PubMed Health⌕ Search

Biomedical subjects

F H Howorth

Publications and source records attributed to F H Howorth.

9 recordsLinked to original sources
PubMed1986

Prevention of airborne infections in operating rooms.

After controlled trial lasting five years in 19 hospitals in Europe, it was found that a substantially downward flow of microbiologically clean air, without any peripheral entrainment of contaminants, reduced wound sepsis more effectively than any other means. This reduction was at least 50% and when a body exhaust system was also used, the reduction in wound sepsis was at least 75%, whether antibiotics were used or not. With these unidirectional downward (laminar) flow systems, the side panels or drapes which were necessary to prevent peripheral entrainment of ambient air, contaminated by body emissions of those outside the clean zone, were found to be restrictive to surgeons and their procedures. An exponential (trumpet shaped) flow of microbiologically clean air was found to overcome these objections. From an overhead canopy, the air flows centrally downwards and then rapidly outwards, so peripheral entrainment cannot occur, consequently restrictive side panels are not required and so the system cannot be abused by leaving them off. Howorth Exflow clean zones for surgery are now in use in over 30 countries and when used in conjunction with the body exhaust and gowns for the members of the surgical team and the patient, it has been shown that zero cfu/3m is achievable in the air during surgery and that wound sepsis from the airborne route is eliminated without inconvenience to anyone in the operating theatre.

Air Conditioning↗
PubMed1985

Prevention of airborne infection during surgery.

Clinical trials carried out in Britain, Europe, and the United States have confirmed that between 80 and 90% of bacterial contaminants found in the wound after surgery come from colony forming units (cfu) present in the air of the operating theatre. When the numbers of cfu are reduced, there is a corresponding reduction in the incidence of would sepsis. The sources, concentration, and movement of airborne cfu during an operation are identified, and various ways of reducing their numbers are reviewed. Only reduction of cfu in the operating zone to less than 1/m3, by means of an exponentially curved flow of microbiologically clean air, together with a total body exhaust system worn by the members of the surgical team and the patient, provides aseptic conditions without imposing restrictions or changes in surgical procedure.

Air Microbiology↗
PubMed1980

Air flow patterns in the operating theatre.

Bacteria-carrying particles and exhaled anaesthetic gases are the two contaminants found in the air flow patterns of operating rooms. Their origin, direction and speed were illustrated by a motion picture using Schlieren photography and smoke tracers. Compared with a conventionally well air conditioned operating theatre, it was shown that a downward flow of clean air reduced the number of bacteria-carrying particles at the wound site by sixty times. The Exflow method of achieving this without the restriction of any side panels or floor obstruction was described. The total body exhaust worn by the surgical team was shown to reduce the bacteria count by a further eleven times. Clinical results show that when both these systems are used together, patient infection was reduced from 9 per cent to between 0.3 per cent and 0.5 per cent, even when no pre-operative antibiotics were used. Anaesthetic gas pollution was measured and shown to be generally 1000 p.p.m. at the head of the patient, in induction, operating and recovery rooms, also in dental and labour rooms. A high volume low pressure active scavenging system was described together with its various attachments including one specially for paediatric scavenging. Results showed a reduction of nitrous oxide pollution to between zero and 3 p.p.m. The economy and cost effectiveness of both these pollution control systems was shown to be good due to the removal of health hazards from patients and theatre staff.

Air Microbiology↗