We investigated the cricoid pressure technique of 135 anaesthetic assistants attending the annual conference of the British Association of Operating Department Assistants in May 1997. Their knowledge and training were assessed using a structured interview. Technique was assessed using a simulator measuring applied force during sham cricoid pressure. Our additional aims were to see whether a knowledge of the required force and practical training in the application of a target force would affect performance. Our results highlight a lack of knowledge relating to the manoeuvre. Only about one-third of subjects could quote an appropriate force and fewer than half could give a single contraindication to its use. Very few subjects had been trained on a model before practising the technique on a patient. Technique was poor and we observed a large variation in the force actually applied. Performance, as assessed by the variability of forces applied and proportion of subjects applying force within our target range (30-44 N), was improved markedly by providing simple instruction about the required force in an understandable form. Performance was further improved by practical training in the application of target force on a simulator.

Anesthesia, General↗

PubMed1998

An epidural training simulator.

Explore the source record for details and available documents.

Letter↗

PubMed1998

Cricoid pressure: can protective force be sustained?

We studied six operating department assistants performing simulated cricoid pressure on a model of the larynx with the arm either flexed to 90 degrees (flexed position) or fully extended with the elbow locked (extended position). Subjects were asked to maintain forces of 20, 30 and 40 Newtons (N) for a target time of 20 min. Subjects rated pain during each assessment on a four-point verbal rating scale (VRS): 1 = uncomfortable; 2 = hurting; 3 = hurting a lot; and 4 = agony. Times to onset of pain were short and mean times to VRS 3 at each force studied were: 40 N, flexed position 2.3 min, extended position 5.4 min; 30 N, flexed position 4.0 min, extended position 7.5 min; and 20 N, flexed position 9.6 min, extended position 12.5 min. None of our subjects was able to sustain 40 N for the target time. Mean times to release at 40 N were: flexed position 3.7 min, extended position 7.6 min. Only one subject was able to sustain 30 N and then only using the extended arm. Mean times to release at 30 N were: flexed position 6.4 min, extended position (five subjects) 10.8 min. Two subjects with the arm flexed and five with the arm extended achieved the target time at 20 N. Mean times to release at 20 N were: flexed position (four subjects) 13.2 min, extended position (one subject) 14.6 min. Use of the extended arm consistently prolonged times to pain and fatigue. These findings are relevant to the management of cricoid pressure during failed intubation.

Arm↗

PubMed1989

Characterization and autoprocessing of precursor and mature forms of human immunodeficiency virus type 1 (HIV 1) protease purified from Escherichia coli.

A recombinant plasmid encompassing the human immunodeficiency virus type 1 (HIV 1) protease coding sequence and flanking regions (Ala-13 to Gly-185 of the pol open reading frame) has been expressed in two distinct strains of Escherichia coli, AR58 and AR68. In the first strain, AR58, the primary translation product, a 25 kilodalton (kDa) precursor protein, is short-lived and rapidly processes itself to the 11 kDa mature protease in vivo. In the second strain, AR68, the 25 kDa species is only partially processed, and it, a 13 kDa intermediate, and the mature 11 kDa enzyme accumulate at a ratio of 3:4.5:2.5, respectively. The 11 kDa mature protease from AR58 and the 25 kDa precursor from AR68 have been purified to homogeneity. The yield of 11 kDa enzyme from AR58 is approximately 0.02 mg/g wet weight of E. coli cell pellet. The protease has both the expected NH2- and COOH-terminal sequences. The yield of 25 kDa enzyme from AR68 is approximately 0.1 mg/g wet weight of E. coli cell pellet. In vitro, the 25 kDa precursor enzyme rapidly (t1/2 approximately equal to 9 min) processes itself into a species with a mass of approximately 13 kDa and a species with a mass of approximately 11 kDa. Both of these latter species can be separated by RP-HPLC, have the NH2-terminal sequence expected for the mature protease, and are active. The 11 kDa enzyme from AR58 comigrates with the 11 kDa enzyme from AR68 on RP-HPLC and SDS polyacrylamide gel electrophoresis. On extended incubation at 4 degrees C at either neutral or acidic pH all species of the protein exhibit further autodegradation at defined sequences. The availability of the mature, 11 kDa enzyme and the 25 kDa precursor will allow biochemical and physical studies on this critical viral enzyme.

Amino Acid Sequence↗

PubMed1975

Lichen striatus: a model for the histologic spectrum of lichenoid reactions.

Three phases of lichenoid reactions are defined: 1) the primary phase, 2) the established phase; and 3) the senescent phase. Lichen striatus is characterized by a primary pattern that may be apparent in the epidermis, the hair follicles, and rarely the sweat glands and ducts. Focal areas of established lichenoid reaction, that are indistinguishable from lichen planus, are common. They usually are confined to the tips of elongated rete ridges. Established lichenoid patterns are occasionally present in hair follicles and are indistinguishable from those seen in lichen planopilaris. Eccrine hidradenitis, a feature of lichen striatus, is rarely seen in lichen planus. Lichen planus may be an adaptive epidermal response to a clone of aggressive lymphocytes and, as such, may be a manifestation of auto-immunity. In lichen striatus, senescent lichenoid patterns resemble those seen in lichen nitidus.

Adolescent↗