The World Federation of Societies of Anaesthesiologists Minimum Capnometer Specifications 2021-A Guide for Health Care Decision Makers.

Capnometry, the measurement of respiratory carbon dioxide, is regarded as a highly recommended safety technology in intubated and nonintubated sedated and/or anesthetized patients. Its utility includes confirmation of initial and ongoing placement of an airway device as well as in detecting gas exchange, bronchospasm, airway obstruction, reduced cardiac output, and metabolic changes. The utility applies prehospital and throughout all phases of inhospital care. Unfortunately, capnometry devices are not readily available in many countries, especially those that are resource-limited. Constraining factors include cost, durability of devices, availability of consumables, lack of dependable power supply, difficulty with cleaning, and maintenance. There is, thus, an urgent need for all stakeholders to come together to develop, market, and distribute appropriate devices that address costs and other requirements. To foster this process, the World Federation of Societies of Anaesthesiologists (WFSA) has developed the "WFSA-Minimum Capnometer Specifications 2021." The intent of the specifications is to set the minimum that would be acceptable from industry in their attempts to reduce costs while meeting other needs in resource-constrained regions. The document also includes very desirable and preferred options. The intent is to stimulate interest and engagement among industry, clinical providers, professional associations, and ministries of health to address this important patient safety need. The WFSA-Minimum Capnometer Specifications 2021 is based on the International Organization for Standardization (ISO) capnometer specifications. While industry is familiar with such specifications and their presentation format, most clinicians are not; therefore, this article serves to more clearly explain the requirements. In addition, the specifications as described can be used as a purchasing guide by clinicians.

The accuracy and cost-effectiveness of strategies used to identify peripheral artery disease among patients with diabetic foot ulcers.

BACKGROUND: Patients with diabetic foot ulcers (DFUs) should be evaluated for peripheral artery disease (PAD). We sought to estimate the overall diagnostic accuracy for various strategies that are used to identify PAD in this population. METHODS: A Markov model with probabilistic and deterministic sensitivity analyses was used to simulate the clinical events in a population of 10,000 patients with diabetes. One of 14 different diagnostic strategies was applied to those who developed DFUs. Baseline data on diagnostic accuracy of individual noninvasive tests were based on a meta-analysis of previously reported studies. The overall sensitivity and cost-effectiveness of the 14 strategies were then compared. RESULTS: The overall sensitivity of various combinations of diagnostic testing strategies ranged from 32.6% to 92.6%. Cost-effective strategies included ankle-brachial indices for all patients; skin perfusion pressures (SPPs) or toe-brachial indices (TBIs) for all patients; and SPPs or TBIs to corroborate normal pulse examination findings, a strategy that lowered leg amputation rates by 36%. Strategies that used noninvasive vascular testing to investigate only abnormal pulse examination results had low overall diagnostic sensitivity and were weakly dominated in cost-effectiveness evaluations. Population prevalence of PAD did not alter strategy ordering by diagnostic accuracy or cost-effectiveness. CONCLUSIONS: TBIs or SPPs used uniformly or to corroborate a normal pulse examination finding are among the most sensitive and cost-effective strategies to improve the identification of PAD among patients presenting with DFUs. These strategies may significantly reduce leg amputation rates with only modest increases in cost.

Provision of home mechanical ventilation and sleep services for England survey.

The Department of Health is promoting the generation of specialist networks to manage long term ventilatory weaning and domiciliary non-invasive ventilation patients. Currently the availability of these services in England is not known. We performed a short survey to establish the prevalence of sleep and ventilation diagnostic and treatment services. The survey focussed on diagnostic services and Home Mechanical Ventilation (HMV) provision, and was divided into (a) availability of diagnostics, (b) funding, and (c) patient groups. This survey has confirmed that the majority of Home Mechanical Ventilation set-ups are currently for Obesity Related Respiratory Failure and Chronic Obstructive Pulmonary Disease. We have found that there is variable provision of diagnostic services, with the majority of units offering overnight oximetry (95%) but only 55% of responders providing a home mechanical ventilation service. Even more interestingly, less than two thirds of units charged their primary care trust for this service. These data may assist in the development of regional networks and specialist home mechanical ventilation centres.

Biomedical sensor using thick film technology for transcutaneous oxygen measurement.

Transcutaneous blood gas monitoring is a non-invasive measurement technique for obtaining fast and relatively accurate responses to determine the respiratory conditions of patients. In this investigation, a screen-printed, disposable, transcutaneous oxygen sensor based on the working principle of amperometry, incorporates an integral heating element to enhance transcutaneous diffusion of blood gases typically at 44 degrees C. A Clark cell configuration is employed with gold working and counter electrodes and a silver/silver chloride reference electrode. Two different types of electrolytes namely potassium nitrate gel and polyelectrolyte (Nafion) have been studied under laboratory test conditions. A fully computer-controlled gas testing rig has been constructed to automate the varying of oxygen levels. Linear relationships have been established with an averaged sensitivity level of 0.029 microA/mmHg. In addition, a brief pilot clinical trial involving a fully grown human subject has been carried out alongside a commercial transcutaneous blood gas analyser. The investigations have shown that although the measured signals are weaker than those obtained from the laboratory test, the thick film sensor displays a repeatable and linear relationship when correlating with the commercial system. This study has greatly contributed towards the understanding for the suitability of the materials in achieving a viable, low-cost biomedical sensor.

[Four new instrument for blood gas analysis are tested: handy cassettes for easier use]. / Fyra nya instrument för analys av blodgaser testade: behändiga kassetter skall ge bättre användarvänlighet.

An entirely new type of blood gas analyser has made its way into the marketplace, to be used, for example, in emergency rooms, intensive care units, ambulances, and bedside with quarantined patients in infectious diseases units. The instruments reviewed here employ new miniaturised analysis circuitry, integrated into the cassette on which the blood sample is applied. These instruments are designed for use by care-givers without specific laboratory training. Four point-of-care blood gas analysers are tested: OPTI 1 (AVL), I-STAT (HP), IRMA (Infiniti) och ABL 70 (Radiometer).

A randomized, controlled trial of transcutaneous carbon dioxide monitoring during ERCP.

BACKGROUND: Pulse oximetry, used to monitor oxygen saturation during endoscopy, does not directly measure hypoventilation. Study goals were to determine whether transcutaneous carbon dioxide (PtcCO(2)) monitoring during endoscopic retrograde cholangiopancreatography (ERCP) prevents severe hypoventilation and to assess the accuracy of clinical observation and pulse oximetry in detecting hypoventilation. METHODS: All patients received intensive clinical and electronic monitoring including pulse oximetry. Supplemental oxygen was administered for pulse oximetry < 90%. Patients were randomized to a treatment arm (group 1) where PtcCO(2) monitoring guided sedation or a control arm (group 2) where PtcCO(2) was recorded but unavailable for guiding sedation. RESULTS: Group 1 had significantly fewer episodes of severe carbon dioxide retention (rise in PtcCO(2) >/=40 mm Hg above baseline) than group 2 (0 of 199 versus 5 of 196, respectively, p = 0.03), as well a shorter mean duration of procedure discomfort (8.3% of procedure duration rated as "uncomfortable" versus 11.5%, p = 0.04). Correlations between clinical observation and objective measures of ventilation were poor: level of sedation versus PtcCO(2) (R = 0.3) or pulse oximetry (R = 0.06); slowest respiratory rate versus PtcCO(2) (R = 0.4) or pulse oximetry (R = -0.4). PtcCO(2) rises of greater than 20 mm Hg occurred without oxygen desaturation in 10.7% of patients receiving supplemental oxygen. CONCLUSIONS: Carbon dioxide retention during ERCP is not reliably detected by clinical observation or by pulse oximetry in patients receiving supplemental oxygen. The addition of PtcCO(2) monitoring prevents severe carbon dioxide retention more effectively than intensive clinical monitoring and pulse oximetry alone. The clinical relevancy of this observation needs to be determined in an appropriately designed outcome study.

A prospective evaluation of transcutaneous oxygen measurements in the management of diabetic foot problems.

PURPOSE: To test the hypothesis that lower extremity transcutaneous oxygen (TcPO2) measurements can accurately predict severity of foot ischemia and can be used to select appropriate treatment (conservative versus operative) for patients with diabetes and tissue necrosis or ischemic rest pain. METHODS: Fifty-five patients with 66 limbs were prospectively treated from June 1993 to July 1994. Noninvasive hemodynamic arterial assessment and TcPO2 mapping of the involved limb were obtained before treatment was selected. If the transmetatarsal TcPO2 level was 30 mm Hg or greater, the patient's foot problem was managed conservatively with local wound care, debridement, or a minor foot amputation. If the transmetatarsal TcPO2 level was less than 30 mm Hg, arteriography was performed with the anticipated need for vascular reconstruction. The endpoints for determining treatment success or failure were complete wound healing or relief of ischemic rest pain. RESULTS: Thirty-one of 36 (86%) limbs with an initial transmetatarsal TcPO2 level of 30 mm Hg or greater were treated successfully with conservative care, including 73% (11 of 15 feet) of limbs without a palpable pedal pulse. After either bypass or angioplasty, 20 of 24 (83%) limbs achieved a transmetatarsal TcPO2 level greater than 30 mm Hg and had complete resolution of their presenting foot problem. An initial or postintervention transmetatarsal TcPO2 level of 30 mm Hg or greater was more accurate (90%, p = 0.001) than a palpable pedal pulse (65%, p = 0.009), in predicting ultimate wound healing or resolution of rest pain. CONCLUSIONS: TcPO2 mapping is a useful noninvasive modality that can prospectively determine severity of foot ischemia, aid in selecting appropriate treatment for patients with diabetes and foot salvage problems, and decrease the total cost of such care.

Cost effectiveness of noninvasive oxygen saturation measurement during exercise for the diagnosis of Pneumocystis carinii pneumonia.

We assessed (1) the sensitivity and specificity of exercise oxygen saturation measurement (EOS) for the diagnosis of Pneumocystis carinii pneumonia (PCP); and (2) the cost of introducing this indirect diagnostic test compared with that of standard diagnostic strategies for PCP. In a prospective study, 85 HIV-infected patients with suspected PCP underwent EOS, followed by induced sputum (IS) and bronchoalveolar lavage (BAL) if IS was negative for P. carinii. The prevalence of PCP was 0.22, the sensitivity of IS was 0.6, and its specificity was perfect. The cost ratios of IS to BAL and EOS to BAL were 0.1 and 0.2, respectively. A desaturation of three points was the best cutoff point, giving perfect sensitivity and a specificity of 0.77. The cost analysis showed that the introduction of EOS into diagnostic strategies for PCP is highly justified when the local prevalence is low. Exercise oxygen saturation measurement is simple and safe, and the results are available rapidly; its sensitivity is perfect and its specificity good. Its economic utility depends on its cost and the local prevalence of PCP in the test population.