Bacterial flora and infection in patients with brain injury

Incidence, risk factors, and outcome of postoperative pneumonia after microsurgical clipping of ruptured intracranial aneurysms

Background:

Occurrence of pneumonia challenges the medical management of patients who have undergone surgery for aneurysmal subarachnoid hemorrhage, and is associated with significant mortality and morbidity. There are very few studies evaluating the incidence and outcome of postoperative pneumonia in patients undergoing microsurgical clipping of ruptured intracranial aneurysms. The aim of this study was to determine the incidence, risk factors, and outcome of postoperative pneumonia in patients undergoing surgery for ruptured intracranial aneurysms.

Methods:

All patients operated for intracranial aneurysms, over a period of 9 months, were included prospectively. They were studied for risk factors predisposing them to pneumonia and their outcomes were noted at discharge. Patients with predisposing chronic lung disease, preexisting pneumonia, and chronic smoking habits were excluded.

Results:

One hundred and three patients [Mean age: 46.01 years; M:F – 58:45] underwent microsurgical clipping of aneurysm during the study period. Of these, 28 patients (27.2%) developed postoperative pneumonia. The variables associated with postoperative pneumonia were: [Preoperative] age >50 years, Glasgow Coma Scale (GCS) at presentation <15 and Hunt and Hess grade before surgery >2; [postoperative] duration of surgery >3 hours, GCS <15 after complete reversal from anesthesia, duration of intubation in the postoperative period >48 hours, tracheostomy, postoperative ventilation, intensive care unit (ICU) stay >5 days. Predictive factors for postoperative pneumonia by multivariate analysis were: Postoperative endotracheal intubation >48 hours, tracheostomy and ICU stay >5 days.

Conclusions:

There is a high incidence of postoperative pneumonia and mortality associated with pneumonia (27.2% and 9.7%, respectively in our study) in patients of ruptured intracranial aneurysms undergoing microsurgical clipping at our center, with Acinetobacter species being the predominant causative organism.

Incidence and risk factors for postoperative pulmonary complications in elective intracranial surgery

OBJECT

It has been shown that craniotomy may lead to a decrease in lung volumes and arterial blood gas tensions as well as a change in the respiratory pattern. The purpose of this study was to determine the incidence of postoperative pulmonary complications (PPCs) and the mortality rate in patients who have undergone elective craniotomy and to evaluate the associations between preoperative and postoperative variables and PPCs in this population.

METHODS

Two hundred thirty-six patients were followed up based on a protocol including a clinical questionnaire, physical examination and observation of clinical characteristics in the preoperative period, type of surgery performed, duration of surgery, time spent in the intensive care unit (ICU) and hospital, and the occurrence of any PPCs.

RESULTS

Postoperative pulmonary complications occurred in 58 patients (24.6%) and 23 other patients (10%) died. Predicting factors for PPCs according to multivariate analyses were as follows: type of surgery performed (p < 0.0001), prolonged mechanical ventilation >or= 48 hours (p < 0.0001), time spent in the ICU > 3 days (p < 0.0001), decrease in level of consciousness (p < 0.002), duration of surgery >or= 300 minutes (p < 0.01), and previous chronic lung disease (p < 0.04).

CONCLUSIONS

The incidence from March 2003 to March 2005 of PPCs in patients who had undergone craniotomy was 25% and death occurred in 10%. Some risk factors for PPCs may be predicted such as the type of surgery performed, prolonged mechanical ventilation, a longer time in the ICU, a decreased level of consciousness, duration of surgery, and previous chronic lung disease.

Postoperative study of vital capacity and ventilation measurements following elective craniotomy

CONTEXT AND OBJECTIVE

Changes in pulmonary function commonly occur after general surgery. The aims were to evaluate vital capacity, tidal volume and respiratory frequency among patients undergoing elective craniotomy and to determine possible correlations of these parameters with surgery duration and etiology for neurosurgery.

DESIGN AND SETTING

Prospective, open study at a tertiary university hospital.

METHODS

Twenty-six patients underwent elective craniotomy for aneurysm clipping (11) or tumor resection (15). Vital capacity (VC), tidal volume (TV), minute volume (VE) and respiratory rate were determined before the operation and on the first to fourth postoperative days.

RESULTS

There were significant decreases of 25% in VC, 22% in TV and 12% in VE (p < 0.05) and no significant increase in respiratory frequency (5%) on the first postoperative day. VE returned to baseline on the second postoperative day and TV on the third postoperative day, while VC was 8% lower on the fourth postoperative day, compared with before the operation (p < 0.05). VC reduction was significantly greater in patients undergoing aneurysm clipping (43%) than in patients undergoing tumor resection (14%) when surgery duration was more than four hours (p < 0.05), with no significant change when surgery duration was less than four hours.

CONCLUSION

Reductions in VC, TV and VE were observed during the postoperative period in patients undergoing aneurysm clipping or tumor resection. The reductions in VC and TV were greater in patients undergoing craniotomy due to aneurysm and with longer surgery duration.

Bacterial colonization patterns in mechanically ventilated patients with traumatic and medical head injury. Incidence, risk factors, and association with ventilator-associated pneumonia

We prospectively evaluated the relation of upper airway, lower airway, and gastric colonization patterns with the development of pneumonia and its etiology in 48 patients with surgical (n = 25) and medical (n = 23) head injury. Initial colonization was assessed by cultures of nasal and pharyngeal swabs, tracheobronchial aspirates, gastric juice, and bronchoscopically retrieved protected specimen brush. Follow-up colonization was determined until the end points extubation, suspected ventilator-associated pneumonia (VAP), or death. The initial colonization rate at any site at ICU admission was 39/47 (83%). It mainly accounted for Group I pathogens (Streptococcus pneumoniae, Staphylococcus aureus, Hemophilus influenzae) of the upper and lower airways. At follow-up, colonization rates with Group II pathogens (Gram-negative enteric bacilli and Pseudomonas spp.) increased significantly. The high initial bacterial load with Group I pathogens of the upper airways and trachea decreased during Days 2 to 4, whereas that of Group II pathogens increased. Upper airway colonization was an independent predictor of follow-up tracheobronchial colonization (odds ratio [OR], 9.9; 95% confidence interval [CI], 1.8 to 56.3 for initial colonization with Group I pathogens; OR, 23.9; 95% CI, 3.8 to 153.3 for follow-up colonization with Group II pathogens). Previous (short-term) antibiotics had a protective effect against colonization with Group I pathogens of the lower respiratory tract (OR, 0.2; 95% CI, 0.05 to 0.86), but they were a risk factor for colonization with Group II pathogens (OR, 6.1; 95% CI, 1.3 to 29). Initial tracheobronchial colonization with Group I pathogens was associated with a higher probability of early onset pneumonia (OR, 4. 1; 95% CI, 0.7 to 23.3), whereas prolonged antibiotic treatment (> 24 h) independently predicted late-onset pneumonia (OR, 9.2; 95% CI, 1.7 to 51.3). We conclude that patients with head injury are colonized in the airways mainly by Group I pathogens early in the evolution of illness. The upper airways represent the main reservoir for subsequent lower airway colonization with Group I pathogens. Previous (short-term) antibiotic treatment is protective against initial tracheobronchial colonization with Group I pathogens, but it represents a risk factor for subsequent lower airway colonization by Group II pathogens.

Complications of tracheostomies in neurosurgical patients

The records of the neurosurgical patients with tracheostomies who were treated at the University of Mississippi Medical Center during the past 5 years were reviewed. Of the 84 such patients, 45% had posttracheostomy complications, including pneumonitis, pneumothorax, pneumomediastinum, infected stoma, subcutaneous emphysema, tracheal stenosis, aspiration, swallowing dysfunction, and tracheoarterial fistula. Reported complications related to prolonged nasotracheal intubation, the alternative to tracheostomy, are reviewed. These complications appear to be less frequent and less serious than those of tracheostomy, in the authors' experience as well as in the reports of others. It is concluded that in neurosurgical patients, tracheostomy is not a benign procedure. Unless a specific indication for tracheostomy exists, consideration should be given to the use of prolonged nasotracheal intubation for airway maintenance.

A prospective study of tracheobronchial bacterial flora in acutely brain-injured patients with and without antibiotic prophylaxis

The authors observed prospectively 28 brain-injured patients, who required respiratory tract intubation, to determine the effect of antibiotic prophylaxis on bacterial flora, the rate of flora change, and the appearance of infection. Antibiotics not only failed to alter the rate of abnormal colonization but were associated with an earlier appearance of Gram-negative bacilli, the organisms that produced the most severe infections. Although more infections occurred in patients initially untreated with antibiotics, these infections were usually mild and caused by organisms susceptible to highly effective and relatively safe drugs. Although highly reproducible as a laboratory determination, the nitroblue tetrazolium dye test score showed no consistent relationship with the presence or absence of bacterial infection. Regular and extensive clinical and laboratory observations, including cultures of the respiratory tract helped to make the antibiotic administration in these patients specific, appropriate, and reasonable. Broad spectrum antibiotic prophylaxis does not prevent and may enhance the development of severe pulmonary infection in these patients.

Analysis of the treatment of basilar skull fractures with and without antibiotics

The efficacy of chemoprophylaxis in the treatment of basilar skull fractures was studied in 129 patients over a 2-year period; antibiotics were found ineffective in preventing central nervous system infections, and in some cases may have proved harmful. It is suggested that a more rational approach to the treatment of basilar skull fractures includes close observation of the patient for early signs of meningitis, and if these should develop, treatment with antibiotics appropriate to the organism involved.