Previous research has identified cognitive impairment in children with sickle cell anemia (SCA, Hemoglobin SS) compared with controls, partly accounted for by overt neuropathology after clinical stroke, “covert” (“silent”) infarction, and severity of anemia. However, cognitive deficits have also been identified in children with SCA with no history of stroke and a normal T2-weighted magnetic resonance imaging (MRI) scan. Our aim was to investigate whether nocturnal hemoglobin oxygen desaturation and sleep fragmentation could be associated with cognitive impairment in children with SCA. We assessed 10 children with SCA (9 with normal MRI) using neuropsychological measures of executive function. Cognitive assessment was immediately followed by overnight polysomnography to record nocturnal hemoglobin oxygen saturation and sleep arousals. Decreases in hemoglobin oxygen saturation and/or increased sleep arousals were associated with reduced performance on cognitive assessment. Nocturnal hemoglobin oxygen desaturation and sleep fragmentation may be a contributing factor to executive dysfunction in SCA. (JINS, 2012, 18, 168–173)

Summary

Background and objective: The best place for the electrode of transcutaneous measurement of oxygen tension (tcPO2) and carbon dioxide tension (tcPCO2) during general anaesthesia was investigated in three different locations. Methods: Fifteen patients for major abdominal surgery in the supine position were studied. The electrode of the TCM4™ (Radiometer, Copenhagen, Denmark) was put on the chest, upper arm or forearm. TcPO2, tcPCO2, end-tidal carbon dioxide tension (etCO2), percutaneous oxygen saturation (SaO2), arterial oxygen tension (PaO2 ) and arterial carbon dioxide tension (PaCO2) were simultaneously measured at four different etCO2 concentrations and inhaled oxygen percentages and the location of the electrode was changed to other places to repeat the same measurement. In total, 12 measurements for each patient and 60 measurements for each place were performed. Results: TcPO2 correlated better than SaO2 (R2 = 0.58) with PaO2 (R2 = 0.76), and tcPCO2 correlated well with PaCO2 (R2 = 0.76) and etCO2 (R2 = 0.74) when the electrode was put on the chest, while not on the upper arm or forearm (R2 < 0.5). However, limits of agreement were too big to use tcPO2 (bias, −67.9; limits of agreement, 16.5, −152.3) and tcPCO2 (bias, −0.47; limits of agreement, 8.7, −9.64) as surrogate measures of PaO2 and PaCO2, respectively even when the electrode was put on the chest. Conclusions: When the electrode was put on the chest, tcPO2 and tcPCO2 might be available as non-invasive monitors of oxygenation and CO2 status during general anaesthesia, while the absolute values were not interchangeable with PaO2 and PaCO2, respectively.

As a result of a previous audit on the management of sleep apnoea hypopnoea syndrome (SAHS) which showed long waiting times that were primarily due to unnecessary interspecialty referrals, a change in practice was adopted. All referrals are now sent a questionnaire about symptoms suggestive of SAHS, the Epworth Sleepiness Scale score and their body mass index (BMI) which when returned are categorized into having a high, intermediate or low risk of SAHS. Those patients with a high probability have home overnight oximetry and those with intermediate probability have video oximetry. Those with a low probability are referred directly to ENT. We audited the first 100 patients referred. All were General Practitioner referrals to either ENT or respiratory medicine. Only two patients had a low probability score and were seen directly in ENT. Following sleep study analysis, 10 patients were referred directly to ENT with no respiratory medicine follow-up and nine were discharged back to the General Practitioner with no apnoea or snoring. Eighty-one patients were followed up by respiratory medicine. Of these, 49 received a trial of nasal continuous positive airway pressure (nCPAP) and six were referred to ENT. Therefore the majority justified an investigation to exclude SAHS in the first instance and an unnecessary initial ENT appointment was avoided. We have reduced the average waiting times to sleep study by approximately 90 days and to nCPAP trial by 32 days, mostly due to decreased delays in interspecialty referrrals. We have also demonstrated a greater than 50 per cent reduction in ENT clinic visits, a small increase in the number of sleep studies but no increase in respiratory clinic workload.

We report our experience with 199 patients requiring admission with a diagnosis of croup over an 18 month period. The value of using pulse oximetry to monitor these children was critically examined. Twenty-nine patients with clinically significant stridor were monitored for an average of 12 hours. There was poor correlation of clinical status and respiratory rate with hypoxia as shown by the technique, with frequent dips in oxygen saturation being caused by technical problems such as movement artefact. Pulse oximetry is a useful adjunct to the clinical assessment of croup, but cannot be relied upon solely for monitoring these labile patients.