Rescue high frequency ventilation for congenital diaphragmatic hernia.

INTRODUCTION: High frequency jet (HFJV) and oscillatory (HFOV) ventilation were used to rescue newborns with congenital diaphragmatic hernia (CDH), who failed conventional mechanical ventilation (CV). Changes in ventilator settings and pulmonary gas exchange were evaluated following transition to high frequency ventilation (HFV). METHODS: Records of patients with CDH rescued with HFV prior to surgical intervention between 2006 and 2015 were reviewed. Mean airway pressure (Paw) and arterial blood gases during CV and those obtained within the first hour of HFV were compared. A composite repeated measure analysis was performed to evaluate longitudinal and intergroup variances. RESULTS: Twenty-seven patients were rescued from CV, 16 by HFJV and 11 by HFOV. The two groups had similar gestational ages and birth weights. Prior to HFV, both groups had similar Paw, PaCO2, FiO2 and PaO2. HFV was associated with a significant improvement in ventilation, and the rate of decrease of PaCO2 was no different between groups. There was a significantly higher increase in Paw increase with HFOV compared to HFJV. CONCLUSIONS: In newborns with CDH rescued with HFV, ventilation improved but Paw was significantly lower in patients supported with HFJV compared to HFOV.

Does hyperglycemia in hypernatremic preterm infants increase the risk of intraventricular hemorrhage?

OBJECTIVE: Hypernatremia and hyperglycemia are highly prevalent in preterm infants during the first week after birth, and both can lead to hyperosmolarity and osmotic shifts. The objective is to determine whether hyperglycemia increases the risk of intraventricular hemorrhage (IVH) in hypernatremic preterm infants. STUDY DESIGN: Single-center retrospective medical record review of 216 infants <1000 g birth weight and <29 weeks gestational age (admitted over a 9-year period) who had serum sodium levels and blood glucose levels monitored at least every 24 h and more frequently if indicated during the first 10 days after birth. Hyperglycemia was defined as persistently high blood glucose (usually >200 mg dl(-1)) treated with an insulin infusion. Hypernatremia was defined as a serum sodium level of ⩾150 mmol l(-1) on repeated measurements. RESULTS: Of the 216 infants studied, 76 (35%) developed hyperglycemia and 126 (58%) developed hypernatremia. IVH developed more frequently in infants with hyperglycemia (P=0.006, odds ratio (OR) 2.3, 95% confidence interval (CI) 1.3 to 4.1), in infants with hypernatremia (P=0.018, OR 2.0, 95% CI 1.2 to 3.5) and in infants with hypernatremia plus hyperglycemia (P=0.001, OR 3.2, 95% CI 1.6 to 6.4). Multivariate regression analysis confirmed the independent association of higher risk of IVH with the presence of hypernatremia plus hyperglycemia (P=0.015, OR 2.6, 95% CI 1.2 to 5.5) but not with hypernatremia or hyperglycemia alone. CONCLUSION: Hyperglycemia increases the risk of IVH in hypernatremic preterm infants.

Impact of warmed inhaled gas from the mechanical ventilator on esophageal temperature during therapeutic whole body hypothermia.

OBJECTIVE: During therapeutic whole body cooling (WBC), the core temperature is usually monitored with an esophageal probe. Most infants receive mechanical ventilation while being cooled. As the temperature in the esophagus responds rapidly to changes in the ambient temperature, inhalation of warmed gas from ventilator may lead to overestimation of ventilated patients' actual temperature, causing automated cooling devices to overcool patients well below the desired set temperature targets. To determine if the esophageal temperature recordings during therapeutic WBC differ between ventilated and non-ventilated infants. STUDY DESIGN: Twenty-two consecutively cooled infants had simultaneous esophageal and rectal temperatures recorded every 4 h during 72 h of WBC. Other clinical monitoring and treatment during hypothermia were provided under an established protocol. RESULTS: Fourteen infants received mechanical ventilation throughout the duration of cooling. The remaining eight infants were initially ventilated but were extubated later and were not on ventilator between 32 and 72 h of WBC. The esophageal temperatures across every 4 h time points during the 32-72 h interval of WBC did not differ between the ventilated and non-ventilated infants. The magnitude (median, interquartile range) of the difference between esophageal and rectal temperatures was also similar between the two groups. CONCLUSION: Warmed inhaled gas does not interfere with the esophageal temperature during WBC.

Do prenatal steroids improve the survival of late preterm infants with complex congenital heart defects?

AIM: We evaluated the use of prenatal steroids (PNS) and the effect of that practice on hospital mortality of late preterm infants with complex congenital heart defects (CHD). METHODS: Retrospective review of records of late preterm infants with complex CHD infants that were cared for in a single tertiary perinatal center between 2002 and 2009. Multivariate logistic regression analysis was performed to determine which of the risk factors commonly associated with death prior to discharge from the hospital predict the outcome (hospital death). RESULTS: Of the 106 late preterm infants with complex CHD, 31(29%) died and 15 (14%) received PNS. Endotracheal intubation in the delivery room (42% vs 15%), necrotizing enterocolitis (10% vs 0%) and hypoplastic left heart syndrome (52% vs 25%) were statistically more frequent in non-surviving infants. Non-surviving infants were more frequently treated with PNS (23% vs 11%) but this difference was not statistically significant (p = 0.131). Using logistic regression analysis, delivery room intubation (OR 4.91; 95% CI 1.78 - 13.51) and the hypoplastic left heart syndrome (OR 3.29; 95% CI 1.28 - 8.48), but not prenatal steroids were independently associated with increased risk of hospital death. CONCLUSIONS: In a selected population of late preterm infants with complex CHD, prenatal steroid treatment did not independently influence survival.

Does clinical status 1 week after therapeutic hypothermia predict brain MRI abnormalities?

OBJECTIVE: Hypothermia improves clinical outcomes and brain magnetic resonance imaging (MRI) findings in infants with hypoxic-ischemic encephalopathy. We hypothesized that clinical status following hypothermia predicts brain MRI abnormalities, and helps determine which infants need an early MRI evaluation before discharge. The objective of this study was to determine whether the clinical evaluation 1 week after completion of 72 h of hypothermia treatment predicts the presence of brain MRI abnormalities related to hypoxia-ischemia. STUDY DESIGN: The medical records of 83 consecutively cooled infants who underwent brain MRI were reviewed. Clinical evaluation by day 10 of life consisted of assessment of oral feeding ability, spontaneous activity, need for mechanical ventilation and a history of clinical seizures. Logistic regression analysis was performed using all four covariates, with an abnormal MRI as the primary outcome. Brain MRI with lesions in both the basal nuclei and the cortex was considered to be severely abnormal. RESULT: MRI was abnormal in 46 (55%) infants. Univariate analysis identified all of the criteria as being significantly associated with an abnormal MRI. On multivariate analysis, only feeding difficulty (P<0.001, OR 9.5, 95% confidence interval (CI) 3 to 29.8) and a history of clinical seizures (P<0.001, OR 12, 95% CI 3 to 46.5) were significantly associated with an abnormal MRI. The areas under the receiver operating characteristic curve for feeding ability and seizure activity combined (0.86, 95% CI 0.77 to 0.94) indicated good accuracy with respect to the primary outcome. The negative predictive values of feeding difficulty and seizure activity for a severely abnormal MRI were 91% and 96%, respectively. CONCLUSION: Infants who do not have a history of clinical seizures and who attained full oral feeding by 1 week after hypothermia are unlikely to have an abnormal brain MRI. This simple assessment provides significant prognostic information that can be useful in parental counseling, and may allow selective use of pre-discharge MRI.

Does phenobarbital improve the effectiveness of therapeutic hypothermia in infants with hypoxic-ischemic encephalopathy?

OBJECTIVE: To determine whether phenobarbital (PB) given before therapeutic hypothermia to infants with hypoxic-ischemic encephalopathy (HIE) augments the neuroprotective efficacy of hypothermia. STUDY DESIGN: Records of 68 asphyxiated infants of 36 weeks' gestation, who received hypothermia for moderate or severe HIE were reviewed. Some of these infants received PB prophylactically or for clinical seizures. All surviving infants had later brain magnetic resonance imaging (MRI). The composite primary outcome of neonatal death related to HIE with worsening multiorgan dysfunction despite maximal treatment, and the presence of post-hypothermia brain MRI abnormalities consistent with hypoxic-ischemic brain injury, were compared between the infants who received PB before initiation of hypothermia (PB group, n=36) and the infants who did not receive PB before or during hypothermia (No PB group, n=32). Forward logistic regression analysis determined which of the pre-hypothermia clinical and laboratory variables predict the primary outcome. RESULT: The two groups were similar for severity of asphyxia as assessed by Apgar scores, initial blood pH and base deficit, early neurologic examination, and presence of an intrapartum sentinel event. The composite primary outcome was more frequent in infants from the PB group (PB 78% versus No PB 44%, P=0.006, odds ratio 4.5, 95% confidence interval 1.6 to 12.8). Multivariate analysis identified only the PB receipt before initiation of hypothermia (P=0.002, odds ratio 9.5, 95% confidence interval 2.3 to 39.5), and placental abruption to be independently associated with a worse primary outcome. CONCLUSION: PB treatment before cooling did not improve the composite outcome of neonatal death or the presence of an abnormal post-hypothermia brain MRI, but the long-term outcomes have not yet been evaluated.

The effect of late preterm birth on mortality of infants with major congenital heart defects.

OBJECTIVE: We evaluated the effect of late preterm delivery (34 to 36 weeks) on hospital mortality of infants with congenital heart defects (CHDs). STUDY DESIGN: Retrospective record review of infants with major CHD born at or after to 34 weeks, cared for in a single tertiary perinatal center between 2002 and 2009. Factors associated with death before discharge from the hospital were ascertained using univariate and multivariate analyses. RESULT: Of the 753 infants with CHD, 117 were born at late preterm. Using logistic regression analysis, white race (OR; 95% CI) (0.60; 0.39 to 0.95), late preterm delivery (2.70; 1.69 to 4.33), and need for intubation in the delivery room (3.15; 1.92 to 5.17) were independently associated with hospital death. CONCLUSION: Late preterm birth of infants with major CHDs was independently associated with increased risk of hospital death compared with delivery at more mature gestational ages.

Is refractory hypotension in preterm infants a manifestation of early ductal shunting?

BACKGROUND: Clinicians frequently use hydrocortisone (HC) to treat vasopressor-resistant hypotension even before establishing its cause. OBJECTIVE: To identify the etiologic factors leading to development of refractory hypotension, and to assess if patent ductus arteriosus (PDA) is associated with refractory hypotension during the first week of life. STUDY DESIGN: The medical records of 290 consecutively born infants

How DRGs hurt academic health systems.

BACKGROUND: Academic health centers continue their mission of clinical care, education, and research. This mission predisposes them to accept patients regardless of their individual clinical variation and financial risk. The purpose of this study is to assess the variation in costs and the attendant financial risk associated with these patients. In addition, we propose a new reimbursement methodology for academic health center high-end DRGs that better aligns financial risks. STUDY DESIGN: We reviewed clinical and financial data from the University of Michigan data warehouse for FY1999 (n = 39,804). The diagnosis-related groups were classified by volume (group 1, low volume to group 4, high volume). The coefficient of variation for total cost per admission was then calculated for each DRG classification. A regression analysis was also performed to assess how costs in the first 3 days estimated total costs. A hybrid methodology to estimate costs was then determined and its accuracy benchmarked against actual Medicare and Blue Cross reimbursements. RESULTS: Low-volume DRGs (< 75 annual admissions) had the highest coefficient of variation relative to each of the three other DRG classifications (moderate to high volume, groups 2, 3, and 4). The regression analysis accurately estimated costs (within 25% of actual costs) in 64.7% of patients with a length of stay > or = 4 days (n = 16,287). This regression fared well compared with actual FY 1999 DRG-based Medicare and Blue Cross reimbursements (n = 9,085 with length of stay > or = 4 days), which accurately reimbursed the University of Michigan Health System in only 43.9% of cases. CONCLUSIONS: Academic health centers receive a disproportionate number of admissions to low-volume, high-variation DRGs. This clinical variation translates into financial risk. Traditional risk management strategies are difficult to use in health care settings. The application of our proposed reimbursement methodology better distributes risk between payers and providers, and reduces adverse selection and incentive problems ("moral hazard").

Tumor necrosis factor activity increases in the early response to trauma.

OBJECTIVE: 1) To determine whether tumor necrosis factor (TNF) up-regulation occurs in the first hours following severe injury. 2) To determine whether the time from injury to blood sampling affects the probability of detecting TNF. METHODS: A prospective, cross-sectional study was performed using a convenience sample of adult major trauma patients ("patients") treated at a university hospital ED (Level-1 trauma center) and 20 healthy volunteers ("controls"). The time interval from injury to specimen collection (delta T), the injury severity scale (ISS) score, patient demographics, and quantitative cytokine [TNF and interleukin (IL-6, IL-8)] levels were measured. In the patients, cytokine levels were analyzed as a function of delta T (using first hourly cutoff points and then the median T as an arbitrary cutoff point) with and without potential confounders (e.g., ISS, age, gender). RESULTS: The mean delta T was 92.8 +/- 49.2 min (range 10-210 min, median 82 min). In the controls, TNF activity was present in 96%, with a mean level of 125 pg/mL. The controls showed no baseline IL-6 activity and only 10% had a measurable baseline IL-8 level. In the patients, TNF was present in 93%, with a mean level of 628 +/- 138 pg/mL. When the patients' specimens were divided at the median to obtain roughly equal-sized groups, more TNF levels were elevated > 2.5 SD above the controls in the early vs late group (51% vs 30%; p = 0.07). The mean levels of TNF and IL-8 also were higher in the early vs late group (756 vs 530 and 287 vs 135, respectively; p < 0.05). CONCLUSIONS: TNF levels are elevated in the immediate 4 hours post-injury. Previous investigators' inability to detect TNF activity increases may be related to delays in sampling. These results are consistent with the theory that increased TNF activity occurs early after major trauma and may initiate subsequent cytokine activity.

Carotenoids and antioxidant vitamins in patients after burn injury.

Oxidative stress may contribute to secondary tissue damage and impaired immune function in patients after burn injury. The purpose of our study was to describe plasma antioxidant micronutrient concentrations in 26 adult patients admitted with extensive burn injuries (> 20 % total burn surface area) to a level-1 trauma burn center during a 21-day period after admission. The effect of administering beta-carotene was also examined with use of a prospective randomized subjects design: patients received either placebo or 30 mg/day in an enteral feeding. Plasma concentrations of alpha- and gamma-tocopherol, carotenoids (alpha and beta-carotene, lycopene, beta-cryptoxanthin, lutein), and retinol were measured with high- performance liquid chromatography, and vitamin C was quantified with spectrophotometry, at baseline and twice per week. Vitamin C, tocopherol, and retinol concentrations were low at baseline, but levels increased significantly over the study period in both groups (p < 0.05). Plasma beta-carotene concentration increased when this carotenoid was provided in the oral feeding. Otherwise, plasma carotenoid concentrations were low at baseline and remained low throughout the study period despite normalization of associated lipids.

The effect of pre-ECLS ventilation time on survival and respiratory morbidity in the neonatal population.

Although mechanical ventilation for more than 7 to 10 days has been considered a contraindication to the application of extracorporeal life support (ECLS) in neonates, the outcome and respiratory morbidity for newborns placed on ECLS after more than 7 days of ventilation have not been well characterized. The purpose of this study was to determine the impact of pre-ECLS ventilation time on the rate of survival, the likelihood of the development of bronchopulmonary dysplasia (BPD), and the need for supplemental oxygen at the time of discharge. Examination of the Extracorporeal Life Support Organization (ELSO) Registry showed that 6,110 neonates were treated for respiratory failure with a pre-ECLS ventilation time of less than 14 days between January 1990 and May 1995. Gestational age (GA), birth weight (BW), indication for ECLS, and diagnosis were compared with the rate of survival, the discharge diagnosis of BPD, and the need for home oxygen. The GA and BW of neonates placed on ECLS during the first week of life (n = 5,888) did not differ significantly from those of neonates whose ECLS was begun in the second week of life (n = 222). The neonates were divided into two groups (early, ventilation time of 3 to 6 days; late, ventilation time of 7 to 10 days) to determine the odds ratios for survival, BPD, and home oxygen. Logistic regression analysis was used to develop a model to predict the rate of survival, the risk for the development of BPD, and the need for home oxygen given the length of pre-ECLS ventilation time. The late group was less likely to survive (odds ratio, 1.8; 95% confidence interval [CI], 1.21 to 2.68). The late group also had approximately twice the risk for the development of BPD (odds ratio, 1.9; 95% CI, 1.2 to 3.04) and a trend toward an increased incidence of home oxygen use (odds ratio, 1.55; 95% CI, 0.92 to 2.60). The authors conclude that (1) there is a greater risk of mortality and BPD and a trend toward an increased need for home oxygen with increased time on the ventilator before ECLS; (2) at 14 days the predicted probability of survival is still 53% (95% CI, 31% to 74%); (3) at 14 days the predicted probability of BPD is 54% (95% CI, 28% to 78%); and (4) based on these data, it is reasonable to consider application of ECLS to patients who have had mechanical ventilation for up to 14 days.

Initial experience with partial liquid ventilation in adult patients with the acute respiratory distress syndrome.

OBJECTIVE: To evaluate the safety and efficacy of partial liquid ventilation (PLV). DESIGN: Before-after trial. SETTING: The surgical intensive care unit at the University of Michigan, Ann Arbor, from April to December 1994. PATIENTS: A consecutive sample of 10 patients aged 19 to 55 years with the acute respiratory distress syndrome who were receiving extracorporeal life support. INTERVENTION: Perflubron was administered into the trachea until the dependent zone of the lung was filled. Gas ventilation of the perflubron-filled lung was then performed (PLV). Volatilized perflubron replacement was repeated daily for from 1 to 7 days with a median cumulative dose of 38 mL/kg (range, 15 to 62 mL/kg). MAIN OUTCOME MEASURES: Physiologic shunt and static pulmonary compliance. RESULTS: Physiologic shunt decreased from a median of 0.72 (range, 0.37 to 1.0) to 0.46 (range, 0.21 to 0.96) over the 72 hours following initiation of PLV (P = .01 by repeated measures analysis of variance). Static pulmonary compliance corrected for patient weight increased from a median of 0.16 mL/cm H2O per kilogram (range, 0.01 to 0.48 mL/cm H2O per kilogram) to 0.27 mL/cm H2O per kilogram (range, 0.05 to 1.11 mL/cm H2O per kilogram) over the same time period (P = .04 by repeated measures analysis of variance). Overall survival was five (50%) of 10 patients. Complications that were potentially associated with PLV included pneumothorax development in one patient and mucus plug formation in one patient. CONCLUSIONS: Perflubron may be safely administered into the lungs of patients with severe respiratory failure receiving extracorporeal life support and may be associated with improvement in gas exchange and pulmonary compliance.

Liquid ventilation in adults, children, and full-term neonates.

We evaluated the safety and efficacy of partial liquid ventilation in a series of 19 adults, children, and neonates who were in respiratory failure and on extracorporeal life support. During partial liquid ventilation, the alveolar-arterial oxygen difference decreased from 590 (SE 25) to 471 (42) mm Hg (p = 0.0002) and static pulmonary compliance increased from 0.18 (0.04) to 0.29 (0.04) mL cm H2O-1 kg-1 (p = 0.0002). 11 patients (58%) survived. These preliminary data suggest that partial liquid ventilation can be safely used in patients with severe respiratory failure and may improve lung function.

A matched pairs analysis of venoarterial and venovenous extracorporeal life support in neonatal respiratory failure.

It has been suggested that venovenous (VV) extracorporeal life support (ECLS) confers a survival advantage over venoarterial (VA) ECLS. These results have been confounded by differences in patient populations. In this study, a matched pairs comparison of survival and complication rates in neonatal respiratory failure patients managed with VA or VV ECLS was performed. Retrospective matching of 643 VA and VV patient pairs from the Extracorporeal Life Support Organization Registry was performed. Pairs were matched by same year, same diagnosis, gestational age +/- 1 week, birth weight +/- 0.3 kg, and oxygenation index +/- 5. Further matching for hemodynamic status was possible for 272 pairs and included pre ECLS CPR, use of epinephrine, and arterial pH +/- 0.1. Statistical significance was defined for outcome and selected complication rates using McNemar's chi-square analysis with correction for multiple comparisons. A survival advantage for VV was significant when matching for respiratory failure (83.8% VA versus 91.5% VV), but was not significant when matching for hemodynamic failure (90.4% VA versus 94.5% VV). In the latter match, hemolysis (10.7% VA versus 23.5% VV) and cannula kinking (0.4% VA versus 10.6% VV) were more common with VV ECLS. The incidence of intracranial hemorrhage did not significantly differ between groups (6.3% VA versus 7.4% VV). Survival is not significantly greater with VV ECLS when patients are matched for degree of respiratory and hemodynamic failure. Hemolysis and cannula kinking are more common with VV ECLS. There is no identified difference in the incidence of intracranial hemorrhage.

Comparative evaluation of the hemodynamic effects of oral cimetidine, ranitidine, and famotidine as determined by echocardiography.

STUDY OBJECTIVE: To evaluate the influence of cimetidine, ranitidine, famotidine, and placebo on cardiac performance as determined by echocardiography. DESIGN: Randomized, four-way crossover trial. SETTING: Echocardiography laboratory at a university hospital. PARTICIPANTS: Twelve healthy volunteers. INTERVENTIONS: Volunteers received oral treatment with placebo, cimetidine 800 mg, ranitidine 300 mg, or famotidine 40 mg once/day for 7 days. MEASUREMENTS AND MAIN RESULTS: On the seventh day of each study phase, 2 hours after administration of the final dose, each subject underwent cardiac echocardiography and Doppler flow studies. No significant differences were detected in ejection fraction, peak flow velocity, or percentage fractional shortening among the treatment phases. A large degree of variability in ejection fraction was observed, with some subjects experiencing marked decreases. CONCLUSION: The histamine-2 (H2)-receptor antagonists had no effect on the hemodynamic variables as determined by echocardiography. The variability in the hemodynamic response may in part explain the conflicting results reported in the literature. It also raises the question as to whether certain individuals are more sensitive to the potential cardiac effects of H2-receptor antagonists.

Geriatric trauma: aggressive intensive care unit management is justified.

The United States population older than 65 years increased 21 per cent from 1980 to 1990. Attempts to characterize geriatric trauma have failed to yield a consensus on basic descriptors or physiologic parameters predictive of outcome. We reviewed the records of 170 trauma patients, aged 60 or above, admitted to our institution in a recent 50-month period. Mortality was 21.8 per cent. None of the 54 general care patients died; 79 (68%) of the 116 ICU patients survived. ICU deaths correlated with number of organ systems failing and severe head injury. Although these results justify aggressive ICU treatment, average hospital stay was 15 days, and one third of patients required skilled nursing facilities for ultimate recovery, so the resource cost is high.

Changes in resting energy expenditure and body composition in anorexia nervosa patients during refeeding.

Accurate prediction of the energy level necessary to promote weight restoration in patients with anorexia nervosa would be clinically useful. Resting energy expenditure (REE), respiratory quotient, and body composition were measured in 10 nonmedicated women with anorexia nervosa during a vigorous refeeding protocol. REE was measured three times per week by open-circuit indirect calorimetry after an overnight fast. Subjects ranged in age from 19 to 38 years and weighed 39.9 +/- 4.3 kg (mean +/- standard deviation) at admission. The refeeding protocol was as follows: phase 1, 1,200 kcal/day for 1 week (baseline); phase 2, an increase of 300 kcal/day for 1 week; phase 3, 3,600 kcal/day until target weight was reached; phase 4, 1,800 to 2,800 kcal/day (stabilization). REE was 30.0 +/- 6.4, 33.5 +/- 6.7, 37.3 +/- 6.6 and 34.5 +/- 4.4 kcal/kg body weight during phases 1, 2, 3, and 4, respectively. The Harris-Benedict equation overestimated phase 1 24-hour REE by a mean of 14% and underestimated REE in phases 2, 3, and 4 by a mean of 8%, 24%, and 23%, respectively. Skinfold measurements revealed percent body fat to be 12 +/- 4% at admission and 19 +/- 5% at discharge, with a mean of 48% of the weight gained during refeeding attributable to increased body fat. These findings indicate that refeeding in anorexia nervosa is associated with increased REE, which cannot be explained by increased body mass, and that caloric requirements for weight restoration in patients with anorexia nervosa are best determined by monitoring individual response.

Pneumonia: incidence, risk factors, and outcome in injured patients.

One hundred thirty (44.2%) of 294 patients hospitalized for trauma and admitted to the Surgical Intensive Care Unit for mechanical ventilation developed hospital-acquired bacterial pneumonia. The predominant pathogens isolated were gram-negative enteric bacilli (72%), but there was not an increase in mortality associated with gram-negative pneumonia compared with similar patients without pneumonia. Of the seven admission risk factors univariately associated with the development of acquired bacterial pneumonia, only emergent intubation (p less than 0.001), head injury (p less than 0.001), hypotension on admission (p less than 0.001), blunt trauma as the mechanism of injury (p less than 0.001), and Injury Severity Score (p less than 0.001) remained significant after stepwise logistic regression. Not surprisingly, as mechanical ventilation is continued, the probability of pneumonia emerging increases. The consequences of hospital-acquired bacterial pneumonia are a significant seven-, five-, and two-fold increase in mechanically ventilated days, intensive care, and hospital stay, respectively. We conclude that the incidence of hospital-acquired pneumonia in injured patients admitted to the ICU for mechanical ventilation occurs in nearly half the patients, is associated with specific risk factors, and significantly increases morbidity but does not increase mortality.

Evaluation of the Velcom-100 pulse Doppler cardiac output computer.

The use of Doppler ultrasound as a means of obtaining cardiac output (CO) measurements quickly, easily, and noninvasively has been made possible by recent technologic developments. We evaluated a new pulse Doppler ultrasonic unit (Velcom-100, Waters Instruments, Inc) in the Surgical Intensive Care Unit at the University of Michigan Medical Center. Accuracy of this device was determined by comparison of CO results obtained from the Velcom-100 (COV) against those of conventional thermal dilution cardiac output (COT) measurements. Twenty-six postoperative patients were used for this study, ranging in age from 20 to 82 years old. Initial studies prior to in vivo standardization demonstrated a significantly lower result (p = 0.039) for the Velcom-100 with a mean difference of 0.86 L/min (COT-COV). This comparison was significantly improved in subsequent studies following in vivo standardization (COT-COV = 0.02 L/min, p = 0.646). Linear regression analysis showed a significant, positive correlation between the two results (r = 0.82, p less than 0.05) indicating an excellent trending capability for the Velcom-100. Our evaluation found the Velcom-100 to be user friendly, allowing rapid training of ICU technicians and applicability for postoperative monitoring.