Multifaceted bench comparative evaluation of latest intensive care unit ventilators.

BACKGROUND: Independent bench studies using specific ventilation scenarios allow testing of the performance of ventilators in conditions similar to clinical settings. The aims of this study were to determine the accuracy of the latest generation ventilators to deliver chosen parameters in various typical conditions and to provide clinicians with a comprehensive report on their performance. METHODS: Thirteen modern intensive care unit ventilators were evaluated on the ASL5000 test lung with and without leakage for: (i) accuracy to deliver exact tidal volume (VT) and PEEP in assist-control ventilation (ACV); (ii) performance of trigger and pressurization in pressure support ventilation (PSV); and (iii) quality of non-invasive ventilation algorithms. RESULTS: In ACV, only six ventilators delivered an accurate VT and nine an accurate PEEP. Eleven devices failed to compensate VT and four the PEEP in leakage conditions. Inspiratory delays differed significantly among ventilators in invasive PSV (range 75-149 ms, P=0.03) and non-invasive PSV (range 78-165 ms, P<0.001). The percentage of the ideal curve (concomitantly evaluating the pressurization speed and the levels of pressure reached) also differed significantly (range 57-86% for invasive PSV, P=0.04; and 60-90% for non-invasive PSV, P<0.001). Non-invasive ventilation algorithms efficiently prevented the decrease in pressurization capacities and PEEP levels induced by leaks in, respectively, 10 and 12 out of the 13 ventilators. CONCLUSIONS: We observed real heterogeneity of performance amongst the latest generation of intensive care unit ventilators. Although non-invasive ventilation algorithms appear to maintain adequate pressurization efficiently in the case of leakage, basic functions, such as delivered VT in ACV and pressurization in PSV, are often less reliable than the values displayed by the device suggest.

[Rational approach of antibioprophylaxis: systematic review in ENT cancer surgery]. / Conduite rationnelle de l'antibioprophylaxie : revue systématique en chirurgie carcinologique ORL.

In head and neck cancer surgery antibiotic prophylaxis is effective in reducing the incidence of surgical site infections (SSI). However, controversies between antibiotic prophylaxis and curative antibiotic therapy exist, particularly when complex and decaying surgeries are performed in risky underlying conditions, with a risk of persisting salivary effusion in the postoperative period, or in the case of reconstruction with myo-cutaneous flaps. We have performed a systematic review of the literature according to PRISMA recommendations to answer the following questions: indications for antibiotic prophylaxis and curative antibiotic therapy, optimal duration, and choice of antibiotics for prophylaxis in head and neck cancer surgery. Literature analysis allows to conclude that patients undergoing Altemeier classes 2 and 3 surgical procedures should receive perioperative antibiotic prophylaxis restricted to the first 24 postoperative hours. No benefit has been shown with its extension beyond these 24 hours. The most adapted combinations of antibiotics in this setting are "amoxicillin+clavulanic acid" and "clindamycin+gentamicin". However, the level of evidence regarding the most decaying surgeries with high risk of SSI is low, making it necessary to perform new high-powered randomized trials in these patients. Eventually, it should be noted that antibiotic prophylaxis should be an integral part of SSI preventive measures, including application of hygiene measures, and postoperative monitoring of SSI clinical signs.

Procedure volume is one determinant of centre effect in mechanically ventilated patients.

Survival rates vary significantly between intensive care units, most notably in patients requiring mechanical ventilation (MV). The present study sought to estimate the effect of hospital MV volume on hospital mortality. We included 179,197 consecutive patients who received mechanical ventilation in 294 hospitals. Multivariate logistic regression models with random intercepts were used to estimate the effect of annual MV volume in each hospital, adjusting for differences in severity of illness and case mix. Median annual MV volume was 162 patients (interquartile range 99-282). Hospital mortality in MV patients was 31.4% overall, 40.8% in the lowest annual volume quartile and 28.2% in the highest quartile. After adjustment for severity of illness, age, diagnosis and organ failure, higher MV volume was associated with significantly lower hospital mortality among MV patients (OR 0.9985 per 10 additional patients, 95% CI 0.9978-0.9992; p = 0.0001). A significant centre effect on hospital mortality persisted after adjustment for volume effect (p < 0.0001). Our study demonstrated higher hospital MV volume to be independently associated with increased survival among MV patients. Significant differences in outcomes persisted between centres after adjustment for hospital MV volume, supporting a role for other significant determinants of the centre effect.

[Tracheal replacement using the abdominal aorta. Comments on a case report]. / Remplacement de la trachée par l'aorte. Réflexions à propos d'un cas.

Tracheal replacement is an uncommon option because of the very limited number of indications and the large number of possibilities for resection anastomosis. There may nevertheless be situations were extensive resection leaves only one solution, tracheal replacement. To date, no prosthesis has provided long-term satisfaction. For tracheal replacement, the prosthesis must provide a large caliber airway which does not collapse during expiration and which enables the development of a ciliary lining, in addition to tolerance without rejection. Recent experimental work, then several clinical cases, would suggest that the abdominal aorta can be successfully transformed into a neotrachea. A temporary endoprosthesis is however necessary to prevent collapse until new tracheal rings develop. Experimental and early clinical work has provided promising results but with problems concerning the endoprosthesis. In our patient, we used the abdominal aorta as a tracheal substitute but replaced the endoprosthesis with an exoprosthesis leaving the aortic lumen free. The result was also encouraging, but the absence of integration of the aortic tissue did not confirm the observations reported by others. Other hypotheses concerning the regeneration of the neotrachea should be put forward.

[ICU performance: results of a French study involving 80,000 ICU stays]. / Performance en réanimation: résultats du PHRC Sfar-SRLF.

OBJECTIVE: The Standard Mortality Ratio (SMR), comparing the observed in-hospital mortality to the predicted, may measure the intensive care units (ICU) performance. STUDY DESIGN: Multicentric retrospective national study. METHODS: A probability model using a severity score such SAPS II calculated the predicted mortality rate. A national French study has been undertaken to compare the SMR of ICUs and looked for explanation. RESULTS: One hundred six units, 34 were medical (32%), 18 surgical (17%) and 57 medical/surgical (51%) participated to the study. Forty-six ICUs (43%) were located in teaching hospitals. The SMR of the 87,099 stays was 0.84 (0.82-0.85). The SMR of ICUs varied from 0.41 to 1.55. Ten units had a SMR>0.85, which suggested a low performance. They had more stays for cardiovascular failures, as compared with others. The best units (SMR<0.82) had more stays for drug overdose. The SMR increased with the number of organ failures, from 0.47 with zero failure to 1.11 with 4 or more organ failures. The stays with cardiovascular failure, either unique or associated, had a higher SMR. The 7935 stays with a drug overdose had a SMR of 0.12 (0.10-0.14), which suggested a bad calibration of the model in theses cases. CONCLUSION: The case mix must be taken in account when comparing the ICUs performance by the mean of SMR, particularly when the units admitted a lot of drug overdoses.

The use of contrast media in deceased kidney donors does not affect initial graft function or graft survival.

Patients receiving cadaveric kidney transplants often experience delayed graft function. As iodinated contrast media injection (ICMI), necessary for cerebral angiography, which is often used to diagnose brain death, can be nephrotoxic, we compared renal function recovery (RFR) and 1-year and long-term graft survival according to the method used to diagnose brain death. Data from 9921 cadaveric kidneys, transplanted between 1 January 1998 and 31 December 2003, were retrieved from the French National Registry for organ donation. We defined RFR as the number of days for the recipient to reach a plasma creatinine less than 250 mumol/l, and/or a 24-h urine output greater than 1000 ml. RFR and 1-year and long-term graft survival were compared between four different donor groups (according to ICMI and diabetes mellitus). A total of 41.5% of deceased donors received ICMI before organ procurement and 1.95% of them were diabetic. History of ICMI or diabetes in the donor did not influence RFR or 1-year graft survival. Long-term graft survival was decreased in the group of patients transplanted with a diabetic graft as compared to patients transplanted with a non-diabetic graft (P=0.001). History of ICMI in the donor did not affect long-term graft survival in the non-diabetic donor group (P=0.2); however, in the diabetic group, ICMI tended to decrease long-term graft survival (P=0.056). ICMI did not affect RFR or graft survival in non-diabetic deceased donors. However, its use in diabetic deceased donors requires further study.

Application of microsatellite typing for the investigation of a cluster of cases of Candida albicans candidaemia.

A cluster of cases of Candida albicans candidaemia in a surgical intensive care unit was investigated. The probability of such a cluster during a single month was highly significant compared with the frequency of candidaemia in the previous year. A molecular typing method, based on length analysis of three (EF3, CDC3, HIS3) microsatellite-containing regions, was used to investigate isolates from patients in and outside the ward. This demonstrated the involvement of different strains, indicating the absence of cross-transmission among patients. Results of microsatellite typing can be obtained almost in real-time, which is particularly useful in an outbreak context.

[Completeness of ICU activity reports sent to French healthcare authorities]. / Exhaustivité des résumés d'unité médicale adressés aux départements d'information médicale.

INTRODUCTION: Hospital units report on their inpatient care activity by writing yearly activity reports, which are used by their Medical Information Department (MID) to develop standardized summaries for communication to healthcare authorities. The data are categorized by uniform patient groups and used to describe inpatient care activity and to guide resource allocation. The objective of this study was to evaluate the completeness of activity reports from intensive care units (ICUs) in France. METHODS: Activity reports sent in 1998 and 1999 by French ICUs participating in the study were collected using dedicated abstracting software supplied to the relevant MIDs. Completeness of data in the activity reports was evaluated, with special attention to the SAPSII score, Omega rating of ICU procedures according to the Classification of Medical Procedures, and primary and secondary diagnoses. RESULTS: The 106 ICUs that volunteered for the study reported data on 107,652-hospital stays. Mean age and SAPSII were 55 +/- 21 years and 35 +/- 21 years, respectively. Mean ICU and hospital lengths of stay were 6.2 +/- 12.4 and 16.1 +/- 21.6 days, respectively. Mean ICU and hospital mortality rates were 15% and 19%. The SAPSII and Omega procedures were reported for 81% and 80% of stays, respectively. The SAPSII and Omega procedures were calculated or coded in 94% (100/106) and 96% (102/106) of ICUs, respectively. Mean number of Omega procedures was 4.3+/-3.9. However, only 5% (5/106) of ICUs entered the SAPSII for every stay, and 21% (22/106) of ICUs failed to enter the SAPSII for over 20% of stays. Similarly, 53% (56/106) of ICUs rated no more than five Omega procedures on average per stay. The primary diagnosis was reported for all stays, and the mean number of secondary diagnoses was 3.5 +/- 3.8. In 80% (86/106) of ICUs, no more than five secondary diagnoses were coded on average per stay. CONCLUSION: The analysis of this national database shows that data communicated to the MIDs and therefore to the healthcare authorities, are incomplete regarding SAPSII, ICU procedures, treatment intensity, and diagnoses. This may lead to the underestimation of ICU activity and resource needs, particularly if the SAPSII and selected procedures identified as markers for high-intensity critical care are used in the future.

[A new cause of postoperative confusion syndrome: nefopam]. / Une nouvelle cause de syndrome confusionnel postopératoire: la prise de néfopam.

We report a case of nefopam intoxication in a severely malnourished postoperative intensive care patient with profound hypoprotidemia. Nefopam induced agitation and confusion associated with anticholinergic symptoms such as tremor, hypertonia, mydriasis, and tachycardia. All these symptoms disappeared after withdrawal of the drug. Nefopam should be considered as a possible cause of confusion in postoperative patients.

[Is there an age limit for organ donors?]. / Existe-t-il un âge limite pour le don d'organes?

Nowadays organ transplantations suffer from a lack of donors. Thus the waiting list of patients is constantly growing. Several ways to increase organ procurement are being evaluated. About 50% of cerebral deaths are related to vascular cerebral in patients older than 60 years. For the last few years, organs have been harvested from these patients despite their age. As the quality of the grafts is reduced, transplantation of one kidney may be insufficient whilst transplantation of the two kidneys to the same recipient is technically possible. We report here a case of a 44-year-old patient who was transplanted with two kidneys in September 2000. The donor was 85-year-old patient who died after prolonged cardiac arrest. Kidney biopsy showed a 16% rate of sclerotic glomeruli and mild interstitial fibrosis. The creatinine clearance estimated by the Cockcroft formula was 50 mL.min-1. The double kidney transplantation was successful, without any surgical or anaesthetic complication. Restoration of urine production was immediate. Three months after the transplantation, creatinine clearance was 80 mL.min-1. This observation gives the opportunity to discuss the criteria for organ harvesting in patients with cerebral death. Donor age should not remain anymore a systematic contra indication for kidney or liver donation. Renal function, macroscopic examination and histological findings seem more important for making a decision in taking the graft. Double transplantation, here the second case in France, has been performed for several years in other countries, and has permitted to expand the pool of donors, thus increasing the number of transplanted patients.

Effect of metformin on fatty acid and glucose metabolism in freshly isolated hepatocytes and on specific gene expression in cultured hepatocytes.

The short-term effect of metformin on fatty acid and glucose metabolism was studied in freshly incubated hepatocytes from 24-hr starved rats. Metformin (5 or 50 mM) had no effect on oleate or octanoate oxidation rates (CO(2)+ acid-soluble products), whatever the concentration used. Similarly, metformin had no effect on oleate esterification (triglycerides and phospholipid synthesis) regardless of whether the hepatocytes were isolated from starved (low esterification rates) or fed rats (high esterification rates). In contrast, metformin markedly reduced the rates of glucose production from lactate/pyruvate, alanine, dihydroxyacetone, and galactose. Using crossover plot experiments, it was shown that the main effect of metformin on hepatic gluconeogenesis was located upstream of the formation of dihydroxyacetone phosphate. Increasing the time of exposure to metformin (24 hr instead of 1 hr) led to significant changes in the expression of genes involved in glucose and fatty acid metabolism. Indeed, when hepatocytes were cultured in the presence of 50 to 500 microM metformin, the expression of genes encoding regulatory proteins of fatty acid oxidation (carnitine palmitoyltransferase I), ketogenesis (mitochondrial hydroxymethylgltaryl-CoA synthase), and gluconeogenesis (glucose 6-phosphatase, phosphoenolpyruvate carboxykinase) was decreased by 30 to 60%, whereas expression of genes encoding regulatory proteins involved in glycolysis (glucokinase and liver-type pyruvate kinase) was increased by 250%. In conclusion, this work suggests that metformin could reduce hepatic glucose production through short-term (metabolic) and long-term (genic) effects.

Clonidine does not impair redistribution hypothermia after the induction of anesthesia.

UNLABELLED: Clonidine is commonly given for premedication, and it impairs normal thermoregulatory responses to warm and cold stimuli while depressing sympathetic tone. We studied the effect of premedication by clonidine on redistribution hypothermia induced by the induction of anesthesia. Sixteen ASA physical status I or II patients were randomly assigned to receive either clonidine 150 micrograms or a placebo. Anesthesia was induced 45 min later by thiopental, fentanyl, and vecuronium i.v. and was maintained by the administration of 0.6% isoflurane. We monitored central core (tympanic) temperature and skin surface temperatures at the forearm and the fingertip during the 2 h after the induction of anesthesia before surgery. We estimated skin blood flow at the level of the forearm by using laser Doppler during the same period. The core temperature decreased comparably in the two groups of patients, from 37.1 +/- 0.2 degrees C to 35.3 +/- 0.4 degrees C and from 37.1 +/- 0.2 degrees C to 35.5 +/- 0.3 degrees C in the clonidine and placebo groups, respectively. The forearm-fingertip surface temperature gradient decreased similarly in the two groups. There was no evidence of cutaneous vasoconstriction. The laser Doppler index at the fingertip increased similarly in the two groups, as did the forearm-fingertip temperature gradient. We conclude that premedication with clonidine does not significantly impair the profile of central hypothermia induced by heat redistribution after the induction of anesthesia. IMPLICATIONS: The induction of general anesthesia is associated with redistribution hypothermia. This study shows that premedication with oral clonidine does not worsen the decrease in core temperature resulting from general anesthesia.

[Interviews with families of organ donors: analysis of motivation for acceptance or refusal of donation]. / Entretiens avec les familles de donneurs d'organes: analyse des motivations d'acceptation ou de refus du don.

OBJECTIVE: The reasons for organ donation acceptance or refusal are still unclear. This study analysed the influence of the circumstances of the conversations with the relatives of brain dead patients on their consent for organ donation. STUDY DESIGN: Prospective study. MATERIAL: The analysis included 41 questionnaires collected over nine months in one organ harvesting centre and focusing on the circumstances of death, the conditions of the conversations and the reasons for acceptance or refusal. METHODS: Questionnaire filled in by the physicians after the interviews of the relatives of brain dead patients. RESULTS: The refusal rate was higher (54 vs 21%) when only one physician participated in the conversation, when more than two relatives had to decide (42 vs 24%), when conversations took place during night or when the request for organ donation followed immediately the announcement of death (43 vs 20%). Most often the relatives gave their decision within minutes following the request. CONCLUSION: The circumstances of conversation with families play an essential role in their decision-making. A written guideline implementation for these conversations would probably be beneficial for the decisions of families in favour of organ donation.

Troglitazone inhibits fatty acid oxidation and esterification, and gluconeogenesis in isolated hepatocytes from starved rats.

The effects of troglitazone and pioglitazone on glucose and fatty acid metabolism were studied in hepatocytes isolated from 24-h-starved rats. These thiazolidinediones inhibited long-chain fatty acid (oleate) oxidation and produced a very oxidized mitochondrial redox state. By contrast, thiazolidinediones did not affect the rate of medium-chain fatty acid (octanoate) oxidation or the activity of mitochondrial carnitine palmitoyltransferase (CPT) I. Thiazolidinediones inhibited selectively triglyceride synthesis but not phospholipid synthesis. The combined inhibition of oleate oxidation and esterification by troglitazone was due to a noncompetitive inhibition of mitochondrial and microsomal long-chain acyl-CoA synthetase (ACS) activities. It was suggested that troglitazone must be metabolized into its sulfo-conjugate derivative in liver cells to inhibit mitochondrial and microsomal ACS activities. Thiazolidinediones inhibited glucose production from lactate/pyruvate or from alanine. Analysis of gluconeogenic metabolite concentrations suggested that troglitazone would inhibit gluconeogenesis at the level of pyruvate carboxylase and glyceraldehyde-3-phosphate dehydrogenase reactions. It was concluded that 1) at a similar concentration, troglitazone was more efficient than pioglitazone to inhibit fatty acid metabolism and gluconeogenesis and 2) the inhibition of gluconeogenesis by troglitazone could be the result of the inhibition of long-chain fatty acid oxidation (decrease in acetyl-CoA, NADH-to-NAD+, and ATP-to-ADP ratios).

Anaesthesia for caesarean section in a patient receiving high dose amiodarone for fetal supraventricular tachycardia.

We report the anaesthetic management of a Caesarean section in a woman treated with high dose amiodarone for fetal supraventricular tachycardia. Most of the interactions between anaesthesia and amiodarone therapy previously reported were observed during general anaesthesia. We therefore chose epidural anaesthesia using incremental doses of lignocaine 2% with adrenaline and fentanyl. This technique appeared to be safe, but since severe refractory vasodilation with hypotension may occur, potent vasopressor agents should be immediately available.