Outcome of repeat anaesthesia after investigation for perioperative anaphylaxis.

BACKGROUND: Perioperative anaphylaxis (POA) is infrequent, but remains an important and potentially life-threatening complication of general anaesthesia. The diagnostic uncertainty surrounding the investigation of anaesthetic allergy poses numerous challenges. We aimed to inform practice by auditing the outcomes of repeat anaesthesia, after an investigation for previous POA. METHODS: One-hundred and seventy-four subjects were investigated after suspected POA between December 2002 and August 2015. Outcome data were obtained for a total of 70 patients who underwent repeat anaesthesia after investigation in the drug-allergy clinic. RESULTS: Sixty-seven out of the 70 patients studied underwent repeat anaesthesia without further complications. Three individuals experienced a further episode of anaphylaxis. In two cases, incomplete referral information led to the offending drugs being omitted from initial testing. The third was found to have underlying systemic mastocytosis (SM). CONCLUSIONS: In our cohort, the incidence of repeat anaphylaxis after a comprehensive assessment in the drug-allergy clinic for suspected POA was 4%. Important risk factors include the completeness of referral information provided to the assessor and the role of exacerbating disorders, particularly SM.

Impact of national guidelines on reporting anaphylaxis during anaesthesia -- an outcome audit.

AIMS: Anaphylaxis during anaesthesia is a rare and potentially fatal event. Adequate reporting and investigation of anaphylaxis associated with anaesthesia results in improved patient safety and outcomes. Guidelines from the Association of Anaesthetists of Great Britain and Ireland (AAGBI) designed to improve this process were first issued in 1990 and updated in 1995, 2003 and 2008. In a setting where no formal guideline was previously in place, we compared the reporting and investigation of anaphylaxis in a large hospital before and after the introduction of the 2008 guideline. METHODS: A retrospective outcome audit was conducted to compare data from 12 patients referred from April 2006 to May 2008 prior to release of the 2008 AAGBI guidance, with 53 patients referred from 2008 until April 2011. Data were collected using the AAGBI Anaphylaxis Referral Form. RESULTS: There was an increase in the number of referrals for suspected anaphylaxis following implementation of the AAGBI guidance. The clinical features observed in patients were consistent with previous studies. There was improved documentation of referral to local and national databases. Most cases resulted in cancellation of surgery, and there were no patient deaths. A substantial increase in the number of patients with amoxicillin allergy was noted in the second time period, which was linked to a change in the local perioperative antibiotic policy. CONCLUSIONS: Implementation of the AAGBI guidelines locally in a large hospital in 2008 resulted in an improved awareness of the importance of reporting and investigation of suspected anaphylaxis under anaesthesia. This tool was implemented coincidentally with the change in hospital antibiotic prophylaxis and enabled the cases detected to be accurately recorded and investigated. This led to a change in the hospital antibiotic policy for surgical prophylaxis. Implementation of structured guidance from a national anaesthesia organisation enhances recognition of the clinical features of anaphylaxis, increases number and completeness of referrals and more thorough immunological investigation, leading to improved patient safety during anaesthesia.

Hypoxia, hypocapnia and spirometry at altitude.

1. Both hypoxia and hypocapnia can cause broncho-constriction in humans, and this could have a bearing on performance at high altitude or contribute to altitude sickness. We studied the relationship between spirometry, arterial oxygen saturation and end-tidal carbon dioxide (ETCO2) concentration in a group of healthy lowland adults during a stay at high altitude, and then evaluated the response to supplementary oxygen and administration of a beta 2 agonist. 2. We collected spirometric data from 51 members of the 1994 British Mount Everest Medical Expedition at sea level (barometric pressure 101.2-101.6 kPa) and at Mount Everest Base Camp in Nepal (altitude 5300 m, barometric pressure 53-54.7 kPa) using a pocket turbine spirometer. A total of 205 spirometric measurements were made on the 51 subjects during the first 6 days after arrival at Base Camp. Further measurements were made before and after inhalation of oxygen (n = 47) or a beta 2 agonist (n = 39). ETCO2 tensions were measured on the same day as spirometric measurements in 30 of these subjects. 3. In the first 6 days after arrival at 5300 m, lower oxygen saturations were associated with lower forced expiratory volume in 1 s (FEV1; P < 0.02) and forced vital capacity (FVC; P < 0.01), but not with peak expiratory flow (PEF). Administration of supplementary oxygen for 5 min increased oxygen saturation from a mean of 81%-94%, but there was no significant change in FEV1 or FVC, whilst PEF fell by 2.3% [P < 0.001; 95% confidence intervals (CI) -4 to -0.7%]. After salbutamol administration, there was no significant change in PEF, FEV1 or FVC in 35 non-asthmatic subjects. Mean ETCO2 at Everest Base Camp was 26 mmHg, and a low ETCO2 was weakly associated with a larger drop in FVC at altitude compared with sea level (r = 0.38, P < 0.05). There was no correlation between either ETCO2 or oxygen saturation and changes in FEV1 or PEF compared with sea-level values. 4. In this study, in normal subjects who were acclimatized to hypobaric hypoxia at an altitude of 5300 m, we found no evidence of hypoxic broncho-constriction. Individuals did not have lower PEF when they were more hypoxic, and neither PEF nor FEV1 were increased by either supplementary oxygen or salbutamol. FVC fell at altitude, and there was a greater fall in FVC for subjects with lower oxygen saturations and probably lower ETCO2.

Effect of altitude on spirometric parameters and the performance of peak flow meters.

BACKGROUND: Portable peak flow meters are used in clinical practice for measurement of peak expiratory flow (PEF) at many different altitudes throughout the world. Some PEF meters are affected by gas density. This study was undertaken to establish which type of meter is best for use above sea level and to determine changes in spirometric measurements at altitude. METHODS: The variable orifice mini-Wright peak flow meter was compared with the fixed orifice Micro Medical Microplus turbine microspirometer at sea level and at Everest Base Camp (5300 m). Fifty one members of the 1994 British Mount Everest Medical Expedition were studied (age range, 19-55). RESULTS: Mean forced vital capacity (FVC) fell by 5% and PEF rose by 25.5%. However, PEF recorded with the mini-Wright peak flow meter underestimated PEF by 31%, giving readings 6.6% below sea level values. FVC was lowest in the mornings and did not improve significantly with acclimatisation. Lower PEF values were observed on morning readings and were associated with higher acute mountain sickness scores, although the latter may reflect decreased effort in those with acute mountain sickness. There was no change in forced expiratory volume in one second (FEV1) at altitude when measured with the turbine microspirometer. CONCLUSIONS: The cause of the fall in FVC at 5300 m is unknown but may be attributed to changes in lung blood volume, interstitial lung oedema, or early airways closure. Variable orifice peak flow meters grossly underestimate PEF at altitude and fixed orifice devices are therefore preferable where accurate PEF measurements are required above sea level.

Anaesthesia for patients with trisomy 13 (Patau's syndrome).

Patau's syndrome (Trisomy 13) is usually fatal within the first six months of life. For the few survivors, corrective surgery is only undertaken if the child has a reasonable chance of living for some time. Hence the reports of anaesthesia and surgery in the literature are rare. We describe the anaesthesia for a repair of cleft lip and palate on two children who presented to our department.