Development of appropriate procedures for inflation of endotracheal tube cuff in intubated patients.

BACKGROUND: Hyperinflation of endotracheal tube cuff causes tracheal mucosal damage and underinflation increases the risk of pneumonia. The current practice on inflation of endotracheal tube cuff in the intubated patients hospitalized at Siriraj Hospital uses the estimation method. The authors determined appropriateness of such current practice and developed an appropriate procedure for inflation of endotracheal tube cuff in intubated patients. MATERIAL AND METHOD: The endotracheal tube cuff pressures of 34 intubated patients in Siriraj Hospital were measured by manometer once daily. Inflation of the endotracheal tube cuffs of 20 patients was done and the volume of air required to optimize the intracuff pressure of 25 cmH2O was recorded. The intracuff pressure was measured every one hour for eight consecutive hours in the patients who had initial intracuff pressure of 25 cmH2O and 30 cmH2O. The nurses in the experimental wards used a manometer as a guide to inflate endotracheal tube cuff until the intracuff pressure was 30 cmH2O every eight hours, whereas the control wards used conventional procedures to inflate the endotracheal tube cuff. The endotracheal tube cuff pressures of the patients in both groups were measured twice daily. RESULTS: Only 34% of intracuff pressure measurements were 20-30 cmH2O. The mean volume of inflated air required to achieve an intracuff pressure of 25 cmH2O was 7.1 ml. An initial intracuff pressure of 30 cmH2O decreased to 20 cmH2O at 7 to 9 hours after inflation. The rate of optimum endotracheal tube cuff pressure was 90.5% in the group guided by manometer and 31.8% in the conventional procedure group (p < 0.001, RR 2.85, 95% CI 2.44-3.32). CONCLUSION: Inflation of endotracheal tube cuff should be guided by manometer to achieve a pressure of 30 cmH2O every eight hours.

Occurrence and protective level of influenza infections using serology in patients with COPD in vaccination study.

OBJECTIVE: To investigate the prevalence, occurrence and protective level of influenza infections using serology in patients with chronic obstructive pulmonary disease (COPD) during a one-year influenza vaccination study. MATERIAL AND METHOD: A total of 123 patients with COPD were enrolled during the period of 1997 to 1998. There were 61 patients in the vaccine group and 62 patients in the placebo group with a mean age +/- SD of 67.6 +/- 8.0 and 69.1 +/- 7.5, respectively. The vaccine was composed of influenza A/Texas/36/91 (H1N1), A/Nanchang/933/95 (H3N2) and B/Harbin/07/94 strains. Antibodies to influenza viruses were detected by hemagglutination inhibition (HI) test using antigens of vaccine strains. RESULTS: The incidence of influenza proven by serological examination was 22/123 (17.9%) cases. Among 17/62 (27.4%) influenza cases in the placebo group representing natural infections, 3 (17.6%) were diagnosed as A (H1N1), 8 (47.1%) as A (H3N2), 3 (17.6%) as type A, 1 (5.9%) as type B and 2 (11.8%) as untypeable viruses. The 8.2% of influenza cases found in the vaccine group was significantly lower than 27.4% of that in the placebo group (Chi-square test, p = 0.01). The protection rate of influenza vaccination was 71%. Among 23 acute blood samples from 22 influenza cases, the titers ranged from < 10 to 20 corresponding to its type/subtype. In the vaccine group, 5 influenza cases occurred at 7, 7, 10, 11 and 11 months after vaccination. The HI antibodies to influenza A (H1N1), A (H3N2) and B viruses at titers of > or = 10 vs > or = 40 were 50.4% vs 21.9%, 54.5% vs 28.5% and 17.9% vs 4.1%, respectively. CONCLUSION: The findings indicated that from 1997 to 1998, the occurrence of influenza as natural infection was 27.4%. Influenza A (H3N2) was more frequently prevalent than A (H1N1) and B viruses. The influenza vaccination in COPD patients was effective. The protective HI antibody titers were > or = 40. The patients without protective HI antibody to A (H1N1), A (H3N2) and B viruses were 78.1%, 71.5% and 95.9%, respectively. Such patients were considered to be at high-risk for influenza and recommended to have vaccination.

Prevalence and incidence of Chlamydia pneumoniae antibodies among the healthy elderly and patients with chronic obstructive pulmonary diseases.

Chlamydia pneumoniae is an obligatory intracellular bacteria which can cause both acute and chronic respiratory tract infection. The significance of chronic and recurrent respiratory infection may be of prime importance in chronic obstructive pulmonary diseases (COPD). The purpose of this study was to determine the prevalence and incidence of C. pneumoniae antibodies in elderly COPD patients compared to a healthy elderly control group. C. pneumoniae antibodies were detected by an enzyme-linked immunosorbent assay in serum samples obtained from 127 elderly COPD patients and a 131 healthy elderly control group. The results showed that the seroprevalence of C. pneumoniae infection as determined by the existence of specific IgG or IgA or IgM antibodies was 96.1% in the COPD patients and 75.6% in the control group (p < 0.01). The prevalence of individual C. pneumoniae IgG, IgA and IgM in elderly COPD vs healthy control was 85.8% vs 66.4%, 85.0% vs 51.1% and 3.9% vs 0%, respectively. The incidence or seroconversion rate of C. pneumoniae antibodies after one year follow-up was found to be 33% in the COPD patients and 67.9% in the control group. High prevalence and incidence of C. pneumoniae antibodies indicates that both acute and chronic C. pneumoniae infection play a role in elderly COPD patients. Therefore, antibiotics of choice for C. pneumoniae infection should probably be considered.

Economic evaluation of influenza vaccination in Thai chronic obstructive pulmonary disease patients.

To determine the cost-effectiveness and cost-benefit of influenza vaccination in chronic obstructive pulmonary disease (COPD) patients the authors conducted a stratified randomized, double-blind, placebo-controlled trial from June 1997 to November 1998 at a university hospital in Thailand. A total of 125 COPD patients were stratified based on their FEV1 as mild COPD (FEV1 > or = 70% predicted), moderate COPD (FEV1 50-69% predicted) and severe COPD (FEV1 < 50% predicted) and in each severity stratum they were randomized to the vaccine group (received intramuscular injection with purified trivalent split-virus vaccine containing A/Texas/36/91 (H1N1), A/Nanchang 1933/95 (H3N2) and B/Harbin 107/94) or the placebo group (received intramuscular injection with vit B1). Number of episodes of acute respiratory illness (ARI) related to influenza (clinical ARI + a serum hemagglutination inhibition antibody titre of 38 or greater and a four fold titre increase in convalescent serum compared to acute serum) as well as severity of each ARI (outpatient treatment, hospitalization or required mechanical ventilation) and costs of treatment (direct medical costs comprised real drug costs from the hospital dispensary in outpatient cases and real charges in hospitalization cases) were collected and analyzed for the cost-effectiveness and cost-benefit of influenza vaccination. The incidence of influenza-related ARI in the study year was 27 per cent in the placebo group and 6.4 per cent in the vaccine group (relative risk [RR] 0.24, vaccine effectiveness 76%). The incidence was 27.3 per cent, 23.5 per cent and 29.2 per cent in mild, moderate and severe COPD respectively in the placebo group and 4.3 per cent, 12.5 per cent, and 4.3 per cent in the mild, moderate and severe COPD respectively in the vaccine group (RR 0.16, 0.53 and 0.15; vaccine effectiveness 84%, 47%, and 85% respectively). The incremental cost-effectiveness ratios demonstrated that for every 100 patients with mild COPD whom the authors decided to vaccinate, the cost would be 24,840 baht more and would prevent 18.2 outpatients, 4.8 hospitalizations and 0 patient from mechanical ventilation due to ARI related to influenza. Likewise, the authors would have prevented 5.1 outpatients, 5.9 hospitalizations, 5.9 mechanical ventilation and 20.8 outpatients, 3.9 hospitalizations, 8.3 mechanical ventilation for every 100 moderate COPD and every 100 severe COPD patients vaccinated respectively. More than 90 per cent of the costs of treatment of influenza-related ARI were costs of hospitalization and for patients with moderate and severe airflow obstruction, more than 90 per cent of these costs were attributed to the costs of treating the patients who required mechanical ventilation. Predicted cost savings for every 100 mild COPD, 100 moderate COPD and 100 severe COPD patients vaccinated were 125,629 baht, 538,184.3 baht, and 680,647.1 baht respectively. In conclusion: Influenza vaccination is highly effective in the prevention of acute respiratory illness related to influenza virus infection in COPD, regardless of severity of airflow obstruction. Vaccination is more cost-effective in preventing mechanical ventilation episodes and more cost-benefit in patients with more severe airflow obstruction. Influenza vaccination should be recommended to all patients with COPD with the higher priority provided to patients with more severe airflow obstruction.