Correction of Doppler-broadened Rayleigh backscattering effects in H2O dial measurements

A general method of solutions for treating effects of Doppler-broadened Rayleigh backscattering in H2O Differential Absorption Lidar (DIAL) measurements are described and discussed. Errors in vertical DIAL measuremtns caused by this laser line broadening effect can be very large and, therfore, this effect has to be accounted for accurately. To analyze and correct effects of Doppler-broadened Rayleigh backscattering in DIAL experiments, a generalized DIAL approximation was derived starting from a lidar equation, which includes Doppler broadening. To evaluate the accuracy of H2O DIAL measurements, computer simulations were performed. It was concluded that correction of Doppler broadened Rayleigh backscattering is possible with good accuracy in most cases of tropospheric H2O DIAL measurements, but great care has to be taken when layers with steep gradients of Mie backscattering like clouds or inversion layers are present

Avoiding adverse outcomes in anaesthesia. The relevant As: allergy, asthma airway and anaphylaxis

The perioperative preparation of children presenting for surgery aims to identify medical problems that might influence the outcome and to institute management strategies to reduce those risks. Adverse respiratory events remain a significant cause of morbidity and mortality in modern paediatric anaesthesia. This manuscript addresses some common medical problems that may impact on the anaesthetic. These include upper respiratory tract infections, and allergy and asthma; conditions whose optimal management should invoke daily discussions, and which can have significant implications if not managed correctly.Keywords: general anaesthesia, paediatric, upper respiratory tract infection, food allergy, asthma, laryngospasm, bronchospas

Neonatal caudal block revisited: can safety be improved?

No Abstract. Southern African Journal of Anaesthesia and Analgesia Vol. 12(1) 2006: 3

Anaesthesia and Rubinstein-Taybi syndrome

No Abstract.South African Psychiatry Review Vol. 11(4) 2005: 135-13

Parental presence at induction of anaesthesia: who benefits?

No Abstract. Southern African Journal of Anaesthesia and Analgesia Vol. 12(1) 2006: 2

Anaesthesia and Beckwith-Weideman syndrome

Synopsis of patient: A 15 hour old, 4.2 kg male presents for closure of a large exomphalos. He was delivered by C-section for foetal distress after a prolonged labour at a peripheral hospital. Apgars were recorded as 6 and 8. His mother was an unmarried primigravida who attended antenatal clinic on one occasion. Meconium aspiration was suspected at birth. Preoperative assessment revealed a large term baby with features of Beckwith-Weideman syndrome - a large tongue; a faint naevus on the forehead; and a skin crease on the ear lobe. Assessment of the liver and spleen was difficult in view of the large omphalocoele (5x6cm). The exomphalos was stained by the meconium in utero. He was tachypnoeic but the chest was clear. There was a 2/6 ejection systolic murmur at the left sternal border. Chest xray was normal apart from mild cardiomegaly. Blood sugar on admission was 1.2 mmol.l ; electrolytes were within normal limits. Haemoglobin was 17gm. (Hct 55)

Meningococcal septicaemia complications involving skin and underlying deeper tissues - management considerations and outcome

Objective: To describe surgical experience with purpura fulminans related to meningococcaemia in a single institution, and to suggest a management protocol. Methods: A retrospective review was done of patients admitted to the intensive care unit at Red Cross War Memorial Children's Hospital in Cape Town with the clinical diagnosis of purpura fulminans. Results: During a 28-year period (1977 - 2005) 112 children (average age 3.4 years) were treated for meningococcaemia with purpura fulminans. Overall mortality was 10.7%. Local treatment consisted of measures to improve circulation, infection control and healing of necrotic tissue. Demarcation of necrotic areas was evident at 5.5 days and the average area of skin necrosis was 14% total body surface area (range 2 - 85%). The lower limbs were predominantly affected. Purpura fulminans resolved in 35 children (31.2%) without skin necrosis. Skin grafting was required in 77 children (68.8%). Factors associated with a poor outcome for peripheral extremity salvage were progressive irreversible skin changes, early disappearance of distal pulses, tense cold swollen extremities and intense pain on passive movement of the affected extremity. Amputations were performed proximal to the area of necrosis, on average 27 days after injury. Conclusions: Meningococcaemia is a disease with potentially devastating consequences. Early surgical consultation is essential. Skin- and soft-tissue-releasing incisions should be considered early to reduce the incidence of extremity necrosis. Small necrotic areas usually separate spontaneously with secondary healing or can be excised and sutured. Larger necrotic areas should be excised only after demarcation has been established, and can be covered with delayed skin grafting. Amputation should be conservative but may require revision

Ilio inguinal block: do we know the correct dose?

No Abstract. Southern African Journal of Anaesthesia and Analgesia Vol. 12(1) 2006: 37-3

Ultra-low threshold CW Triply Resonant OPO in the near infrared using Periodically Poled Lithium Niobate

We have operated a CW triply resonant OPO using a PPLN crystal pumped by a Nd:YAG laser at 1.06 micron and generating signal and idler modes in the 2-2.3 micron range. The OPO was operated stably in single mode operation over large periods of time with a pump threshold as low as 500 microwatts.Comment: 7 pages, 5 figures, submitted to JEOS