Nosocomial pneumonia in the critical care unit

Pulmonary Complications After Cardiac Surgery

Over the past two decades there has been a steady evolution in the practice of adult cardiac surgery with the introduction of “off-pump” surgery. However, respiratory complications remain a leading cause of postcardiac surgical morbidity and can prolong hospital stays and increase costs. The high incidence of pulmonary complications is in part due to the disruption of normal ventilatory function that is inherent to surgery in the thoracic region. Furthermore, patients undergoing such surgery often have underlying illnesses such as intrinsic lung disease (e.g., chronic obstructive pulmonary disease) and pulmonary dysfunction secondary to cardiac disease (e.g., congestive heart failure) that increase their susceptibility to postoperative respiratory problems. Given that many patients undergoing cardiac surgery are thus susceptiple to pulmonary complications, it is remarkable that more patients do not suffer from them during and after cardiac surgery. This is to a large degree because of advances in anesthetic, surgical and critical care that, for example, have reduced the physiological insults of surgery (e.g., better myocardial preservation techniques) and streamlined care in the immediate postoperative period (e.g., early extubation). Moreover, the development of minimally invasive surgery and nonbypass techniques are further evidence of the attempts at reducing the homeostatic disruptions of cardiac surgery. This review examines the available information on the incidences, consequences, and treatments of postcardiac surgery respiratory complications.

Impact of a Program of Intensive Surveillance and Interventions Targeting Ventilated Patients in the Reduction of Ventilator-Associated Pneumonia and Its Cost-Effectiveness

Objective:

We hypothesized that a program of prospective intensive surveillance for ventilator-associated pneumonia (VAP) and concomitant implementations of multimodal, multidisciplinary preventive and intervention strategies would result in a reduction in the incidence of VAP and would be cost-effective.

Setting:

Medical and surgical intensive care units (ICUs) in a university teaching hospital.

Interventions:

All ventilated patients in the medical and surgical ICUs were monitored for VAP from January 1997 through December 1998. Interventions including elevation of the head of the bed, use of sterile water and replacement of stopcocks with enteral valves for nasogastric feeding tubes, and prolongation of changing of in-line suction catheters from 24 hours to as needed were implemented.

Results:

The rates of VAP decreased by 10.8/1,000 ventilator-days in the medical ICU (CI95, 4.65-16.91) and by 17.2/1,000 ventilator-days in the surgical ICU (CI95> 2.85-31.56) when they were compared for 1997 and 1998. With the use of the estimated cost of a VAP of $4,947 from the literature, the reduction resulted in cost savings of $178,092 and $148,410 in the medical and surgical ICUs, respectively, for a total of $326,482. In addition, $25,497 was saved due to the lengthening of the time for the change of in-line suction catheters, resulting in a cost savings of $351,979. This total cost savings of $351,979 minus the cost of enteral valves of $2,100 resulted in total net savings of $349,899.

Conclusion:

Intensive surveillance and interventions targeted at ventilated patients resulted in reduction of VAP and appeared to be cost-effective.

Determination of the frequency of inadequate antibiotic therapy using calculation of indication failure (IF), cumulative indication failure (CIF), and balanced indication failure (BIF)

Because results of pathogen identification are often lacking when antibiotic therapy is initiated, treatment must frequently be instituted on an empirical basis. The type of empirical therapy will depend on the anticipated pathogen spectrum and naturally also on the prevailing resistance patterns. Inadequate antibiotic therapy may not only be associated with increased overall treatment costs, but will also have adverse effects on mortality. The clinician is frequently faced with an overabundant variety of microbiological data and may fail to interpret them correctly. Therefore, the present study has attempted to "translate" the available microbiological resistance data, frequently presented in the form of percentage rates, into concrete patient numbers and thus illustrate the frequency of inadequate antibiotic therapy. For this purpose, "Indication Failure" (IF), "Cumulative Indication Failure" (CIF) and "Balanced Indication Failure" (BIF) have been calculated based on available microbiological data. For the indication "nosocomial pneumonia", calculations of the BIF show that only one out of 67 or one out of 63 patients is inadequately treated with a therapy with cefepime or imipenem, while one out of 25 patients is inadequately treated when using ceftazidime. However, it must be pointed out that these calculations only represent an interpretation of microbiological data and the success of antibiotic therapy will ultimately also depend on parameters such as the pharmacodynamic properties of an antibiotic or on the immunocompetence of the patient treated.

Electronic ventilator temperature sensors as a potential source of respiratory tract colonization with Stenotrophomonas maltophilia

Stenotrophomonas maltophilia (S. maltophilia) is an important cause of nosocomial infection among ventilated and immunocompromised patients, and among patients receiving broad-spectrum antimicrobials. We report a cluster of patients in a surgical intensive care unit who were colonized or infected with S. maltophilia. An epidemiological investigation was initiated after surveillance data revealed that eight patients were culture-positive from sputum for S. maltophilia in the preceding month. Review of respiratory care procedures revealed that when mechanical ventilators were serviced between patients, the electronic temperature probes used with servo-controlled humidifiers were wiped with inadequate disinfection. We collected cultures of case-patient room surfaces, sinks and ventilator equipment. S. maltophilia was recovered from room surfaces, ventilator expiratory circuits and a temperature sensor which had been kept in ambient air after disinfection. Patients and environmental isolates were examined by RAPD-PCR. Three clinical isolates and one environmental isolate had the same profile, which suggests cross-contamination or common source exposure. The outbreak was controlled by adequate disinfection of the temperature sensors. No single epidemic strain was identified but several observations support the conclusion that the temperature probes contributed to the outbreak.

Nosocomial pneumonia. Diagnostic and therapeutic considerations

Many patients with presumed nosocomial pneumonia probably have infiltrates on the chest radiograph, fever, and leukocytosis resulting from noninfectious causes. Because of the high mortality and morbidity associated with nosocomial pneumonias, however, most clinicians treat such patients with a 2-week empiric trial of antibiotics. Before therapy is initiated, the clinician should rule out other causes of pulmonary infiltrates, fever, and leukocytosis that mimic a nosocomial pneumonia (e.g., pre-existing interstitial lung disease, primary or metastatic lung carcinomas, pulmonary emboli, pulmonary drug reactions, pulmonary hemorrhage, collagen vascular disease affecting the lungs, or congestive heart failure). If these disorders can be eliminated from diagnostic consideration, a 2-week trial of empiric monotherapy is indicated. The clinician should treat cases of presumed nosocomial pneumonia as if P. aeruginosa were the pathogen. Although P. aeruginosa is not the most common cause of nosocomial pneumonia, it is the most virulent pulmonary pathogen associated with nosocomial pneumonia. Coverage directed against P. aeruginosa is effective against all other aerobic gram-negative bacillary pathogens causing hospital-acquired pneumonia. The clinician should select an antibiotic for empiric monotherapy that is highly effective against P. aeruginosa, has a good side-effect profile, has a low resistance potential, and is relatively inexpensive in terms of its cost to the institution. The preferred agents for empiric monotherapy for nosocomial pneumonia are cefepime, meropenem, and piperacillin. Single organisms are responsible for nosocomial pneumonia, not multiple pathogens. S. aureus rarely, if ever, causes nosocomial pneumonia but is mentioned frequently in studies based on cultures of respiratory tract secretions. S. aureus, unless accompanied by a necrotizing pneumonia with rapid cavitation within 72 hours, in the sputum indicates colonization rather than infection and should not be addressed therapeutically. Antibiotics associated with a high resistance potential should not be used as monotherapy or included in combination therapy regimens (i.e., ceftazidime, ciprofloxacin, imipenem, or gentamicin). Combination therapy is more expensive than monotherapy and is indicated only when P. aeruginosa is extremely likely, based on its characteristic clinical presentation, or is proved by tissue biopsy. Therapy should not be based on respiratory secretion cultures regardless of technique. Optimal combination regimens include cefepime or meropenem plus levofloxacin or piperacillin or aztreonam or amikacin. Nosocomial pneumonias usually are treated for 14 days. Lack of radiographic or clinical response to appropriate empiric nosocomial pneumonia monotherapy after 14 days suggests an alternate diagnosis. In these patients, a tissue biopsy specimen should be obtained to determine the cause of the persistence of pulmonary infiltrates unresponsive to appropriate antimicrobial therapy.

Nosocomial pneumonia: epidemiology, pathogenesis, diagnosis, treatment and prevention

Nosocomial pneumonia is the second most common nosocomial infection and the leading cause of death from hospital-acquired infection. Supine body position in mechanically ventilated patients, and cardiopulmonary resuscitation and continuous sedation are significant risk factors for developing nosocomial pneumonia. During the past 2 years some new therapeutic approaches for nosocomial pneumonia and modifications to established therapies have been described, such as optimal pharmacodynamic evaluations, monotherapy versus combination therapy, computer-assisted management programmes and antibiotic rotations.