Implementing nitrous oxide cracking technology in the labour ward to reduce occupational exposure and environmental emissions: a quality improvement study. Anaesthesia 2022;77:1228-1236. [PMID: 36108342 DOI: 10.1111/anae.15838]

Nitrous oxide, a potent greenhouse gas, is a common labour analgesic. One method which may reduce its carbon footprint is to 'crack' the exhaled gas into nitrogen and oxygen using catalytic destruction. In this quality improvement project, based on environmental monitoring and staff feedback, we assessed the impact of nitrous oxide cracking technology in the maternity setting. Mean ambient nitrous oxide levels were recorded during the final 30 minutes of uncomplicated labour in 36 cases and plotted on a run chart. Interventions were implemented in four stages, comprising: stage 1, baseline (12 cases); stage 2, cracking with nitrous oxide delivered and scavenged via a mouthpiece (eight cases); stage 3, cracking with nitrous oxide via a facemask with an air-filled cushion (eight cases); stage 4, cracking with nitrous oxide via a low-profile facemask, and enhanced coaching on the use of the technology (eight cases). The median ambient nitrous oxide levels were 71% lower than baseline in stage 2 and 81% lower in stage 4. Staff feedback was generally positive, though some found the technology to be cumbersome; successful implementation relies on effective staff engagement. Our results indicate that cracking technology can reduce ambient nitrous oxide levels in the obstetric setting, with potential for reductions in environmental impacts and occupational exposure.

Implanted constant basal rate insulin infusion devices for Type 1 (insulin-dependent) diabetic patients

A multi-phase study was undertaken to compare the metabolic effect on unstable Type 1 diabetic patients of optimized conventional treatment with that of external or implantable insulin delivery devices. External units were programmed to simulate implantable constant basal rate insulin infusion pumps with additional insulin doses given by subcutaneous injection or delivered by the pump. The study was continued using external devices with an optimal, meal-adjusted insulin profile simulating programmable, remote-controlled, implantable devices. Such good metabolic control was achieved using the constant insulin infusion, supplemented by two subcutaneous injections of insulin daily, that it justified the implantation of constant rate pumps in five Type 1 patients. Patients with the implanted devices achieved a near-normal life style, experienced significantly fewer hypoglycaemic reactions and had significantly improved glycosylated haemoglobin A1 and mean blood glucose values.

Initial experience with SPECT (single-photon computerized tomography) of the brain using N-isopropyl I-123 p-iodoamphetamine: concise communication

Forty-six patients were studied with N-isopropyl I-123 p-iodoamphetamine (IMP) and the Harvard Scanning Multidetector Brain System. In nine control patients, good differentiation between the gray and white matter of the cerebral cortex and the basal ganglia was evident. Regional uptake was affected by physiologic maneuvers (visual stimulation). In 24 patients studied for stroke, IMP images demonstrated areas that were involved in acute infarction in eight patients whose initial transmission computerized tomography (TCT) was normal; IMP also showed perfusion abnormalities larger than the TCT abnormality in ten patients. Perfusion abnormalities were present in 23/24 of these patients. Seven patients studied with a history of TIA had normal TCT and IMP images. In three patients studied during seizure activity, regions of hyperperfusion corresponded to the EEG seizure focus. Markedly decreased activity was present in three patients with brain tumor and corresponded to the focal abnormality on the TCT study. Our study demonstrates the feasibility of assessing regional brain perfusion using a radiopharmaceutical that is lipid soluble and has a high extraction fraction in the brain, together with single-photon ECT.

Early clinical experience with a radionuclide emission computed tomographic brain imaging system

Six selected cases demonstrate the appearance of subdural hematomas, tumor, stroke, and abscess on single-photon emission tomography. Conventional radionuclide images were obtained on every patient, and computed transmission tomographs were obtained on 4 of the patients. This early clinical experience suggests several promising areas for further investigation.

Radionuclide emission computed tomography of the body of laboratory animals

Selective studies in the monkey and baboon demonstrate the normal physiologic distribution of 99mTc radiopharmaceuticals using single-photon emission computed tomography. The cases demonstrated the ability of the Cleon Transverse Section Brain Imager TM to do emission computed tomography of various organs. This experience shows what can be expected when equipment for emission computed tomography of the body becomes available for patient studies.