Reducing the carbon footprint of general anaesthesia: a comparison of total intravenous anaesthesia vs. a mixed anaesthetic strategy in 47,157 adult patients

Global warming is a major public health concern. Volatile anaesthetics are greenhouse gases that increase the carbon footprint of healthcare. Modelling studies indicate that total intravenous anaesthesia is less carbon intensive than volatile anaesthesia, with equivalent quality of care. In this observational study, we aimed to apply the findings of previous modelling studies to compare the carbon footprint per general anaesthetic of an exclusive TIVA strategy vs. a mixed TIVA-volatile strategy. This comparative retrospective study was conducted over 2 years in two French hospitals, one using total intravenous anaesthesia only and one using a mixed strategy including both intravenous and inhalation anaesthetic techniques. Based on pharmacy procurement records, the quantity of anaesthetic sedative drugs was converted to carbon dioxide equivalents. The primary outcome was the difference in carbon footprint of hypnotic drugs per intervention between the two strategies. From 1 January 2021 to 31 December 2022, 25,137 patients received general anaesthesia in the hospital using the total intravenous anaesthesia strategy and 22,020 in the hospital using the mixed strategy. The carbon dioxide equivalent footprint of hypnotic drugs per intervention in the hospital using the total intravenous anaesthesia strategy was 20 times lower than in the hospital using the mixed strategy (emissions of 2.42 kg vs. 48.85 kg carbon dioxide equivalent per intervention, respectively). The total intravenous anaesthesia strategy significantly reduces the carbon footprint of hypnotic drugs in general anaesthesia in adult patients compared with a mixed strategy. Further research is warranted to assess the risk-benefit ratio of the widespread adoption of total intravenous anaesthesia.

The need for maternal critical care education, point-of-care ultrasound and critical care echocardiography in obstetric anesthesiologists training

Globally, the increase in medically complex obstetric patients is challenging the educational approach and clinical management of critically ill obstetric patients. This increase in medical complexity calls into question the educational paradigm in which future physicians are trained. Obstetric anesthesiologists, physician experts in the perio-perative planning and management of complex obstetric patients, represent an essential workforce in the strategies to address maternal mortality. Unfortunately, the development of peri-operative medicine and maternal critical care curricula has only received minor attention in most countries. Proposed guidelines and models highlight the existing need for tiered maternity care services in which critical care infrastructure plays a central role in the delivery of high-risk peripartum care. Therefore, the development of maternal critical care models designed to prepare obstetric anesthesiologists for the clinical challenges of a medically complex patient are warranted. Key critical care topics such as advanced ultrasonography, with the inclusion of quantitative echocardiographic assessments into obstetric anesthesiology educational curricula, will serve to better prepare physicians for the realities of an increasingly complex pregnant patient population, and further reinforce the critical care infrastructure detailed in the Levels of Maternal Care consensus. Despite an increasingly complex obstetric patient population, heterogeneity of maternal critical care practices exists across the globe, warranting standardization and further development of proposed curricula.

Clearsight™ use for haemodynamic monitoring during the third trimester of pregnancy - a validation study

BACKGROUND

We assessed the validity of Clearsight™ as a non-invasive cardiac output and stroke volume monitoring device, comparing it with transthoracic echocardiography measurements during the third trimester of pregnancy.

METHODS

Measurements obtained from Clearsight™ were compared with those from echocardiography as the gold standard. The precision and accuracy of the Clearsight™ was measured using the Bland and Altman method. Clinical agreement with echocardiography was assessed using the agreement tolerability index.

RESULTS

Measurements were recorded from 44 pregnant women with a median [IQR range] gestational age of 33 [30-37] weeks. We found that Clearsight™ measurements presented a systematic overestimation of cardiac output, with mean bias [CI 95%] of 2.7 [2.3-3.0] L/min, with limits of agreement of  -0.1 to 5.4 L/min. It overestimated stroke volume, with a bias of 29.5 [25.0-33.4] mL and a limit of agreement of -1.6 to 60.1 mL. In addition, the analysis of cardiac output showed a percentage of error of 41% and intra-class correlation [CI 95%] of 0.37 [0.17 to 0.53, P <0.001]. For stroke volume, the percentage of error was 40% and intra-class correlation 0.16 [-0.1 to 0.34; P=0.27]. We found that agreement tolerability index scores were unacceptable. We evaluated the ability of the device to track changes in cardiac output by inducing a left lateral decubitus position, but the analysis was inconclusive.

CONCLUSION

The agreement between Clearsight™ and the echocardiography measurements of cardiac output and stroke volume were not within an acceptable range in the third trimester of pregnancy.

Use of speckle-tracking strain in preload-dependent patients, need for cautious interpretation!

BACKGROUND

In critical patients, left ventricular ejection fraction and fractional shortening are used to reflect left ventricular systolic function. An emerging technique, two-dimensional-strain echocardiography, allows assessment of the left ventricle systolic longitudinal deformation (global longitudinal strain) and the speed at which this deformation occurs (systolic strain rate). This technique is of increasing use in critical patients in intensive care units and in the peri-operative period where preload constantly varies. Our objective, in this prospective single-center observational study, was to evaluate the effect of fluid resuscitation on two-dimensional-strain echocardiography measurements in preload-dependent critically ill patients. We included 49 patients with preload dependence attested by an increase of at least 10% in the left ventricular outflow track velocity-time integral measured by echocardiography during a passive leg raising maneuver. Echocardiography was performed before fluid resuscitation (echocardiography 1) and after preload independency achievement (echocardiography 2).

RESULTS

Two-dimensional-strain echocardiography was feasible in 40 (82%) among the 49 patients. With preload dependence correction, the absolute value of global longitudinal strain and systolic strain rate was significantly increased from, respectively, - 13.3 ± 3.5 to - 18.4% ± 4.5 (p < 0.01) and - 1.11 s^-1 ± 0.29 to - 1.55 s^-1 ± 0.55 (p < 0.001). The fluid resuscitation affects GLS and SSR in preload-dependent patients, with a shift, for GLS, from pathological to normal values.

CONCLUSION

In critically ill patients, the assessment of the systolic function by two-dimensional-strain echocardiography needs prior evaluation of preload dependency, in order to adequately interpret this variable. Future studies should assess the ability of global longitudinal strain to guide fluid management in the critically ill patients.

[Maternal deaths due to hypertensive disorders. Results from the French confidential enquiry into maternal deaths, 2010-2012]

Between 2010 and 2012, the rate of maternal death caused by hypertensive disorders (0,5/100,000 living birth) was reduced by 50% compared to the 2007-2009 period. Hypertensive disorders were responsible from 5% of maternal deaths and from 10% of direct maternal mortality. Eleven deaths happened during the postpartum period but 9 hypertensive complications began before delivery. Seventy percent of these deaths seem to be avoidable. The main causes of suboptimal management were: unappropriated or insufficient obstetrical and anesthetic treatments, undiagnosed HELLP syndrome and subcapsular liver hematoma, delayed treatment. The analysis of these maternal deaths gave the opportunity to stress some major lessons to optimize medical management in case of hypertensive diseases during pregnancy: abdominal symptoms during third trimester of pregnancy lead to search hypertensive disorders; HELLP syndrome with severe anemia indicate to carry out abdominal ultrasound.

Can point-of-care ultrasound predict spinal hypotension during caesarean section? A prospective observational study

Spinal anaesthesia for elective caesarean section is associated with maternal hypotension, secondary to alteration of sympathetic tone and hypovolemia, in up to 70% of cases. Measurement of the subaortic variation in the velocity time integral (VTI) after passive leg raising allows prediction of fluid responsiveness. Our objective, in this prospective single-centre observational study, was to assess the ability of change in VTI after 45° passive leg raising to predict hypotension after spinal anaesthesia. Ultrasound measurements were performed just before elective caesarean section. Anaesthesia, intravenous coloading and prophylactic vasopressor treatment were standardised according to current guidelines. We studied 40 women. Hypotension occurred in 17 (45%) women. The area (95%CI) under the receiver operating characteristics (ROC) curve for the prediction of spinal hypotension was 0.8 (0.6-0.9; p = 0.0001). Seventeen women had a change in VTI with leg elevation ≤ 8%, which was predictive for not developing hypotension, and 11 had a change ≥ 21%, predictive for hypotension. The grey zone between 8% and 21%, with inconclusive values, included 12 women. We suggest that cardiac ultrasound provides characterisation of the risk of hypotension following spinal anaesthesia at elective caesarean section, and therefore may allow individualised strategies for prevention and management.

Implementation of lung ultrasound in polyvalent intensive care unit: Impact on irradiation and medical cost

OBJECTIVE

To determine the effect of implementing a daily lung ultrasound round on the number of chest radiographs and chest computed tomography (CT) scans in a polyvalent intensive care unit (ICU).

STUDY DESIGN

Retrospective study comparing two consecutive periods.

PATIENTS

All patients hospitalized for longer than 48 hours in a polyvalent ICU.

METHODS

Implementation of a daily lung ultrasound round after a short educational program. The number of chest radiographs and chest CT scans and the patient outcome were measured before (group PRE) and after (group POST) the implementation of a daily lung ultrasound round.

RESULTS

No demographic difference was found between the two groups, with the exception of a higher severity score in the group POST. For each ICU stay, the number of chest radiographs was 10.3 ± 12.4 in the group PRE and 7.7 ± 10.3 in the group POST, respectively (P<0.005) The number of chest CT scans was not reduced in the group POST, as compared with the group PRE (0.5 ± 0.7 CT scan/patient/ICU stay versus 0.4 ± 0.6 CT scan/patient/ICU stay, P=0.01). The ICU mortality was similar in both groups (21% versus 22%, P=0.75) CONCLUSION: The implementation of a daily lung ultrasound round was associated with a reduction in radiation exposure and medical cost without altering patient outcome.

[Meningitis to Candida albicans at the adult, use of the new diagnosis methods]

Candida albicans or non-albicans are a frequent source of infection but seldom displayed in cerebrospinal fluid although responsible of an important number of nosocomial meningitis. Diagnosis is difficult which often delays treatment, which in turn hinders prognostic. This clinical case shows a patient afflicted with a deadly C. albicans meningitis and allows us to focus on new diagnostic tools and advice against this infection.

Comparative study of three methods of estimation of creatinine clearance in critically ill patients

BACKGROUND

At the bedside, the reference method for creatinine clearance determination is based on the measurement of creatinine concentrations in urine and serum (mCrCl). Several models are available to calculate the creatinine clearance from the serum creatinine concentration. This observational survey aimed at testing the hypothesis that the proposed equations are unreliable to determine accurate creatinine clearance in patients admitted to intensive care unit (ICU).

METHOD

Creatinine clearance was determined by the use of mCrCl. Then, we compared three equations: Cockcroft-Gault (CG), Simplified Modification of Diet in Renal Disease (MDRDs), and Chronic Kidney Disease Epidemiology (CKD-EPI) in 156 consecutive patients within the first 24hours after ICU admission. We tested the hypothesis that the three equations were equivalent. The agreement between the three equations was evaluated by linear regression and Bland and Altman analysis.

RESULTS

Bland and Altman analysis showed similar agreement between the three equations. The biases and precisions were -4.8±51, -1.3±50, and 8.2±44 for CG, MDRDs, and CKD-EPI equations, respectively (P>0.05). The precisions were similar for the three equations (P>0.05). The percentages of outliers at ±30% were 44%, 45%, and 49% for CG, MDRDs, and CKD-EPI, respectively (P>0.05).

CONCLUSION

Regarding the high percentage of outliers, the use of these equations cannot be recommended in ICU patients.

Lung ultrasound-guided management of acute breathlessness during pregnancy

Lung ultrasonography is a standard tool in the intensive care unit and in emergency medicine, but has not been described in the particular setting of the labour ward. During pregnancy, acute respiratory failure and pulmonary oedema are not uncommon life-threatening events. We present two case reports outlining the potential of lung ultrasonography in parturients. In case 1, lung ultrasonography allowed early diagnosis and treatment of acute dyspnoea in a parturient admitted for suspected asthma exacerbation. Lung ultrasonography revealed a 'B-pattern' of vertical lines radiating into the lung tissue, indicating severe pulmonary oedema complicating previously undiagnosed pre-eclampsia. In case 2, a pre-eclamptic patient was managed with combined transthoracic echocardiography and lung ultrasonography. The accuracy of lung ultrasonography in detecting interstitial oedema at a pre-clinical stage allowed adequate fluid resuscitation in this patient who had a high risk of alveolar pulmonary oedema. We believe that these cases strongly support the prospective validation of lung ultrasound for management of lung disorders in pregnant women.

[Lung ultrasound: clinical applications and perspectives in intensive care unit]

OBJECTIVE

To describe the use of lung ultrasound in clinical practice and the new opportunities offered by this technology in intensive care unit (ICU) patients.

METHOD

Review of signs identified by lung ultrasound and systematic analysis of data published within the last 5 years on its use in ICU. The literature has been extracted from the database Pubmed™. Specific keywords were used to select relevant publications. Clinical studies published in French and English languages were assessed.

RESULTS

Lung ultrasound serves to diagnose, quantify, drain and monitor pleural effusions. In patients with acute respiratory failure, lung ultrasound participates to the diagnosis, the implementation of treatments and their follow-up. It helps to manage patients with pneumonia and acute lung injury. Finally, the investigation of the interstitial edema brings information about hemodynamics that can serve to manage our patients.

CONCLUSION

Lung ultrasound is an easy, non-invasive, and non-irradiant technology. It brings lot of useful information at the patient's bedside.