Anaesthesia

Apnoeic oxygenation refers to oxygenation in the absence of spontaneous respiration or mechanical ventilation. It has been described in humans for over half a century and has seen a resurgence in interest given its potential to delay oxygen desaturation during airway management, especially with the advent of high‐flow nasal cannulae. This narrative review summarises our current understanding of the mechanisms of gas exchange during apnoeic oxygenation and its diverse range of clinical applications, including its use at induction of anaesthesia and for the facilitation of ‘tubeless anaesthesia’. Additional discussion covers use in critical care, obese, obstetric and paediatric sub‐populations. The article also highlights current research efforts aiming to enhance the evidence base for the use of this technique.

We investigated the cross‐sectional area of the femoral vein and its relationship to the femoral artery at two anatomical levels, in infants and children. Sixty‐six subjects were allocated to one of two groups: infants (< 1 year, n = 31) or children (1–6 years, n = 35). After induction of general anaesthesia, the femoral vein was evaluated by ultrasound with the patients’ legs at 30° and 60° of abduction and their hips externally rotated. In each position, measurements were taken at the level of the inguinal crease and 1 cm below the crease. Hip rotation with 60° leg abduction decreased femoral artery overlap at the level of the inguinal crease in both infants (p = 0.013) and children (p = 0.003). Thus, the optimal place for femoral vein cannulation in paediatric patients seems to be at the level of the inguinal crease with 60° leg abduction and external hip rotation.

We compared the economics of using two‐dimensional ultrasound locating devices and more traditional landmark methods for central venous cannulation in the National Health Service (NHS). The evaluation consisted of a systematic review of randomised controlled trials and an economic evaluation using decision analytic cost‐effectiveness modelling. Incremental costs per complication avoided associated with landmark and ultrasound central venous cannulation were modelled for patients scheduled for central venous cannulation. The marginal economic cost of using ultrasound for central venous cannulation was less than £10 per procedure, assuming that a machine is used for 15 procedures each week. The base case scenario implied that £2000 worth of resource savings result for every 1000 procedures undertaken and 90 avoided complications. Sensitivity analysis indicated that the results of modelling appear robust to the central assumptions used. Ultrasound guidance used in central venous cannulation procedures saves NHS resources even with conservative modelling assumptions.

The femoral artery and vein are commonly used for access to the circulation. Accidental puncture of one vessel whilst attempting to cannulate the other is a common complication. Identification of relevant surface anatomical landmarks and ultrasonography of both groins was performed on 50 consecutive adult patients admitted to the intensive care unit. In most patients there was overlap of the artery over the vein far closer to the inguinal ligament than conventional anatomical texts would indicate. The frequency and degree of overlap increased as the vessels descended distally towards the knee. Surface anatomical landmarks were not useful in predicting the underlying anatomy. The side‐by‐side relationship of artery and vein is commonest close to the inguinal ligament. Therefore, to avoid damage to the neighbouring vessel, percutaneous access should be undertaken just below the inguinal ligament.

This study evaluated the effects of the reverse Trendelenburg position and additional inguinal compression on the cross‐sectional area of the femoral vein in paediatric patients. Seventy subjects were allocated to two groups: the infants group and the children group. Cross‐sectional area of the femoral vein was measured just below the inguinal ligament using ultrasound. Three measurements were obtained for each patient: (i) supine, (ii) reverse Trendelenburg position and (iii) reverse Trendelenburg position with inguinal compression. In the infants group, femoral vein cross‐sectional area increased by a mean (SD) of 21.1 (15.2) % in the reverse Trendelenburg position and by 60.7 (30.8) % in the reverse Trendelenburg position with inguinal compression; whereas in the children group, femoral vein cross‐sectional area increased by 24.7 (15.8) % in the reverse Trendelenburg position and by 100.3 (50.7) % in the reverse Trendelenburg position with inguinal compression. Inguinal compression in the reverse Trendelenburg position offers a useful means of increasing femoral vein cross‐sectional area in paediatric patients.

This study assessed two disposable devices, the LMA Fastrach^TM and the newly developed supraglottic airway device, the Air‐Q^TM, as a conduit for tracheal intubation in 154 healthy adults undergoing elective surgery. Using a non‐inferiority approach, the primary outcome measure was successful tracheal intubation within two blind insertion attempts. Successful blind intubation after two attempts was achieved in 75/76 (99%) of the patients in the LMA Fastrach group vs 60/78 (77%) in the Air‐Q group (95% CI for the difference 12–32%, p < 0.0001). Fibreoptic intubation was used to assist the third attempt. The rate of successful intubation after three attempts was 100% in the LMA Fastrach group and 95% in Air‐Q group. The single‐use LMA Fastrach appears superior compared with the Air‐Q, as a conduit to facilitate blind tracheal intubation.

Cardiac output can be measured accurately by transpulmonary arterial thermodilution using the PiCCO^® (Pulsion Medical Systems, Munich, Germany) system with a femoral artery catheter. We have investigated the accuracy of a new 50 cm 4 French gauge radial artery catheter and the ability to use the system with a shorter radial catheter. We studied 18 patients who had undergone coronary artery surgery and made three simultaneous measurements of cardiac output by arterial thermodilution and with a pulmonary artery catheter. The radial catheter was withdrawn in 5 cm increments and the measurements were repeated. We found close agreement between arterial thermodilution and pulmonary artery thermodilution with a mean (SD) bias of 0.38 (0.77) l.min⁻¹. Arterial thermodilution became unreliable once the catheter had been withdrawn by more than 5 cm. We conclude that cardiac output measurement with arterial thermodilution with a radial catheter is interchangeable with that derived from a pulmonary artery catheter, and that a centrally sited arterial catheter is required for accurate determination of cardiac output by transpulmonary arterial thermodilution.

Quality of life is often thought to be poor before and after intensive care unit admission. The aim of this study was to investigate changes in quality of life before and after intensive care. A prospective cohort study of 300 consecutive patients admitted to intensive care was performed in a Scottish Teaching Hospital. Quality of life was assessed premorbidly and 3, 6 and 12 months after intensive care admission for surviving patients using SF‐36 as well as EQ‐5D scores at 12 months. The median value for age was 60.5 years and for APACHE II score, 18. The mean length of stay was 6.7 days. SF‐36 physical component scores decreased from premorbid values at 3 months (p = 0.05) and then returned to premorbid values at 12 months (p < 0.001). The mean physical scores were below the population norm at all time points but the mean mental scores were similar or higher than these population norms. Patients who died after intensive care discharge had lower quality of life scores than did survivors (all p < 0.01). Poor premorbid quality of life was demonstrated and appears to reduce after ICU discharge. For survivors there was a slow increase in physical quality of life to premorbid levels by the end of the first year but these remained lower than in the general population. ICU patients experience a considerable longer‐term burden of ill health.

Thiết bị đo lưu lượng tim siêu âm là một thiết bị đo không xâm lấn, sử dụng sóng Doppler liên tục có thể được sử dụng để đo lưu lượng tim. Độ chính xác và độ chính xác của nó trong các trường hợp phẫu thuật và chăm sóc tích cực đã được đánh giá với nhiều kết quả khác nhau. Chúng tôi đã tiến hành một phân tích tổng hợp để tính toán độ lệch trung bình tổng hợp, độ chính xác và tỷ lệ sai số của thiết bị này. Sáu nghiên cứu đã được chọn để đưa vào phân tích tham số tổng hợp với 320 phép đo. Độ lệch trung bình có trọng số là -0.39 l.min⁻¹(95% CI -0.25 đến -0.53 l.min⁻¹), độ chính xác 1.27 l.min⁻¹ và tỷ lệ sai số 42.7% (95% CI 38.5−46.9%). Thiết bị đo lưu lượng tim siêu âm đạt được sự đồng thuận tương tự với phương pháp nhiệt pha bolus so với các phương pháp không xâm lấn khác trong việc theo dõi lưu lượng tim trong phẫu thuật, và có thể đóng một vai trò hữu ích trong theo dõi lưu lượng tim.