Impact of hypotension on cerebral perfusion during general anesthesia induction: A prospective observational study in adults.

INTRODUCTION: During anesthesia, decreases in mean arterial pressure (MAP) are common but the impact on possible cerebral hypoperfusion remains a matter of debate. We evaluated cerebral perfusion in patients with or without cardiovascular comorbidities (Hi-risk vs Lo-risk) during induction of general anesthesia and during hypotensive episodes. METHODS: Patients scheduled for neuroradiology procedure using standardized target-controlled Propofol-Remifentanil infusion were prospectively included. Monitoring included Transcranial Doppler (TCD) measuring mean blood velocity of the middle cerebral artery (Vm), Bispectral Index with burst suppression ratio (SR) and cerebral Near-Infrared Spectroscopy (NIRS). Hypotensive episodes were treated with a 10 µg bolus of Norepinephrine. RESULTS: Eighty-one patients were included, 37 Hi-risk and 44 Lo-risk. During induction of anesthesia, MAP and Vm decreased in all patients, with greater changes observed in Hi-risk patients compared to Lo-risk patients (-34 [38-29]% vs -17 [25-8]%, P < .001 and -39 [45-29]% vs -28 [34-19]%, P < .01 respectively). In Hi-risk patients, the MAP-decrease correlated with the Vm-decrease (r = .48, P < .01), and was associated with more frequent occurrences of SR (21 vs 5 patients, P < .01 for Hi-risk vs Lo-risk). For the MAP-increase induced by norepinephrine, the Vm-increase was greater in Hi-risk than in Lo-risk patients (+15 [8-21]% vs +4 [1-11]%, P < .01). During induction and norepinephrine boluses, NIRS values did not follow acute changes of Vm. CONCLUSION: Our results showed that Hi-risk patients had a higher decrease in MAP and Vm, and a higher occurrence of SR during induction of anesthesia than Lo-risk patients. Correction of MAP with norepinephrine increased Vm mainly in Hi-rik patients.

Evaluation of cardiac output variations with the peripheral pulse pressure to mean arterial pressure ratio.

Cardiac output (CO) optimisation during surgery reduces post-operative morbidity. Various methods based on pulse pressure analysis have been developed to overcome difficulties to measure accurate CO variations in standard anaesthetic settings. Several of these methods include, among other parameters, the ratio of pulse pressure to mean arterial pressure (PP/MAP). The aim of this study was to evaluate whether the ratio of radial pulse pressure to mean arterial pressure (ΔPPrad/MAP) could track CO variations (ΔCO) induced by various therapeutic interventions such as fluid infusions and vasopressors boluses [phenylephrine (PE), norepinephrine (NA) or ephedrine (EP)] in the operating room. Trans-oesophageal Doppler signal and pressure waveforms were recorded in patients undergoing neurosurgery. CO and PPrad/MAP were recorded before and after fluid challenges, PE, NA and EP bolus infusions as medically required during their anaesthesia. One hundred and three patients (mean age: 52 ± 12 years old, 38 men) have been included with a total of 636 sets of measurement. During fluids challenges (n = 188), a positive correlation was found between ΔPPrad/MAP and ΔCO (r = 0.22, p = 0.003). After PE (n = 256) and NA (n = 121) boluses, ΔPPrad/MAP positively tracked ΔCO (r = 0.53 and 0.41 respectively, p < 0.001). By contrast, there was no relation between ΔPPrad/MAP and ΔCO after EP boluses (r = 0.10, p = 0.39). ΔPPrad/MAP tracked ΔCO variations during PE and NA vasopressor challenges. However, after positive fluid challenge or EP boluses, ΔPPrad/MAP was not as performant to track ΔCO which could make the use of this ratio difficult in current clinical practice.

Stenting of the Lateral Sinus in Idiopathic Intracranial Hypertension According to the Type of Stenosis.

BACKGROUND: Over the past decade, stenting of lateral sinus stenosis has been used to treat idiopathic intracranial hypertension. Two types of stenoses have been identified: extrinsic and intrinsic. OBJECTIVE: The aim of this study was to report the results of our use of this procedure to treat patients with extrinsic or intrinsic stenoses in idiopathic intracranial hypertension. METHODS: We retrospectively studied clinical, radiological, and manometric data from patients with idiopathic intracranial hypertension who were treated at our institution between January 2009 and January 2015 by stenting of the lateral sinus. RESULTS: Data were studied from 19 women and 2 men. Average body mass index was 29 kg/m 2 , and the median age at stenting was 33 years. Patients with extrinsic stenoses were younger than those with intrinsic stenoses. Transstenotic gradients measured with patients under general anesthesia were lower than those measured with patients under local anesthesia. In all cases, stenting was effective for papilledema and pulsatile tinnitus. Seventeen patients reporting headaches found that they disappeared completely after stenting. Two complications without long-term effects were reported. CONCLUSION: Irrespective of the type of stenosis, stenting of lateral sinus stenoses is an effective treatment for intracranial hypertension symptoms. At our institution, this treatment has replaced draining of cerebrospinal fluid when treatment with acetazolamide has proved to be ineffective.

Targeting blood products transfusion in trauma: what is the role of thromboelastography?

Viscoelastic hemostatic assays (VHAs), mainly thromboelastography (TEG) and the rotational thromboelastometry (ROTEM), provide global information on clot formation and dissolution at patient bedside, allowing fast identification of coagulation disorders. In trauma patients, VHAs are able to predict massive transfusion and mortality. These devices might also be used for applying targeted administration of procoagulant factors (e.g. fibrinogen concentrate) as an alternative to or in addition to using predefined fixed ratios of red blood cells: platelets: fresh frozen plasma/cryoprecipitate. These goal-directed, individualized treatment algorithms seem to reduce blood product transfusion without deleterious effects on patient outcome. Nevertheless, a clear outcome benefit of using VHAs remains to be demonstrated in trauma patients.