Objective To investigate the correlation between arterial carbon dioxide partial pressure (PaCO2 )and end-tidal carbon dioxide partial pressure (PET CO2 )in prone position operation and calculate the value of PaCO2 according to the PET CO2 .Methods Forty patients with ASA Ⅰ orⅡ undergoing spinal surgery were selected,and the values of PaCO2 and PET CO2 as basic value (T0 ) after induction of general anesthesia in supine position monitor and record the value of PET CO2 and PaCO2 in prone position after 30 min (T1 ),60 min (T2 )and 90 min (T3 ).The correlation between PaCO2 and PET CO2 in each time point were analyzed,and the equation of PaCO2 (y)and PET CO2 (x) with curve fitting and difference of PaCO2 and PET CO2 were calculated.Results There was significant correlation between PaCO2 and PET CO2 in the supine and prone position,their correlation coefficients were r 0 =0.84,r 1 =0.88,r 2 =0.84,r 3 =0.82 (P <0.01).The Pa-ET CO2 was (5.3±2.1)(T0 )in supine position and (6.6± 2.1 )mm Hg (T1 ),(5.8 ± 2.2 )mm Hg (T2 ),(5.9 ± 2.1 )mm Hg (T3 )in prone position.The equation in each time point PaCO2 (y)and PET CO2 (x)were y0 =1.1 x0 +2.5,y1 =1.1 x1 +2.3,y2 =1.1 x2 +2.4,y3 =1.1 x3 +4.6,and the Pa-ET CO2 was 3.7-8.7 mm Hg. There was no significant difference between PaCO2 and PET CO2 at T1-T3 .Conclusion Whenever in prone position or supine position,PET CO2 and PaCO2 have significant correlation in prone position and supine position.The overall range of Pa-ET CO2 is 3.7-8.7 mm Hg,and the PET CO2 can be as indica-tor to estimate PaCO2 in prone position.

Objective To study the sequence variation in the env V3-V4 human immunodeficiency virus (HIV)-1 predominant subtype B strains in Hubei Province and to understand the epidemic characteristics and mutations of HIV-1. Methods Epidemiologic survey was done in the HIV-1 carriers in Hubei area. HIV-1 env V3-V4 regions were amplified by nested-polymerase chain reaction (nPCR). The sequences were determined and then phylogenetic analysis was performed. The difference of gene distance were checked by chi square test and the variation of gene distance were descriptively analyzed. Results Four HIV-1 strains or circulating recombinant forms (CRF) were identified in Hubei Province subtype B', B'/C, CRF01_AE and C were 82.69%, 7.69%, 7.69% and 1.92% ,respectively. B' strains were closely related with B. CN. RL 42 from Yunnan Province and B. CN. 02. 02HN from Province Henan, the gene distances were 7.08 ± 2.19 and 7.88 ± 2.28, respectively. Genetic divergence of env of B' strains showed that subtype B' has existed in Hubei area for about 10 years. Amino acid sequence analysis of section env showed V4 was more variable than C3, V3. The top four peptides of V3 loop were GPGR (46.5%), GPGK (30.2%), GPGQ (13.6%) and GQGR (9.3%). Predictions for the potential use of co-receptors on the basis of the critical amino acids within V3 loop disclosed that 16.28% were CCR5-using (R5/NSI), 13.95% were CXCR4-using (X4/SI) while the co-receptor usage of the vast majority (69.77%) could not be predicted. The analysis of glycosylation sites showed that there were 9 sites in env V3-V4 regions of HIV-1 strains in Hubei area and there were deletions in 8 of them, Conclusions Subtype B' is still the main epidemic subtype in Hubei Province and high homologous to the strains from Yunan and Henan Province.