Carbon footprint of inhalational and total intravenous anaesthesia for paediatric anaesthesia: a modelling study.

BACKGROUND: Tackling the climate emergency is now a key target for the healthcare sector. Avoiding inhalational anaesthesia is often cited as an important element of reducing anaesthesia-related emissions. However, evidence supporting this is based on adult practice. The aim of this study was to identify the difference in carbon footprint of inhalational and i.v. anaesthesia when used in children. METHODS: We used mathematical simulation models to compare general anaesthetic techniques in children weighing 5-50 kg for TIVA, i.v. induction then inhalational maintenance, inhalational induction then i.v. maintenance, and inhalational induction and maintenance. We simulated inhalational induction with sevoflurane alone, and co-induction with sevoflurane and nitrous oxide, and both remifentanil-propofol and propofol-only i.v. anaesthesia. For each technique, we drew on previously published life-cycle data to calculate carbon dioxide equivalents for anaesthetic durations up to 480 min. RESULTS: TIVA with propofol and remifentanil had a smaller carbon footprint over a typical anaesthetic duration of 60 min (1.26 kg carbon dioxide equivalents [CO2e] for a 20 kg child) than i.v. induction followed by inhalational maintenance (2.58 kg CO2e) or inhalational induction and maintenance (2.98 kg CO2e). Inhalational induction followed by i.v. maintenance only had a lower carbon footprint than inhalational induction and maintenance when used in longer procedures (>77 min for children 5-20 kg; >105 min for children 30-50 kg). CONCLUSIONS: In a simulation study, i.v. anaesthesia had climate benefits in paediatric anaesthesia. However, when used after inhalational induction, benefits were only achieved in longer procedures. These findings provide evidence-based guidance for reducing the environmental impact of paediatric anaesthesia, but these will require confirmation using real-world data.

Silencing of TLR4 decreases liver tumor burden in a murine model of colorectal metastasis and hepatic steatosis.

BACKGROUND: The relationship between obesity and cancer has become of particular interest due to the rapidly growing prevalence of overweight individuals. Obesity predisposes individuals to the development of hepatic steatosis and is an independent risk factor for several neoplasms. Toll-like receptor 4 (TLR4) is the innate receptor for endotoxin, and steatotic livers are known to be sensitive to endotoxin. TLR4 signaling has been shown to have proneoplastic effects in vitro due to its effect on immune surveillance. Thus far, studies have predominantly focused on the effect of tumor-cell-derived TLR4 without regard to host TLR4 signaling. RESULTS: In the present study we show that steatotic livers have increased expression of TLR4. Obese animals developed higher metastatic tumor burden in the liver than lean controls regardless of the presence or absence of intact host TLR4. After silencing TLR4 expression using RNAi in the mouse colon cancer cell line MC38, there was a significant decrease in metastatic tumor burden within the liver of obese animals. CONCLUSIONS: These findings demonstrate that steatotic livers have increased susceptibility to metastatic tumor growth and that silencing tumor cell TLR4 reduces metastatic tumor burden in steatotic liver.

2-APB protects against liver ischemia-reperfusion injury by reducing cellular and mitochondrial calcium uptake.

Ischemia-reperfusion (I/R) injury is a commonly encountered clinical problem in liver surgery and transplantation. The pathogenesis of I/R injury is multifactorial, but mitochondrial Ca(2+) overload plays a central role. We have previously defined a novel pathway for mitochondrial Ca(2+) handling and now further characterize this pathway and investigate a novel Ca(2+)-channel inhibitor, 2-aminoethoxydiphenyl borate (2-APB), for preventing hepatic I/R injury. The effect of 2-APB on cellular and mitochondrial Ca(2+) uptake was evaluated in vitro by using (45)Ca(2+). Subsequently, 2-APB (2 mg/kg) or vehicle was injected into the portal vein of anesthetized rats either before or following 1 h of inflow occlusion to 70% of the liver. After 3 h of reperfusion, liver injury was assessed enzymatically and histologically. Hep G2 cells transfected with green fluorescent protein-tagged cytochrome c were used to evaluate mitochondrial permeability. 2-APB dose-dependently blocked Ca(2+) uptake in isolated liver mitochondria and reduced cellular Ca(2+) accumulation in Hep G2 cells. In vivo I/R increased liver enzymes 10-fold, and 2-APB prevented this when administered pre- or postischemia. 2-APB significantly reduced cellular damage determined by hematoxylin and eosin and terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling staining of liver tissue. In vitro I/R caused a dissociation between cytochrome c and mitochondria in Hep G2 cells that was prevented by administration of 2-APB. These data further establish the role of cellular Ca(2+) uptake and subsequent mitochondrial Ca(2+) overload in I/R injury and identify 2-APB as a novel pharmacological inhibitor of liver I/R injury even when administered following a prolonged ischemic insult.

Continuous passive motion in the management of heterotopic ossification in a brain injured patient.

We report a man admitted to inpatient rehabilitation 6 wk after traumatic brain injury, who presented with bilateral knee heterotopic ossification. In addition to conventional physical therapy, we applied a continuous passive motion device during 4 wk increasing the range of motion of the knees. On the basis of the limited current literature and this case, we suggest that the use of continuous passive motion devices for heterotopic ossification may be effective and safe and should be the subject of further study.

Thermal energy balance as a measure of adequate rewarming from hypothermic cardiopulmonary bypass.

OBJECTIVE: To determine whether the amount of heat (thermal energy) used actively to rewarm patients on cardiopulmonary bypass (CPB) was a better indicator of adequate rewarming from hypothermic CPB than core temperature. DESIGN: Prospective study. SETTING: Single hospital. PARTICIPANTS: Fifty-four sequential patients undergoing hypothermic CPB. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Thermal energy balance (TEB) (net heat supplied to or removed from the body, from initiation to termination of CPB) was measured using previously validated apparatus. Adequacy of rewarming was assessed by measuring the coldest postoperative core (tympanic membrane) temperature and the time to rewarm postoperatively to a core temperature of 37.0 degrees C. Core temperature on termination of CPB did not correlate with the degree of postoperative hypothermia as judged by time to rewarm postoperatively to 37.0 degrees C (r = 0.14; p = 0.33), but did correlate with coldest postoperative core temperature (r = 0.47; p = 0.0003). TEB correlated better with time to rewarm to 37.0 degrees C (r = 0.43; p = 0.001) and coldest postoperative core temperature (r = 0.58, p = 0.0001). CONCLUSION: TEB is a better predictor than corresponding values of core temperature on termination of CPB in predicting the coldest postoperative temperature and time to rewarm to 37 degrees C.

The successful use of continuous negative extrathoracic pressure in a child with Glenn shunt and respiratory failure.

Following a Glenn shunt, an infant required mechanical ventilation (IPPV) for pneumonia, a phrenic nerve palsy and chylothoraces. In order to improve her deteriorating clinical condition, we used continuous negative extrathoracic pressure (CNEP) to minimise the deleterious effects of IPPV on pulmonary blood flow. She was successfully weaned from IPPV and supported with CNEP.

Auditory evoked responses and near infrared spectroscopy during cardiac arrest.

We describe a patient who had a cardiac arrest during anaesthesia, in whom regional cerebral oxygen saturation was being measured by near infrared spectroscopy and the auditory evoked responses (AER) were being recorded. Both of these monitors provided useful information on cerebral oxygenation during cardiac arrest. Changes in the AER as the result of either reduced circulation or hypothermia are similar, and should these two situations occur simultaneously there could be difficulty in the interpretation of the AER.

Pulsatile flow during cardiopulmonary bypass speeds thermal energy transfer: a possible explanation for the reduced afterdrop.

The instantaneous thermal energy balance and rates of thermal energy transfer during hypothermic cardiopulmonary bypass were measured for a group of patients receiving continuous flow and compared with a group receiving pulsatile flow. Cooling was more rapid and the rate of thermal energy delivery during rewarming significantly greater in the pulsatile flow group despite similar rewarming times. The final thermal energy balance at the end of cardiopulmonary bypass was larger and the period of postoperative hypothermia shorter in those receiving pulsatile flow. The greater rate of thermal energy transfer may explain the reduced afterdrop.

Malignant peripheral nerve sheath tumor (malignant schwannoma) of urinary bladder in von Recklinghausen neurofibromatosis.

Von Recklinghausen neurofibromatosis occurs in 1 in 3,000 live births; however, urologic manifestations are rare. There have been over 40 reported cases of neurofibroma of the bladder. Malignant degeneration of subcutaneous neurofibroma occurs in about 5 to 10 percent of patients. We believe we present the second reported case of a malignant peripheral nerve sheath tumor involving the bladder in a patient with this disorder.

Impotence following delayed repair of prostatomembranous urethral disruption.

A group of 26 patients with pelvic fracture and disruption of the prostatomembranous urethra were evaluated for impotence. Impotence was defined as inability to achieve an erection firm enough for vaginal penetration. Of the patients 25 were potent before the injury, whereas 1 was only 7 years old at injury. Seven patients admitted to being potent after the injury but before the final urethral anastomosis. Four patients became potent after urethroplasty. The definitive operation to the urethra was done approximately 6 months after the injury. Only 11 of the 26 patients (46%) reported erections adequate for vaginal penetration. No patient who had adequate erections before urethroplasty became impotent postoperatively. We believe that the impotence was caused by damage to the neurovascular supply to the penis at injury.