Association of Anaesthetists guidelines: cell salvage for peri-operative blood conservation 2018.

The use of cell salvage is recommended when it can be expected to reduce the likelihood of allogeneic (donor) red cell transfusion and/or severe postoperative anaemia. We support and encourage a continued increase in the appropriate use of peri-operative cell salvage and we recommend that it should be available for immediate use 24 h a day in any hospital undertaking surgery where blood loss is a recognised potential complication (other than minor/day case procedures).

A mass spectrometry method for the determination of the species of origin of gelatine in foods and pharmaceutical products.

Gelatine is a component of a wide range of foods. It is manufactured as a by-product of the meat industry from bone and hide, mainly from bovine and porcine sources. Accurate food labelling enables consumers to make informed decisions about the food they buy. Since labelling currently relies heavily on due diligence involving a paper trail, there could be benefits in developing a reliable test method for the consumer industries in terms of the species origin of gelatine. We present a method to determine the species origin of gelatines by peptide mass spectrometry methods. An evaluative comparison is also made with ELISA and PCR technologies. Commercial gelatines were found to contain undeclared species. Furthermore, undeclared bovine peptides were observed in commercial injection matrices. This analytical method could therefore support the food industry in terms of determining the species authenticity of gelatine in foods.

Selected reaction monitoring method to determine the species origin of blood-based binding agents in meats: a collaborative study.

Binding products or food 'glues' are used throughout the food industry to increase the meat use rate or to augment economic efficiency. Some of these binders contain thrombin from bovine and porcine blood. The European parliament has recently banned thrombin-based additives and labelling legislation governs their use in the US. A mass spectrometry screening method is available to detect the addition of thrombin agents to foods as there is a need to protect consumers and to avoid misleading trade practices. We report the details of an inter-laboratory trial to determine the transferability of this method to operators in various food testing laboratories, each using a different triple quadrupole mass spectrometer design. The trial was successful with the species origin of the binding agent contained in each of the 43 test materials being correctly reported by the participants. This is consistent with a false positive and false negative rate of 0%. This is the first collaborative study, as far as we are aware, which involves a liquid chromatography mass spectrometry (LC-MS/MS) application to approach a food authenticity issue.

Scrapie infection alters the distribution of plasma metabolites in diseased Cheviot sheep indicating a change in energy metabolism.

Nuclear magnetic resonance (NMR) spectroscopy has been used to profile the metabolic status of plasma from; sheep showing clinical signs of scrapie, those known to be infected with scrapie but yet to show clinical signs, and control animals. The NMR measurements have shown that energy metabolism in scrapie infected animals is altered before the onset of clinical symptoms. These metabolic changes may provide the foundation for a pre-clinical diagnostic test for scrapie in sheep.

Tannin interactions with a full-length human salivary proline-rich protein display a stronger affinity than with single proline-rich repeats.

The protein IB5 has been purified from human parotid saliva. This protein contains several repeats of a short proline-rich sequence. Dissociation constants have been measured at several discrete binding sites using 1H-NMR for the hydrolysable tannins (polyphenols) beta-1,3,6-tri-O-galloyl-D-glucopyranose, beta-1,2,4,6-tetra-O-galloyl-D-glucopyranose and beta-1,2,3,4,6-penta-O-galloyl-D-glucopyranose and the condensed proanthocyanidin (--)-epicatechin. The dissociation constants for trigalloyl glucose and pentagalloyl glucose were 15 X 10(-5) and 1.7 X 10(-5) M, respectively, which are 115 and 1660 times stronger than those previously measured under the same conditions for a single repeat of a mouse salivary proline-rich protein. The increase in affinity is ascribed to intramolecular secondary interactions, which are strengthened by the rigidity of the interacting molecules.

Effect of diabetes mellitus on the cardiovascular responses to induction of anaesthesia and tracheal intubation.

We have compared cardiovascular responses to induction of anaesthesia and to tracheal intubation after propofol 2.5 mg kg-1 and pancuronium 0.1 mg kg-1 in 10 diabetic and 10 matched, non-diabetic (control) ASA I patients. Anaesthesia was maintained with 0.8% enflurane and 50% nitrous oxide in oxygen, with assisted ventilation. The trachea was intubated 3 min after induction of anaesthesia. All 10 diabetic patients (but no controls) had abnormal autonomic function when tested on the day before surgery. There was no difference between the two groups in the pre-induction cardiovascular state. Mean arterial pressure and vascular resistance decreased after induction in each group (P < 0.05). Heart rate increased (P < 0.01) and cardiac index was sustained in the control group, but in the diabetic group heart rate did not change and cardiac index decreased (P < 0.01). There was an earlier decrease in stroke index in the diabetic group (2 min) compared with the controls (5 min). After tracheal intubation, heart rate and cardiac index in the control group and cardiac index in the diabetic group remained unchanged. However, there was a greater increase in heart rate, mean arterial pressure and vascular resistance in the diabetic group compared with the controls after tracheal intubation (P < 0.05). The exaggerated pressor response to tracheal intubation, in the diabetic patients, may reflect autonomic dysfunction.

Timing of surgery in congenital diaphragmatic hernia. Low mortality after pre-operative stabilisation.

Eighty-six consecutive patients with congenital diaphragmatic hernia presenting within 6 hours of birth to a regional neonatal surgical unit were reviewed. Patients were managed under a policy of delayed surgery which has evolved during the 6-year study period. Overall survival (to leave hospital) was 70.9%. There were only seven postoperative deaths (10.3% of operations). Analysis of the 25 deaths in the light of postmortem findings and published exclusion criteria indicates that the availability of extracorporeal membrane oxygenation would have made little difference to overall survival.

Anaesthesia and brain damage in the newborn.

Eighty newborn babies were studied by ultrasound brain scan before and after their first general anaesthetic. Periventricular haemorrhage or ischaemia occurred in 23 patients (29%) and affected both term and premature babies. Four new lesions developed but only three of 19 existing lesions deteriorated. The very premature (less than 33 weeks gestation) were most at risk (four of eight deteriorated). Deterioration or development of lesions occurred only in very ill babies with known risk factors. Anaesthesia did not appear to be implicated in any case.

Atracurium overdose in a small infant.

An error in setting a syringe driver caused a 2.75 kg infant to receive 37 mg atracurium over 75 minutes. Clinically full recovery of muscle power had returned spontaneously 135 minutes after the infusion was stopped. The child suffered no ill effects. Assay of blood and urine for atracurium and laudanosine confirmed rapid clearance of the drug.

Blood pressure response of neonates to tracheal intubation.

Blood pressure and pulse rate responses to tracheal intubation were studied by oscillotonometric technique in 45 term neonates and 15 infants of similar postconceptual age. No hypertensive response was found in neonates intubated awake and pressures did not differ from those of babies intubated under halothane or after thiopentone and muscle relaxant. The infants did however show a significant increase in systolic and diastolic pressures which indicates that this response may develop after the first month of life.

Neutrophil mobility during anaesthesia in children. A trial of ascorbate premedication.

In 20 healthy children undergoing elective surgery, mobility of neutrophils, both unstimulated and stimulated by endotoxin, was studied using a millipore filter system with microscopic determination of leading front migration. Paired samples were incubated with 10(-2) mol l-1 calcium ascorbate and ten children also received 10 mg kg-1 ascorbic acid before premedication. Stimulation of mobility was reduced after the opioid premedication (P less than 0.05) in the ascorbate group only, but not significantly during anaesthesia and surgery. A few individuals showed persisting abnormally low values. No effect of ascorbate in vivo or in vitro was demonstrated. There were no infections.

Ventilation, ventilatory carbon dioxide and hormonal response during halothane anaesthesia and surgery in children after midazolam premedication.

In 14 intubated, spontaneously breathing children with body weight (bw) ranging from 8.3 to 25.6 kg, the influence of midazolam 0.1 mg kg-1 i.m. (group M0.1, n = 7) and 0.2 mg kg-1 i.m. (group M0.2, n = 7) as premedication, on sedation, ventilation, ventilatory response to carbon dioxide and hormonal stress response was studied in connection with minor surgical procedures during halothane anaesthesia. The concentrations of catecholamines, ACTH and cortisol were measured immediately after induction, during undisturbed anaesthesia, during surgery and 15 min after the end of the surgical procedure. Sedation was better and plasma catecholamine concentrations during undisturbed anaesthesia were less in children receiving the larger dose of midazolam. During surgery and in recovery there were no differences in hormone concentrations. In recovery, the concentrations of all hormones were significantly greater compared with during undisturbed anaesthesia. During surgery, VE and respiratory rate were somewhat lower in group M0.2 while E' CO2 was similar. A dose dependent depression of the response to carbon dioxide was found. However, clinically, the ventilatory response to carbon dioxide after surgery was considered to be adequate in both groups.

Ventilation and ventilatory CO2 response in children during halothane anaesthesia after non-opioid (midazolam) and opioid (papaveretum) premedication.

The influence of non-opioid (NO) and opioid (O) premedication on ventilation and ventilatory CO2 response was studied in 18 spontaneously breathing children during halothane anaesthesia. Eight patients in Group NO and 10 in Group O were comparable in age, body weight and type of surgery performed. The sedative effect was evaluated and measurements by pneumotachography and in-line capnography were made immediately after induction of sleep, just before the start of surgery, during surgery and after surgery both before and after 3 min of about 2% CO2 inhalation. Immediately after induction the mean value (+/- s.e. mean) of end-tidal CO2 concentration (ETCO2) was 4.86 +/- 0.21% in Group NO and 5.28 +/- 0.22% in Group O. Before and during surgery, minute ventilation (VE) was higher in Group NO (P less than 0.05) mainly due to higher respiratory rates. ETCO2 was similar in the two groups before, during and after surgery. The ratio of VE to CO2 elimination (VCO2) and of dead space (VD) to tidal volume (VT) was higher in Group NO, but ventilatory response to CO2 inhalation immediately before the postoperative period was similar in both groups. It was concluded that opioid premedication resulted in more efficient ventilation during anaesthesia and surgery, and that CO2 response at the end of surgery was maintained in both groups.

Ventilatory responses to inspiratory mechanical loads in spontaneously breathing children during halothane anaesthesia.

The effect of the addition of two different resistive loads (producing 23 and 36 cmH2O (2.26 and 3.53 kPa) 1(-1) s-1, respectively, at 71 min-1) on minute volume, tidal volume, respiratory rate, duration of inspiration and inspiratory drive was studied in six intubated children during nitrous oxide, oxygen and halothane anaesthesia. With both resistive loads, tidal volume was initially reduced in all patients except one, the reduction being greater in older children. Tidal volume returned to baseline values within 3-5 min in most cases, and a transient increase was seen on removal of the load. Changes in inspiratory drive were also most marked in older children. End-tidal carbon dioxide concentration rose by 0.5% when the higher resistance was used. Respiratory rate and duration of inspiration were unchanged, suggesting the absence of a respiratory off-switch-reflex mechanism directly mediated by stretch receptors within the airways or lungs. Ventilatory compensation occurring after 3-5 min may have resulted from chemical stimulation and/or from reflexes from joint receptors and respiratory muscle spindles.

Ventilatory responses to rebreathing and carbon dioxide inhalation during anaesthesia in children.

In 12 spontaneously breathing intubated children (9.3-25 kg), ventilatory responses to rebreathing and to the inhalation of carbon dioxide (CO2) were investigated during halothane anaesthesia for minor surgical procedures. A T-piece (Mapleson F system) was used, modified by the insertion of a pneumotachograph and a paediatric airway adaptor of an in-line capnograph in the patient limb. Exhaled gas was collected for determination of expired CO2 content. Measurements were made when the fresh gas flow (FGF) was at the borderline for rebreathing (FGFr) and during 10 min with a mean FGF 44% lower, producing a maximal inspired CO2 (ICO2 max) (%) of 1.45 +/- 0.38% (mean +/- 1 SD). Measurements were repeated 5 min after returning to a flow exceeding FGFr and then during CO2 inhalation for 10 min after the addition of 1.24 +/- 0.32% CO2 (mean +/- 1 SD) to this flow. During both rebreathing and CO2 inhalation end-tidal CO2 (E'CO2) was unchanged and VE did not increase significantly (18%), but during CO2 inhalation alveolar ventilation increased (P less than 0.05), indicating an adequate and intact response to this level of CO2 inhalation. Estimations of ICO2 max could be made from the expression: ICO2 max (%) = -0.7 X FGF/VE + 2.5 and FGF to minute ventilation (VE) ratios lower than 1 were found to produce ICO2 max of 1.8% or higher. Such low FGF are likely to result in rebreathing within the alveolar ventilation and are thus of clinical importance. We believe that to increase the margin of safety in anaesthetized spontaneously breathing children, FGF of at least 1.5 to 2 times VE should be used.

Endocrine response to surgery in children after premedication with midazolam or papaveretum.

The effect of two premedications on the sympatho-adrenal and endocrine stress-response to minor surgery under halothane anaesthesia was investigated in 16 children. One group (n = 9) was premedicated with midazolam, 0.1 mg kg-1, and atropine 0.2-0.4 mg i.m. The other group (n = 7) received papaveretum 0.4 mg kg-1 and hyoscine 0.008 mg kg-1 i.m. Plasma concentrations of catecholamines, ACTH and cortisol were measured during undisturbed anaesthesia, during surgery and 15 min post-operatively. There were no differences in catecholamine concentrations between the groups. Prior to surgery, plasma ACTH was significantly lower (P less than 0.05) in the papaveretum group. During surgery, plasma cortisol and plasma ACTH were significantly lower after papaveretum premedication. Post-operatively there were no differences. End-tidal CO2 concentrations were similar in the two groups. It was concluded that the endocrine stress-response immediately after induction of anaesthesia and during surgery was lower after papaveretum than after midazolam premedication.

Ventilatory responses of children to changes in deadspace volume. Studies using the T-piece (Mapleson F) system.

Twelve patients (4.3-25.3 kg) undergoing minor surgical procedures were investigated during halothane anaesthesia with spontaneous breathing through a modified T-piece (Mapleson F) with an apparatus deadspace that could be changed from 2 ml (VDsmall) to 16 ml (VDlarge). Immediately following the switch from VDsmall to Vlarge ETCO2 (mean +/- 1 SD) increased from 6.89 +/- 1.09% to 7.61 +/- 1.14% (ns) then gradually decreased during a 10-min period. The initial plateau of FlCO2 (mean +/- 1 SD) with VDlarge was 0.74 +/- 0.34%, but gradually decreased to 0.63 +/- 0.25% after 10 min. This was achieved by an increase in VE (P less than 0.05 by 2 min). After 10 min VE had increased by more than 40% (P less than 0.01) as a result of an increase in VT (mean +/- 1 SD) of 14.6 +/- 6.5 ml. After 10 min of VDlarge ventilation, VA and VCO2 were maintained at VDsmall values. The adequate ventilatory response to the large deadspace was seen in all patients, but the ventilatory efficiency, as judged by VD/VT and VENCO2 ratios, was reduced significantly in the children weighing less than 10 kg.

Comparison of morbidity between inpatients and outpatients following gynaecological laparoscopy.

Fifty-one inpatients and 58 outpatients undergoing elective gynaecological laparoscopy under general anaesthesia were investigated for post-operation morbidity by means of questionnaires. A high incidence of morbidity was found in both groups extending into the second day, with no marked difference between the two groups.

Ventilatory response during halothane and enflurane anaesthesia.

In six children with body weights between 11.4-18.7 kg, minute ventilation, tidal volume, respiratory rate, end-tidal CO2 concentration and CO2 elimination were measured during both CO2 free breathing and CO2 breathing due to low fresh gas flows (maximal inspired CO2 about 2%) or the addition of CO2 from Rotameters (mean inspired CO2 about 1.5%) during both halothane and enflurane anaesthesia. All patients were undergoing hypospadias repair, received caudal analgesia prior to surgery and were intubated and allowed to breathe halothane/enflurane in O2/N2O (FIO2 0.5) spontaneously through a modified T-piece system (Mapleson F). End-tidal CO2 concentrations were similar with both agents during CO2-free breathing and did not increase during CO2 breathing because of increased minute ventilation, of the same magnitude with both agents, which was achieved by larger tidal volumes. Respiratory rates were unchanged. No differences were found between halothane and enflurane at the light levels of general anaesthesia made possible by combination with caudal block.

Accuracy of prediction of fresh gas flow requirements during spontaneous breathing with the T-piece.

In 40 spontaneously breathing children (7.3-47.9 kg) anaesthetized with halothane for minor surgical procedures the fresh gas flow (FGF) at onset of rebreathing (FGFr) was determined and end-tidal CO2 concentration (ETCO2), minute ventilation (VE), tidal volume (VT) and respiratory rates (f) were registered. The accuracy of predicting the FGFr from 2 X VE, 3 X VE and from two formulae (FGF = 15 X kg X f and FGF = 3 X (1000 + 100 X kg) was evaluated. FGFr ranged from 3.5 to 10 l min-1. FGF calculated from 2 X VE was inadequate. Calculations of FGF from 3 X VE and with the two formulae gave an adequate FGF in more than 80% of the children. No serious under-estimations were found. In a few cases FGF level was overestimated by more than 150%. It is suggested that when the theoretical calculation of FGF results in flow rates well over 10 l min-1 an upper flow rate limit of 10 l min-1 may be used in children weighing less than 30 kg since no child required a FGF over this rate.