Laminar airflow versus turbulent airflow in simulated total hip arthroplasty: measurements of colony-forming units, particles, and energy consumption.

BACKGROUND: The optimal type of ventilation in operating theatres for joint arthroplasty has been debated for decades. Recently, the World Health Organization changed its recommendations based on articles that have since been criticized. The economic and environmental impact of ventilation is also currently an important research topic but has not been well investigated. AIM: To compare how large, high-volume, laminar airflow (LAF) and turbulent airflow (TAF) ventilation systems perform during standardized simulated total hip arthroplasty (THA), as they pertain to colony-forming units (cfu), particle counts, and energy consumption. METHODS: Two identical operating theatres were used to perform simulated THA. The only difference was that one was equipped with LAF and the other with TAF. Cfu and particles were collected from key points in the operating theatre, and energy was measured for each simulation. Thirty-two simulations were done in total. FINDINGS: LAF had significantly reduced cfu and particle count when compared with TAF, at both 100% and 50% air influx. Furthermore, it was shown that lowering the air influx by 50% in LAF did not significantly affect cfu or particles, although reducing the fresh air influx from 100% to 50% significantly lowered the energy consumption. Most simulations in TAF did not meet the cleanroom requirements. CONCLUSION: Cfu were significantly lower in LAF at both 100% and 50% air influx. It is possible to reduce fresh air influx in LAF operating theatres by 50%, significantly reducing energy consumption, while still maintaining cfu and particle counts below the ISO classification threshold required for THA surgery.

Intranasal absorption of buprenorphine--in vivo bioavailability study in sheep.

The bioavailability of buprenorphine, HCl (BPP) in sheep after nasal administration of two formulations has been studied. 0.9 mg BPP in 150 microl was administered nasally and compared to 0.6 mg i.v. The test solutions were formulated with 30% polyethylene glycol 300 (PEG 300) and 5% dextrose, respectively. The bioavailability for PEG 300 was 70% (S.D.+/-27%, n=6), whereas the bioavailability for 5% dextrose was 89% (S.D.+/-23%, n=6). A two-compartment model with initial and terminal serum half-lives of 10 and 23 min, respectively, may describe the pharmacokinetics. The rate of absorption for both nasal formulations was very fast (t(max)=10 min). The C(max) was 37 ng/ml (S.D.+/-17) and 48 (S.D.+/-10) for PEG 300 and dextrose, respectively. No significant difference was found between the two formulations, but PEG 300 has advantages in relation to freezing point depression and solubility, which may be considered if further studies are going to be initiated. The high nasal bioavailability and short time to maximal plasma concentration suggests that it is possible to make a clinically relevant nasal formulation of BPP for the treatment of pain.