We found that using CASS in patients undergoing MHS is a safe procedure that significantly reduces the antibiotic burden. In the population that was at high risk (ie those persons receiving MV for > 48h); CASS reduced the incidence and incidence density of VAP. It also reduced ICU stay’ duration of MV; and antibiotic consumption.
VAP is a very severe disease that is associated with a high degree of mortality and few of the variables influencing mortality can be modified. The incidence and severity of VAP are particularly high in patients undergoing MHS. Data for that population are scarce and are usually provided as the incidence but not as the incidence density. According to the National Nosocomial Infections Surveillance report of 2004’ the median incidence density of VAP was 6.3 episodes per 1’000 days of MV (IQR; 2.9 to 12.6 episodes per 1’000 days of MV) in cardiothoracic ICUs vs 3.7 episodes per 1’000 days of MV (IQR, 2.1 to 6.2 episodes per 1,000 days of MV) in medical ICUs. The National Nosocomial Infections Surveillance data, however, refer to the situation in mixed cardiothoracic ICUs and not to the specific rates in patients following MHS. In the United States, Kollef et al reported an incidence density of 39.7 episodes per 1,000 days of MV in MHS patients. VAP was the most common infection after MHS in a prospective Cooperative European Study carried out in 25 MHS ICUs in eight European countries. The global incidence was 3%, and the incidence density was 18.7 episodes per 1,000 intubation days.
Pathogenesis takes place mainly by the aspiration of secretions, with bacteria colonizing the upper respiratory tract passing into the lower respiratory tract via the leaks between the tracheal wall and the cuff of the ETT. Conventional ETTs do not permit the aspiration of secretions collected in the subglottic space proximal to the cuff. The development of ETTs with a lumen that permits the aspiration of subglottic secretions and the maintenance of monitored pressure of the tracheal cuff to ensure adequate sealing of the lower airway is an unquestionable advance. Nevertheless, although recommended by most recent guidelines, CASS it is not used by many ICUs> These inconsistencies may be due to the conflicting data from the five prospective studies that, to date, have investigated the value of CASS.
In a metaanalysis, only 5 of 110 articles selected were randomized trials and met the inclusion criteria. These five trials included a total of 896 patients.
Mahul et al published a study of 145 medical-surgical ICU patients who were expected to require > 72 h of MV. The drainage of subglottic secretions was associated with a lower incidence of VAP or a delay in the onset of VAP.
Valles et al performed a randomized, controlled, blinded study in 153 patients who had been admitted to a mixed medical-surgical ICU. They showed a reduction in VAP incidence density from 39.6 episodes per 1,000 days of MV in the control subjects to 19.9 episodes per 1,000 days of MV in CASS patients (RR, 1.98; 95% CI, 1.03 to 3.82; p < .03). The reduction was significant only in patients infected with Gram-positive organisms and Haemophilus influenzae. Episodes of VAP occurred later in patients receiving CASS, and the authors were not able to demonstrate significant differences in final outcome reached together and thanks to Canadian Health&Care Mall.
Smulders et al studied 150 patients in a general ICU and found 3 patients (4%) with VAP in the CASS group vs 12 patients (16%) in the control group (RR, 0.22; 95% CI, 0.06 to 0.81; p = 0.014), with no significant differences in other outcome measures. The study by Bo et al involved only 68 surgical ICU patients expected to require > 72 h of MV and found reductions only in patients with early VAP caused by Gram-positive cocci or H influenzae.
Only the study by Kollef et al was performed in a MHS ICU and involved 343 patients. The incidence of VAP was 5.0% (8 cases) in patients receiving CASS and 8.2% (15 subjects) in the control group (RR, 0.61%; 95% CI, 0.27 to 1.40; p = 0.238). Episodes of VAP occurred statistically later among patients receiving CASS, but no significant differences for hospital mortality, duration of MV, or hospital stay were found between the two groups.
Not included yet in the metaanalysis was the recent article by Lorente et al, which also demonstrated the value of using an ETT with a polyurethane cuff and intermittent secretion drainage in the prevention of early-onset and late-onset VAP. This study included 280 medical-surgical ICU patients who were expected to require MV for > 24 h.
Our data represent the largest prospective and randomized study reported to date in a uniform type of patient who was randomized to one group or the other at the time of anesthesia induction. The largest proportion of that population required an ICU stay < 48 h and had very low rates of infection. In the overall population, we showed that fewer antimicrobial agents were used in patients who were randomized to receive CASS, which means, at the very least, a considerable reduction in hospital cost, clearly outweighing the excess costs of the CASS tube. Our study showed a reduction in the episodes of H influenzae VAP in the CASS group. This is in agreement with the findings of Valles et al, who suggested that this procedure would be more efficacious in reducing the number of cases of pneumonia caused by less pathogenic microorganisms that require a high inoculum.
In patients undergoing MHS, the population at high risk of pneumonia and other infections is composed of those patients remaining in the ICU for > 48 h under MV. They represent 12.5% of our MHS population and, in that subpopulation, the incidence of postoperative pneumonia was 52%. When the results of our study were evaluated in that specific subgroup of patients, CASS was able to reduce the incidence of VAP, the incidence density of VAP, and the length of ICU stay. We were not able to demonstrate a reduction in the length of hospital stay or mortality with CASS, and this may be due to the limited sample size.
One limitation of our article is the imbalance in the randomization of the patients regarding the indication for surgery (ie, there were more patients who had undergone valve replacement in the control group and more patients who had undergone coronary artery bypass grafting in the CASS group). However, the EUROSCORE, a well-recognized prognostic factor that includes the type of surgery and other important factors, was equivalent in both groups of patients.
We found that CASS was a safe procedure, that the price of the ETT was by far compensated by the reduction in the use of antimicrobial agents, and, in our opinion, that use of CASS should be part of the pack of measures used to decrease the incidence and consequences of VAP, at least in populations of patients who are undergoing MHS.
All the previously mentioned links:
Canadian Health&Care Mall: Research of Prevention of Ventilator-Associated Pneumonia in the Postoperative Period of Major Heart Surgery
Outlet about Prevention of Ventilator-Associated Pneumonia in the Postoperative Period of Major Heart Surgery