Accuracy and precision of non-invasive cardiac output monitoring devices in perioperative medicine: a systematic review and meta-analysis†.

Cardiac output (CO) measurement is crucial for the guidance of therapeutic decisions in critically ill and high-risk surgical patients. Newly developed completely non-invasive CO technologies are commercially available; however, their accuracy and precision have not recently been evaluated in a meta-analysis. We conducted a systematic search using PubMed, Cochrane Library of Clinical Trials, Scopus, and Web of Science to review published data comparing CO measured by bolus thermodilution with commercially available non-invasive technologies including pulse wave transit time, non-invasive pulse contour analysis, thoracic electrical bioimpedance/bioreactance, and CO2 rebreathing. The non-invasive CO technology was considered acceptable if the pooled estimate of percentage error was <30%, as previously recommended. Using a random-effects model, sd, pooled mean bias, and mean percentage error were calculated. An I2 statistic was also used to evaluate the inter-study heterogeneity. A total of 37 studies (1543 patients) were included. Mean CO of both methods was 4.78 litres min−1. Bias was presented as the reference method minus the tested methods in 15 studies. Only six studies assessed the random error (repeatability) of the tested device. The overall random-effects pooled bias (limits of agreement) and the percentage error were −0,13 [−2.38 , 2.12] litres min−1 and 47%, respectively. Inter-study sensitivity heterogeneity was high (I2=83%, P<0.001). With a wide percentage error, completely non-invasive CO devices are not interchangeable with bolus thermodilution. Additional studies are warranted to demonstrate their role in improving the quality of care.

Ultrasound-guided intermediate cervical plexus block for carotid endarterectomy using a new anterior approach: a two-centre prospective observational study.

The aim of this prospective, double-centre, observational study performed in 116 patients was to describe a new anterior approach of ultrasound-guided intermediate cervical plexus block for carotid endarterectomy. The median (IQR [range]) volume of ropivacaine 0.5% administered was 30 (25-30 [20-45]) ml. Supplemental local anaesthesia (infiltration and topical) was needed in 66 (57%) patients. Overall, 41 (35%) patients needed additional sedation (18 midazolam; 23 remifentanil). There was no intra-operative complication or systemic toxicity of ropivacaine. One regional anaesthesia procedure was converted to general anaesthesia because of patient agitation. Adverse effects were of short duration and did not affect surgery. Satisfaction scores were high for 92 (79%) patients (63 satisfied; 29 very satisfied) and 104 (90%) surgeons (51 satisfied; 53 very satisfied). This study shows that the ultrasound-guided intermediate cervical plexus block using an anterior approach is feasible and provides similar results to other regional techniques during carotid endarterectomy.

[Interhospital transport with extracorporeal life support: results and perspectives after 5 years experience]. / Transport interhospitalier sous extracorporeal life support : résultats et perspectives après cinq ans d'expérience.

OBJECTIVE: Describing the experience of a referral center for interhospital patients transport treated with extracorporeal circulatory or respiratory support (ECLS), the difficulties encountered and the results obtained. STUDY DESIGN: Retrospective and observational study. PATIENTS AND METHODS: All patients with respiratory or circulatory failure accepted for extracorporeal assistance for which routine medical transport was life threatening. STATISTICAL ANALYSIS: A descriptive analysis was performed (median and interquartile deviation). Comparison of biological data was performed using a non-parametric Wilcoxon test and 5 years overall survival was determined by a Kaplan-Meier analysis. RESULTS: Over a 55-month period, 29 patients were selected for transportation under ECMO or ECLS. Indication was respiratory failure in 38 % of cases, hemodynamic instability in 52 % of cases and combined symptoms in 10 % of cases. Average duration of transportation was 40 km (9-64 km). No complication related to transport was observed. Incidence of intrahospital death was 57 %. There was no correlation between death and indication of ECLS. Five-year survival was 55 % and 39 % for venovenous and arteriovenous ECLS, respectively. CONCLUSION: In our experience, interhospital transport of patients under ECMO is feasible in satisfactory conditions of safety with trained team and standard procedures.

[Anaesthetic approach of paediatric pulmonary hypertension]. / Anesthésie et hypertension artérielle pulmonaire chez l'enfant en chirurgie non cardiaque.

Paediatric pulmonary arterial hypertension (PAH) is a challenge for the paediatric anaesthetist. Due to its high morbidity and mortality, support should be provided by a dedicated team. Understanding the pathophysiology of PAH allows performing an appropriate therapeutic approach. In case of high vascular pulmonary resistance, the main objectives of anaesthetic management are to maintain an optimal pulmonary flow and to avoid the decrease in systemic arterial pressure. Haemodynamic monitoring is essential to detect the onset of an acute PAH crisis but also to give direct information on the efficacy of treatment.

Influence of the site of measurement on the ability of plethysmographic variability index to predict fluid responsiveness.

BACKGROUND: Plethysmographic variability index (PVI) is an accurate predictor of fluid responsiveness in mechanically ventilated patients. However, the site of measurement of the plethysmographic waveform impacts its morphology and its respiratory variation. The goal of this study was to investigate the ability of PVI to predict fluid responsiveness at three sites of measurement (the forehead, ear, and finger) in mechanically ventilated patients under general anaesthesia. METHODS: We studied 28 subjects after induction of general anaesthesia. Subjects were monitored with a pulmonary artery catheter and three pulse oximeter sensors (the finger, ear, and forehead). Pulse pressure variation, central venous pressure, cardiac index (CI), and PVI measured at the forehead, ear, and finger (PVI(forehead), PVI(ear), and PVI(finger)) were recorded before and after fluid loading (FL). Subjects were responders to volume expansion if CI increased >15% after FL. RESULTS: Areas under the receiver-operating curves to predict fluid responsiveness were 0.906, 0.880, and 0.836 for PVI(forehead), PVI(ear), and PVI(finger), respectively (P<0.05). PVI(forehead), PVI(ear), and PVI(finger) had a threshold value to predict fluid responsiveness of 15%, 16%, and 12% with sensitivities of 89%, 74%, and 74% and specificities of 78%, 74%, and 67%, respectively. CONCLUSIONS: PVI can predict fluid responsiveness in anaesthetized and ventilated subjects at all three sites of measurement. However, the threshold values for predicting fluid responsiveness differ with the site of measurement. These results support the use of this plethysmographic dynamic index in the cephalic region when the finger is inaccessible or during states of low peripheral perfusion.

[Automatic and continuous monitoring of preload dependence in the perioperative period: Interests and limits]. / Monitorage continu et automatisé de la précharge dépendance en anesthésie et en réanimation : intérêts et limites.

OBJECTIVES: To describe preload dependence monitoring tools currently available as well as their limits and potential applications in the anaesthesiology setting. DATA SOURCE: References were obtained from PubMed data bank (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) using the following keywords: fluid responsiveness, cardiopulmonary interactions, preload dependence, hypovolemia, cardiac output. DATA SYNTHESIS: When measured in optimal conditions, dynamic parameters are the best predictors of fluid responsiveness as compared to static indicators in patients under general anaesthesia and mechanical ventilation. These dynamic parameters rely on cardiopulmonary interactions and allow evaluating preload dependence and the ability of the heart to transform an increase in preload into an increase in cardiac output. Recently, it is possible to monitor these dynamic parameters either invasively (from the arterial pressure waveform) or noninvasively (from the plethysmographic waveform). These tools have intrinsic limitations. However, they have potential to be used for fluid optimization during anaesthesia.

[Comparison of ICG thoracic bioimpedance cardiac output monitoring system in patients undergoing cardiac surgery with pulmonary artery cardiac output measurements]. / Comparaison des valeurs de débit cardiaque obtenues à l'aide d'un nouveau système d'impédancemétrie thoracique avec les données du cathéter artériel pulmonaire en postopératoire de chirurgie cardiaque.

OBJECTIVE: Thoracic bioimpedance has been proposed for cardiac output (CO) determination and monitoring without calibration or thermodilution (ICG Monitor 862146, Philips Medical System, Philips, Suresnes, France). The accuracy and clinical applicability of this technology has not been fully evaluated in the cardiac surgery setting. We designed this prospective study to compare the accuracy of the ICG Monitor (CO(ICG)) versus pulmonary artery catheter standard bolus thermodilution (CO(PAC)) in patients after cardiac surgery or having benefited from cardiac surgery. STUDY DESIGN: Prospective, monocentric. MATERIAL AND METHODS: We studied 13 patients in the postoperative period. CO(ICG) and CO(PAC) were determined at the arrival in the intensive care unit and every four hours. Bland-Altman and Critchley and Critchley's analysis were used to assess the agreement between CO(ICG) and CO(PAC). RESULTS: CO(PAC) ranged from 2.6 to 11.0 l/min and CO(ICG) ranged from 1.8 to 11.7 l/min. There was a significant relationship between CO(PAC) and CO(ICG) (r=0.61 ; p<0.001). Agreement between CO(PAC) and CO(ICG) was -0.5+/-1.3 l/min (Bland-Altman analysis). Percentage error between the two methods was 49% (Critchley and Critchley's analysis). CONCLUSION: We found clinically unacceptable agreement between CO(ICG) and CO(PAC) in this setting. Despite its non invasiveness, this device cannot be recommended for CO monitoring in the postoperative period following cardiac surgery.

Pleth variability index to monitor the respiratory variations in the pulse oximeter plethysmographic waveform amplitude and predict fluid responsiveness in the operating theatre.

BACKGROUND: Respiratory variations in pulse oximetry plethysmographic waveform amplitude (DeltaPOP) can predict fluid responsiveness in mechanically ventilated patients but cannot be easily assessed at the bedside. Pleth variability index (PVI) is a new algorithm allowing for automated and continuous monitoring of DeltaPOP. We hypothesized that PVI can predict fluid responsiveness in mechanically ventilated patients under general anaesthesia. METHODS: Twenty-five patients were studied after induction of general anaesthesia. Haemodynamic data [cardiac index (CI), respiratory variations in arterial pulse pressure (DeltaPP), DeltaPOP, and PVI] were recorded before and after volume expansion (500 ml of hetastarch 6%). Fluid responsiveness was defined as an increase in CI > or =15%. RESULTS: Volume expansion induced changes in CI [2.0 (sd 0.9) to 2.5 (1.2) litre min(-1) m(-2); P<0.01], DeltaPOP [15 (7)% to 8 (3)%; P<0.01], and PVI [14 (7)% to 9 (3)%; P<0.01]. DeltaPOP and PVI were higher in responders than in non-responders [19 (9)% vs 9 (4)% and 18 (6)% vs 8 (4)%, respectively; P<0.01 for both]. A PVI >14% before volume expansion discriminated between responders and non-responders with 81% sensitivity and 100% specificity. There was a significant relationship between PVI before volume expansion and change in CI after volume expansion (r=0.67; P<0.01). CONCLUSIONS: PVI, an automatic and continuous monitor of DeltaPOP, can predict fluid responsiveness non-invasively in mechanically ventilated patients during general anaesthesia. This index has potential clinical applications.

Effects of sodium nitroprusside on splanchnic microcirculation in a resuscitated porcine model of septic shock.

BACKGROUND: We tested the hypothesis that sodium nitroprusside (SNP) might improve the impairment of hepatosplanchnic microcirculatory blood flow (MBF) in septic shock. METHODS: Fourteen pigs were anaesthetized and their lungs mechanically ventilated. Sepsis was induced with i.v. infusion of live Pseudomonas aeruginosa [1x10(8) colony forming units (CFU) ml(-1) kg(-1)] for 1 h. Sixty minutes later, the animals received in a random succession either SNP or normal saline for 30 min. Mean arterial pressure (MAP), cardiac index (CI), mean pulmonary artery pressure (MPAP), carbon dioxide tension of the ileal mucosa (PCO2; by gas tonometry), ileal mucosal and hepatic MBF by laser Doppler flowmetry, blood gases, and lactates were assessed before, during administration, and 30 min after discontinuing the test drug. RESULTS: Bacterial infusion promoted hypodynamic shock (MAP -18%, CI -33%, ileal MBF -19%, and hepatic MBF -27%), which was converted to normodynamic shock by resuscitation. During SNP infusion, ileal mucosal MBF significantly increased (+19%) compared with control (P = 0.033). Although hepatic MBF increased (+42% from baseline), this did not differ from control. In order to maintain a constant central venous pressure and MAP, fluid loading and norepinephrine (P < 0.01) were increased. Acid-base status was not altered by SNP. CONCLUSIONS: In a resuscitated porcine model of the early phase of septic shock, SNP improved ileal mucosal MBF but required a concomitant increase in fluid and norepinephrine supplements to maintain constant systemic haemodynamic parameters.

Respiratory variations in pulse oximeter waveform amplitude are influenced by venous return in mechanically ventilated patients under general anaesthesia.

BACKGROUND AND OBJECTIVES: Respiratory variations in pulse oximetry plethysmographic waveform amplitude (DeltaPOP) are related to respiratory variations in arterial pulse pressure (DeltaPP) in the critical care setting. The aims of this study were to test the hypothesis that in mechanically ventilated patients undergoing general anaesthesia, DeltaPOP calculation is feasible and can detect changes in preload. METHODS: Twenty-five mechanically ventilated patients were studied immediately after induction of general anaesthesia. Haemodynamic data (mean arterial pressure [MAP], central venous pressure [CVP], DeltaPP and DeltaPOP) were recorded at baseline, before and after tilting the patient from anti-Trendelenburg to Trendelenburg position in order to induce preload changes. RESULTS: Change from anti-Trendelenburg to Trendelenburg position induced changes in MAP (58 +/- 9 to 67 +/- 10 mmHg, P < 0.05), CVP (4 +/- 4 to 13 +/- 5 mmHg, P < 0.05), DeltaPP (14 +/- 8 to 7 +/- 5%, P < 0.05) and DeltaPOP (17 +/- 12 to 9 +/- 5%, P < 0.05). There was a significant relationship between DeltaPOP in anti-Trendelenburg position and percent change in MAP after volume expansion (r = 0.82; P < 0.05). CONCLUSIONS: DeltaPOP can be determined in the operating room and is influenced by changes in preload. This new index has potential clinical applications for the prediction of fluid responsiveness.