Correspondence
77
Bacteraemia and insertion of laryngeal mask airways Manipulations within the oral cavity can produce a transient bacteraemia [I], which has significance as a risk factor in infective endocarditis. Transient bacteraemia following nasotracheal intubation has been reported to be 16% in 25 patients [2], whilst another study found that the incidence following tracheal intubation was 2% [3]. The Brain laryngeal mask airway (LMA) is the latest addition to the anaesthetist’s armamentarium for maintenance of an airway, and is introduced by a blind procedure that may produce unrecognised mucosal trauma. The LMA is not presented as a sterile package and whilst in position possibly lies in contact with a greater surface area, with a varied and more dense bacterial flora than would a tracheal tube. We carried out a randomised, prospective study comparing the incidence of bacteraemic episodes in three groups of patients who required maintenance of a n airway by means of oral or nasal tracheal tubes, or the LMA. Sixty patients were studied (I5 orotracheal, 15 nasotracheal, 30 LMA) The groups were standardised for age, sex and ASA grading. Subjects were routine hospital inpatients scheduled for elective procedures, with no evidence of existing infection or structural heart disease and who had not received any antibiotic therapy for 2 weeks before surgery admission or whilst in hospital. Portex disposable tracheal tubes were used. The red rubber nasal tubes and the LMAs were not in sterile packs but were autoclaved and kept in clean storage. Five ml of venous blood were collected immediately before induction and at I , 3 and 7 min after instrumentation. A quantitative method was used to determine bacteraemia. The 5 ml of venous blood was diluted in 15 ml of molten agar and allowed to solidify in each of two sterile petri dishes. Both plates were incubated at 3 7 T , one in an atmosphere of air with 5% CO,, the second in an anaerobic atmosphere. Plates were examined daily for growth, and colonies counted and subcultured for identification by standard methods [4]. Further identification of isolates was performed with API Staph and API Coryne (bio Merieux UK Ltd). Seven patients had a bacteraemia. Six grew either
Staphlococcus epidermidis or Micrococcus species. Four followed nasotracheal intubation and two introduction of LMAs. These represent contamination with skin flora, rather than a true bacteraemia following oropharyngeal manipulation. The level of bacteraemia was between 0.2 and 1.0 organisms per ml of blood. One patient had a bacteraemia with Corynebacterium hofmannii a t I , 3 and 7 rnin following tracheal intubation. Levels of bacteraemia were 1.4 organisms per ml blood at 1 rnin and 0.6 organisms per ml blood at 7 min. Our results show that in healthy patients the risk of inducing a significant bacteraemia with an anaesthetic manipulation is virtually nil. However, for patients potentially immunocompromised, an anaesthetic procedure per se can induce a significant and prolonged bacteraemia. The significant bacteraemic episode occurred in a patient with widespread carcinoma who possibly had an unrecognised pre-operative infection, which was exacerbated following intubation. It is important to know not only the incidence of bacteraemia, but also the identity of the organism involved and the duration of the bacteraemia. The incidence of bacteraemia is no more with a LMA than with either oral or nasal intubation. Queen Elizabeth Military Hospital, Woolwich SE18 4QH
J.M. STONE L.D. KARALLIEDDE M.L. CARTER N.S. CUMERLAND
References [I] EVERETT ED, HIRSCHMANN JV. Transient bacteraemia and endocarditis prophylaxis. A review. Medicine (Baltimore) 1977; 5 6 61-77. [2] BERRYFA, BLANKENBAKER WL, BALL CG. A comparison of bacteraemia occurring with nasotracheal and orotracheal intubation. Anesthesia and Analgesia 1973: 52: 873-6. [3] GERBER MA, GASTANADUY ZX, BUCKLEY JJ, KAPLAN EL. Risk of bacteraemia after endotracheal intubation for general anesthesia. Southern Medical Journal 1980: 7 3 1478-80. [4] COWANST, STEELKJ. Manual for ideniificaiion of medical bacreria, 2nd edn. Cambridge: Cambridge University Press, 1974.
Identical twins too Having just read the September issue of Anaesthesia and the letter on identical twins (Anaesthesia 1991; 4 6 800), imagine my delight at being presented with identical twin boys to anaesthetise the following day. The boys, aged 3 years, had an interesting past surgical history in that on the same day in 1988 they had cleft lip repairs and similarly in 1990 cleft palate repairs. Sadly the second operations were not successful and both patients now required further surgery on palatal fistulae. I, too, decided to alter my technique as a small clinical trial. The boys weighed 12.8 kg and 13.2 kg respectively and were otherwise well. Neither was premedicated apart from the application of EMLA cream 90 rnin before operation. Anaesthesia was induced and maintained in twin 1 by computer-controlled propofol infusion, tracheal intubation facilitated by suxamethonium and breathing spontaneously a mixture of oxygen and nitrous oxide. A 12.5 mg diclofenac suppository was inserted at the time of induction. Anaesthesia in twin 2 was induced with thiopentone and maintained by the patient breathing isoflurane in an oxygen, nitrous oxide mixture, again following tracheal tube insertion with suxamethonium. An intramuscular injection of codeine phosphate (1 mg.kg) was given at induction.
The operations were similar in length and performed by the same surgeon who infiltrated the operating sites with 0.25% bupivicaine and adrenaline. At the end of the procedure 100% oxygen was administered to both twins and their tracheas were extubated when they were fully awake. For the next 24 h the nursing staff kept excellent clinical records of the patients’ vital signs, including oxygen saturation, and allocated an hourly pain and sedation score according to a hospital protocol. Neither patient required further analgesia and appeared comfortable throughout. It was, however, very noticeable that twin 1 recovered more quickly and remained alert during the period of observation when compared to his brother. Prolonged sedation following cleft palate surgery is worrying and this little study allowed me to contrast two different anaesthetic techniques. The combination of propofol and diclofenac provided very satisfactory operating conditions and fast postoperative recovery and should be considered for surgery on the upper airway.
Royal Hospital f o r Sick Children, Glasgow G3 8SJ
W.A. MCFADZEAN
77
Bacteraemia and insertion of laryngeal mask airways Manipulations within the oral cavity can produce a transient bacteraemia [I], which has significance as a risk factor in infective endocarditis. Transient bacteraemia following nasotracheal intubation has been reported to be 16% in 25 patients [2], whilst another study found that the incidence following tracheal intubation was 2% [3]. The Brain laryngeal mask airway (LMA) is the latest addition to the anaesthetist’s armamentarium for maintenance of an airway, and is introduced by a blind procedure that may produce unrecognised mucosal trauma. The LMA is not presented as a sterile package and whilst in position possibly lies in contact with a greater surface area, with a varied and more dense bacterial flora than would a tracheal tube. We carried out a randomised, prospective study comparing the incidence of bacteraemic episodes in three groups of patients who required maintenance of a n airway by means of oral or nasal tracheal tubes, or the LMA. Sixty patients were studied (I5 orotracheal, 15 nasotracheal, 30 LMA) The groups were standardised for age, sex and ASA grading. Subjects were routine hospital inpatients scheduled for elective procedures, with no evidence of existing infection or structural heart disease and who had not received any antibiotic therapy for 2 weeks before surgery admission or whilst in hospital. Portex disposable tracheal tubes were used. The red rubber nasal tubes and the LMAs were not in sterile packs but were autoclaved and kept in clean storage. Five ml of venous blood were collected immediately before induction and at I , 3 and 7 min after instrumentation. A quantitative method was used to determine bacteraemia. The 5 ml of venous blood was diluted in 15 ml of molten agar and allowed to solidify in each of two sterile petri dishes. Both plates were incubated at 3 7 T , one in an atmosphere of air with 5% CO,, the second in an anaerobic atmosphere. Plates were examined daily for growth, and colonies counted and subcultured for identification by standard methods [4]. Further identification of isolates was performed with API Staph and API Coryne (bio Merieux UK Ltd). Seven patients had a bacteraemia. Six grew either
Staphlococcus epidermidis or Micrococcus species. Four followed nasotracheal intubation and two introduction of LMAs. These represent contamination with skin flora, rather than a true bacteraemia following oropharyngeal manipulation. The level of bacteraemia was between 0.2 and 1.0 organisms per ml of blood. One patient had a bacteraemia with Corynebacterium hofmannii a t I , 3 and 7 rnin following tracheal intubation. Levels of bacteraemia were 1.4 organisms per ml blood at 1 rnin and 0.6 organisms per ml blood at 7 min. Our results show that in healthy patients the risk of inducing a significant bacteraemia with an anaesthetic manipulation is virtually nil. However, for patients potentially immunocompromised, an anaesthetic procedure per se can induce a significant and prolonged bacteraemia. The significant bacteraemic episode occurred in a patient with widespread carcinoma who possibly had an unrecognised pre-operative infection, which was exacerbated following intubation. It is important to know not only the incidence of bacteraemia, but also the identity of the organism involved and the duration of the bacteraemia. The incidence of bacteraemia is no more with a LMA than with either oral or nasal intubation. Queen Elizabeth Military Hospital, Woolwich SE18 4QH
J.M. STONE L.D. KARALLIEDDE M.L. CARTER N.S. CUMERLAND
References [I] EVERETT ED, HIRSCHMANN JV. Transient bacteraemia and endocarditis prophylaxis. A review. Medicine (Baltimore) 1977; 5 6 61-77. [2] BERRYFA, BLANKENBAKER WL, BALL CG. A comparison of bacteraemia occurring with nasotracheal and orotracheal intubation. Anesthesia and Analgesia 1973: 52: 873-6. [3] GERBER MA, GASTANADUY ZX, BUCKLEY JJ, KAPLAN EL. Risk of bacteraemia after endotracheal intubation for general anesthesia. Southern Medical Journal 1980: 7 3 1478-80. [4] COWANST, STEELKJ. Manual for ideniificaiion of medical bacreria, 2nd edn. Cambridge: Cambridge University Press, 1974.
Identical twins too Having just read the September issue of Anaesthesia and the letter on identical twins (Anaesthesia 1991; 4 6 800), imagine my delight at being presented with identical twin boys to anaesthetise the following day. The boys, aged 3 years, had an interesting past surgical history in that on the same day in 1988 they had cleft lip repairs and similarly in 1990 cleft palate repairs. Sadly the second operations were not successful and both patients now required further surgery on palatal fistulae. I, too, decided to alter my technique as a small clinical trial. The boys weighed 12.8 kg and 13.2 kg respectively and were otherwise well. Neither was premedicated apart from the application of EMLA cream 90 rnin before operation. Anaesthesia was induced and maintained in twin 1 by computer-controlled propofol infusion, tracheal intubation facilitated by suxamethonium and breathing spontaneously a mixture of oxygen and nitrous oxide. A 12.5 mg diclofenac suppository was inserted at the time of induction. Anaesthesia in twin 2 was induced with thiopentone and maintained by the patient breathing isoflurane in an oxygen, nitrous oxide mixture, again following tracheal tube insertion with suxamethonium. An intramuscular injection of codeine phosphate (1 mg.kg) was given at induction.
The operations were similar in length and performed by the same surgeon who infiltrated the operating sites with 0.25% bupivicaine and adrenaline. At the end of the procedure 100% oxygen was administered to both twins and their tracheas were extubated when they were fully awake. For the next 24 h the nursing staff kept excellent clinical records of the patients’ vital signs, including oxygen saturation, and allocated an hourly pain and sedation score according to a hospital protocol. Neither patient required further analgesia and appeared comfortable throughout. It was, however, very noticeable that twin 1 recovered more quickly and remained alert during the period of observation when compared to his brother. Prolonged sedation following cleft palate surgery is worrying and this little study allowed me to contrast two different anaesthetic techniques. The combination of propofol and diclofenac provided very satisfactory operating conditions and fast postoperative recovery and should be considered for surgery on the upper airway.
Royal Hospital f o r Sick Children, Glasgow G3 8SJ
W.A. MCFADZEAN
