Biomedical subjects
Publications and source records attributed to A Mackersie.
A case of unexpected difficult laryngoscopy in a patient with gross hydrocephalus and generalized hypertonus is described. The 30-month-old girl had no antecedent history of such difficulty, having had two recent uneventful anaesthetics. We suggest that the reason for our inability to open the patient's mouth was a result of contracture of the temporalis muscle. The patient was managed using a laryngeal mask airway with controlled ventilation.
BACKGROUND: Use of the sitting position for neurosurgery is controversial. The main concern is the risk of venous air embolus (VAE) and its sequelae. METHODS: The paediatric neurosurgeons at our institution routinely use the sitting position for posterior fossa and pineal surgery, and a retrospective audit of the incidence of VAE from 1982 to 1998 has been performed. RESULTS: Venous air embolism, defined as a fall in end-tidal carbon dioxide pressure >0.4 kPa, was detected in 38 of 407 operations (9.3%). A fall in systolic arterial pressure >10% accompanied the VAE in nine out of 43 episodes (20.9%); this represents 2% of all operations. All VAE episodes responded promptly to treatment and there was no perioperative morbidity or mortality directly attributed to it. CONCLUSIONS: This is the largest study of the incidence of VAE in children undergoing neurosurgery. Our results suggest that the sitting position can be used safely for neurosurgery in children.
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BACKGROUND: This study compared the respiratory effects of sevoflurane with those of halothane in anesthetized infants and young children. METHODS: Infants were randomized to receive 1 minimum alveolar concentration (MAC) halothane or sevoflurane in a mixture of nitrous oxide and oxygen. Anesthetic management included the use of a laryngeal mask. Flow, airway pressure, and the end-tidal carbon dioxide pressure (PETCO2) were measured during spontaneous ventilation and airway occlusions. Respiratory inductive plethysmography was used to assess chest wall motion. RESULTS: Measurements were obtained in 30 infants and young children (mean (SD) age, 14.5 (5.9) months), 15 of whom received sevoflurane and 15 received halothane. Some respiratory depression, as indicated by a PETCO2 of 45 mmHg (6 kPa), was present in both groups. Minute ventilation and respiratory frequency were significantly lower during sevoflurane than halothane anesthesia (4.5 compared with 5.4 (1/ m2)/min, and 37.5 compared with 46.7 breaths/min, respectively, P < 0.05). There was no difference in respiratory drive, but the shape of the flow waveform differed according to anesthetic agent, with peak inspiratory flow reached later, and peak expiratory flow reached earlier, in the sevoflurane group. There was also significantly less thoracoabdominal asynchrony during sevoflurane anesthesia. CONCLUSIONS: Minute ventilation and respiratory frequency were lower in infants during 1 MAC sevoflurane in nitrous oxide than during halothane anesthesia. However, these differences may not be clinically relevant at these concentrations, given the modest increase in PETCO2. Differences in parameters of breath timing and shape between sevoflurane and halothane suggest different effects of these anesthetic agents on ventilatory control.
The aim of this study was to compare tidal volume (VT) derived from the Qualitative Diagnostic Calibration (QDC) method (VT,QDC) with measurements from pneumotachography (VT,PN,T) in anaesthetized infants. Measurements were made during spontaneous (SV) and intermittent positive pressure (IPPV) ventilation, sighs and airway occlusions. The VT,DIF was the difference between VT,QDC and VT,PNT (%VT). The contribution of the ribcage (rc) to VT,QDC (%rc) and the thoracoabdominal phase lag were also derived. Twenty-eight infants, mean (SD) age 14.0 (6.2) months were studied. VT,QDC represented VT,PNT most closely when > or = 20 breaths were analysed. There was close agreement during SV immediately after the calibration period (95% limits of agreement (LA; QDC - PNT) -23, 3.0%). The 95% LA increased to -9.6, 10.2% after 10 min. Accuracy diminished during IPPV (95% LA -38, 31%), and sighs. During airway occlusions, when VT,PNT was zero, the 95% LA were -63, 4.1 mL x kg(-1). Mean phase lag was 36 and 2%, respectively, during SV and IPPV (p<0.05). The %rc appeared to be overestimated, being in excess of 50% in infants under 12 months. The Qualitative Diagnostic Calibration method used to estimate tidal volume in anaesthetized infants was limited by the need to analyse > or = 20 breaths and by a loss of within-subject accuracy if measurement conditions or pattern of breathing changed.
The induction characteristics of sevoflurane and halothane were compared in 81 children aged 6 months to 6 years. The mean time taken to achieve loss of eyelash reflex was significantly shorter with sevoflurane than with halothane (sevoflurane, mean time (SD) 1 min 41 s (35 s), halothane, mean time (SD) 2 min 17 s (43 s), t = 4.11, p = < 0.01). The mean time taken to complete induction (to achieve steady spontaneous ventilation and small pupils with central gaze) was also shorter in children induced with sevoflurane (sevoflurane, mean time (SD) 3 min 58 s (1 min 8 s), halothane, mean time (SD) 4 min 50 s, (1 min 27 s), t = 2.29, p = 0.027). Effects on heart rate, blood pressure and oxygen saturation during induction were similar for both agents. There were no major complications during induction with either halothane or sevoflurane.
The recovery characteristics of sevoflurane and halothane anaesthesia were compared in 40 children aged 6 months to 6 years undergoing day case surgery. The mean time taken to open eyes after surgery had ended was appreciably and significantly shorter after sevoflurane than after halothane (sevoflurane, mean time (SD) 7 min 52 s (5 min 46 s), halothane, mean time (SD) 15 min 50 s (9 min 2 s), t = 3.32, p = 0.002). The time taken to be ready for discharge from the recovery unit to the ward was also significantly shorter after sevoflurane than after halothane (sevoflurane, mean time (SD) 12 min 46 s (4 min 11 s), halothane, mean time (SD) 19 min 13 s (9 min 48 s), t = 2.7, p < 0.01). However, more children were in pain and given analgesia after sevoflurane (p < 0.01) and the mean time to reach the criteria for discharge home was similar in both groups (sevoflurane, mean time (SD) 2 h 9 min (17 min), halothane, mean time (SD) 2 h 4 min (8 min)). There were no major complications in either group.
We describe the case of a 6-month-old achondroplastic baby who underwent foramen magnum decompression to relieve congenital cervical cord compression. During the procedure, acute hypotension occurred secondary to cord compression, and following attempts to alleviate this, torrential haemorrhage ensued and air was entrained into the circulation through large venous channels in the surgical field. This resulted in an asystolic cardiac arrest from which the baby was resuscitated whilst remaining in the prone position. Haemorrhage remained difficult to control and a second episode of air embolism occurred 5 min later leading to a profound bradycardia and hypotension again requiring full cardiorespiratory resuscitation in the prone position. In total, 11 min elapsed before an adequate spontaneous cardiac output was re-established. The procedure was abandoned and the patient transferred to the intensive care unit for postoperative management. An electroencephalogram performed after 24 h was reported as normal, and clinically the child made a full neurological recovery.
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During the five year period December 1980 to November 1985, 106 infants with hypertrophic pyloric stenosis were treated. There were no operative deaths, but two late deaths occurred from associated abnormalities. The combination of preoperative rehydration, skilled anaesthesia, and the use of the Fredet-Ramstedt operation (pyloromyotomy) have virtually eliminated mortality from uncomplicated infantile hypertrophic pyloric stenosis. The most common complications were gastro-oesophageal reflux in 11 (11%), perforation of the duodenal fornix in nine (8%), and wound infection in five (5%); no wound dehisced.
This is a report of ten patients in whom the esophagus is replaced by the whole stomach brought through the chest. It was used for children with long gap or previously failed esophageal atresia repair. It documents complications (anastomotic leak and stricture) and morbidity, and highlights precautions that must be taken.