Déjà vu: Ralstonia mannitolilytica infection associated with a humidifying respiratory therapy device, Israel, June to July 2011.

Following a bloodstream infection in June 2011 with Ralstonia mannitolilytica in a premature infant treated with a humidifying respiratory therapy device, an investigation was initiated at the Hadassah Medical Centres in Jerusalem. The device delivers a warmed and humidified mixture of air and oxygen to patients by nasal cannula. The investigation revealed colonisation with R. mannitolilytica of two of 15 patients and contamination of components of five of six devices deployed in the premature units of the Hadassah hospitals. Ten isolates from the investigation were highly related and indistinguishable from isolates described in an outbreak in 2005 in the United States (US). Measures successful in containing the US outbreak were not included in user instructions provided to our hospitals by the distributor of the device.

Randomized controlled trial of external cephalic version in term multiparae with or without spinal analgesia.

BACKGROUND: Neuraxial analgesia significantly increases the success rate of external cephalic version (ECV) among nulliparae. The study objective was to compare ECV success among multiparae with and without spinal analgesia. METHODS: Prospective randomized controlled trial performed over a pre-defined 6 yr period in a tertiary referral delivery suite. Healthy multiparae at term requesting ECV for breech presentation, without fetal or uterine anomaly, were enrolled after written informed consent. Women were randomized to receive either spinal analgesia (bupivacaine 7.5 mg) or no analgesia before the ECV. The primary outcome was successful conversion from breech to vertex presentation, confirmed by ultrasound. Visual analogue pain score and adverse outcomes (complications of anaesthesia or ECV) were recorded. Statistical analysis was performed according to intention to treat using two-sided tests. RESULTS: Among 265 multiparae who underwent ECV, 65 consented to enrol, one subsequently refused ECV; therefore, data from 64 women were analysed. ECV was successful in 27 of 31 patients (87.1%) receiving spinal analgesia vs 19 of 33 (57.5%) with no analgesia (P=0.009; 95% CI of difference: 0.075-0.48). ECV with spinal analgesia reduced visual analogue pain score, mean (sd) 1.7 (2.4) vs 5.5 (2.9) without (P<0.0001). Maternal hypotension was seen after spinal analgesia in 10 of 31 (32%) (P=0.0003) and easily treated without adverse outcome. No complications were noted after the ECV. CONCLUSIONS: Administration of spinal analgesia significantly increased the rate of successful ECV among multiparae at term with increased patient comfort. The trial was registered at the National Institute of Health Trials Registry, NCT00119184, www.clinicaltrials.gov.

Antepartum continuous epidural ropivacaine therapy reduces uterine artery vascular resistance in pre-eclampsia: a randomized, dose-ranging, placebo-controlled study.

BACKGROUND: No therapy is currently available to improve the reduced uteroplacental blood flow (UPBF) that characterizes pre-eclampsia. We hypothesized that sympathectomy induced by epidural local anaesthesia reduces uterine vascular resistance (which is inversely correlated with UPBF) in pre-eclampsia. METHODS: Ten pregnant women between 24 and 32 weeks of gestation with pre-eclampsia and uterine artery flow abnormalities were randomized to antepartum continuous epidural therapy (ACET) or control. ACET was initiated by a 5 day dose-ranging trial (ACET-1) of 0.04, 0.06, 0.08, and 0.1% ropivacaine and saline placebo, each at 10 ml h(-1) for 24 h. Doses were randomized and double-blind. Doppler ultrasound indices of vascular resistance were assessed at baseline and after each 24 h dosing period in both uterine arteries. Subsequently, these ACET patients were administered 0.1% ropivacaine until delivery (ACET-2), with one additional randomized double-blind placebo day. RESULTS: Five patients were randomized to ACET. In each patient, one uterine artery exhibited a dose-dependent reduction in vascular resistance (P=0.035), a response that returned to baseline following placebo (P<0.001). The contralateral uterine artery exhibited either increased vascular resistance or no change. In all cases, the uterine artery that responded to ACET had higher baseline resistance than its pair (P=0.043). Baseline right-left difference in resistance between paired uterine arteries was greatly diminished following ACET. Although ACET patients had a mean (sd) duration to delivery of 19 (9) days compared with control 2 (1) days (P=0.008), this should be interpreted with caution because of demographic differences between groups. CONCLUSIONS: ACET reduces uterine artery resistance in pre-eclampsia <32 weeks. Uteroplacental re-distribution is a novel observation and warrants further investigation.

Holy consent--a dilemma for medical staff when maternal consent is withheld for emergency caesarean section.

A parturient (grand multipara) developed arrested labour complicated by severe fetal heart rate decelerations. Senior physicians explained the need for a caesarean section, but she chose to deliver vaginally since rabbinical blessing could not be obtained. Forcing the mother to have a cesarean section without consent is considered "civil battery." The dilemma faced by medical staff and the implications of her refusal for the treating medical staff are described.

Phase II study of liposomal doxorubicin in platinum- and paclitaxel-refractory epithelial ovarian cancer.

PURPOSE: Stealth liposomal doxorubicin (Alzal Corp, Palo Alto, CA) has a slower clearance rate than free doxorubicin, resulting in sustained serum levels. Liposomal encapsulation also leads to increased concentration of drug in tumor tissue. Meta-analysis of previous studies has shown that doxorubicin has activity in epithelial ovarian cancer. The current study was developed to examine the activity of Stealth liposomal doxorubicin in platinum- and paclitaxel-refractory ovarian cancer. PATIENTS AND METHODS: Patients had epithelial ovarian cancer that either progressed on or recurred within 6 months of completion of platinum and paclitaxel chemotherapy. All patients had measurable disease. Stealth liposomal doxorubicin was administered at 50 mg/m(2) every 4 weeks as a 1-hour infusion. RESULTS: Eighty-nine patients were treated and included in an intent-to-treat analysis. There were 82 patients who were platinum and paclitaxel refractory and met all study criteria. There was one complete response and 14 partial responses, for a total response rate of 16.9% (95% confidence interval [CI], 9.1% to 24.6%). For platinum- and paclitaxel-refractory patients, the response rate was 18.3% (95% CI, 9.9% to 26.7%). Median time to progression was 19. 3 weeks for the entire population. Ten patients (11.2%) withdrew because of adverse events related to the drug (palmar-plantar erythrodysesthesia [PPE], n = 3; asthenia, n = 2; cardiac, n = 2; neutropenia, n = 1; stomatitis, n = 1; and edema, n = 1). There were no drug-related fatal events. There were only eight grade 4 adverse events attributable to the drug. Stomatitis, PPE, and skin lesions were managed with dose reductions and delays in most cases. CONCLUSION: Stealth liposomal doxorubicin has activity in refractory epithelial ovarian cancer. PPE and stomatitis can usually be managed by dose adjustment. The ease of administration makes this an attractive agent.

Myocardial infarction after vascular surgery: the role of prolonged stress-induced, ST depression-type ischemia.

OBJECTIVES: The goal of this study was to investigate the nature of the association between silent ischemia and postoperative myocardial infarction (PMI). BACKGROUND: Silent ischemia predicts cardiac morbidity and mortality in both ambulatory and postoperative patients. Whether silent stress-induced ischemia is merely a marker of extensive coronary artery disease or has a closer association with infarction has not been determined. METHODS: In 185 consecutive patients undergoing vascular surgery, we correlated ischemia duration, as detected on a continuous 12-lead ST-trend monitoring during the period 48 h to 72 h after surgery, with cardiac troponin-I (cTn-I) measured in the first three postoperative days and with postoperative cardiac outcome. Postoperative myocardial infarction was defined as cTn-I >3.1 ng/ml accompanied by either typical symptoms or new ischemic electrocardiogram (ECG) findings. RESULTS: During 11,132 patient-hours of monitoring, 38 patients (20.5%) had 66 transient ischemic events, all but one denoted by ST-segment depression. Twelve patients (6.5%) sustained PMI; one of those patients died. All infarctions were non-Q-wave and were detected by a rise in cTn-I during or immediately after prolonged, ST depression-type ischemia. The average duration ofischemia in patients with PMI was 226+/-164 min (range: 29 to 625), compared with 38+/-26 min (p = 0.0000) in 26 patients with ischemia but not infarction. Peak cTn-I strongly correlated with the longest, as well as cumulative, ischemia duration (r = 0.83 and r = 0.78, respectively). Ischemic ECG changes were completely reversible in all but one patient who had persistent new T wave inversion. All ischemic events culminating in PMI were preceded by an increase in heart rate (delta heart rate = 32+/-15 beats/min), and most (67%) of them began at the end of surgery and emergence from anesthesia. CONCLUSIONS: Prolonged, ST depression-type ischemia progresses to MI and is strongly associated with the majority of cardiac complications after vascular surgery.

Prevalence of fibromyalgia and co-morbid bipolar disorder: A systematic review and meta-analysis.

BACKGROUND: Fibromyalgia (FM) is a chronic disorder with high morbidity and significant health service utilization costs. Few studies have reported on the phenotypic overlap of FM and bipolar disorder (BD). The aim of this review is to qualitatively and quantitatively summarize the results and clinical implications of the extant literature on the co-occurrence of FM and BD. METHODS: A systematic search of PubMed/Medline, Cochrane, PsycINFO, CINAHL and Embase was conducted to search for relevant articles. Articles were included if incidence and/or prevalence of BD was determined in the FM sample. Results of prevalence were pooled from all studies. Pooled odds ratio (OR) was calculated based on case-control studies using standard meta-analytic methods. RESULTS: A total of nine studies were included. The pooled rate of BD comorbidity in samples of FM patients was 21% (n=678); however, results varied greatly as a function of study methodology. Case-controlled studies revealed a pooled OR of 7.55 of BD co-morbidity in samples of FM patients [95% Confidence Interval (CI)=3.9-14.62, FM n=268, controls n=413] with low heterogeneity (I(2)=0%). LIMITATIONS: The current study was limited by the low number of available studies and heterogeneity of study methods and results. CONCLUSIONS: These data strongly suggest an association between BD and FM. Future studies employing a validated diagnostic screen are needed in order to more accurately determine the prevalence of BD in FM. An adequate psychiatric assessment is recommended in FM patients with suspected symptoms consistent with BD prior to administration of antidepressants in the treatment of FM.

Prostaglandin E2 changes in the retina and optic nerve of an eye with injured optic nerve.

Changes in arachidonic acid metabolism were studied in the optic nerve, the chorioretina, and in the vitreous following crush injury to the optic nerve of rats. Crush injury led to: (i) a 3.9-fold increase in optic nerve prostaglandin type E2 in vitro production which peaked on day 5 and was followed by a gradual decline, but was still significantly higher than baseline levels by day 12; (ii) a two-fold increase in the chorioretina prostaglandin type E2 in vitro production which peaked on day 1, and resumed baseline levels by day 3; (iii) a 3.5-fold increase in vitreous prostaglandin type E2 levels on day 1 which remained at 1.5-2 times higher than baseline levels for the rest of the study period (12 days). The findings indicate that the pattern of changes in prostaglandin type E2 production by the optic nerve (consisting mostly of white matter) is different from that described for injured brain tissues. The prolonged accumulation of vitreal prostaglandin type E2 in eyes with damaged optic nerve may lead to undesirable effects on the retina beyond those directly manifested in the retina by altered axonal flow in the injured optic nerve.

Corticosteroid treatment of laser retinal damage affects prostaglandin E2 response.

The current study investigated the effect of steroid treatment of eyes subjected to a single retinal argon laser lesion on vitreal accumulation of both prostaglandin E2 (PGE2) and protein and their relationship with the amounts of PGE2 released from the retina-choroid. Laser exposure resulted in an elevation in the amounts of PGE2 released by the retina-choroid of laser-treated eyes: there was an initial peak on day 1, followed by a higher peak on day 7 (13.0 +/- 3.9 ng/mg protein and 32.9 +/- 4.9 ng/mg protein, respectively) after which levels progressively declined. Steroid treatment prevented the initial peak, but did not prevent the enhanced PGE2 amounts released during the second week. Thus, on day 7 the amounts released were lower by 32% than in the untreated group (21.0 +/- 8.6 ng/mg protein vs 32.9 +/- 4.9 ng/mg protein, P = 0.000); by day 14, however, peak values in the treated group were higher than in the untreated group (32.2 +/- 12.4 ng/mg protein and 10.6 +/- 4.5 ng/mg protein, respectively). In steroid-treated eyes, vitreal PGE2 concentration remained unchanged from baseline over a 2-week follow-up, whereas in the untreated laser group, levels peaked on day 7 to 10.7 +/- 3.6 ng/ml, exceeding baseline levels of 5.8 +/- 1.7 ng/ml (P = 0.0002). Laser exposure was also associated with a biphasic elevation in vitreal protein concentrations on days 3 and 14 (0.68 +/- 0.16 mg/ml and 0.79 +/- 0.13 mg/ml, respectively); these were significantly higher than the baseline value of 0.43 +/- 0.12 mg/ml (P = 0.03 and P = 0.004, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

The oxygen uptake-oxygen delivery relationship during ICU interventions.

There is much interest in the relationship between oxygen delivery and oxygen consumption in the critically ill patient. This interest is occasioned by the observation that patients with sepsis and the adult respiratory distress syndrome have a linear or "supply-dependent" relationship instead of the normally observed biphasic or "supply-independent" relationship. These relationships are only valid when subjects are at rest, since during exercise, as VO2 increases, so do DO2 and the oxygen extraction ratio (ER, VO2/DO2). We examined the VO2-DO2 relationship in a group of 16 mechanically-ventilated surgical ICU patients while they were at rest and during activities that increase VO2. At low levels of activity, where mean VO2 increased from 207 +/- 38 (SD) ml/min at rest to 241 +/- 44 ml/min, there were significant increases in mean DO2 but not mean ER. With the greater (greater than 50 percent) increases in VO2 seen with chest physical therapy, there were increases in both DO2 and ER. When the VO2-DO2 relationship during low levels of exercise and rest are plotted, a linear pattern emerges that could be misinterpreted as a "supply dependent" pattern. Therefore, it is important to pay close attention to the activity state of a patient when examining the VO2-DO2 relationship.

Assessing hypermetabolism and hypometabolism in the postoperative critically ill patient.

To determine whether a patient is hypermetabolic or hypometabolic, measured resting energy expenditure is compared with estimated (or predicted) energy expenditure. The latter is calculated using equations derived from measurements made in groups of healthy individuals. Body weight or body surface area are among the variables used in these equations. Yet, in critically ill patients, body weight often rises because of fluid resuscitation. This study examined the differences between using preoperative, postoperative, and ideal body weights on the determination of hypermetabolism and hypometabolism in mechanically ventilated, critically ill patients. When the elevated postoperative weights were used instead of the preoperative ones to predict energy expenditure, the degree of hypermetabolism was underestimated. Subtracting the weight of the cumulative net fluid balance from the postoperative weight was found to accurately reflect preoperative weight. The influence of various predictive equations on the magnitude of hypermetabolism was also explored. In conclusion, it is important, when determining hypermetabolism or hypometabolism, to consider the influence of the specific predictive equation used and the effect of resuscitation fluid.

The new onset of atrial arrhythmias following major noncardiothoracic surgery is associated with increased mortality.

STUDY OBJECTIVES: To examine the incidence and consequences of atrial arrhythmias in surgical ICU patients following major noncardiac, nonthoracic surgery. DESIGN: Prospective observational study. SETTING: University hospital surgical ICU. PATIENTS: Four hundred sixty-two consecutive patients after noncardiothoracic surgery. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Patients were assigned to one of three groups: group 1-new-onset atrial arrhythmias (n=47); group 2-history of atrial arrhythmias (n=58); and group 3-no atrial arrhythmias (n=357). New arrhythmias occurred in 10.2% of patients. Most began within the first 2 postoperative days. These patients had a higher mortality rate (23.4%), longer ICU stay (8.5+/-17.4 [SD] days), and extended hospital stay (23.3+/-23.6 days) than patients without atrial arrhythmias (mortality, 4.3%; ICU stay, 2.0+/-4.5 days; hospital stay; 13.3+/-17.7 days; p<0.02). Thirteen percent of patients had a history of atrial arrhythmias. They had a higher mortality rate (8.6%) and longer ICU stays (2.9+/-4.9 days; p<0.02) than patients without arrhythmias. Most deaths in the two arrhythmia groups were not due to cardiac problems, but to sepsis or cancer. CONCLUSIONS: Patients admitted to a surgical ICU after noncardiothoracic surgery with a history of or who developed new atrial arrhythmias had greater mortality and longer ICU stays than patients without arrhythmias. The incidence of new-onset arrhythmias was lower than reported after cardiac and thoracic surgery, but higher than in the general population. Atrial arrhythmias were not the cause of death and appear to be markers of increased mortality and morbidity.

Midazolam attenuates the metabolic and cardiopulmonary responses to an acute increase in oxygen demand.

Critically ill patients are subjected to routine clinical activities that increase oxygen demand. This results in increased heart rate, blood pressure, minute ventilation, and oxygen delivery in patients with often already compromised cardiopulmonary systems. This study examines whether the benzodiazepine, midazolam, could attenuate the increase in metabolism, respiration, and circulation seen during chest physical therapy. Two groups of mechanically ventilated postoperative patients were studied. One group (n = 15) received, in random order, 0.015 mg/kg of midazolam and placebo prior to two consecutive chest physical therapy sessions, while the other (n = 13) received 0.030 mg/kg and placebo. Both doses of midazolam significantly attenuated the increases in oxygen consumption, heart rate, and systemic blood pressure observed during placebo administration. The cardiac output increase was also attenuated. Although midazolam reduced minute ventilation and respiratory rate, no excess CO2 retention occurred when the drug was administered likely as the result of reduced CO2 production. The administration of midazolam (0.015 mg/kg and 0.030 mg/kg) prior to chest physical therapy reduces metabolic, hemodynamic, and ventilatory responses to chest physical therapy.

Pressure support ventilation attenuates the cardiopulmonary response to an acute increase in oxygen demand.

Critically ill patients undergo interventions, such as chest physical therapy, that acutely increase metabolic rate. Previous observations revealed that chest physical therapy is accompanied by increases of 40 to 50% in oxygen consumption (Vo2) and 40% in minute ventilation contributes to the rise in Vo2 and its associated hemodynamic responses. This was done by increasing mandatory ventilatory support during the chest physical therapy session: In phase 1 the mandatory ventilation rate was increased by 35% and in phase 2 pressure support ventilation 15 cm h2O was added. In phase 1 (n = 12), the increase in mandatory rate did not attenuate the chest physical therapy induced rises in heart rate, arterial blood pressure and Vo2. The increase in minute ventilation when the mandatory rate was increased prevented a rise in PaCO2. In phase 2 (n = 15), no change in the increase in Vo2 with chest physical therapy was observed with the addition of pressure support. Yet the rises in heart rate and systemic and pulmonary artery pressures were attenuated, as was the increase in PaCO2. Respiratory rate did not increase as much with pressure support. There appears to be a role for pressure support ventilation in attenuating the pulmonary and hemodynamic responses to interventions that increase oxygen demand.

Patterns of sedation and analgesia in the postoperative ICU patient.

Control of pain, discomfort, and agitation is an integral part of the postoperative management of critically ill patients. We examined the sedative and analgesic practices in a surgical ICU during two six-month periods, one in 1986-1987 and the other in 1989-1990. Narcotics, especially morphine and Fentanyl, were the most commonly used drugs. The amount of Fentanyl received by the endotracheal patients in the 1986-1987 group was quite large, 5.5 +/- 4.3 (SD) mg/day. The use of midazolam during the second survey period was associated with a reduced dose of narcotics in artificially ventilated patients receiving continuous intravenous Fentanyl and morphine. The use of epidural Fentanyl, especially following thoracic surgery, was greatly increased during the second study period. More work is needed to assess the effects and effectiveness of ICU sedative and analgesic regimens.

Dynamic respiratory patterns after laparoscopic cholecystectomy.

Important alterations in respiratory function have been observed after open cholecystectomy. These include a decrease in the abdominal tidal volume, forced vital capacity, and forced expiratory volume at 1 s. Laparoscopic cholecystectomy is a new procedure allowing removal of the gallbladder without a subcostal or midline incision. The result is less postoperative pain and earlier ambulation. This study sought to determine whether changes in rib cage and abdominal wall motion are different after laparoscopic than open cholecystectomy. Twelve otherwise healthy patients underwent respiratory inductive plethysmography prior to and one day after laparoscopic cholecystectomy. Frequency of resting breathing increased 29 percent after laparoscopic cholecystectomy (p = 0.03), while abdominal motion decreased 32 percent (p = 0.03). During coached abdominal breathing, rib cage tidal volume increased 70 percent (p = 0.005) and abdominal tidal volume decreased 29 percent (p = 0.01). These alterations in respiratory pattern after laparoscopic cholecystectomy were smaller in magnitude than those reported following the open procedure.

Continual trending of Fick variables in the critically ill patient.

We continually monitored components of the Fick equation (oxygen consumption, arterial and mixed venous oxygen saturation) simultaneously in ten hemodynamically stable, mechanically ventilated postoperative patients in order to evaluate our ability to continually calculate cardiac output (Qc) from its Fick determinants. Qc underestimated (p less than 0.001) cardiac output calculated from intermittent CO-oximeter measurements (6.2 vs 6.4 L/min) with good correlation (r = .96), while it consistently overestimated (p less than 0.05) thermodilution cardiac output (Qtd) (6.2 vs 5.9 L/min, r = .84). Measured oxygen consumption correlated with Qtd (r = .78) nearly as well as did Qc, while mixed venous oxygen saturation correlated poorly with Qtd (r = -.10). Trends of multiple Fick variables were helpful in interpreting changes in a single parameter. We conclude that continual trending of Fick variables in critically ill patients is both feasible and useful and that Qc agrees well with both traditional Fick cardiac output computed from CO-oximetry data and thermodilution measurements. Finally, measured oxygen consumption, available continuously, correlates well with changes in cardiac output in this subset of critically-ill patients.

Respiratory patterns after cholecystectomy. Effects of posture and CO2 stimulation.

A marked reduction in the ratio of abdominal to rib cage motion has been observed after upper abdominal surgery. This study seeks to determine the effects on respiratory pattern of stimulation with CO2 and a change in posture from supine to semirecumbent posture (hips flexed, head of bed elevated at 30 degrees to the horizontal) in patients having undergone cholecystectomy. Canopy spirometry and respiratory inductive plethysmography were used to measure minute ventilation, tidal volume, and rib cage and abdominal motion in 14 otherwise healthy women, prior to elective cholecystectomy and on the first and third postoperative days. Preoperatively, the relative contribution of the chest wall compartment to tidal volume (Vc/VT) was increased both by moving from the supine to the semirecumbent posture and by stimulation with 4 percent inhaled CO2. On the first postoperative day, there was a reduction in abdominal motion. In contrast to what happened in the preoperative period, there was no change in the relative contribution of the rib cage and abdomen when the patients moved from the supine to semirecumbent position. With CO2 stimulation, there was a further increase in the already increased absolute tidal volume of the chest. On the third postoperative day, there was an increase in abdominal motion in the supine and sitting position and during 4 percent CO2 stimulation. These results demonstrate that the response to a change in posture and to 4 percent CO2 stimulation are markedly altered in the postoperative period by the reduction in abdominal motion.

The effect of helium on ventilator performance: study of five ventilators and a bedside Pitot tube spirometer.

OBJECTIVE: To assess in vitro the performance of five mechanical ventilators-Siemens 300 and 900C (Siemens-Elma; Solna, Sweden), Puritan Bennett 7200 (Nellcor Puritan Bennett; Pleasanton, CA), Evita 4 (Dragerwerk; Lubeck, Germany), and Bear 1000 (Bear Medical Systems; Riverside CA)-and a bedside sidestream spirometer (Datex CS3 Respiratory Module; Datex-Ohmeda; Helsinki, Finland) during ventilation with helium-oxygen mixtures. DESIGN: In vitro study. SETTING: ICUs of two university-affiliated hospitals. METHODS AND MEASUREMENTS: Each ventilator was connected to 100% helium through compressed air inlets and then tested at three to six different tidal volume (VT) settings using various helium-oxygen concentrations (fraction of inspired oxygen [FIO(2)] of 0.2 to 1.0). FIO(2) and VT were measured with the Datex CS3 spirometer, and VT was validated with a water-displacement spirometer. MAIN RESULTS: The Puritan Bennett 7200 ventilator did not function with helium. With the other four ventilators, delivered FIO(2) was lower than the set FIO(2). For the Siemens 300 and 900C ventilators, this difference could be explained by the lack of 21% oxygen when helium was connected to the air supply port, while for the other two ventilators, a nonlinear relation was found. The VT of the Siemens 300 ventilator was independent of helium concentration, while for the other three ventilators, delivered VT was greater than the set VT and was dependent on helium concentration. During ventilation with 80% helium and 20% oxygen, VT increased to 125% of set VT for the Siemens 900C ventilator, and more than doubled for the Evita 4 and Bear 1000 ventilators. Under the same conditions, the Datex CS3 spirometer underestimated the delivered VT by about 33%. CONCLUSIONS: At present, no mechanical ventilator is calibrated for use with helium. This investigation offers correction factors for four ventilators for ventilation with helium.

Energy expenditure in patients with chronic obstructive pulmonary disease.

Energy expenditure was studied in ten patients with chronic obstructive pulmonary disease (COPD) and weight loss, and in five malnourished patients without clinical evidence of COPD (control group) prior to and after a two-week refeeding regimen. Patients received 5 percent dextrose solution (plus electrolytes) for 36 hours to establish standard baseline conditions and were then randomly assigned to either a carbohydrate-based (CB; 53 percent of calories) or fat-based (FB; 55 percent of calories) diet for the first week. The alternate diet was given the following week. Total calorie intake was set at 70 percent above the energy expenditure measured prior to institution of nutritional support. During energy repletion, energy expenditure was greater than predicted (116 percent) in patients with COPD and less than predicted (90 percent) in the control patients. Thermic effect of nutrients during administration of either regimen was significantly greater (p less than .05) in patients with COPD than in those without COPD during both diets. The difference between the two groups was enhanced during the CB regimen. These observations suggest that malnourished patients with COPD have an elevated resting energy expenditure, and an enhanced thermic response to nutrients as compared to malnourished patients without COPD. Increased diet-induced thermogenesis may contribute to weight loss in patients with COPD, in addition to factors previously described such as decreased caloric intake and increased resting energy expenditure.