-19 and 27 COVID-19 patients with severe pneumonia were enrolled. Most of them required intensive care. Plasma lipid levels, lipoprotein metabolism, and clinical and biological (including plasma cytokines) features were assessed. Despite similar initial metabolic comorbidities and respiratory severity, COVID-19 patients displayed a lower acute phase response but higher plasmatic concentrations of non-esterified fatty acids (NEFAs). NEFA profiling was characterised by higher level of polyunsaturated NEFAs (mainly linoleic and arachidonic acids) in COVID-19 patients. Multivariable analysis showed that among severe pneumonia, COVID-19-associated pneumonia was associated with higher NEFAs, lower apolipoprotein E and lower high-density lipoprotein cholesterol concentrations, independently of body mass index, sequential organ failure (SOFA) score, and C-reactive protein levels. NEFAs and PUFAs concentrations were negatively correlated with the number of ventilator-free days. Among hospitalized patients with severe pneumonia, COVID-19 is independently associated with higher NEFAs (mainly linoleic and arachidonic acids) and lower apolipoprotein E and HDL concentrations. These features might act as mediators in COVID-19 pathogenesis and emerge as new therapeutic targets. Further investigations are required to define the role of NEFAs in the pathogenesis and the dysregulated immune response associated with COVID-19.Trial registration: NCT04435223.

Echocardiographic measure of dynamic arterial elastance predict pressure response during norepinephrine weaning: an observational study

The purpose of this study was to determine whether dynamic elastance E_Adyn derived from echocardiographic measurements of stroke volume variations can predict the success of a one-step decrease of norepinephrine dose. In this prospective single-center study, 39 patients with vasoplegic syndrome treated with norepinephrine and for whom the attending physician had decided to decrease norepinephrine dose and monitored by thermodilution were analyzed. E_Adyn is the ratio of pulse pressure variation to stroke volume variation and was calculated from echocardiography stroke volume variations and from transpulmonary thermodilution. Pulse pressure variation was obtained from invasive arterial monitoring. Responders were defined by a decrease in mean arterial pressure (MAP) > 10% following norepinephrine decrease. The median decrease in norepinephrine was of 0.04 [0.03-0.05] µg kg^-1 min^-1. Twelve patients (31%) were classified as pressure responders with a median decrease in MAP of 13% [12-15%]. E_Adyn was lower in pressure responders (0.40 [0.24-0.57] vs 0.95 [0.77-1.09], p < 0.01). E_Adyn was able to discriminate between pressure responders and non-responders with an area under the curve of 0.86 (CI_95% [0.71 to1.0], p < 0.05). The optimal cut-off was 0.8. E_Adyn calculated from the echocardiographic estimation of the stroke volume variation and the invasive arterial pulse pressure variation can be used to discriminate pressure response to norepinephrine weaning. Agreement between E_Adyn calculated from echocardiography and thermodilution was poor. Echocardiographic E_Adyn might be used at bedside to optimize hemodynamic treatment.

Impact of High-Dose Prophylactic Anticoagulation in Critically Ill Patients With COVID-19 Pneumonia

BACKGROUND

Because of the high risk of thrombotic complications (TCs) during SARS-CoV-2 infection, several scientific societies have proposed to increase the dose of preventive anticoagulation, although arguments in favor of this strategy are inconsistent.

RESEARCH QUESTION

What is the incidence of TC in critically ill patients with COVID-19 and what is the relationship between the dose of anticoagulant therapy and the incidence of TC?

STUDY DESIGN AND METHODS

All consecutive patients referred to eight French ICUs for COVID-19 were included in this observational study. Clinical and laboratory data were collected from ICU admission to day 14, including anticoagulation status and thrombotic and hemorrhagic events. The effect of high-dose prophylactic anticoagulation (either at intermediate or equivalent to therapeutic dose), defined using a standardized protocol of classification, was assessed using a time-varying exposure model using inverse probability of treatment weight.

RESULTS

Of 538 patients included, 104 patients experienced a total of 122 TCs with an incidence of 22.7% (95% CI, 19.2%-26.3%). Pulmonary embolism accounted for 52% of the recorded TCs. High-dose prophylactic anticoagulation was associated with a significant reduced risk of TC (hazard ratio, 0.81; 95% CI, 0.66-0.99) without increasing the risk of bleeding (HR, 1.11; 95% CI, 0.70-1.75).

INTERPRETATION

High-dose prophylactic anticoagulation is associated with a reduction in thrombotic complications in critically ill patients with COVID-19 without an increased risk of hemorrhage. Randomized controlled trials comparing prophylaxis with higher doses of anticoagulants are needed to confirm these results.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT04405869; URL: www.clinicaltrials.gov.

Agreement between different non-invasive methods of ventricular elastance assessment for the monitoring of ventricular-arterial coupling in intensive care

Ventricular-arterial coupling is calculated as the arterial elastance to end systolic elastance ratio (E_A/Ees). Although the gold standard is invasive pressure volume loop analysis, Chen method is the clinical reference non-invasive method for estimating end systolic elastance (Ees). Several simplified methods calculate Ees from the end systolic pressure to volume ratio (ESP/ESV). The objective of the present study was to determine whether ESP/ESV simplification can be used instead of the Chen formula to measure ventricular-arterial coupling and to monitor changes following therapeutic intervention. In this retrospective, single-center study, 3 non-invasive E_A/Ees calculation methods were applied to 86 cardiac ICU patients. The Chen method was used as the reference method. Ees was also calculated according to method 1: Ees₁ = 0.9 × SAP/ESV and method 2: Ees₂= E_A/(1/LVEF) - 1. E_A was estimated as 0.9 × SAP/SV (mmHg ml^-1). After simplification: E_A/Ees1 = E_A/Ees2 = (1/LVEF) - 1, with the stroke volume estimated as the product of the aortic velocity-time integral (VTIAo) and the aortic area or as the difference between the end diastolic volume (EDV) and the ESV. All patients received fluid infusion, norepinephrine, or dobutamine. At baseline, the concordance correlation coefficient with E_A/Ees_Chen was 0.13 [- 0.07; 0.31] for E_A/Ees₁ and 0.32 [0.19; 0.44] for E_A/Ees₂. Bias and limit of agreement were 0.28 [- 0.02; 0.36] and [- 5.8; 2.6] for E_A/Ees₁ and of 0.44 [0.31; 0.53] and [- 3.2; 2.6] for E_A/Ees₂. When used to follow variations in E_A/Ees following therapeutic interventions, only 65% (for E_A/Ees₁) and 70% (for E_A/Ees₂) of measures followed the same trend as E_A/Ees_Chen. Our results do not support the use of ESP/ESV based method as substitute for Chen method to measure and assess changes in ventriculo-arterial coupling (E_A/Ees) in cardiac intensive care patients. Further investigations are needed to establish the most reliable non-invasive method.

Brief summary of French guidelines for the prevention, diagnosis and treatment of hospital-acquired pneumonia in ICU

Background

The French Society of Anaesthesia and Intensive Care Medicine and the French Society of Intensive Care edited guidelines focused on hospital-acquired pneumonia (HAP) in intensive care unit. The goal of 16 French-speaking experts was to produce a framework enabling an easier decision-making process for intensivists.

Results

The guidelines were related to 3 specific areas related to HAP (prevention, diagnosis and treatment) in 4 identified patient populations (COPD, neutropenia, post-operative and paediatric). The literature analysis and the formulation of the guidelines were conducted according to the Grade of Recommendation Assessment, Development and Evaluation methodology. An extensive literature research over the last 10 years was conducted based on publications indexed in PubMed™ and Cochrane™ databases.

Conclusions

HAP should be prevented by a standardised multimodal approach and the use of selective digestive decontamination in units where multidrug-resistant bacteria prevalence was below 20%. Diagnosis relies on clinical assessment and microbiological findings. Monotherapy, in the absence of risk factors for multidrug-resistant bacteria, non-fermenting Gram-negative bacilli and/or increased mortality (septic shock, organ failure), is strongly recommended. After microbiological documentation, it is recommended to reduce the spectrum and to prefer monotherapy for the antibiotic therapy of HAP, including for non-fermenting Gram-negative bacilli.

Lung ultrasound for diagnosis and monitoring of ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is the most frequent nosocomial infection in intensive care units (ICU) and is associated with increased mortality, use of antimicrobials, longer mechanical ventilation, and higher healthcare costs. Lung ultrasonography (LUS) can be used at the bedside and gained widespread acceptance in ICU. Although the visualization of a single LUS sign cannot be considered specific for a diagnosis, clinically-driven LUS examination in particular setting and clinical conditions allow ruling in or out quickly and accurately several causes of acute respiratory failure. This article reviews LUS signs for VAP diagnosis and summarizes the studies testing LUS for VAP diagnosis and monitoring. Many VAP occurs in already injured regions, thus presence of lobar consolidation is not enough to affirm VAP. However, a linear/arborescent air-bronchogram confirms the diagnosis of VAP with a good specificity, a normal LUS rules out the diagnosis of VAP (in experimented hands). LUS, thanks to its bedside ready availability, has the potential to become a key tool in early VAP diagnosis. LUS could ideally represent the decision-making tool for antimicrobial therapy administration in the timeframe of the technical time required for bronchoalveolar lavage analysis. A systematic approach for diagnosis and monitoring of VAP with LUS is also proposed in this review. But specific data on LUS specificity and sensitivity for the diagnosis of VAP are still lacking and should be investigated.

Modified Lung Ultrasound Score for Assessing and Monitoring Pulmonary Aeration

Purpose Lung Ultrasound Score (LUSS) is a useful tool for lung aeration assessment but presents two theoretical limitations. First, standard LUSS is based on longitudinal scan and detection of number/coalescence of B lines. In the longitudinal scan pleura visualization is limited by intercostal space width. Moreover, coalescence of B lines to define severe loss of aeration is not suitable for non-homogeneous lung pathologies where focal coalescence is possible. We therefore compared longitudinal vs. transversal scan and also cLUSS (standard coalescence-based LUSS) vs. qLUSS (quantitative LUSS based on % of involved pleura). Materials and methods 38 ICU patients were examined in 12 thoracic areas in longitudinal and transversal scan. B lines (number, coalescence), subpleural consolidations (SP), pleural length and pleural involvement (> or ≤ 50 %) were assessed. cLUSS and qLUSS were computed in longitudinal and transversal scan. Results Transversal scan visualized wider (3.9 [IQR 3.8 - 3.9] vs 2.0 [1.6 - 2.5] cm, p < 0.0001) and more constant (variance 0.02 vs 0.34 cm, p < 0.0001) pleural length, more B lines (70 vs 59 % of scans, p < 0.0001), coalescence (39 vs 28 %, p < 0.0001) and SP (22 vs 14 %, p < 0.0001) compared to longitudinal scan. Pleural involvement > 50 % was observed in 17 % and coalescence in 33 % of cases. Focal coalescence accounted for 52 % of cases of coalescence. qLUSS-transv generated a different distribution of aeration scores compared to cLUSS-long (p < 0.0001). Conclusion In unselected ICU patients, variability of pleural length in longitudinal scans is high and focal coalescence is frequent. Transversal scan and quantification of pleural involvement are simple measures to overcome these limitations of LUSS.

Impact of restrictive fluid protocol on hypoxemia after aneurysmal subarachnoid hemorrhage

PURPOSE

In patients with aneurysmal subarachnoid hemorrhage (aSAH), acute cardiac dysfunction and triple-H-therapy, can lead to hypoxemia. Our aim was to assess impact of a protocoled fluid restrictive approach on hypoxemia in these patients.

METHODS

We included prospectively ICU patients with aSAH admitted within 24h after the bleed. The study was divided into 2 phases. The first phase, from January to December 2012, was designated as control group (group C). The second phase, from February 2014 to January 2015, was designated as study group (group S). Between these periods, a protocoled fluid intake approach was implemented to maintain as low as possible the cumulative fluid balances.

RESULTS

Effective fluid restriction was obtained: at day 3 cumulative fluid balances were respectively for group C and group S, 1559±2402ml and 759±1855ml (p=0.04); and 2211±4918ml vs 529±2806ml (p=0.04) at day 7. We observed reduction in proportion of hypoxemic patient in group S compared to group C, at day 3 (22% vs 40%, p=0.047) and at day 7 (28% vs 57%, p=0.007).

CONCLUSIONS

Fluid restrictive management of patients with aSAH decreases number of hypoxemic patients at day 3 and day 7.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Thoracic ultrasound: Potential new tool for physiotherapists in respiratory management. A narrative review

The use of diagnostic ultrasound by physiotherapists is not a new concept; it is frequently performed in musculoskeletal physiotherapy. Physiotherapists currently lack accurate, reliable, sensitive, and valid measurements for the assessment of the indications and effectiveness of chest physiotherapy. Thoracic ultrasound may be a promising tool for the physiotherapist and could be routinely performed at patients' bedsides to provide real-time and accurate information on the status of pleura, lungs, and diaphragm; this would allow for assessment of lung aeration from interstitial syndrome to lung consolidation with much better accuracy than chest x-rays or auscultation. Diaphragm excursion and contractility may also be assessed by ultrasound. This narrative review refers to lung and diaphragm ultrasound semiology and describes how physiotherapists could use this tool in their clinical decision-making processes in various cases of respiratory disorders. The use of thoracic ultrasound semiology alongside typical examinations may allow for the guiding, monitoring, and evaluating of chest physiotherapy treatments. Thoracic ultrasound is a potential new tool for physiotherapists.

Doppler study of the effects of inhaled nitric oxide and intravenous almitrine on regional pulmonary blood flows in patients with acute lung injury

BACKGROUND

Lung ultrasound can be used at bedside to assess initial lung morphology in hypoxemic patients. We hypothesized that blood flow in consolidated lung and therefore effects of inhaled nitric oxide (iNO) and intravenous almitrine could be directly assessed using Doppler transesophageal echocardiography (TEE).

METHODS

We conducted a prospective study including 13 ALI patients with consolidated left lower lobe (LLL). Regional arterial and venous flow signals within the consolidation were recorded with TEE using Doppler at baseline, after iNO (5 ppm), almitrine (4 μg/kg/min) and their combination. Pulmonary shunt (Qs/Qt) was measured using a Swan-Ganz catheter. Arterial and venous velocity time integral (VTI), peak velocity (Vmax) and mean velocity (Vmean) were measured. Patients were responders if PaO2 basal value increased by 20% after iNO or almitrine.

RESULTS

In 7 NO responders, iNO decreased regional arterial VTI (8.1±1.9 vs. 6.7±1.6, P<0.05). In 8 almitrine responders, almitrine decreased regional arterial and venous VTI (from 6.7±2.0 to 4.5±2.3 cm and from 12.3±5.4 to 7.5±3.8 cm, respectively, P<0.05). For all patients, combination of iNO and almitrine decreased regional arterial and venous VTI (from 7.3±0.3 to 4.1±0.3 cm and from 12.6±0.7 to 6.7±0.8 cm, respectively, P<0.05). Arterial and venous Vmean and Vmax significantly decreased. Variations of arterial VTI and venous Vmean were correlated to variations of Qs/Qt (r=.71, P<.001 and r=.62, P<.01, respectively).

CONCLUSION

Doppler of consolidated LLL allows assessment of regional pulmonary circulation in ICU settings. It detects changes in flow profiles resulting from the administration of NO and/or almitrine. Further applicability remains to be determined.

Clinical review: Bedside lung ultrasound in critical care practice

Lung ultrasound can be routinely performed at the bedside by intensive care unit physicians and may provide accurate information on lung status with diagnostic and therapeutic relevance. This article reviews the performance of bedside lung ultrasound for diagnosing pleural effusion, pneumothorax, alveolar-interstitial syndrome, lung consolidation, pulmonary abscess and lung recruitment/derecruitment in critically ill patients with acute lung injury.

Transthoracic ultrasound approach of thoracic aorta in critically ill patients with lung consolidation

PURPOSE

Normally, the aortic arch and the descending aorta are not visible using transthoracic ultrasonography. We hypothesize that lung consolidation of upper and lower lobes, by opening an acoustic window, may allow the ultrasound examination of the thoracic aorta.

METHODS

During a 2-month period, 18 consecutive patients hospitalized in the intensive care unit with consolidation of upper and/or lower lobes diagnosed by lung ultrasound were studied. The ascending and descending aorta and the aortic arch were systematically searched for by positioning the probe on the anterior, lateral, and posterior regions of the chest wall.

RESULTS

Among the 16 patients with left lower lobe consolidation, the descending aorta was always visible by positioning the probe on lateral and posterior parts of the chest wall. In the 4 patients with consolidation of the left upper lobe, the aortic arch was visible when positioning the probe on anterior and upper parts of the left chest wall. In the patient with right upper lobe consolidation, both the ascending aorta and the aortic arch were visible when positioning the probe on anterior and upper parts of the right chest wall.

CONCLUSIONS

In critically ill patients, the presence of consolidated upper and left lower lobes may allow the ultrasound examination of the different parts of the thoracic aorta.

Effects of halogenated anaesthetics on diaphragmatic actin-myosin cross-bridge kinetics

BACKGROUND

The effects of halogenated anaesthetics on cross-bridge (CB) kinetics are unclear. As halogenated anaesthetics do not markedly modify the intracellular calcium transient in the diaphragm, we used an isolated rat diaphragm preparation to assess the effects of halothane and isoflurane on CB kinetics.

METHODS

The effects of halothane and isoflurane (1 and 2 minimum alveolar concentration (MAC)) on rat diaphragm muscle strips were studied in vitro (Krebs-Henseleit solution, 29 degrees C, oxygen 95%/carbon dioxide 5%) in tetanus mode (50 Hz). From the force-velocity curve and using A. F. Huxley's equations, we determined the main mechanical and energetic variables and calculated CB kinetics.

RESULTS

At 1 and 2 MAC, isoflurane and halothane induced no significant inotropic effects. Whatever the concentrations tested, halothane and isoflurane did not significantly modify the CB number, the elementary force per CB, the attachment and detachment constants, the duration of the CB cycle and mean CB velocity.

CONCLUSION

In the rat diaphragm at therapeutic concentrations, halogenated anaesthetics do not significantly modify CB mechanical and kinetic properties.

Echocardiographic Doppler assessment of pulmonary capillary wedge pressure in surgical patients with postoperative circulatory shock and acute lung injury

BACKGROUND

In cardiac patients, pulmonary capillary wedge pressure (PCWP) is estimated using color M-mode Doppler study of left ventricular filling and Doppler tissue imaging. The goal of this study was to assess whether echocardiography accurately estimates PCWP in critically ill patients.

METHODS

Sixty ventilated patients admitted for septic shock and acute lung injury were prospectively studied using simultaneously transesophageal echocardiography and pulmonary artery catheterization. Initial PCWP values and their changes measured invasively were compared to initial values and corresponding changes of early diastolic velocity of mitral annulus displacement measured by Doppler tissue imaging (Ea), flow propagation velocity of early diastolic mitral inflow measured by color M-mode Doppler (Vp), and their respective ratio to early mitral inflow velocity (E) measured by conventional Doppler: E/Ea and E/Vp. Relations between E/Ea, E/Vp, and PCWP were prospectively tested in 20 additional patients.

RESULTS

E/Ea and E/Vp gave a rough estimate of initial PCWP values with mean biases of 0.4 +/- 2.2 and 0.1 +/- 2.9 mmHg, respectively. Receiving operating characteristic curves demonstrated that an E/Ea of 6 or greater is an accurate predictor of a PCWP of 13 mmHg or greater and that an E/Ea of 5.4 is a good predictor of a PCWP of 8 mmHg or less. Changes in PCWP were significantly correlated to changes in E/Ea (Rho = 0.84, P < 0.0001).

CONCLUSIONS

In patients with postoperative circulatory shock and acute lung injury, transesophageal echocardiography estimates noninvasively PCWP. However, echocardiographic estimation of PCWP may not be accurate enough for adjusting therapy.

Effects of halothane and isoflurane on the contraction, relaxation and energetics of rat diaphragmatic muscle

BACKGROUND

The inotropic effects of halogenated anaesthetics on diaphragmatic muscle remain a matter of debate. Their effects on its relaxation are poorly understood, although diaphragmatic relaxation is recognized as an important physiological process that may interfere with diaphragmatic performance, fatigue and arterial blood flow.

METHODS

The effects of halothane and isoflurane (1 or 2 x minimum alveolar concentration [1 or 2 MAC]) on contraction and relaxation of rat diaphragm muscle strips (n = 40) were studied in vitro from force-velocity curves obtained at various loads from isotonic to isometric conditions. From these curves we determined the peak power output and the curvature. Data are mean (SD) percentage of baseline values.

RESULTS

At I MAC, isoflurane and halothane induced no significant inotropic and lusitropic effects. At 2 MAC, isoflurane induced a negative inotropic effect (active force, 93(5)% of baseline). Halothane and isoflurane induced a significant decrease in the peak power output at 2 MAC (88(8) and 86(9)% of baseline; P < 0.05), without significant changes in the curvature of the force-velocity curve. At 2 MAC isoflurane under high loads and halothane under low loads induced moderate negative lusitropic effects.

CONCLUSION

Halothane and isoflurane induced very moderate inotropic and lusitropic effects, suggesting that the decrease in diaphragm function observed in vivo is not related to a direct effect on diaphragmatic contractility.

Minimum alveolar concentration of volatile anesthetics in rats during postnatal maturation

BACKGROUND

Although neonatal rats have become widely used as experimental laboratory animals, minimum alveolar concentration (MAC) values of volatile anesthetics in rats during postnatal maturation remain unknown.

METHODS

We determined MAC values of volatile anesthetics in spontaneously breathing neonatal (2-, 9-, and 30-day-old) and adult Wistar rats exposed to increasing (in 0.1-0.2% steps) concentrations of halothane, isoflurane, or sevoflurane (n = 12-20 in each group), using the tail-clamp technique. MAC and its 95% confidence intervals were calculated using logistic regression and corrected for body temperature (37 degrees C).

RESULTS

In adult rats, inspired MAC values corrected at 37 degrees C were as follows: halothane, 0.88% (confidence interval, 0.82-0.93%); isoflurane, 1.12% (1.07-1.18%); and sevoflurane, 1.97% (1.84-2.10%). In 30-day-old rats, the values were as follows: halothane, 1.14% (1.07-1.20%); isoflurane, 1.67% (1.58-1.76%); and sevoflurane, 2.95% (2.75-3.15%). In 9-day-old rats, inspired MAC values were as follows: halothane, 1.68% (1.58-1.78%); isoflurane, 2.34% (2.21-2.47%); and sevoflurane, 3.74% (3.64-3.86%). In 2-day-old rats, inspired MAC values were as follows: halothane, 1.54% (1.44-1.64%); isoflurane, 1.86% (1.72-2.01%); and sevoflurane, 3.28% (3.09-3.47%).

CONCLUSION

As postnatal age increases, MAC value significantly increases, reaching the greatest value in 9-day-old rats, and decreases thereafter, and at 30 days is still greater than the adult MAC value.

Bacterial meningitis following combined spinal-epidural analgesia for labour

We report a case of Streptococcus salivarius meningitis following combined spinal-epidural analgesia for labour. Although rare, bacterial meningitis following combined spinal-epidural anaesthesia is being increasingly described. We review the previously reported cases and discuss the possible aetiological causes and the aseptic precautions likely to reduce the incidence of infectious complications.