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.

Neuro-oncological patients admitted in intensive-care unit: predictive factors and functional outcome.

The prognosis of oncology patients admitted to the intensive care unit (ICU) is considered poor. Our objective was to analyze the characteristics and predictive factors of death in the ICU and functional outcome following ICU treatment for neuro-oncology patients. A retrospective study was conducted on all patients with primary brain tumor admitted to our institutional ICU for medical indications. Predictive impact on the risk of death in the ICU was analyzed as well as the functional status was evaluated prior and following ICU discharge. Seventy-one patients were admitted to the ICU. ICU admission indications were refractory seizures (41 %) and septic shock (17 %). On admission, 16 % had multi-organ failure. Ventilation was necessary for 41 % and catecholamines for 13 %. Twenty-two percent of patients died in the ICU. By multivariate analysis, predictive factors associated with an increased risk of ICU death were: non-neurological cause of admission [p = 0.045; odds ratio (OR) 5.405], multiple organ failure (p = 0.021; OR 8.027), respiratory failure (p = 0.006; OR 9.615), and hemodynamic failure (p = 0.008; OR 10.111). In contrast, tumor type (p = 0.678) and disease control status (p = 0.380) were not associated with an increased risk of ICU death. Among the 35 evaluable patients, 77 % presented with a stable or improved Karnofsky performance status following ICU hospitalization compared with the ongoing status before discharge. In patients with primary brain tumor admitted to the ICU, predictive factors of death appear to be similar to those described in non-oncology patients. ICU hospitalization is generally not associated with a subsequent decrease in the functional status.

Controlled general anaesthesia for subthalamic nucleus stimulation in Parkinson's disease.

OBJECTIVE: To report the short-term (1 year) and long-term (5 years) outcome of patients with Parkinson's disease (PD) with subthalamic nucleus (STN) stimulation operated upon under controlled general anaesthesia (GA). METHODS: 213 consecutive patients with PD were included between January 2000 and March 2009 and operated upon under a particular type of GA with close control of the level of sedation allowing intraoperative recordings. 188 patients were assessed 1 year postoperatively. 65 patients also completed the long-term observation period and were evaluated 5 years postoperatively. RESULTS: The Unified PD Rating Scale III score in the 'Off drug--On stim' condition was improved at 1 year and 5 years by 61% and 37%, respectively, (p<0.001). Motor complications decreased at short-term and long-term by 68% and 65%, respectively, for dyskinesia and by 52% and 48%, respectively, for fluctuations, (p<0.001). Dopaminergic treatment could also be reduced at short-term and long-term by 46% and 49%, respectively (p<0.001). There was no significant modification of mood and cognition assessments (Mattis scale and Beck depression inventory) at 1 year and 5 years. Concerning the main adverse events related to the surgery, we report four haematomas (1.9%) with two deaths (0.9%), eight cases of transient confusion (3.7%) and no epileptic seizure. CONCLUSIONS: Our results confirm that STN stimulation performed under controlled GA is efficient and has similar short-term and long-term motor effects than intervention under local anaesthesia. Furthermore, this specific procedure is not associated with more adverse events. The success of such an intervention requires strict anaesthetic monitoring and accurate STN identification.

[Cell therapy for stroke: from myth to reality]. / La thérapie cellulaire de l'accident vasculaire cérébral ischémique : du mythe à la réalité

INTRODUCTION: Stroke is one of the leading causes of death and disability worldwide. Intravenous recombinant tissue plasminogen activator is the only available therapy for acute ischemic stroke, but its use is limited by a narrow therapeutic window and cannot stimulate endogenous repair and regeneration of damaged brain tissue. Stem cell-based approaches hold much promise as potential novel treatments to restore neurological function after stroke. STATE OF THE ART: In this review, we summarize data from preclinical and clinical studies to investigate the potential application of stem cell therapies for treatment of stroke. Stem cells have been proposed as a potential source of new cells to replace those lost due to central nervous system injury, as well as a source of trophic molecules to minimize damage and promote recovery. Various stem cells from multiple sources can generate neural cells that survive and form synaptic connections after transplantation in the stroke-injured brain. Stem cells also exhibit neurorevitalizing properties that may ameliorate neurological deficits through stimulation of neurogenesis, angiogenesis and inhibition of inflammation. PERSPECTIVES/CONCLUSION: Performed in stroke, cell therapy would decrease brain damage and reduce functional deficits. After the damage has been done, it would still improve neurological functions by activating endogenous repair. Nevertheless, many questions raised by experimental studies particularly related to long-term safety and technical details of cell preparation and administration must be resolved before wider clinical use.

Transient locked-in syndrome and basilar artery vasospasm.

BACKGROUND: Cerebral vasospasm is the main cause of neurological mortality and morbidity following subarachnoid hemorrhage. Basilar artery vasospasm (BAVS) is associated with a high morbidity and may have multiple clinical presentations. METHODS: We report the case of a 43 years-old man with BAVS presenting as a reversible locked-in syndrome (LIS) after stopping sedation. RESULTS: The symptoms were successfully managed by intra-arterial infusion of vasodilators and balloon angioplasty. Magnetic resonance imaging did not reveal any brainstem lesion 48 h after the complication, demonstrating a hemodynamic mechanism. CONCLUSION: LIS can reveal BAVS. Its diagnosis relies on clinical examination. In this case, rapid neuro-interventional treatment permitted reversal of symptoms. This could not have been possible under sedation.

Time rescaling reproduces EEG behavior during transition from propofol anesthesia-induced unconsciousness to consciousness.

General anesthesia (GA) is a reversible manipulation of consciousness whose mechanism is mysterious at the level of neural networks leaving space for several competing hypotheses. We recorded electrocorticography (ECoG) signals in patients who underwent intracranial monitoring during awake surgery for the treatment of cerebral tumors in functional areas of the brain. Therefore, we recorded the transition from unconsciousness to consciousness directly on the brain surface. Using frequency resolved interferometry; we studied the intermediate ECoG frequencies (4-40 Hz). In the theoretical study, we used a computational Jansen and Rit neuron model to simulate recovery of consciousness (ROC). During ROC, we found that f increased by a factor equal to 1.62 ± 0.09, and δf varied by the same factor (1.61 ± 0.09) suggesting the existence of a scaling factor. We accelerated the time course of an unconscious EEG trace by an approximate factor 1.6 and we showed that the resulting EEG trace match the conscious state. Using the theoretical model, we successfully reproduced this behavior. We show that the recovery of consciousness corresponds to a transition in the frequency (f, δf) space, which is exactly reproduced by a simple time rescaling. These findings may perhaps be applied to other altered consciousness states.

[Intracerebral haemorrhage, what's new?]. / Accident vasculaire cérébral hémorragique : nouveautés sur la prise en charge.

Haemorrhagic stroke is frequent and associated with a high mortality and morbidity. Less than 30% of patients are still alive five years after onset and few patients regain functional independence. The worsening effect of anticoagulation has been demonstrated and the failure to rapidly normalize coagulation further increases haematoma expansion. In a recent phase II trial, recombinant activated factor VII given within 4 hours of stroke onset, reduced haematoma growth, mortality and disability. An aggressive blood pressure and intracranial pressure control early after the haemorrhage seems beneficial. A large prospective randomized study (the STICH trial) did not demonstrate any beneficial effect of surgery.

[Thromboprophylaxis in neurosurgery and head trauma]. / Thromboprophylaxie en neurochirurgie et en neurotraumatologie intracrânienne.

The incidence of deep vein thrombosis (DVT) is between 20 and 35% using contrast venography, with a rate of symptomatic DVT between 2.3 and 6% in neurosurgery without any prophylaxis. The risk of DVT is poorly evaluated in head injured patients but is around 5%. Specific risk factors in neurosurgery are: a motor deficit, a meningioma or malignant tumour, a large tumour, age over 60 years, surgery lasting more than 4 hours, a chemotherapy. The benefit of mechanical methods or low molecular weight heparin (LMWH) for the prevention of DVP in neurosurgery is demonstrated (grade A). Each method decreases the risk by about 50%. A postoperative prophylaxis with a LMWH does not seem to increase the risk of intracranial bleeding (grade C). There is no demonstrated benefit to begin a prophylaxis with LMWH before the intervention. The duration of the prophylaxis is 7 to 10 days but this has not been scientifically determined.

[Thromboprophylaxis in elective spinal surgery and spinal cord injury]. / Thromboprophylaxie en chirurgie rachidienne traumatologique et non traumatologique.

The risk of deep vein thrombosis (DVT) after spinal cord injury is very high. Without prophylaxis the incidence of DVT using venography is 81% and the risk of symptomatic DVT is between 12 and 23%. The risk is much lower in elective spine surgery. After discectomy or laminectomy on less than two spine levels, the risk of DVT is less than 1%. After spinal fusion or extended laminectomy, the risk can be estimated between 0.3 and 2.2%. A prophylaxis is recommended for all patients after spinal cord injury (grade A). The association of a mechanical method and heparin is recommended (grade B). The duration of prophylaxis is 3 months in patients with a motor deficit (grade C). No prophylaxis is recommended after discectomy or limited laminectomy in patients without additional risk factors. Mechanical methods are recommended after spinal fusion or extended laminectomy. For patients with additional risk factors a low molecular weight heparin is recommended.

[Prevention of venous perioperative thromboembolism in ENT and maxillofacial surgery]. / Prévention de la maladie thromboembolique veineuse périopératoire en chirurgie ORL et maxillofaciale.

There are few studies of poor methodological quality on the risk of thromboembolism in head and neck surgery. The incidence of symptomatic deep vein thrombosis is estimated between, 0.1% and 0.6%. The patient's risk factors (cancer, alcoholism, smoking, malnutrition) determine for the assessment of the potential benefit of thromboembolism prophylaxis. No method can be recommended based on the literature. In patients receiving anticoagulant therapy undergoing superficial head and neck surgery or dental extraction, the literature suggest to continue anticoagulation throughout the perioperative period.

A comparison of extradural and intraparenchymatous intracranial pressures in head injured patients.

The reliability of extradural pressure measurements for the measure of intracranial pressure (ICP) is still controversial. This study was undertaken to assess the limits of agreement between extradural and intraparenchymatous pressures using respectively the Plastimed extradural sensor and the Camino fiberoptic system. The study took place in a neurosurgical intensive care unit. Ten head injured patients were included in the study, leading to the comparison of 1032 pairs of hourly ICP values. Although the measures were significantly correlated, there was no agreement between the two methods of ICP monitoring. Extradural pressure was higher than intraparenchymatous pressure (bias 9 mmHg; 95% confidence interval of bias -9.8 to 27.8 mmHg). The lack of agreement between the two methods is probably due to the unreliability of extradural pressure for the measurement of ICP.

Resection of a giant intracranial dural arteriovenous fistula with the use of low-flow deep hypothermic cardiopulmonary bypass after partial embolization: technical case report.

OBJECTIVE AND IMPORTANCE: To describe the surgical resection of a giant intracerebral arteriovenous fistula with involvement of dura mater and surrounding bone. Intraoperative bleeding was controlled by hypothermic circulatory arrest. CLINICAL PRESENTATION: This 46-year-old woman complained of persistent headache for 1 year; her diagnostic workup revealed the presence of an arteriovenous fistula in the dura mater of the left temporal region fed by the meningeal artery of the external and internal carotid arteries, with normal run-off into Labbé's and Trolard's veins. Magnetic resonance imaging depicted a Chiari I malformation that was most likely a result of insufficient cerebral venous drainage. INTERVENTION: In preparation for surgery, staged embolization of feeders from the left meningeal artery and the left occipital artery was performed under controlled hypotension. This procedure failed to achieve a significant reduction in flow because of the immediate recruitment of internal branches of the internal carotid artery and dural branches of the right external carotid artery. Surgical treatment was undertaken without further embolization. Because of involvement of surrounding bone and the high risk of uncontrollable bleeding, the procedure was carried out with the patient under deep hypothermic cardiopulmonary bypass. Forty-five minutes of low flow (1.5 L/min) at 18 degrees C allowed total resection of the involved dura mater and surrounding bone. Postoperative recovery was marked by left brain edema that disappeared within 10 days. Findings on follow-up angiography were normal, and the patient was discharged with no neurological deficit. CONCLUSION: Low-flow deep hypothermic cardiopulmonary bypass can be used to control intraoperative bleeding for surgical excision of a giant intracerebral dural arteriovenous fistula.

Intraoperative autologous blood transfusion in intracranial surgery.

OBJECTIVE: The purpose of this study was to evaluate the benefits of intraoperative autotransfusion of autologous blood on the conservation of allogenic blood, including cost-effectiveness and the consequences for hemoglobin level and coagulation tests. METHODS: The Hoemonetics Cell Saver 4 autotransfusion system (Hoemonetics Corporation, MA) was used when the estimated blood loss was equal to or more than 500 ml. A total of 472 patients undergoing intracranial surgery were included in the study. RESULTS: Ninety patients (19%) received transfusions either with autologous blood or allogenic blood. Fifty-five patients (61%) received only autologous blood transfusions, 10 patients (11%) received both autologous and allogenic blood transfusions, and 25 patients (28%) received only allogenic blood transfusions. The amount of autologous blood transfused was 600 +/- 590 ml (range, 230-3000 ml). The amount of allogenic blood transfused was 3 +/- 3 units (range, 2-15 units). Autologous blood represented 68% of all blood products transfused. Mild abnormalities during coagulation tests occurred without clinical bleeding. CONCLUSION: Autologous blood transfusions were demonstrated to be safe in patients undergoing intracranial surgery and to be more cost-effective than allogenic blood transfusions. Intraoperative autologous blood transfusions may be used alone in more than half of the patients requiring transfusions during intracranial surgery and decrease the amount of allogenic blood used. Improvements in the monitoring for the need of performing this technique, as well as preoperative blood donations, would decrease the amount of allogenic blood transfused.

Recovery from anesthesia and postoperative extubation of neurosurgical patients: a review.

The most feared complications after intracranial surgery are development of an intracranial hematoma and major cerebral edema. Both may result in cerebral hypoperfusion and brain injury. Arterial hypertension via catecholamine release or sympathetic stimulation and hypercapnia may be predisposing factors. Other systemic secondary insults to the brain such as hypoxia and hypotension may exacerbate neuronal injury in hypoperfused areas of the brain. Thus, the anesthetic emergence of a neurosurgical patient should include maintenance of stable respiratory and cardiovascular parameters. Minimal reaction to the endotracheal tube prevents sympathetic stimulation and increases in venous pressure. On one hand, a delayed emergence and later extubation in the intensive care unit (ICU) might be recommended to achieve better thermal and cardiovascular stability after major intracranial procedures. On the other hand, the timely diagnosis of neurosurgical complications is required to limit brain damage; the diagnosis of complications relies on rapid neurological examination after early awakening. After uncomplicated surgery, normothermic and normovolemic patients generally recover from anesthesia with minimal metabolic and hemodynamic changes. Thus, early recovery and extubation in the operating room is the preferred method when the preoperative state of consciousness is relatively normal and surgery does not involve critical brain areas or extensive manipulation. In the complicated or unstable patient, the risks of early extubation may outweigh the benefits. It is, however, often possible to perform a brief awakening of the patient without extubation to allow early neurological evaluation, followed by delayed emergence and extubation. Close hemodynamic and respiratory monitoring are mandatory in all cases. The availability of ultrashort intravenous anesthetic agents and adrenergic blocking agents has added to the flexibility in the immediate emergence period after intracranial surgery.

[Acute Weston Hurst necrotizing hemorrhagic leukoencephalitis]. / Leucoencéphalite aiguë hémorragique et nécrosante de Weston Hurst.

The clinical and pathological findings of a 43-year-old woman, diagnosed as having acute hemorrhagic leukoencephalitis at postmortem examination, are presented. The acute hemorrhagic leukoencephalitis affects mainly young adults and is the most fulminant from of demyelinating disease. It is frequently preceded by a respiratory infection. Diagnosis is facilitated by CT scanning and MRI, which reveal the massive lesion in the cerebral white matter. Many cases terminate fatally in 2 or 4 days, but in others survival is longer. The pathological findings are distinctive.

[Use of Diprivan in neurosurgery]. / Utilisation du Diprivan en neurochirurgie.

Propofol is an appropriate agent in neurosurgery, where it represents an alternative to the thiopentone-isoflurane anaesthetic technique. Some patients are at risk of hypotension during induction of anaesthesia which may be associated with an important decrease in cerebral perfusion pressure. The administration of propofol as a continuous infusion is therefore preferable in these patients. In the absence of nitrous oxide, propofol anaesthesia allows the monitoring of sensory evoked potentials during spinal surgery. For surgery of epilepsy, it is preferable to avoid giving propofol in the minutes preceding the electroencephalographic location of the areas to be excised.

[Anaesthesia for patients with intracranial hypertension due to cerebral oedema]. / Anesthésie et hypertension intracrânienne sur oedème cérébral.

The main objective for anaesthesia in patients with intracranial hypertension (ICH) is to maintain the cerebral perfusion pressure (CPP). Before the operation, the assessment of the level of intracranial pressure relies on the Glasgow coma score and the signs of ICH on the CT-scan. In the perioperative period, repeated transcranial Doppler examinations may help in determining the adequate CPP. Haemodynamic and respiratory complications are common after subarachnoid haemorrhage or head injury. Careful preoperative screening of the cardiovascular and respiratory system is mandatory before anaesthesia. There is no recommended anaesthetic technique for patients with ICH. Nitrous oxide should be avoided in patients with severe ICH or during emergency surgery. Theoretically, intravenous anaesthesia is a better choice than inhalation anesthesia because of the cerebral vasodilatation induced by inhalation agents. In the most severe cases thiopental is the only anaesthetic agent to consider. Treatment of hypovolaemia with fluid loading and the early use of vasoactive agents can be recommended to maintain CPP. Before intracranial surgery, large doses of mannitol have been demonstrated to improve neurological recovery in brain injured patients. The urinary losses due to the infusion of mannitol should be replaced with isotonic saline. Emergence and extubation are best performed in the intensive care unit under close systemic and cerebral haemodynamic control.

[Cerebral and systemic haemodynamic changes during neurosurgical recovery]. / Modifications hémodynamiques cérébrale et systémiques au moment du réveil en neurochirurgie.

Major complications after intracranial surgery occur in 13-27% of patients. Among multiple causes, haemodynamic and metabolic changes of anaesthesia recovery may be responsible for intracranial complications. Recovery from neurosurgical anaesthesia is followed by an increase in body oxygen consumption and catecholamines concentrations. However, in normothermic patients, theses changes are usually mild and not prevented by a 2-h recovery delay. Systemic hypertension is common after neurosurgery and a link between perioperative hypertension and intracranial haemorrhage has been established. The cerebral consequences of recovery associate cerebral hyperaemia and increased ICP in patients with a tight brain at the end of surgery. Cerebral hyperaemia may promote or exacerbate cerebral haemorrhage or oedema. This has been demonstrated in patients operated for subdural haematoma removal or undergoing carotid surgery. Prevention of hypothermia and pain are key factors to prevent metabolic changes. Beta-blockers seem to be suitable agents to obtain haemodynamic control in neurosurgical patients.

[Vascular loading in the first 24 hours following severe head injuries]. / Remplissage vasculaire au cours des 24 premières heures après traumatisme crânien grave.

The main goal at the acute phase of head injury is to prevent a decrease in blood pressure, which promotes cerebral ischemia. Volume loading is therefore frequently indicated. A normal or increased plasma osmolarity should be maintained. Thus hypotonic fluids should be avoided. Hyperglycaemia is also a risk factor for brain injury and glucose use has to be restricted in the first hours after trauma. Isotonic saline 0.9% is the first solution to be infused. Lactated Ringer solutions are mildly hypotonic as approximately 114 mL of free water is contained in each litre of the solution. Isotonic colloids are indicated to replace blood losses, but have no advantage over cristalloids, concerning the development of cerebral oedema. Fluid restriction minimally affects cerebral edema. Because of the severe consequences of hypovolaemia and hypotension, fluids should not be restricted until haemodynamic stability is achieved. Hypertonic fluids rapidly restore intravascular volume and decrease intracranial pressure. Although they probably have a place in prehospital intensive therapy, the demonstration of their benefit is still lacking. Monitoring of intravascular volume is essential. Continuous arterial pressure and central venous pressure monitoring are mandatory. New monitoring techniques as the measurement of systolic pressure variations or transoesophageal Doppler echocardiography will probably find a place in the management of trauma patients in the near future.