Topical antimicrobial prophylaxis of nosocomial pneumonia in mechanically ventilated patients. Microbiological observations

Generally, reduction of colonization and infection with potentially pathogenic microorganisms in intensive care units (ICU) is attempted by a combination of antimicrobial agents administered topically in the digestive tract and systematically. We tested the efficacy of topical antimicrobial prophylaxis of the oropharynx and stomach administered in combination with sucralfate without systemic prophylaxis in 25 mechanically ventilated ICU patients. The regimen successfully reduced colonization with potentially pathogenic microorganisms in the oropharynx and trachea without modifying the intestinal flora. However, colonization and infections with gram-positive cocci and gram-negative rods other than Enterobacteriaceae and Pseudomonadaceae and resistant to one or both the antimicrobial agents used were observed.     

Enhancement of alcohol-induced hypoglycaemia by H2-receptor antagonists

Male Wistar rats were kept in a hypoxia chamber (9% O2) for eight hours. Control animals breathed room air in the same chamber for a similar period of time. One week later the brains of all rats were prepared for the immunohistochemical demonstration of Mn-superoxide dismutase (Mn-SOD). In comparison with the sham-exposed controls, the hypoxia-treated animals showed an increase in the number of Mn-SOD-immunoreactive neurons in several hippocampal structures. The 72 kD heat shock protein was not found to be induced one week after a moderate hypoxia.     

Therapeutic-interchange program for oral histamine H2-receptor antagonists

A therapeutic-interchange (TI) program for oral histamine H2-receptor antagonists at a hospital is described. In 1992 the pharmacy and therapeutics committee at a large teaching hospital accepted cimetidine as the preferred oral H2 antagonist. However, the program to promote cimetidine met with little success. The manufacturer of nizatidine then offered the hospital that drug at a reduced cost relative to all other members of the drug class. The committee recommended including nizatidine on the formulary; implementing a TI program so that when an order for an oral H2 antagonist was written nizatidine would be dispensed; deleting cimetidine and ranitidine tablets from the formulary; and retaining cimetidine and ranitidine oral liquid and i.v. formulations. The program was approved by the medical executive committee and was implemented in August 1994. Extensive efforts to inform the pharmacy, medical, and nursing staffs about the program were undertaken, and the pharmacy established mechanisms for monitoring compliance. Two months into the program, 97% of eligible patients were receiving nizatidine. Actual cost savings in the first four months exceeded $40,000. In July 1997 the same program was applied to famotidine, which had replaced nizatidine as the most cost-effective H2 antagonist. A successful TI program for oral H2 antagonists was achieved by gaining physician support for the program, educating providers, monitoring compliance, and responding to changes in drug costs.     

Gastric intramucosal acidosis in mechanically ventilated patients: role of mucosal blood flow

To examine the roles of Arg-vasopressin (AVP)- and vasoactive intestinal peptide (VIP)-containing neurons in the suprachiasmatic nucleus (SCN) in production of circadian rhythmicity of locomotor activity, variations in the contents of AVP and VIP in punched-out SCN tissue and locomotor activity were measured under a light-dark cycle as well as under conditions of constant light for up to 3 weeks. Under the light-dark cycle, contents of AVP and VIP, and locomotor activity showed marked circadian rhythmicity. Under constant light, AVP content showed circadian rhythmicity until 3 weeks, while VIP rhythm disappeared from the first week with decreases in its content. Locomotor activity showed a free-running circadian rhythm for more than 3 weeks under constant light conditions in most cases. These results suggest that AVP but not VIP in the SCN may be involved in the generation of locomotor activity rhythm under conditions of constant light.     

Assessment of ventilation-perfusion mismatching in mechanically ventilated patients

The multiple inert gas elimination technique (MIGET) is a robust tool to assess both ventilation-perfusion (V'A/Q') distributions and the role of extrapulmonary factors determining arterial oxygenation during spontaneous breathing and in mechanically ventilated patients. Mixed expired gas sampling used in the MIGET is most often obtained from a 10-L mixing box (10L-MB) placed in the expiratory side of the ventilator circuit. Consequently, a considerable increase in the compression volume (Vc) would be expected which, in turn, can give rise to potential errors in the estimation of the effective tidal volume delivered to the patient. The effects of the 10L-MB on the Vc were compared with those produced by a newly designed 1-L, mixing box (IL-MB). At a given peak pressure (Ppeak) within the ventilator circuit, the Vc generated by the 10L-MB was about six-times higher than that produced by the 1L-MB. At a Ppeak =50 cmH2O, the Vc were 377 mL (10L-MB) and 67 mL (1L-MB) (p<0.001). In six patients, the mixed expired partial pressures of the six inert gases simultaneously collected from the two mixing boxes fell on the identity line. V'A/Q' distributions recovered using each of the two mixing boxes were equivalent. With the IL-MB, the effects of different positive end-expiratory pressure levels (0, 6 and 12 cmH2O) on Vc and arterial carbon dioxide tension were negligible. In conclusion, the new 1-L mixing box provides efficient gas mixing and substantially decreases the compression volume. It is, therefore, recommended when studies requiring mixed expired gas are performed in ventilated patients.     

Diagnosis of pulmonary infections in mechanically ventilated patients

The optimal management strategy for ventilator-dependent patients who develop symptoms suggestive of lung infection remains controversial. Proponents of the empirical approach prefer to treat most patients with fever and pulmonary infiltrates with one or more new antibiotics, even if it may be difficult (1) to determine whether pneumonia has developed in such patients, (2) in case of infection, to precisely identify the responsible microorganisms and thereby select the optimal antimicrobial treatment, and (3) to avoid resorting to broad-spectrum drug coverage in patients without true infection. Our personal bias is that using bronchoscopic techniques to obtain protected specimen brush and bronchoalveolar lavage specimens from the affected area in the lung permits to devise a therapeutic strategy superior to the one based only on clinical evaluation. These bronchoscopic techniques, when they are performed before new antibiotics are administered, enable physicians to identify most patients who need immediate treatment and select optimal therapy, in a manner that is safe and well tolerated by patients. Furthermore, they frequently permit the clinician to withhold antimicrobial treatment in patients without infection, minimizing the risk of the emergence of resistant microorganisms in the intensive care unit. In patients with clinical evidence of severe sepsis, the initiation of antibiotic therapy should not, however, be delayed while awaiting bronchoscopy, and patients should be given immediate treatment with antibiotics. In that case, "simplified" non-bronchoscopic diagnostic procedures might allow obtaining reliable distal pulmonary secretions for quantitative cultures on a 24-hour basis just before the initiation of a new antimicrobial therapy.     

Rate of decay or increment of PaO2 following a change in supplemental oxygen in mechanically ventilated patients with diffuse pneumonia

It has been shown that patients with COPD require as long as 20 min for equilibration of oxygen tension to occur after changing the fraction of inspired oxygen (FIO2). To date, there have been no studies to determine the equilibration time for the PaO2 in mechanically ventilated patients with diffuse pneumonia. We studied seven patients (five males, two females) with radiographic evidence of diffuse pneumonia. All patients required mechanical ventilation. After introducing a change in FIO2, arterial blood gas values were measured at 5-min intervals for 30 min. Four patients achieved maximal change in PaO2 after 5 min, while four patients required 10 min. These results are similar to those found in patients with left ventricular failure who experience equilibration rapidly; however, patients with COPD experience it at a much slower pace. These observations have clinical importance when managing unstable patients where time is a critical element.     

Radiographic estimation of intracuff pressure in mechanically ventilated patients

We evaluated the usefulness of roentgenographic tracheal tube cuff shadow to tracheal wall diameter ratio (CTW ratio) and cuff minus tracheal diameter difference (C-T diameter) in estimating intracuff pressure (ICP) in intubated and mechanically ventilated patients. Seventy-one measurements of ICP, CTW ratio and C-T diameter were obtained from 20 mechanically ventilated male patients intubated with high volume low pressure cuffs in the surgical and medical intensive care units. The mean age was 61 years (range 30 to 83 years). ICP was measured by one observer, while CTW ratio and C-T diameter was measured by another observer. No significant relationship was seen between ICP and CTW ration (r = 0.092, p = 0.873), or between ICP and C-T diameter (r = 0.093, p = 0.42) by linear regression analysis. In conclusion, roentgenographic estimation of ICP by portable plain chest films in intensive care units was not found useful in this study.     

Endoscopic appearances of hemorrhagic peptic ulcers and efficacy of H2-receptor antagonists

BACKGROUND/AIMS: In this retrospective study, we compared the effects of histamine H2-receptor antagonists to those of antacids and anticholinergics in patients with hemorrhagic ulcers with various endoscopic appearances of bleeding. PATIENTS AND METHODS: Patients with hemorrhagic ulcers (n = 376) were examined by emergency endoscopy and were treated with 1) antacids and anticholinergic drugs or 2) H2-receptor antagonists. RESULTS: In ulcer patients with oozing or fresh red coagulation, H2-receptor antagonists ceased further hemorrhage more effectively (65.9% of the cases) than antacids and anticholinergic drugs (46.7%). In patients with projectile bleeding, both of the treatments failed to stop hemorrhage. There were no significant differences in favorable outcome in the patients only with old black coagulation between antacid and anticholinergic drugs-treated group and H2-receptor antagonists-treated group (94.4% and 93.8%, respectively). CONCLUSIONS: The results suggest that H2-receptor antagonists are more effective than antacids and anticholinergic drugs in patents with peptic ulcer with fresh coagulation or oozing, but not with projectile bleeding or old black coagulation. The results also indicate that endoscopic appearances of peptic ulcer bleeding are good predictors for the effects of medication.     

Ligands of the histamine H3-receptor: new potent antagonists of the 2-thioimidazole type

INTRODUCTION AND OBJECTIVES: The temporal stability of the positive and negative symptoms in schizophrenia deserves a special interest due to its consequences in the outcome and the treatment of the disease. This study determines the temporal stability of positive/negative subtypes in schizophrenia during the acute phase. MATERIAL AND METHODS: This is a clinical, observational and prospective study of a dynamic cohort of patients with acute exacerbation of schizophrenia defined by DSM III-R criteria. Patients with severe and unstable organic pathology, substance dependence, mental organic disorder, mental retardation, depression, or medicamentous parkinsonism were excluded. Clinical assessment was performed with the PANSS scale. Schizophrenic subtypes were established according to inclusive and restrictive criteria of PANSS. All patients were treated with new antipsycotics and biperiden if necessary. RESULTS: 51 patients were assessed for 8 weeks. In the baseline, the negative subtype (63.3% and 52.5% by inclusive and restrictive system respectively) and paranoid form (45.1%) were predominant. Three types of analysis were performed to determine the temporal stability: 1. Concordance (Kappa index). The concordance of the inclusive and restrictive System, regarding to the baseline assessment, indicated that both criteria had a low temporal stability. 2. Mc Nemar Ji Square. This test showed that these changes were bi-directional except for the first visit, which was significant through the restrictive system (higher change from the negative to other subtypes). 3. Transition analysis among groups by First Order Morkov Chains analysis indicated that this change was stationary (the change was the same in all phases). CONCLUSIONS: 1o The variable "time" has to be considered for the definition of subtypes in schizophrenia. 2o The restrictive system is more specific. It allows to identify a subgroup of patients with "Negative" schizophrenia with a high specificity and validity in clinical and epidemiological studies. 3o The use of the baseline visit as a reference (gold standard) is recommended because it exits a higher concordance among criteria and a more florid psychopathology.     

Concealed lung abscess in critically ill, mechanically ventilated patients

This article reports on phenomenological research designed to discover how caring was taught in a nursing education program. The basic questions were: 1) What is the meaning of caring to the faculty and students; 2) How do the faculty communicate this meaning to the students; and 3) How does this meaning shape the experience of the students? Data were collected from a small associate degree nursing program using: a) semi-structured interviews with all faculty and a selected group of students, b) classroom observations, and c) review of documents. Data were analyzed for and found to have content explaining the meaning of caring, how caring was being taught, and what students were learning about caring as the essence of nursing. Implications derived speak to the need for faculty and administrators to have caring as a way of being if they wish to communicate caring as the essence of nursing to students.     

Flow resistance in mechanically ventilated patients with severe neurological injury

In 5 mechanically ventilated patients with severe neurological injury (SNI), we measured the respiratory system's flow resistance (Rrs) over a range of inspiratory flows between 0.2 to 2 L/s, at inflation volumes (delta V) ranging from 0.1 to 1 L. Under baseline ventilatory conditions (V = 1 L/s; delta V = 0.95 L), we also partitioned Rrs into airway resistance (Raw) and the additional resistance offered by the tissues of the lung and chest wall (delta Rrs). At all inflation volumes, Rrs decreased hyperbolically with increasing flow but was higher than in normal anesthetized paralyzed subjects (N). At V of 1 L/s and delta V of 0.5 L, Rrs was significantly greater in SNI than in N (7.7 +/- 1.5 v 4.2 +/- 0.5 cm H2O/L/s; P < .01). This discrepancy was due to higher Raw in SNI. Indeed, at V of 1 L/s, Raw (mean +/- SEM) was significantly higher in SNI than in N (4.0 +/- 0.9 v 2.4 +/- 0.2 cm H2O/L/s; P < .001), whereas delta Rrs did not differ significantly. The increased Raw in SNI was due to the fact that these patients were therapeutically hyperventilated (PaCO2 = 30.4 +/- 4.2 mm Hg) and as a result their airways were bronchoconstricted. We conclude that in the intensive care unit setting, hyperventilated patients with severe neurological injury can not be considered to be adequate controls in terms of Rrs and Raw, because hypocapnia induces an increase of Raw and consequently also in Rrs (= Raw+delta Rrs).     

Impaired gastric emptying in mechanically ventilated, critically ill patients

OBJECTIVE: To measure gastric emptying in critically ill patients using an acetaminophen absorption model and determine which variables are associated with impaired gastric emptying. DESIGN: A prospective, cohort study. SETTING: A medical/surgical ICU at a tertiary care hospital: Hamilton General Hospital, Hamilton, Ontario. PATIENTS AND PARTICIPANTS: We recruited 72 mechanically ventilated patients expected to remain in the ICU for more than 48 h. Our results were compared to those in healthy volunteers. INTERVENTION: Within 48 h of admission to the ICU, 1.6 g acetaminophen suspension were administered via a nasogastric tube into the stomach. Blood samples were drawn a t = 0, 30, 60, 90, and 120 min for measurement of plasma acetaminophen levels determined by the enzymatic degradation method. MEASUREMENTS AND RESULTS: Maximal concentration of acetaminophen was 94.1 (75.3) mumol/l compared to 208.4 (33.1) mumol/l in a control population (p < 0.0001). The time to reach the maximal concentration was 105 min (60-180) compared to 30 min (15-90) in controls (p < 0.0001). The area under the time-acetaminophen concentration curve t = 120 was 9301 (7343) mumol/min per l compared to 11644 (1336) mumol/min per l in the controls (p = 0.28). The variables associated with delayed gastric emptying were age, sex and use of opioids for analgesia and sedation. CONCLUSIONS: Gastric emptying is delayed in critically ill patients. The important consequences of this phenomenon include intolerance to enteral nutrition and gastric colonization. Strategies to minimize the use of narcotics may improve gastric emptying. Studies to examine the effect of gastrointestinal prokinetic agents on gastric emptying are needed.     

Ultrasonographic bedside evaluation of maxillary sinus disease in mechanically ventilated patients

GABA modulates dopamine concentrations in the nucleus accumbens and corpus striatum. Using in vivo microdialysis techniques we examined this modulatory role and the extent to which three different GABAergic drugs can attenuate cocaine's ability to increase extracellular dopamine concentrations and gross locomotor activity. Ethanol, lorazepam (Ativan), and gamma-vinyl GABA (GVG) significantly and dose-dependently attenuated cocaine-induced dopamine release in the corpus striatum of freely moving animals. Unlike ethanol or lorazepam, however, GVG is not a sedative hypnotic in the doses used, and hence the strategy of selectively increasing GABAergic activity by suicide inhibition of the catabolic enzyme, GABA-transaminase, offers the unique advantage of attenuating cocaine-induced dopamine release without the apparent side effects typically associated with sedative hypnotics.     

Effects of tracheal suctioning on respiratory resistances in mechanically ventilated patients

OBJECTIVE: To evaluate the effects of tracheal suctioning (TS) on respiratory resistances in sedated critical care patients receiving mechanical ventilation (MV). SETTING: Surgical ICU of Bichat Hospital, Paris. PATIENTS AND PARTICIPANTS: Thirteen sedated critical care patients receiving MV for various conditions. MEASUREMENTS AND RESULTS: Airway resistances (R1), airway and pulmonary resistances (R2), and intrinsic positive end-expiratory pressure (PEEPint) were measured according to the end-inspiratory and end-expiratory occlusion methods before and after TS. R1 and R2 increased by 49.1% and 46.3%, respectively, 0.5 min after TS (p<0.01) but returned to baseline values at 1 min without any change thereafter. PEEPint decreased progressively following TS to reach a significant level (-13.3%) at 10 min (p<0.05) and was persistently reduced at 30 min (p<0.01). Nine patients received 500 microg of inhaled albuterol before another suctioning procedure. R1 and R2 decreased by 11.5% and 9.9%, respectively, 20 min after inhalation (p<0.05), but the R1 and R2 initial increase following TS did not differ between the two suctioning procedures. CONCLUSIONS: TS evokes only a transient bronchoconstrictor response, but thereafter, does not reduce respiratory resistances below presuctioning values. However, the decrease of PEEPint following TS suggests an increase of expiratory flow. Effective beta2-adrenergic receptor blockade fails to suppress the TS-induced bronchoconstrictor response.     

Changes in pulmonary mechanics after fiberoptic bronchoalveolar lavage in mechanically ventilated patients

We describe perinatal findings in a female fetus with partial trisomy 8q(8q24.1-->8qter) and partial monosomy 15q(15q26.1-->15qter) resulting from a paternal t(8;15) reciprocal translocation. Prenatal sonographic examination showed intra-uterine growth retardation, bilateral ventriculomegaly, cardiomegaly with arrhythmia, anhydramnios, and absent kidney and urinary bladder images. The pregnancy was terminated at 28 weeks of gestation. At birth, the infant manifested typical dysmorphic features of partial trisomy 8q. Necropsy further revealed hydrocephalus, congenital diaphragmatic hernia, ventricular septal defect, a horseshoe kidney with renal hypoplasia, and kyphoscoliosis. Our case shows that the coexistence of partial trisomy 8q24.1-->8qter and partial monosomy 15q26.1-->15qter are more detrimental than either defect alone and can result in a complex of major malformations. Prenatal ultrasound examination and cytogenetic assessment should be offered in subsequent pregnancies.     

Quantification of aortic stenosis in mechanically ventilated patients using multiplane transesophageal Doppler echocardiography

OBJECTIVE: The development of sudden postoperative hearing loss as a complication of microvascular decompression (MVD) operations in the cerebellopontine angle has already been reported. A sudden hearing loss of vascular origin may also occur hours or days after such operations, but even in such cases an improvement of hearing over the following weeks is possible. Here we report on a gradual deterioration of hearing over a period of two weeks after MVD which has not been described in the literature up to now. CLINICAL PRESENTATION: A MVD operation was performed twice on a 36 year old patient with trigeminal neuralgia. After the second operation the patient developed a slight hearing impairment 3 days postoperatively which increased over a period of two weeks and ended up with total deafness. The course of intra-operative brainstem auditory evoked potentials and postoperative audiograms is documented. CONCLUSION: Because of gradual development of the delayed hearing loss, we conclude that postoperative tissue scarring may be the underlying pathology.