Predictors of successful extubation in neurosurgical patients.

A respiratory therapist-driven weaning protocol incorporating daily screens, spontaneous breathing trials (SBT), and prompts to caregivers has been associated with superior outcomes in mechanically ventilated medical patients. To determine the effectiveness of this approach in neurosurgical (NSY) patients, we conducted a randomized controlled trial involving 100 patients over a 14-mo period. All had daily screens of weaning parameters. If these were passed, a 2-h SBT was performed in the Intervention group. Study physicians communicated positive SBT results, and the decision to extubate was made by the primary NSY team. Patients in the Intervention (n = 49) and Control (n = 51) groups had similar demographic characteristics, illness severity, and neurologic injuries. Among all patients, 87 (45 in the Control and 42 in the Intervention group) passed at least one daily screen. Forty (82%) patients in the Intervention group passed SBT, but a median of 2 d passed before attempted extubation, primarily because of concerns about the patient's sensorium (84%). Of 167 successful SBT, 126 (75%) did not lead to attempted extubation on the same day. The median time of mechanical ventilation was 6 d in both study groups, and there were no differences in outcomes. Overall complications included death (36%), reintubation (16%), and pneumonia (9%). Tracheostomies were created in 29% of patients. Multivariate analysis showed that Glasgow Coma Scale (GCS) score (p < 0.0001) and partial pressure of arterial oxygen/fraction of inspired oxygen ratio (p < 0.0001) were associated with extubation success. The odds of successful extubation increased by 39% with each GCS score increment. A GCS score > or = 8 at extubation was associated with success in 75% of cases, versus 33% for a GCS score < 8 (p < 0.0001). Implementation of a weaning protocol based on traditional respiratory physiologic parameters had practical limitations in NSY patients, owing to concerns about neurologic impairment. Whether protocols combining respiratory parameters with neurologic measures lead to superior outcomes in this population requires further investigation.

Self-reported health status predictors of healthcare services utilization and charges in elderly asthmatic patients.

This study examined the associations between self-reported health status predictors and healthcare service utilization in a cohort of elderly asthmatic patients. The results of the study showed a strong association among self-reported prior healthcare utilization, comorbidities, patient's perception of health status, and self-reported quality of life with healthcare service utilization and charges. A large amount of variance in healthcare service utilization and charges in this population was explained by these factors. Patient's self-reported health status could be important in earlier detection of high-risk older adults with asthma, and targeting them for disease management interventions.

Cell-specific expression of group X and group V secretory phospholipases A(2) in human lung airway epithelial cells.

Secretory phospholipase A(2) (sPLA(2)) enzymes contribute to inflammatory injury in human lungs by several mechanisms, including eicosanoid production and hydrolytic damage to surfactant phospholipids. Several distinct sPLA(2) genes have been described in human tissue but little is known regarding their presence, localization, or function(s) within lungs. We hypothesized that sPLA(2)s would have cell-specific distributions within lung. We used reverse transcriptase/polymerase chain reaction to identify sPLA(2) messenger RNAs (mRNAs) in adult human lung tissue. Resulting complementary DNA (cDNA) sequences indicated that total lung extracts contained mRNA for Groups IB, IIA, V, and X sPLA(2). An epithelial cell line, BEAS cells, expressed only Groups IIA, V, and X. We used these cDNAs to clone these enzymes, especially the recently described Group X and Group V enzymes. Digoxigenin-labeled complementary RNA probes were used to determine localization of each sPLA(2) by in situ hybridization of human lung. Hybridization was strongly positive for Group X and Group V in airway epithelial cells, which failed to hybridize Group IB or IIA probes. Although four known mammalian sPLA(2) isotypes were expressed in lung, only Group X and Group V sPLA(2) mRNAs appear uniquely expressed in airway epithelium, suggesting they could provide a mechanism of pulmonary surfactant hydrolysis during lung injury.

Education of physicians-in-training can decrease the risk for vascular catheter infection.

BACKGROUND: Procedure instruction for physicians-in-training is usually nonstandardized. The authors observed that during insertion of central venous catheters (CVCs), few physicians used full-size sterile drapes (an intervention proven to reduce the risk for CVC-related infection). OBJECTIVE: To improve standardization of infection control practices and techniques during invasive procedures. DESIGN: Nonrandomized pre-post observational trial. SETTING: Six intensive care units and one step-down unit at Wake Forest University Baptist Medical Center, Winston-Salem, North Carolina. PARTICIPANTS: Third-year medical students and physicians completing their first postgraduate year. INTERVENTION: A 1-day course on infection control practices and procedures given in June 1996 and June 1997. MEASUREMENTS: Surveys assessing physician attitudes toward use of sterile techniques during insertion of CVCs were administered during the baseline year and just before, immediately after, and 6 months after the first course. Preintervention and postintervention use of full-size sterile drapes was measured, and surveillance for vascular catheter-related infection was performed. RESULTS: The perceived need for full-size sterile drapes was 22% in the year before the course and 73% 6 months after the course (P < 0.001). The perceived need for small sterile towels at the insertion site decreased reciprocally (P < 0.001). Documented use of full-size sterile drapes increased from 44% to 65% (P < 0.001). The rate of catheter-related infection decreased from 4.51 infections per 1000 patient-days before the first course to 2.92 infections per 1000 patient-days 18 months after the first course (average decrease, 3.23 infections per 1000 patient-days; P < 0.01). The estimated cost savings of this 28% decrease was at least $63000 and may have exceeded $800000. CONCLUSIONS: Standardization of infection control practices through a course is a cost-effective way to decrease related adverse outcomes. If these findings can be reproduced, this approach may serve as a model for physicians-in-training.

Venous air embolism from central venous catheterization: a need for increased physician awareness.

OBJECTIVES: To report a series of patients with clinically diagnosed venous air embolism (VAE) and major sequelae as a complication of the use of central venous catheters (CVCs), to survey health care professionals' practices regarding CVCs, and to implement an educational intervention for optimizing approaches to CVC insertion and removal. SETTING: Tertiary care, university-based 806-bed medical center. INTERVENTIONS: We surveyed 140 physicians and 53 critical care nurses to appraise their awareness of the proper management and complications of CVCs. We then designed, delivered, and measured the effects of a multidisciplinary educational intervention given to 106 incoming house officers. MEASUREMENTS AND MAIN RESULTS: Although most physicians (127, 91%) chose the Trendelenburg position for CVC insertion, only 42 physicians (30%) reported concern for VAE. On CVC removal, only 36 physicians (26%) cited concern for VAE. Some physicians (13, 9%) reported elevating the head of the bed during CVC removal, possibly increasing the risk of VAE. Awareness of VAE or its prevention did not correlate with the level of physician training, experience, or specialty. After the educational intervention, concern for and awareness of proper methods of prevention of VAE improved (p < .001). At 6-month follow-up, reported use of the Trendelenburg position continued, but concern cited for VAE had returned to baseline. CONCLUSIONS: There is inadequate awareness of VAE as a complication of CVC use. Focused instruction can improve appreciation of this potentially fatal complication and knowledge of its prevention, but the effect declines rapidly. To achieve a more sustained improvement, a more intensive, hands-on, periodic educational program will likely be necessary, as well as reinforcement through enhanced supervision of CVC insertion and removal practices.

Nosocomial pneumonia in the ICU--year 2000 and beyond.

Diagnostic and treatment strategies in ICU patients with ventilator-associated pneumonia (VAP) remain controversial, largely because of the paucity of well-controlled comparison trials using clinically important end points. Recent studies indicating that early appropriate antibiotic therapy significantly lowers mortality underscore the urgent need for well-designed comparative trials. When quantitatively cultured, bronchial specimens obtained by noninvasive techniques may provide clinically useful information and avoid the higher costs and risks of invasive bronchoscopic diagnostic techniques. Previous antibiotic use before onset of nosocomial pneumonia raises the likelihood of infection with highly virulent organisms, such as Pseudomonas aeruginosa and Acinetobacter sp. Thus, the empiric antibiotic regimen should be active against these Gram-negative pathogens as well as other common Gram-negative and Gram-positive causative organisms. Promising preventive modalities for nosocomial VAP include use of a semirecumbent position, endotracheal tubes that allow continuous aspiration of secretions, and heat and moisture exchangers. Rotating their standard empiric antibiotic regimens and restricting the use of third-generation cephalosporins as empiric therapy may help hospitals reduce the incidence of nosocomial pneumonia caused by resistant Gram-negative pathogens.

Large scale implementation of a respiratory therapist-driven protocol for ventilator weaning.

We prospectively investigated the large-scale implementation of a respiratory-therapist-driven protocol (TDP) that included 117 respiratory care practitioners (RCPs) managing 1,067 patients with respiratory failure over 9,048 patient days of mechanical ventilation. During a 12-mo period, we reintroduced a previously validated protocol that included a daily screen (DS) coupled with spontaneous breathing trials (SBTs) and physician prompt, as a TDP without daily input from a physician or "weaning team." With graded, staged educational interventions at 2-mo intervals, RCPs had a 97% completion rate and a 95% correct interpretation rate for the DS. The frequency with which patients who passed the DS underwent SBTs increased throughout the implementation process (p < 0.001). As the year progressed, RCPs more often considered SBTs once patients had passed a DS (p < 0.001), and physicians ordered more SBTs (46 versus 65%, p = 0.004). Overall, SBTs were ordered more often on the medicine than on the surgical services (81 versus 63%, p = 0.001), likely reflecting medical intensivists' prior use of this protocol. Important barriers to protocol compliance were identified through a questionnaire (89 respondents, 76%), and included: Physician unfamiliarity with the protocol, RCP inconsistency in seeking an order for an SBT from the physician, specific reasons cited by the physician for not advancing the patient to a SBT, and lack of stationary unit assignments by RCPs performing the protocol. We conclude that implementation of a validated weaning strategy is feasible as a TDP without daily supervision from a weaning physician or team. RCPs can appropriately perform and interpret DS data more than 95% of the time, but significant barriers to SBTs exist. Through a staged implementation process, using periodic reinforcement of all participants in ventilator management, improved compliance with this large-scale weaning protocol can be achieved.

Radiographic assessment of hyperinflation: correlation with objective chest radiographic measurements and mechanical ventilator parameters.

BACKGROUND: Pulmonary barotrauma is a potentially fatal complication of positive pressure ventilation. We previously found that barotrauma occurred in patients with radiographic hyperinflation, but few objective data define the relationships among hyperinflation, objective chest radiograph (CXR) measurements, ventilator parameters, and development of barotrauma. OBJECTIVES: We sought (1) to assess the relationships among hyperinflation, objective CXR findings, mechanical ventilator parameters, and development of barotrauma. (2) To compare radiographic hyperinflation, ventilator parameters, and incidence of barotrauma in a current group of ICU patients with historical control subjects. SETTING: Medical and surgical ICU patients in a university hospital. DESIGN: Prospective blinded observational study; comparison of current series with historical control subjects. METHODS: One hundred two prospectively enrolled mechanically ventilated medical and surgical ICU patients each received portable supine CXRs that were reviewed independently by three radiologists who made objective measurements and subjectively determined the likelihood of hyperinflation. Ventilator parameters were recorded at the bedside at the time each CXR was obtained. CXR measurements and ventilator parameters were then related to the development of barotrauma during the course of ventilation and compared with findings of a prospective study at our institution 1 year earlier. RESULTS: Radiographically recognizable hyperinflation occurred in 18 of 102 mechanically ventilated ICU patients (18%) and correlated with lung length (24.7 vs 19.8 cm; p<0.05) and the anterior rib number that intersects the hemidiaphragm (5.4 vs 4.7; p<0.05). Patients with hyperinflation were ventilated at higher tidal volume per kilogram (VT/kg) (11.0 vs 9.4; p=0.0081), but peak airway pressure, plateau pressure, and positive end-expiratory pressure were similar. There were significant decreases in VT (810 vs 739 mL; p=0.015) and VT/kg (11.0 vs 10.1 mL/kg; p<0.001) in these mechanically ventilated ICU patients in comparison to hospital control subjects evaluated during the previous year. Paralleling these changes was a decrease in the frequency of CXR hyperinflation (p=0.003) and the incidence of ventilator-associated barotrauma (6.5% vs 0.98%; p=0.048). CONCLUSIONS: Ventilation at higher VT/kg is associated with a higher incidence of CXR hyperinflation. Radiographic hyperinflation is associated with lung length > or =24.7 cm and visualization of the sixth anterior rib. Patients with hyperinflation may be at greater risk for developing barotrauma or volutrauma. Ventilatory strategies utilizing lower volumes are associated with a lower incidence of such trauma in the current sample as compared with historical control subjects.

Skin sensitivity to allergen does not accurately predict airway response to allergen.

BACKGROUND: Allergen challenge of the asthmatic airway has become widely applied in the study of allergic asthma in humans. Skin sensitivity correlates with inhaled sensitivity in some populations. Skin test titration has been proposed as a useful tool to guide the selection of initial allergen concentration. OBJECTIVE: To determine the relationship between skin test sensitivity and inhaled reactivity to allergen. METHODS: We examined the relationship between skin test and inhaled reactivity in 22 allergic asthmatic subjects. Methacholine bronchoprovocation was performed using a standardized tidal breathing technique. Prick skin test titrations were done using serially diluted lyophilized antigen extracts reconstituted in normal saline from 1:100,000 to 1:10. Inhaled allergen challenge was routinely performed in the morning using the same allergen employed in skin test titration. RESULTS: There was no correlation between skin test threshold and the inhaled concentration required to produce a 20% fall in FEV1 (r = 0.07; P = .78). If subjects who manifested marked cutaneous reactivity (i.e., skin reactivity at dilutions greater than 1:10,000) were excluded from analysis, there was a significant correlation between cutaneous and inhaled reactivity (r = 0.84; P < .001). CONCLUSION: While a correlation between skin test threshold and inhaled reactivity is present in some subjects with allergic asthma, the relationship is inconsistent.

Phospholipase A2 and arachidonate increase in bronchoalveolar lavage fluid after inhaled antigen challenge in asthmatics.

Phospholipases A2 (PLA2) hydrolyze phospholipids resulting in the release of fatty acids including arachidonic acid (AA) and lysophospholipids. AA, in turn, serves as a substrate for the synthesis of leukotrienes which can cause bronchoconstriction and airways edema and appear to be important mediators of clinical asthma. Further, lysophospholipids may be cytotoxic and/or impair the function of surfactant. We examined the release of secretory PLA2 (sPLA2) and AA into the airways after antigen challenge in 16 subjects with allergic asthma. Asthmatic subjects underwent bronchoscopy with bronchoalveolar lavage (BAL) before and after inhaled antigen challenge; in addition, a single BAL, without inhaled antigen, was performed in 10 control subjects. BAL was obtained at 4 h (n = 7), the time of the late asthmatic response (LAR) (n = 5), or 24 h (n = 4) after challenge. There was no difference between normal and asthmatic subjects in either BAL fluid (BALF) sPLA2 activity or AA concentration at baseline. Both sPLA2 and AA increased after antigen challenge (p < 0.01 and 0.05, respectively). These changes were most marked 4 h after challenge (p < 0.03 for both). sPLA2 may play an important role in the generation of AA in patients with asthma.

Effect on the duration of mechanical ventilation of identifying patients capable of breathing spontaneously.

BACKGROUND: Prompt recognition of the reversal of respiratory failure may permit earlier discontinuation of mechanical ventilation, without harm to the patient. METHODS: We conducted a randomized, controlled trial in 300 adult patients receiving mechanical ventilation in medical and coronary intensive care units. In the intervention group, patients underwent daily screening of respiratory function by physicians, respiratory therapists, and nurses to identify those possibly capable of breathing spontaneously; successful tests were followed by two-hour trials of spontaneous breathing in those who met the criteria. Physicians were notified when their patients successfully completed the trials of spontaneous breathing. The control subjects had daily screening but no other interventions. In both groups, all clinical decisions, including the decision to discontinue mechanical ventilation, were made by the attending physicians. RESULTS: Although the 149 patients randomly assigned to the intervention group had more severe disease, they received mechanical ventilation for a median of 4.5 days, as compared with 6 days in the 151 patients in the control group (P=0.003). The median interval between the time a patient met the screening criteria and the discontinuation of mechanical ventilation was one day in the intervention group and three days in the control group (P<0.001). Complications -- removal of the breathing tube by the patient, reintubation, tracheostomy, and mechanical ventilation for more than 21 days -- occurred in 20 percent of the intervention group and 41 percent of the control group (P=0.001). The number of days of intensive care and hospital care was similar in the two groups. Total costs for the intensive care unit were lower in the intervention group (median, $15,740, vs. $20,890 in the controls, P=0.03); hospital costs were lower, though not significantly so (median, $26,229 and $29,048, respectively; P=0.3). CONCLUSIONS: Daily screening of the respiratory function of adults receiving mechanical ventilation, followed by trials of spontaneous breathing in appropriate patients and notification of their physicians when the trials were successful, can reduce the duration of mechanical ventilation and the cost of intensive care and is associated with fewer complications than usual care.

Chest X-ray changes in air space disease are associated with parameters of mechanical ventilation in ICU patients.

To assess relationships between parameters of mechanical ventilation (MV) and portable chest X-ray (CXR) measurements of lung length (LL) and severity of air space disease, a prospective, randomized, blinded comparison of 102 adults in a university hospital was performed. Each patient received two portable, supine CXRs on different MV breaths within 5 min of one another. Ventilator parameters were recorded. All 204 CXRs were randomly assorted and read independently by three radiologists. Air space disease was considered more severe with pressure support ventilation (PSV) breaths than with intermittent mandatory ventilation (IMV) breaths (p = 0.0003), and its extent correlated inversely with static compliance (p = 0.0001, r = -0.40). Among patients having CXRs on both IMV and PSV breaths, 15 of 67 (22%) had their overall degree of air space disease read differently by one category (mild, moderate, or severe). Increases in LL between the two CXRs were associated with increasing peak (p = 0.0038) or mean (p = 0.0065) airway pressure, tidal volume (VT) (p = 0.022), and VT per kilogram (p = 0.006). We conclude that lung volume changes during MV, typically not noted nor controlled for during portable chest radiography, may substantially alter the interpretation of air space disease and LL. Physicians monitoring intensive care unit (ICU) patients with daily CXRs should be aware of the variables influencing interpretation of portable CXRs of ICU patients.

Gamma radiation-sterilized, triple-lumen catheters coated with a low concentration of chlorhexidine were not efficacious at preventing catheter infections in intensive care unit patients.

In a randomized, double-blind trial, gamma radiation-sterilized, chlorhexidine-coated triple-lumen catheters were compared with uncoated control catheters for their ability to prevent catheter infection in 254 intensive care unit patients. The chlorhexidine coating was not efficacious, and a rabbit model demonstrated that reduction of chlorhexidine activity by gamma radiation sterilization was the likely explanation for the failure.

Pulmonary section development influences general medical house officer interests and ABIM certifying examination performance.

To determine whether sectional development in pulmonary and critical care medicine influences medical house officers' (HO) interests and knowledge about respiratory medicine, we reviewed HO performance on the American Board of Internal Medicine (ABIM) certifying examination during 4 years before and 5 years after reorganization of our section. After major changes in the program and introduction of new educational opportunities, HOs more often selected pulmonary consultation electives (68.6% vs 47.8%; p = 0.009) and entered pulmonary fellowships after completion of residency training (12% vs 3%; p = 0.047). Total ABIM examination score did not change, but performance on its respiratory disease component improved from a median national percentile score of 48.5% (1986 to 1989) to 80.0% (1990 to 1994) (p = 0.0365). In relation to other specialty component scores, the rank of the respiratory disease percentile improved from the lowest specialty score to the highest. ABIM examination scores correlated with the cumulative faculty effort directed toward HO teaching (r = 0.70; p = 0.04) and the total number of clinical teachers (faculty and fellows) interacting with HOs (r = 0.73; p = 0.02). Academic development in pulmonary/critical care faculty has an important influence on medical HO interests in and knowledge of that discipline. Plans for the future structure of academic pulmonary/critical care sections must take into account this impact on the training of generalists. Although institutional priorities, resources, and shifting external forces will define how, where, and by whom respiratory medicine will be taught, an appropriate number of faculty members and sufficient commitment of their time to HO education must be preserved.

Comparison of the infusion requirements and recovery profiles of vecuronium and cisatracurium 51W89 in intensive care unit patients.

The selection and administration of neuromuscular blocking (NMB) drugs in intensive care unit (ICU) patients remain controversial. We compared the dose-response and recovery pharmacodynamics of a new intermediate-acting NMB drug, cisatracurium besylate, to the intermediate-acting NMB drug, vecuronium (VEC), in a prospective, randomized, double-blind, multicenter study in critically ill adults. After informed consent, 58 mechanically ventilated ICU patients from five medical centers were randomized to receive either cisatracurium or VEC. Fifty-four of the 58 patients received NMB drugs before entering this study but demonstrated at least partial recovery (> or = one twitch) in the train-of-four (TOF) response before initiation of the NMB study drug. NMB drug infusion was titrated by peripheral nerve stimulation to maintain at least one twitch in the TOF response. NMB drugs were infused for 1-5 days. After discontinuation of NMB drug infusion, recovery of neuromuscular transmission was monitored with an accelerometer. NMB drug infusion for 28 cisatracurium patients averaged 2.6 +/- 0.2 (mean +/- SEM) micrograms.kg-1.min-1 with a mean duration of 80 +/- 7 h. After discontinuing cisatracurium administration, recovery to 70% TOF ratio averaged 68 +/- 13 min. The mean infusion rate for 30 VEC patients was 0.9 +/- 0.1 micrograms.kg-1.min-1 with a mean duration of 66 +/- 12 h. Neuromuscular recovery after VEC averaged 387 +/- 163 min, which was significantly longer (P = 0.02) than that after cisatracurium. Prolonged recovery of neuromuscular function after discontinuation of NMB drug infusion (identified by the primary investigator at each medical center) was reported in two cisatracurium patients and 13 VEC patients (P = 0.002), and occurred despite the routine use of neuromuscular twitch monitoring. Seven VEC and one cisatracurium patients died during the infusion of study drug or within 48 h after discontinuation of the NMB drug infusion. In summary, we found recovery of neuromuscular function after discontinuation of NMB drug infusion in ICU patients is significantly faster with cisatracurium than with VEC. In addition, routine neuromuscular monitoring was not sufficient to eliminate prolonged recovery and myopathy in ICU patients.

Education and experience improve transbronchial needle aspiration performance.

To determine whether the diagnostic yield of transbronchial needle aspiration (TBNA) improves over time and to obtain insights about factors influencing its performance, we reviewed our experience during a 3-yr period. After serial multifaceted educational interventions directed toward bronchoscopists and their technical staff, TBNA yield increased significantly from 21.4 to 47.6% (p < 0.001). More frequent and more detailed notations in bronchoscopy reports (p < 0.05), a lower frequency of cytopathology specimens contaminated by endobronchial material (p < 0.05), and higher yields in patients with small cell carcinoma (p < 0.01) suggested that bronchoscopists' TBNA proficiency had increased. More frequent diagnoses with small cell carcinoma and fewer cytologically unsatisfactory specimens (p < 0.01) suggested that education of bronchoscopy technicians, and use of a direct smear technique for specimen preparation also contributed to improved TBNA yield. Increased experience with TBNA and focused education regarding its performance can enhance the role of this procedure in diagnosis and staging of patients with lung cancer.

Decision making in nosocomial pneumonia. An analytic approach to the interpretation of quantitative bronchoscopic cultures.

Quantitative cultures of specimens obtained at fiberoptic bronchoscopy have been used to diagnose nosocomial pneumonia in research settings, but their clinical role remains controversial. We reviewed the literature comparing these culture techniques with other accepted methods to diagnose pneumonia in mechanically ventilated patients and extracted data to describe the receiver operator characteristics (ROC) of quantitative cultures of protected specimen brush (PSB) and bronchoalveolar lavage (BAL) samples. Analysis of ROCs reveals that these tests have a discriminating power comparable or superior to that of many widely accepted routinely used tests. Current data do not suggest that either culture technique offers an advantage over the other. Since benefits of antibiotic therapy of pneumonia and risks of treatment of noninfected critically ill patients are not well quantified, universally applicable recommendations for appropriate values to define an abnormal test result cannot logically be made. Multiple decision analytic tools show that values lower than those previously recommended are more appropriate in patients suspected of having pneumonia unless the risk of antibiotic therapy is judged to be extreme. On the basis of these findings, we suggest guidelines for clinicians' interpretation of PSB and BAL quantitative culture results.