Reconciling Oxygen and Aerosol Delivery with a Hood on In Vitro Infant and Paediatric Models

This study aimed to evaluate optimal aerosol and oxygen delivery with a hood on an infant model and a paediatric model. A facemask and a hood with three inlets, with or without a front cover, were used. A small-volume nebuliser with a unit-dose of salbutamol was used for drug delivery and an air entrainment nebuliser was used to deliver oxygen at 35%. Infant and paediatric breathing patterns were mimicked; a bacterial filter was connected to the end of a manikin trachea for aerosol drug collection, and an oxygen analyser was used to measure the oxygen concentration. For the infant model, inhaled drug dose was significantly higher when the nebuliser was placed in the back of the hood and with a front cover. This was verified by complementary computational simulations in a comparable infant-hood model. For the paediatric model, the inhaled dose was greater with a facemask than with a hood. Oxygen delivery with a facemask and a hood with a front cover achieved a set concentration in both models, yet a hood without a front cover delivered oxygen at far lower concentrations than the set concentration.

Charles Porter Ellington. 31 December 1952—30 July 2019

Charles Ellington graduated at Duke University, North Carolina, and came to Cambridge in 1973 to work for a PhD on insect flight dynamics. He developed novel methodology and software for the kinematic analysis of freely hovering insects and applied them to his own high-speed films of a range of species. He identified five new non-steady-state mechanisms for lift generation, was the first to develop a vortex theory for flapping flight and developed and extended the use of morphometric parameters in calculating the forces and power requirements of flight. He remained in Cambridge, married a colleague, joined the staff of the Department of Zoology, became a fellow of Downing College and continued to work on insect aerodynamics and energetics, publishing on flight muscle efficiency, the factors limiting flight performance and the aerodynamic implications of the origin of insect flight. Building a closed-circuit wind tunnel connected with a sensitive oxygen analyser, he studied with colleagues how the aerodynamics and metabolic power input of bumblebees vary with flight speed, challenging the orthodox theory that this should follow a U-shaped curve. Outstanding among later research was the discovery that hawkmoths, and by implication many other insects, gain high levels of lift by generating a vortex above the leading edge, stabilized by spiralling out along the span—a major focus of animal flight research ever since. His many administrative roles included editorship of theJournal of Experimental Biology. He became a British citizen in 1995, was elected FRS in 1998 and to a chair of animal mechanics in 1999. Awards include the Scientific Medal of the Zoological Society and the University of Cambridge Pilkington Prize for teaching excellence. He was diabetic throughout his adult life, and suffered progressive ill health following a heart attack in 1996. He took early retirement in 2010, lived quietly with his wife and two sons at home near Newmarket, and died in July 2019.

Reliability of methods to estimate the fraction of inspired oxygen in patients with acute respiratory failure breathing through non-rebreather reservoir bag oxygen mask

Severity of hypoxaemia can be assessed using the partial pressure of arterial oxygen to fraction of inspired oxygen ratio (FiO2). However, in patients breathing through non-rebreather reservoir bag oxygen mask, accuracy of bedside FiO2 estimation methods remains to be tested. In a post-hoc analysis of a multicentre clinical trial, three FiO2 estimation methods were compared with FiO2 measured with a portable oxygen analyser introduced in the oxygen mask. Among 262 patients analysed, mean (SD) measured FiO2 was 65% (13). The 3%-formula (21% + oxygen flow rate in L/min × 3) was the most accurate method to estimate FiO2. Other methods overestimated FiO2 and hypoxaemia severity, so they should be avoided.

Effects of sprint interval training on sloping surfaces on aerobic and anaerobic power

SummaryStudy aim: Several sprint interval training applications with different slope angles in the literature mostly focused on sprint running time and kinematic and dynamic properties of running. There is a lack of comparative studies investigating aerobic and anaerobic power. Therefore, this study aimed to examine the effects of sprint interval training on sloping surfaces on anaerobic and aerobic power.Material and methods: A total of 34 male recreationally active men aged 20.26 ± 1.68 years and having a BMI of 21.77 ± 1.74 were assigned to one of the five groups as control (CON), uphill training (EXP1), downhill training (EXP2), uphill + downhill training (EXP3) and horizontal running training (EXP4) groups. Gradually increased sprint interval training was performed on horizontal and sloping surfaces with an angle of 4°. The training period continued for three days a week for eight weeks. The initial and the final aerobic power was measured by an oxygen analyser and anaerobic power was calculated from the results of the Margaria-Kalamen staircase test.Results: Following the training programme, an increase in aerobic power was found in all training groups (EXP1 = 20.79%, EXP2 = 14.95%, EXP3 = 26.85%, p < 0.01) and EXP4 = 20.46%) (p < 0.05) in comparison with the CON group (0.12%), but there were no differences among the training groups. However, significant increases in anaerobic power were found in uphill training (4.91%) and uphill + downhill training (8.35%) groups (p < 0.05).Conclusion: This study showed that all sprint interval studies on horizontal and sloping surfaces have a positive effect on aerobic power, and uphill and combined training are the most effective methods for the improvement of anaerobic power.

Development of Experimental-Bed for Observation of Locomotory Small Animals

The animal experimental is a fundamental equipment for biomechanics experimental, which attached to electric shock instrument, oxygen analyser or high speed recording system. The animal experimental has an advantage that it offers a single environment excluded the interfere from natural regimes. In this paper, a small animal observation experimental-bed was developed based on C++. The interface of control program was developed using Visual Basic 6.0 and the COM port communication between SCM LM3S8962 and PC was developed based on C++ Builder 6.0. The velocities of belt of the small animal experimental can run according to line, sinusoidal curves, triangular wave curves and square wave curves. Moreover, the control program provides a combined velocity based on above curves for satisfy the sophisticated experiment of locomotory small animals.

Pulse Oximetry

The pulse oximeter is a device for non-invasive, continuous measurement of oxygen saturation. As such it is arguably one of the most important intraoperative monitors at the disposal of anaesthetists, and efforts are being made to make pulse oximeters available at all operating locations throughout the world [Walker et al. 2009]. Although the device measures oxygen saturation of arterial blood, which is the physiological end point of interest, it is not a replacement for monitoring all the events which may lead to hypoxaemia; in other words it does not replace an oxygen analyser at the common gas outlet of the anaesthetic machine. Depending on the site of the probe, usually ear lobe or finger, there is a variable delay between the onset of a causative hypoxaemic event and detection of hypoxaemia by the pulse oximeter, the delay being longer the more peripherally placed is the probe. Appropriate size and design of the probe for accuracy and safety in children is important [Howell et al. 1993] and finger probes are more accurate but slower to respond than ear probes [Webb et al. 1991]. Forehead reflectance probes have been used with good results [Casati et al. 2007]. It is also true that the human eye is notoriously bad at detecting cyanosis in the range of saturations 81–85%. For additional information on Monitoring Principles see Chapter 11. It is clear, however, that in a hierarchy of monitors for anaesthesia, the pulse oximeter is indispensable. A pulse oximeter uses two separate technologies: one is plethysmography, where reproduction of the pulsatile waveform takes place; the other is spectroscopy, where absorption of light of specific wavelengths by body tissues occurs and is analysed. The spectroscopic aspects depend on the laws of Beer and Lambert, which can be combined to state that the amount of light absorbed by a substance is proportional to the thickness of the substance sample (the path length of the light) and the concentration of the substance.