Towards the Improvement of Soil Salinity Mapping in a Data-Scarce Context Using Sentinel-2 Images in Machine-Learning Models.

Several recent studies have evidenced the relevance of machine-learning for soil salinity mapping using Sentinel-2 reflectance as input data and field soil salinity measurement (i.e., Electrical Conductivity-EC) as the target. As soil EC monitoring is costly and time consuming, most learning databases used for training/validation rely on a limited number of soil samples, which can affect the model consistency. Based on the low soil salinity variation at the Sentinel-2 pixel resolution, this study proposes to increase the learning database's number of observations by assigning the EC value obtained on the sampled pixel to the eight neighboring pixels. The method allowed extending the original learning database made up of 97 field EC measurements (OD) to an enhanced learning database made up of 691 observations (ED). Two classification machine-learning models (i.e., Random Forest-RF and Support Vector Machine-SVM) were trained with both OD and ED to assess the efficiency of the proposed method by comparing the models' outcomes with EC observations not used in the models´ training. The use of ED led to a significant increase in both models' consistency with the overall accuracy of the RF (SVM) model increasing from 0.25 (0.26) when using the OD to 0.77 (0.55) when using ED. This corresponds to an improvement of approximately 208% and 111%, respectively. Besides the improved accuracy reached with the ED database, the results showed that the RF model provided better soil salinity estimations than the SVM model and that feature selection (i.e., Variance Inflation Factor-VIF and/or Genetic Algorithm-GA) increase both models´ reliability, with GA being the most efficient. This study highlights the potential of machine-learning and Sentinel-2 image combination for soil salinity monitoring in a data-scarce context, and shows the importance of both model and features selection for an optimum machine-learning set-up.

Clinical profiles of placenta accreta spectrum: the PACCRETA population-based study.

OBJECTIVE: To describe and compare the characteristics of women with placenta accreta spectrum (PAS) and their pregnancy outcomes according to the presence of placenta praevia and a prior caesarean section. DESIGN: Prospective population-based study. SETTING: All 176 maternity hospitals of eight French regions. POPULATION: Two hundred and forty-nine women with PAS, from a source population of 520 114 deliveries. METHODS: Women with PAS were classified into two risk-profile groups, with or without the high-risk combination of placenta praevia (or an anterior low-lying placenta) and at least one prior caesarean. These two groups were described and compared. MAIN OUTCOME MEASURES: Population-based incidence of PAS, characteristics of women, pregnancies, deliveries and pregnancy outcomes. RESULTS: The PAS population-based incidence was 4.8/10 000 (95% CI 4.2-5.4/10 000). After exclusion of women lost to follow up from the analysis, the group with placenta praevia and a prior caesarean included 115 (48%) women and the group without this combination included 127 (52%). In the group with both factors, PAS was more often suspected antenatally (77% versus 17%; P < 0.001) and more often percreta (38% versus 5%; P < 0.001). This group also had more hysterectomies (53% versus 21%, P < 0.001) and higher rates of blood product transfusions, maternal complications, preterm births and neonatal intensive care unit admissions. Sensitivity analysis showed similar results after exclusion of women who delivered vaginally. CONCLUSION: More than half the cases of PAS occurred in women without the combination of placenta praevia and a prior caesarean delivery, and these women had better maternal and neonatal outcomes. We cannot completely rule out that some of the women who delivered vaginally had placental retention rather than PAS; however, we found similar results among women who delivered by caesarean. TWEETABLE ABSTRACT: Half the women with PAS do not have both placenta praevia and a prior caesarean delivery, and they have better maternal outcomes.

Gestational anaemia and severe acute maternal morbidity: a population-based study.

Anaemia is frequently diagnosed during pregnancy. However, there are few data regarding its incidence, and the association with severe maternal morbidity remains uncertain and potentially biased in high-resource countries. The purpose of this study was to explore the association between gestational anaemia and severe acute maternal morbidity during and after delivery. We performed a cohort-nested case-control analysis from the epidemiology of severe maternal mortality (EPIMOMS) prospective study conducted in six French regions (2012-2013, n = 182,309 deliveries). There were 1669 women with severe acute maternal morbidity during or after delivery, according to a standardised definition obtained by expert consensus. The control group were randomly selected among women without severe morbidity who delivered in the same health centres (n = 3234). We studied the association between gestational anaemia and severe acute maternal morbidity during or after delivery overall, by cause, and by mode of delivery, using multivariable logistic regression and multiple imputation. Gestational anaemia was significantly more frequent in women with severe acute maternal morbidity (25.3%) than in controls (16.3%), p < 0.001, and mostly mild in both groups. After adjustment for confounders, women with gestational anaemia were at increased risk of overall severe acute maternal morbidity during and after delivery (adjusted OR (95%CI) 1.8 (1.5-2.1)). This association was also found for severe postpartum haemorrhage (adjusted OR (95%CI) 1.7 (1.5-2.0)), even after omitting the transfusion criterion (adjusted OR (95%CI) 1.9 (1.6-2.3)), and for severe acute maternal morbidity secondary to causes other than haemorrhage or pregnancy-related hypertensive disorders (adjusted OR (95%CI) 2.7 (1.9-4.0)). These results highlight the importance of optimising the diagnosis and management of anaemia during pregnancy.

Anaphylaxis in pregnancy: a population-based multinational European study.

Anaphylaxis in pregnancy is a rare but severe complication for both mother and infant. Population-based data on anaphylaxis in pregnancy are lacking from mainland European countries. This multinational study presents the incidence, causative agents, management and maternal and infant outcomes of anaphylaxis in pregnancy. This descriptive multinational study used a combination of retrospective (Finnish medical registries) and prospective population-based studies (UK, France, Belgium and the Netherlands) to identify cases of anaphylaxis. Sixty-five cases were identified among 4,446,120 maternities (1.5 per 100,000 maternities; 95%CI 1.1-1.9). The incidence did not vary between countries. Approximately three-quarters of reactions occurred at the time of delivery. The most common causes were antibiotics in 27 women (43%), and anaesthetic agents in 11 women (17%; including neuromuscular blocking drugs, 7), which varied between countries. Anaphylaxis had very poor outcomes for one in seven mothers and one in seven babies; the maternal case fatality rate was 3.2% (95%CI 0.4-11.0) and the neonatal encephalopathy rate was 14.3% (95%CI 4.8-30.3). Across Europe, anaphylaxis related to pregnancy is rare despite having a multitude of causative agents and different antibiotic prophylaxis protocols.

Seasonal effect on trace metal elements behaviour in a reservoir of northern Thailand.

Trace metal elements (TME) can be real threats for living organisms. However, few studies dealt with TME in reservoirs in rural areas where farming practises could induce negative effects. Mae Thang reservoir (northern Thailand) has been studied for 3 years to understand the seasonal behaviour of dissolved TME: Fe, Mn, Cd, Al, Pb, V, Cr, Co, Ni, Cu, Zn, Mo, U and As and associated physicochemical parameters. In situ measurements of these parameters were done during the dry and the wet seasons as well as water samples along the water column for further analyses and TME determination by inductively coupled plasma-mass spectrometry (ICP-MS). In the dry season, the water column was characterized by a strong stratification and anoxic conditions in the hypolimnion. High rain and water input from the watershed during the wet season induced mixing of the water. All TME, except Ni, Co and Cr were less concentrated in the wet season indicating a dilution effect by water input. There was thus no important dissolved pollution coming from the watershed. The anoxic conditions in the dry season enhanced the reduction of Fe and Mn and the desorption processes. Depth, and thus oxic-anoxic conditions were the main drivers of TME in the dry season, while in the wet season, dissolution processes from parent rocks of watershed were favoured. The average concentrations of TME in the reservoir were in the limit of the international and Thai standards. Only localized values in the bottom of the reservoir for Fe and Mn were higher than the limits.

Risk factors for conversion to general anesthesia for urgent cesarean among women with labor epidural analgesia: A retrospective case-control study.

OBJECTIVES: General anesthesia for cesarean is associated with an increased risk of maternal morbidity compared with neuraxial anesthesia. Reducing the rate of general anesthesia for urgent cesarean in women with epidural analgesia may improve maternal outcomes. Our objective was to identify the rate and factors associated with the conversion to general anesthesia for urgent cesarean among women with labor epidural analgesia. STUDY DESIGN: We performed a retrospective case-control study including singleton-laboring women with epidural analgesia who delivered after 37 gestational weeks by urgent cesarean (Port Royal Maternity unit, 2012-2017). Cases were all women who required conversion from neuraxial analgesia to general anesthesia. Controls were women just before and after each case included. Factors associated with the conversion to general anesthesia were identified using logistic regression analysis. RESULTS: Among 3,300 laboring women with an epidural analgesia who delivered by urgent cesarean during the study period, 113 (3.4%,) had a conversion to general anesthesia. Factors associated with conversion to general anesthesia were a cervical dilation ≥ 5 cm at the time of epidural placement (aOR 2.55, 95%CI 1.05-6.21), asymmetric sensory blockade (aOR 3.39, 95%CI 1.11-10.36), need for ≥2 rescue top-ups (aOR 2.88, 95%CI 1.29-6.44), and category 1 cesarean (aOR 3.61, 95%CI 1.77-7.33). CONCLUSION: Among women with labor epidural analgesia, suboptimal analgesia significantly increased the risk for conversion to general anesthesia for urgent cesarean. Epidural placement without delay during labor, regular checks of epidural analgesia efficiency, and epidural replacement in case of inadequate epidural analgesia may decrease the rate of avoidable general anesthesia for urgent cesarean.

[Reprint of: Severe pre-eclampsia: guidelines for clinical practice from the French Society of anesthesiology and intensive care (SFAR) and the French College of gynaecologists and obstetricians (CNGOF)]. / Republication de : recommandations formalisées d'experts. Prise en charge de la patiente avec une pré-éclampsie sévère­RFE communes Société française d'anesthésie-réanimation (SFAR)­Collège national des gynécologues et obstétriciens français (CGNOF).

OBJECTIVE: To provide national guidelines for the management of women with severe preeclampsia. DESIGN: A consensus committee of 26 experts was formed. A formal conflict of interest (COI) policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independently of any industrial funding. The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE®) system to guide assessment of quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. METHODS: The last SFAR and CNGOF guidelines on the management of women with severe preeclampsia was published in 2009. The literature is now sufficient for an update. The aim of this expert panel guidelines is to evaluate the impact of different aspects of the management of women with severe preeclampsia on maternal and neonatal morbidities separately. The experts studied questions within 7 domains. Each question was formulated according to the PICO (Patients Intervention Comparison Outcome) model and the evidence profiles were produced. An extensive literature review and recommendations were carried out and analyzed according to the GRADE® methodology. RESULTS: The SFAR/CNGOF experts panel provided 25 recommendations: 8 have a high level of evidence (GRADE 1±), 9 have a moderate level of evidence (GRADE 2±), and for 7 recommendations, the GRADE method could not be applied, resulting in expert opinions. No recommendation was provided for 3 questions. After one scoring round, strong agreement was reached between the experts for all the recommendations. CONCLUSIONS: There was strong agreement among experts who made 25 recommendations to improve practices for the management of women with severe preeclampsia.

When and how should I transfuse during obstetric hemorrhage?

The incidence of maternal hemorrhage and blood transfusion has increased over time. Causes of massive hemorrhage, defined as a transfusion > 10 units of erythrocytes, include abnormal placental insertion, preeclampsia, and placental abruption. Although ratio-based transfusion has been described for managing massive hemorrhage, a goal-directed approach using laboratory or point-of-care data may lead to better outcomes. Autotransfusion, which involves the collection, washing, and filtration of maternal shed blood, avoids many of the complications associated with allogeneic blood transfusion. In this review, we provide an overview of transfusion practices related to the management of obstetric hemorrhage.

A population-based analysis of French transfusion practices for women experiencing severe postpartum hemorrhage.

BACKGROUND: Transfusion is a major therapy for severe postpartum hemorrhage but there are few population-based descriptions of practice. The objective of this retrospective French population-based study was to describe transfusion practices in women with severe postpartum hemorrhage and the compliance with guidelines. METHODS: Study data were sourced from a prior prospective population-based study of 182 309 deliveries in France between 2012 and 2013. Transfusion practices and compliance with French national guidelines were described for all women with severe postpartum hemorrhage who had been transfused with red blood cells. RESULTS: In 1495 women with severe postpartum hemorrhage (0.8% of all deliveries), 35.1% were not transfused, 50.0% were transfused during active bleeding and 14.9% exclusively after control of bleeding. Among 697 women with a hemoglobin level <7 g/dL, 21.4% were not transfused. In 747 women transfused during active bleeding, 68.8% also received fresh frozen plasma (fresh frozen plasma to red blood cell ratio between 0.5 and 1 in 80.4%). Forty-four percent received fibrinogen concentrate (including 37.4% with a plasma fibrinogen level >2 g/L) and 8.6% had a massive transfusion. Among 223 women transfused after bleeding was controlled, 5.4% received fresh frozen plasma and 13% had a hemoglobin level >7 g/dL. CONCLUSIONS: One in five women with severe postpartum hemorrhage and a low hemoglobin concentration did not receive blood transfusion, which does not comply with French national recommendations. Over-transfusion occurred in women in whom bleeding had been controlled. The use of tools to help clinicians with transfusion decision-making should be developed.

Evaluation of the 4 diagnosis criteria proposed by the SMFM and the AFE foundation for amniotic fluid embolism in a monocentric population.

OBJECTIVE: The Society of Maternal Fetal Medicine (SMFM) and the Amniotic Fluid Embolism Foundation have recently proposed four diagnostic criteria for amniotic fluid embolism (AFE): presence of (1) sudden cardiac arrest or both respiratory and hemodynamic collapse, and (2) biological disseminated intravascular coagulopathy (DIC), and (3) absence of fever, and (4) clinical onset during labor or within 30 min of delivery. The objectives of our study were to describe the clinical presentation of women with a strong suspicion of AFE and to assess the validity of the four criteria proposed for AFE definition. MATERIAL AND METHODS: We performed a retrospective study including all patients with a strong suspicion of AFE who delivered between 2006 and 2018 at the Port Royal maternity unit, Paris. Strong suspicion of AFE was defined by a clinical presentation in favor of AFE associated with a biological pattern and/or autopsy result supporting AFE. The mention of AFE in files was essential to include the patients in our study. We estimated the incidence and mortality rate of AFE. Then, the presence of each of the four diagnosis criteria of the SMFM score was described, as well as the clinical and biological patterns. RESULTS: Among the 54 140 women who delivered during the study period, 14 had a strong suspicion of AFE (0.03 %), accounting for 25.9/100 000 deliveries (95 %CI (12.3-39.5/100,000)). All women had biological tests or autopsy supporting the diagnosis of AFE. Six of 14 patients (43 %) presented with all the four diagnostic criteria of the SMFM definition. All 14 women presented a hemodynamic collapse, but respiratory symptoms were lacking in 8 patients (57 %); 71 % fulfilled the criterion of biological DIC, and all patients had a clinical coagulopathy and a massive postpartum hemorrhage. Absence of fever was lacking in three women. In addition, all patients presented premonitory symptoms such as neurological disorders or irreversible and inaugural fetal bradycardia. CONCLUSION: The four SMFM diagnostic criteria were present in less than half of the women with a strong suspicion of AFE. We propose an alternative clinical and pragmatic definition to diagnose AFE, which has to be validated in the future. Early diagnosis of AFE based solely on clinical criteria can help clinicians anticipate the severity of the situation and optimize care.

Update: Focus in-hospital maternal cardiac arrest.

The incidence of maternal cardiac arrest ranges from 1/55,000 to 1/12,000 births. It is due most frequently to cardiovascular, hemorrhagic, and anesthesia-related causes, as well as to amniotic fluid embolism. The basic principles of resuscitation remain applicable in this situation, but the physiological modifications of pregnancy must be taken into account, in particular, the aortocaval compression syndrome. After 24 weeks of gestation, a salvage cesarean delivery must be performed immediately, without transfer to the operating room, if resuscitation maneuvers have failed 4 min after arrest, because this interval conditions the mother's neurological prognosis and improves neonatal survival.

Effect of prophylactic 5-HT3 receptor antagonists on pruritus induced by neuraxial opioids: a quantitative systematic review.

Pruritus is a frequent adverse event observed after neuraxial administration of opioids. Central 5-hydroxytryptamine subtype 3 (5-HT3) receptors may be activated in this process. This systematic review aimed to evaluate the efficacy of prophylactic 5-HT3 receptor antagonists on neuraxial opioid-induced pruritus. We searched Medline, Embase, and Cochrane Collaboration Library databases. Studies were evaluated with the Oxford Validity Scale. Studies with a score of 3 or more and reporting prophylactic administration of 5-HT3 receptor antagonists vs placebo were included. Fifteen randomized double-blind controlled trials (n=1337) were selected. 5-HT3 antagonists (n=775) significantly reduced pruritus [odds ratio (OR) 0.44 (95% confidence interval, 95% CI, 0.29-0.68), P=0.0002, number-needed-to-treat (NNT) 6 (95% CI, 4-14)], the treatment request for pruritus [OR 0.58 (95% CI, 0.43-0.78), P=0.0003, NNT 10 (95% CI, 7-20)], the intensity of pruritus [weighted mean difference (WMD) -0.35 (95% CI, -0.59 to -0.10), P=0.007], the incidence and the intensity of postoperative nausea and vomiting (PONV), and the need of rescue treatment [respectively, Peto odds ratio (Peto OR) 0.43 (95% CI, 0.31-0.58), P<0.00001, NNT 7 (95% CI, 6-10); WMD -0.12 (95% CI, -0.24 to 0.00), P=0.05 and OR 0.42 (95% CI, 0.20-0.86), P=0.02, NNT 8 (95% CI, 5-35)]. However, the funnel plot was asymmetric, suggesting a risk of publication bias. 5-HT3 receptor antagonists may be an effective strategy in preventing neuraxial opioid-induced pruritus and PONV. Further large randomized controlled trials are required to confirm these findings.

Intrathecal hematoma and arachnoiditis mimicking bacterial meningitis after an epidural blood patch.

We present a case of arachnoiditis and an intrathecal hematoma after an epidural blood patch. A 24-year-old parturient underwent an epidural blood patch three days after an accidental dural puncture during epidural labor analgesia. Four days later, the patient developed severe lower back pain, bilateral leg pain, persistent headache and fever. Bacterial meningitis was initially suspected and antibiotics started. Lumbar magnetic resonance imaging was performed and showed an intrathecal hematoma, with no blood in the epidural space. This report briefly reviews the few cases in the literature of arachnoiditis caused by an intrathecal hematoma and discusses the mechanism which resulted in blood in the subarachnoid space.

[Epidemiology of post-partum haemorrhage]. / Épidémiologie de l'hémorragie du post-partum.

OBJECTIVES: To synthesize the available evidence regarding the incidence, causes, risk factors of post-partum haemorrhage (PPH) and the associated maternal morbidity. METHODS: Consultation of the Medline database and of national reports on maternal mortality. RESULTS: PPH is defined as a post-partum blood loss≥500mL, and severe PPH as a post-partum blood loss≥1000mL, whatever the delivery route. In population-based studies, the incidence of PPH is around 5% of deliveries when blood loss is not precisely assessed and around 10% when it is. The incidence of severe PPH is around 2%. Uterine atony if the main cause of PPH. Maternal mortality due to obstetric haemorrhage has decreased in France (currently 1.6 death/100,000 live births) but remained the first cause of maternal death (16%) and the most avoidable (80%). In high-resource countries, PPH is the main cause of acute severe maternal morbidity, and of pregnancy-related ICU admissions. In addition to the direct consequences of acute hypovolemia, PPH exposes the women to the complications of transfusion, of intensive care and to infertility in case of hysterectomy. The main risk factors for PPH are factors of uterine atony, but they are globally poorly predictive. CONCLUSION: PPH is the principal cause of severe maternal morbidity, most often due to uterine atony. Risk factors related to components of care during labor and delivery are amenable to change, and the assessment of their risks-benefits balance should take into account the associated risk of PPH.

[Transfusion for post-partum haemorrhage: what's new in 2011?]. / Hémorragie du post-partum: actualités dans la prise en charge transfusionnelle.

Post-partum haemorrhage is the first cause of maternal death in France. In addition to the treatment of the cause, its treatment consists in the association of procoagulant drugs and blood transfusion. At risk situations requiring blood transfusion are well identified. However, they are not found in one third of the actually transfused patients. Therefore, for all deliveries, the medical team should be prepared to face a post-partum haemorrhage and to transfuse. As post-partum haemorrhage onset is most frequently acute, it is rare to be able to base the transfusion decision on biological parameters such as haemoglobin concentration and / or coagulation tests. The recently defined policy of early use of fresh frozen plasma in order to better control the coagulopathy frequently associated with a large haemorrhage has not been established in obstetrical situations. However, it is recommended to apply it in large volume post-partum haemorrhage, with a fresh frozen plasma/red blood cells concentrate ratio between 1/1 and 1/2. The post-partum haemorrhage treatment may benefit from the use of drugs, the most frequently used being antifibrinolytics, such as tranexemic acid, which help to reduce the magnitude of post-partum haemorrhage. Conversely, activated factor VII use should be restricted to situations where all other conventional treatments failed, as a last attempt to avoid hysterectomy.

Selected new antithrombotic agents and neuraxial anaesthesia for major orthopaedic surgery: management strategies.

We propose recommendations to reduce the risk of haemorrhagic events associated with regional anaesthesia in patients treated with newer anticoagulants after orthopaedic surgery. The risk/benefit ratio should be individualised for each patient according to the type and dose of anticoagulant, the type of regional anaesthesia and patient risk factors. Neuraxial anaesthetic management strategy can be based on the pharmacokinetic properties of specific anticoagulants, including the time required to reach maximal concentration, half-life, and dose regimen. Central neuraxial blocks should not be performed and epidural catheters should not be removed until at least two half-lives after the last injection of anticoagulant, the half-life depending on renal function. After removing a catheter or after a haemorrhagic puncture, the timing of the next anticoagulant injection should be based on the time required for an anticoagulant dose to reach maximum activity. Vigilance remains paramount during the initial days after removal of a neuraxial catheter.

[Anaesthesia, a cause of fetal distress?]. / L'anesthésie comme cause de souffrance foetale?

OBJECTIVE: To describe the effects of anaesthetic techniques and agents on the risk of fetal distress during labour pain relief and anaesthesia for caesarean section. STUDY DESIGN: Data on obstetric anaesthesia- and analgesia-induced fetal distress were searched in Medline database using MESH terms: fetal distress, anaesthesia, analgesia, labour, caesarean section, and umbilical artery pH. Trials published in English or French language were selected. RESULTS: Because of their haemodynamic effects, regional anaesthesia and analgesia, especially spinal anaesthesia for Caesarean section, could induce a decrease in umbilical artery pH (UApH). Moreover, intravenous ephedrine, especially when used in large doses can worsen the acidosis. Labour epidural analgesia is associated with a better acid-base balance than systemic analgesia. Experimental studies have demonstrated harmful effects of systemic opioids and hypnotic drugs on UApH and the foetal brain respectively. Clinical implications of these potentially detrimental effects remain to be determined. CONCLUSION: All obstetric anaesthesia and analgesia techniques are associated with a theoretical risk of fetal distress, but given the fact that regional anaesthesia techniques are also associated with well-demonstrated benefits for the mother and the newborn, the latter remain the preferred choice in obstetric practice.

[Spinal anaesthesia for caesarean section: fluid loading, vasopressors and hypotension]. / Rachianesthésie pour césarienne: remplissage, vasopresseurs et hypotension.

OBJECTIVE: To analyze the different preventive and curative strategies for the management of hypotension during spinal anaesthesia for caesarean section. DATA SOURCES: Data related to hypotension during spinal anesthesia for caesarean section were searched in the Medline database. Trials published in English or French were reviewed. DATA SYNTHESIS: Hypotension during caesarean section under spinal anaesthesia is very frequent (55 to 90%) if not prevented. It can induce complications for the mother and/or the fetus. Crystalloid preload alone is ineffective. Colloid preload is effective but might be better used as a second line treatment. Ephedrine has been the vasopressor of choice for long, but has a weak prophylactic efficacy. In addition, it can induce maternal cardiovascular adverse effects and fetal acidosis. Prophylactic phenylephrine, with or without ephedrine according to maternal heart rate, is at least as effective as ephedrine, with less adverse effects. Crystalloid loading at the time of spinal injection ("co-/post-loading") enhances the haemodynamic control provided by vasopressors. CONCLUSION: Hypotension during spinal anesthesia for caesarean section must be systematically detected, prevented and treated without delay. The association of vasopressor(s) (phenylephrine with or without ephedrine) with a rapid crystalloid loading at the time of spinal injection represents the most interesting strategy nowadays.

The relationship of intracranial pressure Lundberg waves to electroencephalograph fluctuations in patients with severe head trauma.

Lundberg (or B) waves, defined as repetitive changes in intracranial pressure (ICP) occurring at frequencies of 0.5 to 2 waves/min, have been attributed to cerebral blood flow fluctuations induced by central nervous system pace-makers or cerebral pressure autoregulation. We prospectively recorded and digitalized at a frequency rate of 10 Hz (AcqKnowledge software) the following parameters in 6 brain injured patients: mean arterial pressure, heart rate, ICP, mean flow velocity of the middle cerebral artery (MFVMCA) (transcranial Doppler WAKI) and left and right spectral edge frequency (SEFl, SEFr) of continuous electroencephalogram (EEG) recordings (Philips technologies). All patients were sedated using a combination of sufentanil and midazolam and mechanically ventilated. Cerebral electrical activity (oscillations of SEF at a mean frequency of 26+/-9 mHz) and MFVMCA fluctuations were found strongly correlated with the intracranial Lundberg B waves (mean frequency 23+/-7 mHz). These result support the existence of a neuropacemaker at the origin of the Lundberg B waves. The change in cerebral electrical activity, resulting from cerebral pacemakers, could increase cerebral metabolic rate of oxygen (CMRO2) and thus lead to an increase in cerebral blood flow and secondarily of ICP through a change in cerebral blood volume.