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.

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.

The Advanced Renal Cell Carcinoma Sorafenib (ARCCS) expanded access trial: Safety and efficacy in patients (pts) with non-clear cell (NCC) renal cell carcinoma (RCC)

5036

Background: A phase III trial showed that sorafenib (SOR) doubled progression-free survival (PFS) in previously treated pts with clear cell RCC. Activity of SOR in pts with NCC RCC has not been previously reported. Methods: Pts eligible for this open-label, nonrandomized trial in North America were not eligible for other SOR clinical trials, had recovered from prior treatment-related toxicity, and had advanced RCC; ECOG PS of 0–2; age =15 yrs; no treatment with other investigational drugs within 4 wks; life expectancy >2 mos; no active coronary artery disease, ischemia or hypertension; and no severe renal impairment requiring dialysis. In the US, ARCCS enrollment ended with SOR approval in 12/05, and pts were transitioned to commercial drug with NCC pts being eligible for an additional 6-mo follow-up in an extension protocol (EP), which was designed to better assess PFS in NCC. Tumor assessments and radiological evaluations were conducted every 4 wks in the main protocol and every 8 wks in the EP. Results: Of 2,488 pts valid for safety in ARCCS, 212 (8.5%) had NCC RCC classified as papillary, chromophobe, collecting duct, or oncocytoma, of whom 24 enrolled in the EP. Baseline characteristics and efficacy are shown in the table . Grade 3 and 4 adverse events (AEs) with > 2% incidence across all histologies included fatigue 7.1%, hand-foot skin reaction 6.6%, rash/ desquamation 6.2%, hypertension 4.7%, abdominal pain 3.8% dyspnea 3.8%, pleural effusion 3.3%, nausea 3.8%, vomiting 2.4%, and ascites 2.4%. Grade 3 and 4 serious AEs were reported in 20% of patients. Of those enrolled in the EP with NCC, median PFS was 34.5 wks (65.2% censored). Conclusions: SOR was well tolerated among pts with NCC RCC. Within the limitations of no central pathologic review, SOR toxicity in NCC RCC was similar to that in the broader ARCCS population and SOR may have antitumor activity in papillary and chromophobe subtypes.

[Table: see text]

[Table: see text]

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.

Anaesthetic management of placenta accreta: use of a pre-operative high and low suspicion classification

Placenta accreta may be suspected prior to surgery, but the actual diagnosis is only confirmed at surgery. This prospective and observational study was performed to assess whether preparations should be made for potential massive blood loss prior to Caesarean surgery in all patients with suspected placenta accreta. Patients were classified as high or low suspicion for placenta accreta based on ultrasonography and clinical factors. Among 28 suspected cases of placenta accreta, diagnosis was confirmed at surgery in 50% (12/17 high and 2/11 low suspicion) cases. Hysterectomy was only performed in the 12 high suspicion patients with placenta accreta (p < 0.001). High suspicion patients required more blood transfusions: mean(SD) 6.5 (7.0) units vs 1.09 (1.1) units, p = 0.017. Anaesthetists should be prepared for major haemorrhage in all cases of suspected placenta accreta, although use of a system to grade level of suspicion may identify those at greater risk.

Retroviral Transduction of FACS-Purified Hematopoietic Stem Cells

Since the mid-1980s, murine retroviral vectors have been used extensively by a number of investigators to clonally mark and genetically modify primitive hematopoietic stem cells (HSC) (1,2). During this period, both vectors and packaging systems used to generate virus have undergone considerable modification. This has led to increased production of high-titer, replication-defective retrovirus that is more resistant to gene inactivation following integration into hematopoietic cells. Current approaches to murine HSC transduction have become increasingly more standardized, although there remain numerous variations on a theme (see Chapter 15). This "classical" method utilizes preconditioned bone-marrow cells (typically from 5-fluorouracil [5-FU]-treated animals) and coculture of these cells with virus-producing packaging cells in the presence of exogenous cytokines. This approach generally yields high proportions of transduced cells that can repopulate lethally irradiated recipient mice for long periods of time, indicating that self-renewal activity is maintained-at least to some extent-in conditions that promote stem-cell cycling. With this approach, it is difficult to re-isolate transduced cells from packaging cells and from nontransduced bone marrow, which would be desirable in some clinically relevant cases.

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.

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.

Preoperative dipyridamole-thallium scanning, selective coronary revascularization and long-term survival in patients with critical lower limb ischemia

BACKGROUND

A large proportion of patients with critical limb ischemia have advanced, often asymptomatic coronary artery disease which is associated with increased perioperative risk and decreased long-term survival.

METHODS

We evaluated retrospectively the short and long-term effect of routine dipyridamole-thallium cardiac scanning (DTS) and selective coronary revascularization in 113 consecutive patients who were scheduled for revascularization of the lower extremity.

RESULTS

DTS was abnormal in 60 (53.1%) patients and demonstrated a moderate-severe reversible defect in 26 (23.0%) patients. On the basis of DTS and clinical evaluation 33 (29.2%) patients were referred for coronary catheterization. Of these, 9 underwent PTCA and 4 underwent coronary artery bypass, without complications. Surgical revascularization of the limbs was performed in all but two patients. Two (1.8%) patients died postoperatively, three (2.7%) sustained nonfatal postoperative myocardial infarctions. None of the patients who underwent preoperative coronary revascularization suffered a cardiac complication after the peripheral vascular operation. During mean follow-up of 31.7 months, 30 (28.0%) patients died. A moderate-severe reversible defect on DTS was the strongest predictor for shortened survival (Exp(b)=0.61, CI 95%=0.42-0.88; p=0.006). Patients who underwent preoperative coronary revascularization followed a survival curve approaching those without a reversible defect on DTS (mean survival 61+/-8 vs 63+/-4 months; NS) which was significantly better than those with such a defect who did not undergo coronary revascularization (mean survival 34+/-5 months; p=0.03).

CONCLUSIONS

While the perioperative benefits of routine preoperative DTS screening in patients with critical limb ischemia, remain debatable, it provides an opportunity for identification and treatment of life-limiting coronary artery disease and improving survival.

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.

Analyzing the impact of long-term patients on ICU bed utilization

OBJECTIVE

To establish ways of defining long-term ICU patients and to develop methods of quantifying their impact on bed utilization.

DESIGN

Retrospective analysis of prospectively collected sample data.

SETTING

Two university hospital adult surgical ICUs.

PATIENTS

6,588 consecutive patients admitted over 8 years to ICU 1 and 2,913 patents admitted over 5 years to ICU 2.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Patients with uncommon but expected long stays were designated as long-term patients and those with exceptional and unexpected long stays were designated as outliers. Visualization of the length-of-stay frequency distributions revealed that the "tail" of the distributions began at a stay of about 10 days, and this was chosen as the threshold for long-term patients. A threshold of 30 days was chosen as the outlier threshold since only isolated patients stayed longer. The impact (long-term patients/total admissions) of long-term patients on bed utilization was assessed and year-to-year differences examined. Long-term patients staying at least 10 days used 2.7-5.0 bed-years.

CONCLUSIONS

Long-term patients can have a major impact on ICU bed utilization. With 23-45% of the beds occupied by long-term patients, the availability of beds for short-stay patients is reduced. This is important in ICUs where efficient patient throughput is vital, so that beds are availability for both elective and emergency admissions.

Lipoxygenase metabolism following laser induced retinal injury in rabbits

PURPOSE

1) to investigate whether leukotriene B(4) (LTB(4)) is a factor in the inflammatory reaction following chorioretinal laser injury in rabbits; 2) to study its relationship with the cyclooxygenase (COX) metabolic pathway; 3) to study the influence of Nordihydroguaiaretic acid (NDGA), an inhibitor; of the lipoxygenase (LOX) cascade, on both COX and LOX metabolism.

METHODS

Prostaglandin E(2) (PGE(2)) and LTB(4) synthesis by incubated samples of chorioretina obtained from rabbits' eyes exposed to Neodymium:Yag laser along with these eicosanoids accumulation in the vitreous were measured over one week follow-up period. The effect of NDGA pre-treatment on the COX and the LOX pathways in the laser-injured chorioretina was also assessed. PGE(2) and LTB(4) levels in the vitreous and in the chorioretina incubation medium were quantified using the radioimmunoassay technique with the appropriate antibodies.

RESULTS

LTB(4) in vitro production by rabbits' chorioretina subjected to ND; YAG laser was significantly elevated compared to control, peaking on day 7 to levels 2.45 fold greater than baseline (p < 0.01). PGE(2) formation, following a different pattern, was also enhanced and its maximal level (5.2 fold higher than control, p < 0.01) was achieved at the initial phase (day 1 post laser). Laser irradiation caused also an increase in the two eicosanoids accumulation in the vitreous, which was however not proportional to their production levels. NDGA treatment was associated with a sustained decrease in LTB(4) content in the vitreous, but had no effect on PGE(2) vitreal levels.

CONCLUSIONS

Laser irradiation of the rabbits' retina induces an alteration in the LOX metabolic pathway, which is dissociated from the influence on the COX cascade, pointing for the first time to a possible role played by LTB( 4) as a mediator in the chorioretinal inflammatory reaction, with no connection to the role played by PGE(2). NDGA selectively inhibited LOX activity without affecting COX activity.

Factors influencing changes in surgical intensive care unit utilization

OBJECTIVES

To determine the factors that cause changes in surgical intensive care unit (ICU) utilization. The aim was to uncover the causes of these changes and examine whether any could have been predicted statistically.

DESIGN

Retrospective analysis of prospectively collected representative data.

SETTING

University hospital adult surgical ICU.

PATIENTS

A total of 6,571 consecutive patients admitted over 8 yrs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Changes in annual admission rates and lengths of stay were examined to determine their causes, whether they were because of structural changes caused by alterations of physical facilities, functional changes caused by changes in personnel or policies, or clinical changes caused by alterations in clinical practice. The medical literature was examined to determine whether these changes reflected medical trends. During the 8 yrs there was a steady increase in the number of admissions and a steady reduction in the length of stay. These changes in unit utilization were often not predictable statistically and were attributable to a combination of clinical, structural, and functional factors.

CONCLUSIONS

Surgical ICU utilization was notable for continual, and not predictable, changes. Clinical issues included new surgical techniques and anesthetic practices; structural causes included changes in bed capacity and opening an intermediate care unit; and functional factors involved changes in surgical personnel, policy revisions, and pressures to reduce ICU length of stay. This was further complicated by the observation that changes in the number of admissions were often not paralleled by similar changes in the number of patient days. This complex situation demonstrated the problems of basing predictions of future utilization on previous experiences.

A submicron emulsion of HU-211, a synthetic cannabinoid, reduces intraocular pressure in rabbits

PURPOSE

To study the ocular hypotensive effect of a nonpsychotropic cannabinoid, HU-211 (11 -hydroxy-delta8-tetra-hydrocannabinol, dimethylheptyl), an N-methyl-D-aspartate (NMDA) agonist, in normotensive rabbits.

METHODS

The cannabinoid HU-211, being lipophilic, was incorporated into a stable oil-in-water submicron sterile emulsion, consisting of 0.12% (w/w) HU-211. A single- dose, randomized and double-masked study was designed, using a Digilab 30R pneumotonometer to measure intraocular pressure (IOP) in normotensive rabbits.

RESULTS

Application of a single dose of HU-211 ophthalmic preparation resulted in an IOP reduction of 5.3 mmHg (24% of baseline), first evident at 1.5 h post application and persisting for over 6 h. A small but significant lowering of pressure (12.5% of baseline) occurred in the contralateral eyes of HU-211 treated rabbits, lasting for 4 h post treatment.

CONCLUSION

Our work demonstrated that HU-211, incorporated into submicron emulsion, caused a 6-h-long reduction in IOP in the treated eye, with a lesser reduction in the contralateral untreated eye.

Pulmonary function after cardiac and thoracic surgery

Cardiac and thoracic surgery cause alterations in ventilatory function that can lead to significant postoperative pulmonary complications. These complications often occur among patients with pre-existing pulmonary dysfunction and cause significantly longer hospital stays. This review explores some of the recent literature concerning this issue, including the effects of lung reduction surgery.

Respiratory flow measurements and anesthetic drugs: some in vitro observations

STUDY OBJECTIVE

To illustrate the influence of anesthetic gases on respiratory flow measurements and to correct this influence.

DESIGN

In vitro evaluation.

SETTING

Laboratory.

MEASUREMENTS AND MAIN RESULTS

An in vitro method using a 120-L Tissot water-seal spirometer was used along with a Bicore CP-100, designed for use in intensive care units, and a Datex Ultima, designed for use in the operating room. The flow transducer of one of the instruments being tested was placed in the gas inlet of the Tissot so that simultaneous measurements could be made. Timed flows (2 to 60 L/min) of various gases (O2 and air) and gas mixtures (halothane-O2, isoflurane-O2, N2O-O2, and N2O-O2-isoflurane) were used and the measurements made by the Tissot and the test instrument compared. The Datex Ultima, which includes software corrections for anesthetics, was able to accurately measure gas flows (2 to 60 L/min) of air, 100% oxygen, and anesthetic gas mixtures to within +/- 10% of measurements made by the Tissot. The Bicore CP-100, intended for use with mechanically ventilated patients, accurately measured air and 100% oxygen flow rate to within +/- 8% of the measurements made by the Tissot, but there were large errors (up to 40%) when anesthetics were used.

CONCLUSIONS

This study illustrates the effects of anesthetic gases on measurements of ventilatory flow and the need to ascertain whether corrections are needed to improve the accuracy of flow transducers.

Influence of lower limb pneumatic compression on pulmonary artery temperature: effect on cardiac output measurements

OBJECTIVES

To characterize the decreases in pulmonary artery temperature that coincide with the inflation cycle of pneumatic calf compression stockings and to examine their effects on the thermodilution measurement of cardiac output.

DESIGN

Three-part observational study.

SETTING

University hospital surgical intensive care unit.

PATIENTS

Postoperative patients with indwelling pulmonary artery catheters.

INTERVENTION

Thermodilution cardiac output measurements with and without pneumatic calf compression.

MEASUREMENTS AND MAIN RESULTS

Phase 1 (n = 18) examined the effects of pneumatic compression on pulmonary artery temperature. There was no effect on pulmonary artery temperature (device off, 37.468+/-0.008 degrees C; device on, 37.458+/-0.014 degrees C), but the difference between the maximum and minimum pulmonary artery temperatures was increased (off, 0.031+/-0.006 degrees C; on, 0.055+/-0.012 degrees C [p < .001]). Phase 2 (n = 12) found that the mean thermodilution cardiac output with 10 mL of cold (0-5 degrees C) injectate was unchanged by pneumatic compression (off, 7.00+/-2.28 L/min; on, 6.89+/-2.22 L/min). However, when the compression devices were operating, the variability between the individual measurements was increased, as reflected by larger coefficients of variation (off, 3.19+/-1.96; on, 8.72+/-6.56 [p < .02]). Similar results were obtained during phase 3 (n = 5), when cardiac output was measured with room temperature Injectate.

CONCLUSIONS

Intermittent pneumatic calf compression increased lower limb venous return, causing acute but transient decreases in pulmonary artery blood temperature. This did not affect the accuracy of thermodilution cardiac output measurements that were made using 10 mL of either cold or room temperature injectate.

Nutrition in the intensive care unit

Nutritional support has become a routine part of the care of the critically ill patient. It is an adjunctive therapy, the main goal of which is to attenuate the development of malnutrition, yet the effectiveness of nutritional support is often thwarted by an underlying hostile metabolic milieu. This requires that these metabolic changes be taken into consideration when designing nutritional regimens for such patients. There is also a need to conduct large, multi-center studies to acquire more knowledge of the cost-benefit and cost effectiveness of nutritional support in the critically ill.

Preoperative thallium scanning, selective coronary revascularization, and long-term survival after carotid endarterectomy

BACKGROUND AND PURPOSE

Long-term survival in patients after carotid endarterectomy (CEA) is determined mainly by their concomitant cardiac disease. We tested to determine whether preoperative thallium scanning (PTS) and subsequent selective coronary revascularization (CR), by either percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG), improve long-term survival after CEA.

METHODS

Two hundred twenty-six of 255 consecutive patients (88%) undergoing CEA from 1990 to 1996 had PTS. Those with significant reversible defects on PTS were referred for coronary angiography and possible CR. Patients who had undergone PTS were divided into the following 4 groups: group 1, normal or mild defects on PTS; group 2, moderate-severe fixed and/or reversible defects in patients who did not undergo CR; group 3, patients who had CR secondary to their PTS results; and group 4, patients who had CR in the past that was not related to the PTS. Perioperative data were prospectively recorded, and data on long-term survival and cardiac and neurological complications were collected.

RESULTS

Seventy-seven patients (34%) had preoperative coronary angiography, and 42 (19%) had subsequent CR: preoperative PTCA or CABG in 24, combined CEA+CABG in 10, and post-CEA CABG in 8 patients. No deaths resulted from the coronary angiography, CR, or CEA. Six patients had perioperative nonfatal myocardial infarction and 8 had stroke. During the follow-up (40+/-23 months), 47 patients (18%) died, 31 (66%) from cardiac disease and 4 (8.5%) from stroke. Independent predictors of long-term overall mortality were diabetes mellitus, preoperative T-wave inversion on ECG, lower-extremity arterial disease, and history of neurological symptoms [exp(beta)=3. 5, 3.4, 2.5, and 2.4; P=0.0003, 0.0004, 0.01, and 0.04, respectively]. In addition, preoperative moderate-severe thallium defect without CR (group 2) independently predicted long-term cardiac mortality [exp(beta)=2.8; P=0.04]. Patients with preoperative CR (group 3) had long-term survival rate similar to that of group 1 and significantly better than that of group 2 (P=0. 02).

CONCLUSIONS

PTS predicts long-term survival, and selective CR based on the thallium results improves the survival rate of patients undergoing CEA.

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.

Fluid resuscitation, nutritional support, and cholesterol in critically ill postsurgical patients

STUDY OBJECTIVE

To determine how and why cholesterol concentrations decrease after surgery, and the effect of the administration of nutritional support.

DESIGN

Prospective, observational study.

SETTING

Surgical intensive care unit of a university hospital.

PATIENTS

213 consecutive patients admitted to a surgical intensive care unit after major surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Serum concentrations of cholesterol, serum albumin and total protein. The initial portion of this study demonstrated that serum concentrations of cholesterol, like those of serum albumin and total protein, decreased by approximately 30% immediately following surgery. These changes were directly related to changes in hematocrit and inversely correlated with the volume of perioperative intravenous (IV)fluid, the degree of positive fluid balance, and the estimated blood loss. The study's second phase examined the 19 patients who received at least 10 days of nutritional support. After 1 week of feeding, serum total protein concentrations increased significantly, but did not return to preoperative levels. Serum concentrations of cholesterol, which were markedly decreased prior to nutritional repletion, increased significantly after 9 days of treatment. The changes in serum cholesterol concentration were negatively correlated (r = -0.32) with the daily intake of IV fluid.

CONCLUSION

Serum cholesterol concentrations, like those of serum albumin and total protein, are markedly reduced immediately following major abdominal surgery, often to levels reported in malnutrition. Dilution by IV fluid and redistribution into an expanded extracellular fluid space are likely the major causes of these decreases. Serum cholesterol concentrations are therefore not useful in the nutritional assessment of patients in the immediate postoperative period.

Analyzing intensive care unit length of stay data: problems and possible solutions

OBJECTIVES

To explore methods of evaluating the length of stay patterns of intensive care unit (ICU) patients. It was hypothesized that the mean does not adequately describe the typical length of stay (central tendency) because distribution patterns are often markedly skewed by patients with extended stays. Therefore, other descriptors are needed. In addition, ways are needed to identify outliers-patients with stays longer or shorter than the bulk of the data.

DESIGN

Review of retrospective data.

SETTING

University hospital surgical ICU.

PATIENTS

Representative data included all (4,499) patients admitted over a 6-yr period. Each was assigned to a diagnostic group that represented either a frequently performed surgical procedure (e.g., thymectomy) or in cases where there was no predominant procedure, a surgical discipline (e.g., otolaryngology).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The frequency distributions were usually skewed to the right and included two populations of interest: The portion with the majority of observations ("body"), which described "typical" behavior, and the "tail", which provided information on outliers. The average of the mean lengths of stay of all diagnostic groups was higher than the average of the medians (3.9 +/- 1.8 [SD] vs. 2.7 +/- 1.1 days, p < .001) and modes (2.1 +/- 1.2 days, p < .001), reflecting the rightward skewness of the length of stay frequency distributions. The median +/- 1 day included 75 +/- 13% of the patients, thus confirming that the median was the most useful descriptor of central tendency. Various methods were used to identify outliers. Histograms of the frequency distributions were examined and outliers visually identified. Conventional outlier analysis labeled as outliers patients staying greater than two standard deviations from the mean stay. This method underestimated the number of outliers when the distributions were skewed to the right. Another method involved designating a specific length of stay (e.g., 7 or 10 days) or percentage of patients as the outlier threshold. Each method designated different numbers of patients as outliers.

CONCLUSIONS

When analyzing length of stay data it is important to visually examine the frequency distribution because it is often skewed to the right. This skewness renders traditional parameters such as the mean and standard deviation less useful for describing the typical length of stay. Instead, the median, mode, and harmonic mean should be used. When reporting length of stay, some indication of the characteristics of the data should be presented. A graph of the frequency distribution rapidly allows the reader to determine its shape. A simple method is to report the mean, median, and range.

Can hospital discharge diagnoses be used for intensive care unit administrative and quality management functions?

OBJECTIVE

To determine whether hospital discharge diagnoses can be used for intensive care unit (ICU)-related activities.

DESIGN

Comparison between the diagnoses coded by physicians at the time of ICU admission and those diagnoses coded by medical records personnel.

SETTING

University hospital adult surgical ICU.

PATIENTS

Consecutive ICU admissions (n = 622).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The ICU admission and hospital discharge codes were compared in two ways. Initially, each discharge code was subtracted from the corresponding ICU admission code. There was no difference in 150 (24%) cases. In 216 (35%) patients, the codes differed by +/-10. In 221 (36%) instances, the codes differed by >200. The secondary discharge diagnoses were also compared with the ICU admission diagnoses. In 56 patients, the ICU admission diagnosis was one of the secondary diagnoses. The second comparison involved having two physicians not associated with the study examine each pair of codes to determine if the two diagnoses were medically different. Review of the codes by physicians not involved in the study found that in 318 (48%) patients, the two diagnoses were not different, i.e., the codes were either the same or the codes were so similar as not to functionally change the actual diagnosis.

CONCLUSIONS

The primary discharge diagnosis often failed to reflect the reason for ICU admission, making it impossible to consistently establish the reason for ICU admission from the discharge data. The reason for ICU admission was also frequently not included among the secondary discharge diagnoses. Administrative data are therefore not useful for ICU quality management and other functions. Intensivists need to establish their own databases.

Insights into the increased oxygen demand during chest physiotherapy

OBJECTIVES

To determine the mechanism responsible for the increase in oxygen consumption (VO2) during chest physical therapy. Specifically, to examine the hypothesis that muscular activity is the major contributor to the increase in oxygen demand.

DESIGN

Prospective, observational study.

SETTING

University hospital surgical intensive care unit.

PATIENTS

Phase one included 13 patients who were mechanically ventilated after coronary artery bypass surgery. Phase two involved seven mechanically ventilated patients who had undergone major vascular or abdominal surgery.

INTERVENTIONS

Phase one involved turning patients to the lateral decubitus position. During the second phase, patients were given midazolam (0.15 microg/kg) 2 mins before an initial chest physiotherapy session and midazolam plus vecuronium (0.7 mg/kg) before a subsequent session. Physiologic measurements were made during the resting periods before and following each session, as well as at the completion of the intervention.

MEASUREMENTS AND MAIN RESULTS

Turning patients to the lateral position resulted in significant increases in oxygen uptake and CO2 elimination (VCO2). VO2 increased from 219 +/- 21 (SD) mL/min at rest to 324 +/- 58 mL/min (p <.05) with turning. These increases in oxygen demand were met by increases in both oxygen delivery (852 +/- 238 mL/min at rest to 1116 +/- 430 mL/min, p < .05) and extraction (0.27 +/- 0.7 at rest to 0.32 +/- 0.09, p < .05). There were associated increases in hemodynamic and respiratory variables including heart rate and systolic blood pressure. The administration of vecuronium completely suppressed the 50% increases in VO2 and VCO2 seen without the use of a muscle relaxant. The increases in systolic blood pressure were unaffected by vecuronium. The magnitude of the increase in PaCO2 (32 +/- 5 torr [4.3 +/- 0.7 kPa] at rest to 36 +/- 5 torr [4.8 +/- 0.7 kPa] during therapy, p < .05), was not accentuated by vecuronium (30 +/- 4 torr [4.0 +/- 0.5 kPa] to 35 +/- 6 torr [4.7 +/- 0.8 kPa], p < .05) despite a lack of any increase in minute ventilation or respiratory rate. This change was due to the parallel suppression of VCO2.

CONCLUSIONS

The increase in metabolic demand during chest physiotherapy is the result of increased muscular activity as evidenced by the suppression of VO2 following the administration of the muscle relaxant and the observation that turning a patient into the lateral decubitus position produces similar increases in VO2. The increases in blood pressure and cardiac output are due to another mechanism, most likely enhanced sympathetic output. The increase in physiologic activity produced by chest physiotherapy is thus secondary to both exercise-like and stress-like responses.

Dynamic ventilatory characteristics during weaning in postoperative critically ill patients

Postoperative patients occasionally require more than 48 h of mechanical ventilation. This study examined whether there were distinct differences in dynamic respiratory variables between patients who successfully weaned from mechanical ventilation and those who failed. Forty general and thoracic surgery patients underwent a standardized weaning sequence: 25 min of synchronous intermittent mandatory ventilation (SIMV) at 8 bpm plus 5 cm H2O pressure support ventilation (PSV), then SIMV at 4 bpm plus 5 cm H2O PSV, followed by continuous positive airway pressure (CPAP) plus 5 cm H2O PSV and, finally, CPAP without PSV. Twenty-eight patients successfully weaned and 12 failed. During SIMV at 4 bpm plus 5 cm H2O PSV, the spontaneous respiratory rate to spontaneous tidal volume ratio (sRR/sV(T)) and total and spontaneous respiratory rates were higher (P < 0.01) in the failure group. sRR/sV(T) values (threshold 65 bpm/L, sensitivity 1.00, specificity 0.82) and sRR values (threshold 12 bpm, sensitivity 0.95, specificity 0.84) were distinctive. During CPAP plus 5 cm H2O of PSV, respiratory rate, minute ventilation, patient work of breathing, and P0.1 were higher (P < 0.01) in those who failed. P0.1 (threshold 4.5 cm H2O, sensitivity 1.00, specificity 1.00), patient work of breathing (threshold 1.3 J/L, sensitivity 0.92, and specificity 0.98), and the sRR/sV(T) ratio (threshold 65 bpm/L, sensitivity 0.90, specificity 0.80) were distinctive. Most unique was the analysis of spontaneous breaths during low SIMV rates. This appears to permit an early determination of whether weaning would succeed.

Urinary pyridinium cross-link excretion is increased in critically ill surgical patients

OBJECTIVES

To determine: a) the rate of pyridinium cross-links of collagen excretion, breakdown products of bone, in critically ill surgical patients in the intensive care unit (ICU); and b) the relationship between cross-link excretion and nitrogen excretion and balance to ascertain whether collagen breakdown products contribute to protein losses during a hypercatabolic state.

DESIGN

Observational study starting on the first postoperative day to 20 days or until discharge.

SETTING

A surgical ICU in a University hospital.

PATIENTS

Nine mechanically ventilated, postoperative surgical patients (73 +/- 3 [SD] yrs), receiving routine parenteral nutrition (18% protein) and 17 age-matched healthy subjects.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Resting energy expenditure was determined daily for < or = 5 days after admission, and energy intake was set at 1.04 times the initial energy expenditure; thereafter, values of intake were reset weekly. Daily 24-hr urine samples were analyzed for cross-links, total and urea nitrogen, calcium, and creatinine for 20 days or until discharge. Two urine samples were also analyzed for cross-links in the healthy subjects. The excretion of cross-links from the surgical patients was markedly higher (p < .001) than in the healthy subjects, and calcium balance was significantly negative (p < .05). Patients who were discharged from the ICU within 5 days showed a lower rate of cross-link excretion (p < .02) and less day-to-day variability, compared with those patients who stayed longer, whether calculated over the course of the study or over the first 2 days in the ICU. There was no correlation between cross-links and energy expenditure, nitrogen excretion, or balance.

CONCLUSIONS

The rate of cross-link excretion in critically ill patients: a) is markedly increased; b) is greater within the first two postoperative days in those patients who have an extended stay (> 5 days) in the ICU; and c) is independent of the rate of nitrogen excretion. These findings suggest that critically ill postoperative patients experience an acute breakdown of collagen, which is likely due to resorption of bone or possibly comes from other collagen sources.

Modulating effects of propofol on metabolic and cardiopulmonary responses to stressful intensive care unit procedures

OBJECTIVE

Patients in the intensive care unit (ICU) undergo acute increases in metabolic and cardiopulmonary demands in response to routine care interventions, such as chest physical therapy. This study examined whether the short-acting drug, propofol, could blunt the responses to chest physical therapy.

DESIGN

Prospective, randomized, crossover (placebo vs. drug) study.

SETTING

University hospital surgical ICU.

PATIENTS

Postoperative ICU patients being ventilated in the synchronized intermittent mandatory ventilation mode.

INTERVENTIONS

Two groups of 16 patients were studied. Each patient received two successive sessions of chest physical therapy. In random fashion, one was preceded by the administration of placebo and the other by an intravenous bolus of propofol (0.75 mg/kg in one group and 0.35 mg/kg in the other group). Each session was preceded and followed by a period of rest.

MEASUREMENTS AND MAIN RESULTS

The increases in oxygen uptake, CO2 elimination, oxygen delivery, heart rate, and systolic blood pressure associated with chest physical therapy were attenuated with the low dose and suppressed with the high dose of propofol. The Paco2 concentration was slightly increased during both placebo and drug administration.

CONCLUSIONS

Propofol, in the doses administered in this study, significantly reduced the hemodynamic and metabolic stresses caused by chest physical therapy.

Mice homozygous for a modified beta-amyloid precursor protein (beta APP) gene show impaired behavior and high incidence of agenesis of the corpus callosum

The amyloid precursor protein (beta APP) gene of the mouse was disrupted by homologous recombination; however, contrary to expectation, brain and other tissues still contained beta APP-specific RNA, albeit at a level 5-10 fold lower than wild-type and lacking the disrupted exon, which had been spliced out. The brain contained shortened beta APP-specific protein at a low level. Mutant mice were severely impaired in spatial learning and exploratory behavior and showed increased incidence of agenesis of the corpus callosum.

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.

Do synthetic adrenergic agents interfere with the measurement of endogenous plasma catecholamine concentrations?

PURPOSE

It is common to administer synthetic sympathomimetic and sympatholytic agents in the intensive care unit and operating room. The present study examines whether such agents, as well as the products of catecholamine metabolism, interfere with the quantitation of endogenous catecholamines by high-performance liquid chromatography.

METHODS

Samples of drugs and metabolites were assayed before and after alumina extraction and their relative retention times were compared with dopamine, norepinephrine, and epinephrine relative retention times. Blood samples from patients receiving these drugs were also assayed for their interferences with catecholamine determination.

RESULTS

Phenylephrine interfered with the quantitation of epinephrine. Isoproterenol's peak was so delayed it appeared in the following chromatogram. Dobutamine had two small peaks in vitro, whereas in the patient samples only one peak was identified; the other was probably masked by the dopamine peak. Labetalol had one peak when the pure drug was assayed but multiple peaks in patient samples, that were probably caused by metabolites of labetalol.

CONCLUSION

Synthetic adrenergic agents and catecholamine metabolites can potentially interfere with the quantitation of the endogenous catecholamines. Thus, it is important to examine whether such interference occurs when conducting high-performance liquid chromatography assays.

Metabolic measurements in the critically ill

Measurements of VO2 and VCO2 can be used to calculate REE, which can be used to determine the caloric requirements and metabolic state of critically ill patients. These measurements are made using the gas exchange method--measuring the minute ventilation and the differences between the inspired and expired concentrations of oxygen and carbon dioxide. Mechanical ventilation provides a challenging environment in which to make these measurements because of elevated oxygen concentrations, fluctuating airway pressures, and humidity. Careful attention must be paid to details to ensure accurate measurements under these conditions.

An in vitro evaluation of an instrument designed to measure oxygen consumption and carbon dioxide production during mechanical ventilation

OBJECTIVE

To determine the ability of the Puritan-Bennett 7250 metabolic monitor to measure CO2 production and oxygen consumption (VO2) under simulated clinical conditions.

DESIGN

An in vitro validation study.

SETTING

Laboratory of a large university medical center.

METHODS

An in vitro evaluation was performed by adding precise amounts of CO2 and nitrogen to a lung model to simulate CO2 production and VO2. CO2 production and VO2 values measured by the metabolic monitor were compared with simulated values at various FIO2 values (0.21 to 0.80), levels of positive end-expiratory pressure (0 to 20 cm H2O), and flow-by mode flow rates (0 to 20 L/min). This comparison was also made at increased peak airway pressures (60 cm H2O). The effects of various concentrations of oxygen on the accuracy of the CO2 production measurements were also examined.

RESULTS

The measurements made by the instrument were within 7% of values predicted from the CO2 and nitrogen infusions. There was no effect of various oxygen concentrations on the accuracy of CO2 production measurements.

CONCLUSION

Under the in vitro conditions tested, the metabolic monitor provided accurate measurements of VO2 and CO2 production.

Response of critically ill patients to increased oxygen demand: hemodynamic subsets

OBJECTIVE

To ascertain how patients with different abnormalities of oxygen transport at rest respond to an acute increase in oxygen demand.

DESIGN

Observational study with retrospective assignment to subgroups, based on resting oxygen extraction ratio or increased cardiac output.

SETTING

University hospital surgical intensive care unit (n = 96).

PATIENTS

Postoperative, mechanically ventilated, critically ill patients (n = 96).

INTERVENTION

Chest physical therapy.

MEASUREMENTS AND MAIN RESULTS

Metabolic, hemodynamic, and respiratory measurements were made during an initial rest period and then during chest physical therapy. During chest physical therapy, patients (n = 10) having low resting oxygen extraction ratios (< or = 0.20) increased oxygen extraction, without changing oxygen delivery (DO2); while those patients (n = 19) with high resting oxygen extraction ratios (> or = 0.30) increased DO2, but not oxygen extraction. Patients (n = 46) with oxygen extraction ratios between 0.2 and 0.3 had an intermediate response; both DO2 and oxygen extraction increased. The group (n = 19) with increased resting cardiac output (> 9 L/min) and associated low resting oxygen extraction ratios and high DO2 values, increased their extraction of oxygen during chest physical therapy.

CONCLUSIONS

The response to an acute increase in oxygen demand was influenced by resting conditions and was characterized by the use of "reserve" capacity. Patients with a resting hyperdynamic state (high DO2 and low oxygen extraction) were able to further increase oxygen extraction during the increase in oxygen demand.

Encoding a post-operative coronary artery bypass surgery care plan in the Arden Syntax

The Arden Syntax for medical logic modules (Arden) was used to test the feasibility of encoding large, complex care plans. The critical portions of an existing paper-based care plan for the management of patients following coronary artery bypass graft (CABG) surgery were encoded in Arden and an X-windows user-interface was developed. The Arden Syntax proved adequate for encoding all of the necessary functions of the care plan. The limitations of the current Arden Syntax and possible additions to Arden are discussed.

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.

The use of analgesics and sedatives in critically ill patients: physicians' orders versus medications administered

OBJECTIVE

To examine the difference between the prescribed and actually administered dose of analgesic and sedative drugs in critically ill patients.

DESIGN

Prospective survey.

SETTING

University hospital surgical intensive care unit.

SUBJECTS

One hundred fifty consecutive adult patients admitted to a surgical intensive care unit over a 3-month period.

METHODS

Data were gathered on a daily basis. The sedation and analgesia given were compared with the daily physician orders.

RESULTS

Narcotics and benzodiazepines were most commonly used. On average only 22% to 52% of the mean ordered dose of intravenous and intramuscular morphine was actually administered. Larger doses of morphine were administered to intubated patients than to nonintubated ones. Patients receiving intravenous fentanyl infusions generally were administered more than the ordered dose. The actual and prescribed doses of epidural fentanyl were well matched. Midazolam was the most frequently prescribed benzodiazepine. Like morphine, the amount administered was below the maximum ordered by the physicians.

CONCLUSIONS

Physicians tended to write fairly nonspecific orders that were used by the nursing staff as very broad guidelines. A need exists to educate physicians as to what patients actually receive for sedation and analgesia and at the same time improve the dialogue between nurses and physicians as to what patients actually require.

Alfentanil attenuates the cardiopulmonary response of critically ill patients to an acute increase in oxygen demand induced by chest physiotherapy

Critically ill patients often are subjected to interventions that acutely increase oxygen demand and require increased output of the cardiac and respiratory systems. This study explored whether alfentanil could attenuate the response to chest physical therapy, a procedure that increases oxygen consumption by 40%-50%. Patients were examined during two consecutive therapy sessions. In random order, they received either a placebo or alfentanil (30 or 60 micrograms/kg) 2 min before treatment. In Group 1 (n = 11, 30 micrograms/kg alfentanil) only the arterial blood pressure increases induced by chest physical therapy were attenuated. In Group 2 (n = 12, 60 micrograms/kg) alfentanil attenuated the increases in heart rate, central venous pressure, and pulmonary artery systolic pressures as well as systemic blood pressure. Neither dose of alfentanil altered the increases in oxygen consumption, carbon dioxide elimination, oxygen delivery, or extraction ratio. Thus alfentanil attenuated the hemodynamic responses to chest physiotherapy in a dose-dependent fashion. This was likely due to its vagotonic actions. In contrast, alfentanil had no effect on the balance between oxygen demand and delivery during chest physiotherapy. There was thus a dissociation between the hemodynamic and metabolic responses.