Observations on blood gas tensions and acid-base status in respiratory illnesses in infants and children

The causes of death of 550 infants and children dying in hospital over a ten year period were analysed as a prelude to the main study. Serial measurements of blood gas tensions and pH were made in 50 children with acute lower respiratory tract infections, 21 with acute asthma, 25 with cystic fibrosis, and 23 newly born infants in the first hour of life. Arterial blood lactate and pyruvate concentrations were measured in 35 children with acute or chronic hypoxaemia. The effects of treatment, particularly oxygen and alkali therapy on these variables were investigated. Measurements were also made of the concentrations of oxygen attainable in tents and incubators, tested under ideal, and routine working conditions.The analysis of deaths shows that respiratory disorders, particularly pneumonia, account for approximately 25 per cent of 'medical' deaths in hospital. The main conclusions, in answer to the questions posed in Section I, p. 7, are enumerated:1. Hypoxaemia, an increase in carbon dioxide retention and metabolic acidosis are commonly present in acute lower respiratory tract infections and severe acute asthma. In cystic fibrosis, an increase in Pco2, often well compensated, occurs only in the late stages of the disease.2. Clinical signs are unreliable as estimates of Po2, Pco2 and pH in acute respiratory illnesses. In cystic fibrosis there is a good relation between the clinical 'grade' in groups of patients and arterial oxygen tension. There are, however, no reliable methods of predicting blood gas tensions in individual patients.3. Metabolic acidosis in acute respiratory disorders is due, at least in part, to the accumulation of lactic acid. Measurements of blood lactate and lactate /pyruvate ratio as indices of hypoxia are of limited value in routine clinical practice.4. In acute lower respiratory tract infections and acute asthma hypoxaemia is not invariably relieved by the administration of 40 per cent oxygen. There appears to be no danger of producing CO2 narcosis with oxygen in acute respiratory infections. During exacerbations of infection in cystic fibrosis and in severe asthma with ventilatory failure, however, oxygen is potentially hazardous.5. The administration of sodium bicarbonate is of value in the treatment of severe respiratory failure in asthma, and is an important adjunct to intermittent positive pressure respiration (IPPR) in the manage- ment of asphyxiated newly born infants.6. In acute respiratory infections in infancy a Pco2 above 65 mm Hg and pH below 7.20 are of grave prognostic significance in the absence of prompt treatment. In cystic fibrosis sustained hypercapnia is usually a terminal occurrence.7. Therapeutic concentrations of oxygen in tents are often difficult to maintain in routine practice

Design of a slender tuned ultrasonic needle for bone penetration

This paper reports on an ultrasonic bone biopsy needle, particularly focusing on design guidelines applicable for any slender tuned ultrasonic device component. Ultrasonic surgical devices are routinely used to cut a range of biological tissues, such as bone. However the realisation of an ultrasonic bone biopsy needle is particularly challenging. This is due to the requirement to generate sufficient vibrational amplitude capable of penetrating mineralised tissue, while avoiding flexural vibrational responses, which are known to reduce the performance and reliability of slender ultrasonic devices. This investigation uses finite element analysis (FEA) to predict the vibrational behaviour of a resonant needle which has dimensions that match closely to an 8Gx4inch bone marrow biopsy needle. Features of the needle, including changes in material and repeated changes in diameter, have been included and systematically altered to demonstrate that the location of and geometry of these features can significantly affect the resonant frequency of bending and torsional modes of vibration while having a limited effect on the frequency and shape of the tuned longitudinal mode. Experimental modal analysis was used to identify the modal parameters of the selected needle design, validating the FEA model predictions of the longitudinal mode and the close flexural modes. This verifies that modal coupling can be avoided by judicious small geometry modifications. Finally, the tuned needle assembly was driven under typical operational excitation conditions to demonstrate that an ultrasonic biopsy needle can be designed to operate in a purely longitudinal motion

Ultrasonic needles for bone biopsy

Bone biopsy is an invasive clinical procedure where a bone sample is recovered for analysis during the diagnosis of a medical condition. When the architecture of the bone tissue is required to be preserved, a core-needle biopsy is taken. Although this procedure is performed while the patient is under local anaesthesia, the patient can still experience significant discomfort. Additionally, large haematoma can be induced in the soft tissue surrounding the biopsy site due to the large axial and rotational forces which are applied through the needle to penetrate bone. It is well documented that power ultrasonic surgical devices offer advantages of low cutting force, high accuracy and preservation of soft tissues. This paper reports a study of the design, analysis and test of two novel power ultrasonic needles for bone biopsy that operate using different configurations to penetrate bone. The first utilises micrometric vibrations generated at the distil tip of a full-wavelength resonant ultrasonic device, while the second utilises an ultrasonic-sonic approach where vibrational energy generated by a resonant ultrasonic horn is transferred to a needle via the chaotic motion of a free-mass. It is shown that the dynamic behaviour of the devices identified through experimental techniques closely match the behaviour calculated through numerical and FEA methods, demonstrating that they are effective design tools for these devices. Both devices were able to recover trabecular bone from the metaphysis of an ovine femur, and the biopsy samples were found to be comparable to a sample extracted using a conventional biopsy needle. Furthermore, the resonant needle device was also able to extract a cortical bone sample from the central diaphysis, which is the strongest part of the bone, and the biopsy was found to be superior to the sample recovered by a conventional bone biopsy needle

Beware the painful nerve palsy; neurostenalgia, a diagnosis not to be missed

We present a case of painful radial nerve palsy following application of a humeral lengthening frame. At re-operation, the radial nerve was found to be compressed against a distal pin. This was re-sited providing immediate pain relief and a gradual resolution of the radial nerve palsy. Pain in association with a nerve palsy should alert the clinician to the possibility of nerve compression that may benefit from urgent decompression

Acceptance and commitment therapy delivered in a dyad after a severe traumatic brain injury: a feasibility study

Objective: There is a high prevalence of complex psychological distress after a traumatic brain injury but limited evidence of effective interventions. We examined the feasibility of Acceptance and Commitment Therapy after a severe traumatic brain injury using the criteria, investigating a therapeutic effect, and reviewing the acceptability of measures, treatment protocol, and delivery method (in a dyad of two clients and a therapist). Method: Two male outpatients with severe traumatic brain injury and associated psychological distress jointly engaged in a seven session treatment program based on Acceptance and Commitment Therapy principles. Pre- and post-treatment measures of mood, psychological flexibility, and participation were taken in addition to weekly measures. Results: The intervention showed a therapeutic effect with one participant, and appeared to be acceptable for both participants with regard to program content, measures, and delivery mode by in a dyad. One participant showed both significant clinical and reliable change across several outcome measures including measures of mood and psychological flexibility. The second participant did not show a reduction in psychological inflexibility, but did show a significant drop in negative affect. Significant changes pre- to post-treatment for measures of participation were not indicated. Qualitatively, both participants engaged in committed action set in accordance with their values. Conclusions: This study suggests that Acceptance and Commitment Therapy may be feasible to be delivered in a dyad with individuals who have a severe traumatic brain injury. A further test of its potential efficacy in a phase II clinical trial is recommended