Lung ultrasound for early diagnosis of postoperative need for ventilatory support: a prospective observational study.

Pulmonary complications have a significant impact on morbidity and mortality in patients after major surgery. Lung ultrasound can be used at the bed-side, and has gained widespread acceptance in the intensive care unit. We conducted a prospective study to evaluate whether lung ultrasound could be used as a predictive marker for postoperative ventilatory support in high-risk surgical patients. We included 109 patients admitted to the intensive care unit while having mechanical ventilation of the lungs following major surgery. The PaO2 /FI O2 ratio was calculated on admission and an ultrasound examination performed, including: lung ('lung ultrasound score', number of consolidated lung areas); cardiac (mitral flow); and inferior vena cava imaging (diameter and respiratory variation). Respiratory outcomes included: the need for ventilation support (mechanical ventilation, non-invasive ventilation or high-flow nasal cannula oxygen therapy); acute respiratory distress syndrome; cardiogenic pulmonary oedema; and early or late pulmonary infection. Patients with a lung ultrasound score ≥ 10 had a lower PaO2 /FI O2 ratio, and needed more postoperative ventilatory support, than patients with lung ultrasound score < 10. Twenty patients had acute respiratory distress syndrome, and 14 had cardiogenic pulmonary oedema. The presence of ≥ 2 areas of consolidated lung was associated with a lower PaO2 /FI O2 ratio, postoperative ventilatory support, longer intensive care stay and episodes of ventilator-associated pneumonia requiring antibiotics. Our results suggest that at intensive care unit admission, lung ultrasound scoring and detection of atelectasis can predict postoperative pulmonary outcomes after major visceral surgery, and could enhance bed-side decision making.

Dynamic arterial elastance measured by uncalibrated pulse contour analysis predicts arterial-pressure response to a decrease in norepinephrine.

BACKGROUND: Dynamic arterial elastance (Eadyn) has been proposed as an indicator of vascular tone that predicts the decrease in arterial pressure in response to changes in norepinephrine (NE). The purpose of this study was to determine whether Eadyn measured by uncalibrated pulse contour analysis (UPCA) can predict a decrease in arterial pressure when the NE dosage is decreased. METHODS: We conducted a prospective study in a university hospital intensive care unit. Patients with vasoplegic syndrome for whom the intensive care physician planned to decrease the NE dosage were included. Haemodynamic and UPCA (VolumeView and FloTrac; Edwards Lifesciences, Irvine, CA, USA) values were obtained before and after decreasing the NE dosage. Responders were defined by a >10% decrease in mean arterial pressure (MAP). RESULTS: Of 35 patients included, 11 (31%) were pressure responders with a median decrease of 13%. Eadyn was correlated to systolic arterial pressure (SAP) (r=0.255; P=0.033), diastolic arterial pressure (r=0.271; P=0.024), MAP (r=0.310; P=0.009), heart rate (r=0.543; P=0.0001), and transthoracic echography cardiac output (r=0.264; P=0.024). Baseline Eadyn was correlated with MAP changes (r=0.394; P=0.019) and SAP changes (r=0.431; P=0.009). Eadyn predicted the decrease in arterial pressure with an area under the receiver-operating-characteristic curve of 0.84 (95% confidence interval: 0.70-0.97). The best cut-off was 0.90. CONCLUSIONS: The present study confirms the ability of Eadyn measured by UPCA to predict an arterial pressure response to a decrease in NE. Eadyn may constitute an easy-to-use functional approach to arterial tone assessment regardless of the monitor used to measure its determinant. CLINICAL TRIAL REGISTRATION: DRCIT95.

Respiratory stroke volume variation assessed by oesophageal Doppler monitoring predicts fluid responsiveness during laparoscopy.

BACKGROUND: This study was designed to assess the ability of the stroke volume respiratory variation (ΔrespSV) determined by oesophageal Doppler monitoring (ODM) to predict the response to volume expansion (VE) during pneumoperitoneum. The predictive value of ΔrespSV was evaluated according to the concept of the 'grey zone'. METHODS: Patients operated on laparoscopy and monitored by ODM were prospectively included. The exclusion criteria were frequent ectopic beats or preoperative arrhythmia, right ventricular failure, and spontaneous breathing. Haemodynamic parameters and oesophageal Doppler indices [stroke volume (SV), peak velocity (PV), cardiac output (CO), corrected flow time (FTc), respiratory variation of PV (ΔrespPV) and SV (ΔrespSV)] were collected before and after VE. Responders were defined as a ≥15% increase in SV after VE. RESULTS: Thirty-eight (64%) of the 59 patients were responders. A cut-off of >14% ΔrespSV predicted fluid responsiveness with an area under the ROC curve (AUC) of 0.92 [95% confidence interval (CI): 0.82-0.98, P<0.0001]. The grey zone of ΔrespSV ranged between 13 and 15%. With an AUC of 0.71 (95% CI: 0.56-0.83, P=0.005), ΔrespPV fairly accurately predicted fluid responsiveness. FTc was unable to accurately predict fluid responsiveness. CONCLUSIONS: ΔrespSV and ΔrespPV predicted fluid responsiveness during laparoscopy under strict physiological conditions. FTc was not predictive of fluid responsiveness during laparoscopy.

End-expiratory occlusion manoeuvre does not accurately predict fluid responsiveness in the operating theatre.

BACKGROUND: The objective of this study was to determine whether assessment of stroke volume (SV) and measurement of exhaled end-tidal carbon dioxide [Formula: see text] during an end-expiratory occlusion (EEO) test can predict fluid responsiveness in the operating theatre. METHODS: Forty-two subjects monitored by oesophageal Doppler who required i.v. fluids during surgery were studied. Haemodynamic variables [heart rate, non-invasive arterial pressure, SV, cardiac output (CO), respiratory variation of SV (ΔrespSV), variation of SV during EEO, and E'(CO2) were measured at baseline, during EEO (Δ(EEO)), and after fluid expansion. Responders were defined by an increase in SV over 15% after infusion of 500 ml of crystalloid solution. RESULTS: Of the 42 subjects, 28 (67%) responded to fluid infusion. A cut-off of >2.3% ΔSV(EEO) predicted fluid responsiveness with an area under the receiver-operating characteristic (AUC) curve of 0.78 [95% confidence interval (95% CI): 0.63-0.89, P=0.003]. The AUC of ΔrespSV was 0.89 (95% CI: 0.76-0.97, P<0.001). With an AUC of 0.68 (95% CI: 0.51-0.81, P=0.07), E'(CO2)(EEO) was poorly predictive of fluid responsiveness. CONCLUSIONS: ΔSV(EEO) and ΔE'(CO2) were unable to accurately predict fluid responsiveness during surgery.

Accuracy of impedance cardiography for evaluating trends in cardiac output: a comparison with oesophageal Doppler.

BACKGROUND: Impedance cardiography (ICG) enables continuous, beat-by-beat, non-invasive, operator-independent, and inexpensive cardiac output (CO) monitoring. We compared CO values and variations obtained by ICG (Niccomo™, Medis) and oesophageal Doppler monitoring (ODM) (CardioQ™, Deltex Medical) in surgical patients. METHODS: This prospective, observational, single-centre study included 32 subjects undergoing surgery with general anaesthesia. CO was measured simultaneously with ICG and ODM before and after events likely to modify CO (vasopressor administration and volume expansion). One hundred and twenty pairs of CO measurements and 94 pairs of CO variation measurements were recorded. RESULTS: The CO variations measured by ICG correlated with those measured by ODM [r=0.88 (0.82-0.94), P<0.001]. Trending ability was good for a four-quadrant plot analysis with exclusion of the central zone (<10%) [95% confidence interval (CI) for concordance (0.86; 1.00)]. Moderate to good trending ability was observed with a polar plot analysis (angular bias: -7.2°; 95% CI -12.3°; -2.5°; with radial limits of agreement -38°; 24°). After excluding subjects with chronic obstructive pulmonary disease, a Bland-Altman plot showed a mean bias of 0.47 litre min(-1), limits of agreements between -1.24 and 2.11 litre min(-1), and a percentage error of 35%. CONCLUSION: ICG appears to be a reliable method for the non-invasive monitoring of CO in patients undergoing general surgery.

Ability of stroke volume variation measured by oesophageal Doppler monitoring to predict fluid responsiveness during surgery.

BACKGROUND: The objective of this study was to test whether non-invasive assessment of respiratory stroke volume variation (ΔrespSV) by oesophageal Doppler monitoring (ODM) can predict fluid responsiveness during surgery in a mixed population. The predictive value of ΔrespSV was evaluated using a grey zone approach. METHODS: Ninety patients monitored using ODM who required i.v. fluids to expand their circulating volume during surgery under general anaesthesia were studied. Patients with a preoperative arrhythmia, right ventricular failure, frequent ectopic beats, or breathing spontaneously were excluded. Haemodynamic variables and oesophageal Doppler indices [peak velocity (PV), stroke volume (SV), corrected flow time (FTc), cardiac output (CO), ΔrespSV, and respiratory variation of PV (ΔrespPV)] were measured before and after fluid expansion. Responders were defined by a >15% increase in SV after infusion of 500 ml crystalloid solution. RESULTS: SV was increased by ≥15% after 500 ml crystalloid infusion in 53 (59%) of the 90 patients. ΔrespSV predicted fluid responsiveness with an area under the receiver-operating characteristic (AUC) curve of 0.91 [95% confidence interval (95% CI): 0.85-0.97, P<0.0001]. The optimal ΔrespSV cut-off was 14.4% (95% CI: 14.3-14.5%). The grey zone approach identified 12 patients (14%) with a range of ΔrespSV values between 14% and 15%. FTc was not predictive of fluid responsiveness (AUC 0.49, 95% CI: 0.37-0.62, P=0.84). CONCLUSIONS: ΔrespSV predicted fluid responsiveness accurately during surgery over a ΔrespSV range between 14% and 15%. In contrast, FTc did not predict fluid responsiveness.

[Regulation of vasomotor tone]. / Régulation du tonus vasomoteur.

This article provides a synthesis of physiology and pathophysiology of the cardiovascular system and briefly presents the principles of regulation at the level of the whole organism and regional circulations. Decision algorithms, based on knowledge of physiology and pathophysiology are proposed. Their goal is to contribute to the improvement of cardiopulmonary bypass practice.

[Transcutaneous aortic valve implantation: Anesthetic and perioperative management]. / Implantation valvulaire aortique percutanée: prise en charge par l'anesthésiste-réanimateur.

OBJECTIVE: To describe the perioperative management, from the point of view of the anesthesia-intensive care unit specialist, of patients with aortic stenosis who undergo transcatheter aortic valve implantation (femoral or apical TAVI). DATA SOURCE: The PubMed database (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) was queried, using the following keywords: aortic stenosis, transcatheter aortic valve implantation TAVI, outcome, complications, anesthesia. DATA SYNTHESIS: TAVI is performed in patients suffering from aortic stenosis and presenting with numerous comorbidities, high-predicted perioperative mortality and/or contraindications to conventional cardiac surgery. TAVI is performed either by percutaneous transfemoral or transapical puncture of the left ventricle (LV) apex. These patients are older, have more comorbidities than those undergoing aortic valve replacement surgery and perioperative mortality predicted by risk scores is higher. While transapical TAVI is performed with general anaesthesia, transfemoral TAVI can be performed with either general or locoregional anaesthesia and/or sedation. The choice of the anaesthetic technique for transfemoral TAVI depends on the patient's medical history, the technique chosen for valve implantation, the type of monitoring and the anticipated hemodynamic problems. The incidence of complications following TAVI is high, some are common to surgical aortic valve replacement, and others are specific to this technique. Because of the prevalence of comorbidities, the hemodynamic-specific constraints of this technique and the incidence of complications, anaesthetic and perioperative management (evaluation, anaesthetic technique, monitoring, post-surgery care) requires the same level of expertise as in cardiac surgery anaesthesia. CONCLUSION: TAVI expands treatment options for patients with aortic valve stenosis. The anaesthesia team must be involved in the care of these patients with the same level of expertise and care as in heart surgery on critical patients.

[Fatal air embolism during open eye surgery]. / Embolie gazeuse fatale lors d'une chirurgie du segment postérieur en ophtalmologie.

Gas embolism is well known for a specific subset of surgical interventions. Prevention and early detection are the main objectives of the anesthetic and surgical team. However, it may exceptionally occur during eye surgery with dramatic outcomes. We report the case of a 51-year-old man, ASA physical status 1, who presented a cardiac arrest during an open eye surgery for the extraction of a foreign body with intraocular air injection. Multiple organ failure has not been improved by hyperbaric oxygen therapy and the outcome was fatal.