Donor liver selection. The South-Eastern Organ Procurement Foundation Liver Committee

OBJECTIVE: To investigate the effectiveness of noninvasive (face mask) versus invasive (endotracheal tube) equal pressure values on blood gases and respiratory pattern and to evaluate the feasibility of using mask ventilation after the short term physiologic study. DESIGN: Open, prospective, physiologic study and uncontrolled clinical study. SETTING: Intensive care unit of a trauma center. PATIENTS: 22 intubated trauma patients were studied. INTERVENTIONS: Patients were intubated and ventilated in a pressure support mode (IPSV) of 13.5 +/- 1.5 cmH2O and a post end-expiratory pressure (PEEP) of 5.8 +/- 2.57 cmH2O. After a T-piece trial to assess patient's ability to breath spontaneously, patients were switched over to noninvasive pressure support (NIPSV). The pressure levels were set as during IPSV. Blood gases and respiratory parameters were measured during IPSV, during the T-piece trial, and after 1 h of NIPSV. After the physiologic study, all patients were asked if they wished to continue on NIPSV. The patient's subjective compliance with IPSV and NIPSV was measured by means of an arbitrary score. A successful outcome was defined as no need for reintubation. MEASUREMENTS AND RESULTS: IPSVand NIPSV showed no statistical differences for blood gas and respiratory parameters by using the same values of PSV (13 +/- 5 vs 12.8 +/- 1.7 cmH2O, NS) and PEEP (5.8 +/- 2.5 and 5.2 +/- 2.2 cmH2O NS). The median length of time on NIPSV was 47 h (range 6 to 144). All patients wished to continue on NIPSV, but 9 patients (40.9%) were reintubated after 54 +/- 54 h. Six of them died after 36 +/- 13 days while still on mechanical ventilation. There was no statistically significant difference in compliance score between IPSVand NIPSV. CONCLUSIONS: NIPSV is comparable to IPSV in terms of blood gases and respiratory pattern. The clinical uncontrolled study indicates that NIPSV could be used in selected trauma patients.     

Doctoral education in nursing for practitioner knowledge and for academic knowledge: the University of Adelaide, Australia

A retrospective review was made of 49 survivors who were mechanically ventilated for more than 48 hours in the neurosurgical ICU. Thirty-two patients (Gp I) were successfully extubated, 9 patients (Gp II) underwent tracheostomy after one or more failed extubations, and 8 patients (Gp III) underwent elective tracheostomy. Glasgow Coma Scale (GCS) scores at extubation were 11.3 +/- 2.8 (mean (SD) for Gp I vs 7.8 +/- 2.7 for Gp II (P = n.s.) and at elective tracheostomy (Gp III) was 5.4 +/- 2.3. Incidence of ventilator-associated pneumonia were 35% in Gp I vs 100% of patients in Gp II and III (P < 0.05). Reasons for reintubation in 7 of 9 patients (Gp II) were upper airway obstruction and tenacious tracheal secretions while 14 of 17 patients were weaned off the ventilator within 48 hours of tracheostomy. The length of stay in ICU was 16.8 +/- 7.1 days in Gp II vs 11.7 +/- 2.9 days in Gp III (P < 0.05). In our study, elective tracheostomy for selected patients with poor GCS scores and nosocomial pneumonia has resulted in shortened ICU length of stay and rapid weaning from ventilatory support.     

Stellettamide B, a new indolizidine alkaloid from a sponge of the genus Stelletta

BACKGROUND: The availability of nasal mask bi-level positive airway pressure (BiPAP) support in managing respiratory failure following cardiovascular surgery was studied. MATERIALS AND METHODS: BiPAP support was used for eight patients requiring postoperative prolonged respiratory support of 72 hours or longer. Their mean age was 65 years of age and the mean periods of postoperative endotracheal intubation was 12+/-5 days. BiPAP support was removed within 48 hours in six out of eight patients. Reintubation of an endotracheal tube was not necessary in all eight patients after the BiPAP treatment. RESULTS: The respiratory rates during the BiPAP management remained unchanged. The values of the respiratory index significantly (p<0.01) improved after BiPAP management (1.5+/-0.2 --> 0.9+/-0.2). A-aDO2 and Qs/Qt decreased (p<0.1) after the BiPAP management. There were no significant differences in central venous pressure and circulatory states during BiPAP support. CONCLUSIONS: In conclusions, BiPAP support is a noninvasive management technique for postoperative respiratory failure and may also prevent prolonged endotracheal intubation.     

PSA screening--current controversy

OBJECTIVE: To evaluate treatment with noninvasive ventilation (NIV) by nasal mask as an alternative to endotracheal intubation and conventional mechanical ventilation in patients with hematologic malignancies complicated by acute respiratory failure to decrease the risk of hemorrhagic complications and increase clinical tolerance. DESIGN: Prospective clinical study. SETTING: Hematologic and general intensive care unit (ICU), University of Rome "La Sapienza". PATIENTS: 16 consecutive patients with acute respiratory failure complicating hematologic malignancies. INTERVENTIONS: NIV was delivered via nasal mask by means of a BiPAP ventilator (Respironics, USA); we evaluated the effects on blood gases, respiratory rate, and hemodynamics along with tolerance, complications, and outcome. MEASUREMENTS AND RESULTS: 15 of the 16 patients showed a significant improvement in blood gases and respiratory rate within the first 24 h of treatment. Arterial oxygen tension (PaO2), PaO2/FIO2 (fractional inspired oxygen) ratio, and arterial oxygen saturation significantly improved after 1 h of treatment (43+/-10 vs 88+/-37 mmHg; 87+/-22 vs 175+/-64; 81+/-9 vs 95+/-4%, respectively) and continued to improve in the following 24 h (p < 0.01). Five patients died in the ICU following complications independent of the respiratory failure, while 11 were discharged from the ICU in stable condition after a mean stay of 4.3+/-2.4 days and were discharged in good condition from the hospital. CONCLUSIONS: NIV by nasal mask proved to be feasible and appropriate for the treatment of respiratory failure in hematologic patients who were at high risk of intubation-related complications.     

Comparing two heat and moisture exchangers, one hydrophobic and one hygroscopic, on humidifying efficacy and the rate of nosocomial pneumonia

OBJECTIVE: Many heat and moisture exchangers with filter (HMEF) have been developed. In-house data from companies provide some information about their performances; unfortunately, to our knowledge, no comparative evaluation in clinical conditions has been undertaken of these newer products. The aim of this study was to compare the efficiency of two HMEFs, one hydrophobic and one hygroscopic, on humidifying capacity and the rate of bronchial colonization and ventilator-associated pneumonia in ICU patients. DESIGN: Prospective, randomized study. SETTING: ICU of a university hospital. PATIENTS: All patients who required mechanical ventilation for > or = 24 h during the study period. INTERVENTIONS: On admission to the ICU, patients were randomly assigned to one of two groups. In one group, the patients were ventilated with a hygroscopic device (Humid-Vent Filter Light HMEF; Gibeck; Upplands Vaesby, Sweden). The condensation surface was made of paper (Microwell) impregnated with CaCl2. The filter membrane was made of polypropylene. In the other group, the patients were ventilated with a hydrophobic device (Pall BB100 HMEF). The condensation surface was made of a hydrophobic resin with a hydrophylic layer. The filter membrane was made of ceramic fibers. In both groups, HMEFs were changed daily. MEASUREMENTS AND RESULTS: Both groups of patients were similar for the tested characteristics, including parameters of mechanical ventilation. Sixty-six patients were ventilated for 11.7+/-11 days with the Humid-Vent Filter Light HMEF and 70 patients for 12.2+/-12 days with the Pall BB 100. Patients ventilated with the Humid-Vent Filter Light underwent 6.0+/-3.0 tracheal aspirations and 1.7+/-2.0 instillations per day, and those with the Pall BB 100, 6.0+/-3.0 and 1.6+/-2.0 per day, respectively (not significant [NS]). Abundance of tracheal secretions, presence of blood, and viscosity, evaluated by semiquantitative scales, were similar in both groups. No difference in the rate of atelectasis was observed between the two groups (7.5% and 7.1%, NS). One episode of tracheal tube occlusion was observed with the Humid-Vent Filter Light HMEF, and one with the other HMEF (NS). One patient in each group (NS) was switched to an active heated humidifier because of very tenacious bronchial secretions despite repeated instillations. Tracheal colonization was observed at a rate of 67% with the Humid-Vent Filter Light and 58% with the Pall BB 100 (NS). A small, but NS difference was observed in the rate of ventilator-associated pneumonia: Humid-Vent Filter Light, 32% (27.1 per 1000 ventilator days); and Pall BB 100, 37% (30.4 per 1000 ventilator days). Bacteria responsible for tracheal colonization and pneumonia were similar in both groups. Three patients in each group died from their nosocomial pneumonia. CONCLUSION: Despite differences in their components, the two HMEFs tested achieved similar performances in terms of humidification and heating of inspired gases. Only one episode of endotracheal tube occlusion was detected and very few patients (one in each group) had to be switched to an active heated humidifier. No difference was observed either in the rate of tracheal colonization or of ventilator-associated pneumonia. These data show that the hygroscopic HME (Humid-Vent Filter Light) and the hydrophobic HME (Pall BB 100) are suited for use in ICU patients.     

Out-of-hospital ventilation: bag--valve device vs transport ventilator

OBJECTIVE: To examine the patterns of out-of-hospital airway management and to compare the efficacy of bag-valve ventilation with that of the use of a transport ventilator for intubated patients. METHODS: A prospective, nonrandomized, convenience sample of 160 patients requiring airway management in the out-of-hospital urban setting was analyzed. A survey inquiring about airway and ventilatory management was completed by emergency medical services (EMS) personnel, and arterial blood gas (ABG) samples were obtained within 5 minutes of patient arrival in the ED. The ABG parameters were compared for patients grouped by different airway techniques and presence or absence of cardiac arrest (systolic blood pressure < 50 mm Hg) upon ED presentation. RESULTS: Over a one-year period, 160 surveys were returned. The majority (62%) of the patients were men; the population mean age was 61 +/- 19 years. Presenting ABGs were obtained for 76 patients; 17% (13/76) had systemic perfusion and 83% (63/76) were in cardiac arrest. There was no difference in ABG parameters between the intubated cardiac arrest patients ventilated with a transport ventilator (pH 7.17 +/- 0.17, PaCO2 37 +/- 20 torr, and PaO2 257 +/- 142 torr) and those ventilated with a bag-valve device (pH 7.20 +/- 0.16, PaCO2 42 +/- 21 torr, and PaO2 217 +/- 138 torr). The patients ventilated via an esophageal obturator airway (EOA) device had impaired gas exchange, compared with the groups who had endotracheal (ET) intubation (pH 7.09 +/- 0.13, PaCO2 76 +/- 30 torr, and PaO2 75 +/- 35 torr). The intubated patients not in cardiac arrest had similar ABG parameters whether ventilated manually with a bag-valve device or with a transport ventilator. Endotracheal intubation was successfully accomplished in 93% (123/132) of attempted cases. CONCLUSIONS: In this sample, ET intubation was the most frequently used airway by EMS providers. When ET intubation was accomplished, adequate ventilation could be achieved using either bag-valve ventilation or a transport ventilator. Ventilation via the EOA proved inadequate.     

Antibodies to prothrombin crossreact with plasminogen in patients developing myocardial infarction

This study aimed to determine the differences in haemodynamic responses to a standard incremental exercise test between outpatients with chronic obstructive pulmonary disease (COPD) and age-matched controls and to discover the relationship between severity of airflow obstruction and exercise haemodynamics in COPD. Twenty-two male patients with COPD (forced expiratory volume in one second (FEV1)/vital capacity (VC))<80% predicted) and 20 age-matched male controls performed an incremental exercise test (10 W x min(-1)) with ventilatory function and changes in stroke volume (deltaSV) and cardiac output (deltaCO) measured by means of electrical impedance cardiography (EIC). Submaximal deltaSV and deltaCO were lower in COPD patients. Peak exercise deltaSV were equal in patients and controls (128+/-33 versus 129+/-29%, p=0.98), whereas peak deltaCO was lower in patients (COPD versus controls: 232+/-71 versus 289+/-54%, p<0.005). In COPD patients, FEV1 (% pred) was significantly correlated to deltaSV at all submaximal exercise intensities, to peak exercise deltaSV and to peak exercise deltaCO. FEV1/VC (% pred) was significantly correlated to deltaSV at 30 and 60 W. In conclusion, in chronic obstructive pulmonary disease an aberrant haemodynamic response to exercise was found, especially in patients with severe airflow obstruction. This aberrant response is related to the degree of airflow obstruction and may limit exercise performance in patients with severe chronic obstructive pulmonary disease.     

Outcomes of coronary artery bypass surgery in elderly people

The role of non-invasive nocturnal domiciliary ventilation (NNV) in chronic obstructive pulmonary disease (COPD) patients with chronic hypercapnia is still discussed. The aims of this study were to evaluate the long-term survival, the clinical effectiveness and side-effects of NNV in these patients. Forty-nine stable hypercapnic COPD patients on long-term oxygen therapy (LTOT) were assigned to two groups: in Group 1, 28 patients performed NNV by pressure support modality in addition to LTOT; in Group 2, 21 patients continued their usual LTOT regimen. Treatment was assigned according to the compliance to NNV, after an in hospital period. Mortality rate, hospital stay (HS) and ICU admissions (IA) were recorded in the two groups. HS and IA were compared to those recorded in a similar period of follow-back. Lung and respiratory muscle function, dyspnoea, and exercise capacity (by 6-min walk test) were evaluated baseline and every 3-6 months up to 3 yr. Mean follow-up time was 35 +/- 7 months. Mortality rate was not different between the two groups: 16, 33, 46% and 13, 28, 50% at 1, 2 and 3 yr in Groups 1 and 2 respectively. Lung and respiratory muscle function did not significantly change over time. A significant increase in 6-min walk test (from 245 +/- 78 to 250 +/- 88, 291 +/- 75, 284 +/- 89 m after 1, 2 and 3 yr respectively, P < 0.01) was observed only in patients undergoing NNV. In comparison to the follow back HS significantly decreased in both groups (from 37 +/- 29 to 15 +/- 12 and from 32 +/- 18 to 17 +/- 11 days/pt/yr in Groups 1 and 2 respectively, P < 0.001) whereas IA significantly decreased only in patients performing also NNV (from 1.0 +/- 0.7 to 0.2 +/- 0.3/pt/yr, P < 0.0001). Addition of NNV by pressure support modality to LTOT does not improve long term survival but significantly reduces ICU admissions and improves exercise capacity in severe COPD with hypercapnia.     

Extended operation for T4 lung carcinoma

PURPOSE: The study objective was to determine an "optimal" individual pressure support (PS) level for beginning weaning with PS ventilation in patients with chronic obstructive pulmonary disease (COPD). MATERIALS AND METHODS: Eleven COPD patients intubated and ventilated for acute respiratory failure and judged ready for weaning were studied. The technique consisted of lowering the PS level from a point that was characteristic for each patient and measurable under controlled mechanical ventilation, after setting the ventilator as recommended for COPD patients judged ready for weaning, that is, peak inflation pressure (PIP). This determination was based mainly on exploring the diaphragm with an electromyographic technique by defining the optimal PS level as the lowest PS level associated with no EMG evidence of diaphragmatic stress. Diaphragmatic electromyographic activity (diEMG) was recorded by a bipolar esophageal electrode (Disa-Denmark), and the high-frequency electrical component/low-frequency ratio (H/L) was calculated. The reference H/L was determined during a few spontaneous ventilatory cycles. Muscle stress was defined as a greater than 20% reduction in H/L compared with the reference value. RESULTS: Optimal PS levels ranged from 4 to 24 cm H2O with a mean of 14+/-6 cm H2O. Two patients with optimal PS level at 4 cm H2O did not require weaning and were quickly extubated. For the nine other patients, optimal PS levels were found to be 70% of PIP; in none was it necessary during weaning to use PS levels higher than individual optimal PS levels. CONCLUSIONS: Optimal PS level established with diEMG monitoring seems to be a useful index for beginning weaning in the PS ventilation mode in COPD patients. The hypothesis of beginning weaning with a PS level equal to 70% of PIP needs to be tested.     

Change in anaesthesia practice and postoperative sedation shortens ICU and hospital length of stay following coronary artery bypass surgery

We randomized prospectively 144 patients, undergoing elective coronary artery bypass surgery, to either early or to routine extubation [mechanical ventilatory support for 4-7 h (Group A), or 8-14 h (Group B)]. Anaesthesia was modified for both groups. The groups were well matched in terms of sex, age, NYHA class, preoperative left ventricular ejection fraction, bypass time and aortic cross-clamp time, number of grafts used, and blood units transfused. All patients had normal preoperative respiratory, renal, hepatic and cerebral functions. Mechanical ventilatory support (mean +/- SD) was 6.3 +/- 0.7 h for Group A and 11.6 +/- 1.3 h for Group B. Mean ICU stay was 17 +/- 1.3 h for Group A and 22 +/- 1.2 h for Group B, while the mean hospital stay was 7.3 +/- 0.8 days and 8.4 +/- 0.9, respectively. There were no statistically significant differences in the frequency of all postoperative complications among the two groups. There were no reintubation, readmission to the ICU or death in either group. We concluded that change in anaesthesia practice and early postoperative sedation in patients undergoing elective coronary artery bypass graft (CABG) surgery resulted in earlier tracheal extubation, shorter ICU and hospital length of stay without organ dysfunction or postoperative complications. Early extubation was only possible due to the modification of anaesthesia and ICU sedation regime.     

Study of the use of noninvasive ventilation of the lungs in acute respiratory insufficiency due exacerbation of chronic obstructive pulmonary disease

Noninvasive positive pressure ventilation (NPPV) is a life-saving procedure in acute respiratory failure (ARF), but its technique is not yet in routine use in many respiratory centers. We carried out a prospective randomized study comparing the combination of NPPV with conventional therapy (oxygen, bronchodilators, steroids, and theophylline) with conventional therapy alone in patients with acute respiratory failure caused by exacerbation of chronic obstructive pulmonary disease (COPD). A total of 58 patients were recruited from a large group of patients admitted to our hospital between September 1995 and March 1997. Twenty-nine patients were randomly assigned to the NPPV group and 29 to the conventional (non-NPPV) group. The patients were matched for demographic and physiological norm values (mean age 63.4 +/- 5.5 vs. 66.2 +/- 7.1 years, mean FEV1 0.68 +/- 0.15 vs. 0.74 +/- 0.16 L, PaO2 51.4 +/- 6.8 vs. 52.3 +/- 6.5 mm Hg, PaCO2 63.4 +/- 10.9 vs. 64.9 +/- 9.7 mm Hg, and pH 7.28 +/- 0.07 vs. 7.26 +/- 0.06). The outcome end points were needed for endotracheal intubation, length of hospital stay, and incidence of complications. NPPV was administered using BiPAP ventilatory device (Respironics, Inc.) by spontaneous and spontaneous/timed modes via nasal and facial masks. The mean time of NPPV was 29 +/- 25 h. Three patients refused from NPPV because of intolerance of mask or ventilation procedure. Two of them were eventually intubated and one of them died. In patients administered NPPV, we observed a significant rise of pH and fall of PaCO2 after 1 h of ventilation, in contrast to the non-NPPV group (7.34 +/ 0.09 vs. 7.21 +/- 0.08, p < 0.05; 53.2 +/- 10.7 vs. 71.4 +/- 10.2 mm Hg, p < 0.01, respectively). The need in intubation was lower in the NPPV group as compared to the reference group (12 vs. 28%, p = 0.18), mortality rate was higher in the non-NPPV group (31 vs. 8%, p = 0.03), and hospital stay was shorter in NPPV patients (26 +/- 7 vs. 34 +/- 10 days). The incidence of complications was lower in the NPPV group, they were less significant, and did not involve discontinuation of ventilation. Hence, NPPV is a first-line therapy in patients with ARF caused by COPD exacerbation, due to obvious advantages over conventional methods of treatment.     

Bacteraemia during the aplastic phase after allogeneic bone marrow transplantation is associated with early death from invasive fungal infection

OBJECTIVE: The main objective of this study was to evaluate the effect of switching from parenteral to enteral feeding on liver blood flow and propofol steady-state blood concentrations in patients in the intensive care unit (ICU). DESIGN AND PATIENTS: Steady-state blood concentrations of propofol were measured in eight ICU patients before (on days D -3, D -2, and D -1) and after (on days D + 1, D + 2, and D + 3) switching from parenteral to enteral feeding (on day DO). All patients received a continuous intravenous infusion of propofol (4.5 mg x kg(-1) x h(-1)) from several days before the start of the study, continuing throughout the experimental period. Hepatic blood flow was estimated by measuring steady-state D-sorbitol hepatic clearance. RESULTS: Hepatic blood flow was high and was not affected by switching from parenteral to enteral feeding: 33 +/- 8 ml x min(-1) x kg(-1) (mean +/- SD) and 33 +/- 10 ml min(-1) x kg(-1) on D -3 and D -1, respectively, as compared to 37 +/- 11 ml x min(-1) kg(-1) and 34 +/- 8 ml x min(-1) x kg(-1) on days D + 1 and D + 3, respectively. Systemic clearance of propofol was much higher than liver blood flow with average values on the six observation days ranging from 74.0 to 81.2 ml x min(-1) x kg(-1) and was not affected by switching from parenteral to enteral feeding. CONCLUSIONS: Liver blood flow and systemic clearance of propofol were not affected by switching from parenteral to enteral feeding in the eight ICU patients studied. Extrahepatic clearance accounted for at least two thirds of the overall systemic clearance of propofol.     

Subanesthetic concentrations of isoflurane suppress learning as defined by the category-example task

It has been shown that chronic oral steroid therapy (ST) does not induce respiratory muscle dysfunction in normal and asthmatic subjects. As corticosteroids are sometimes chronically used in the treatment of the patients with chronic obstructive pulmonary disease (COPD), the aim of our study was to verify whether ST could cause respiratory muscle impairment and, since ST also affects the central nervous system, whether ST could influence the ventilatory pattern. We retrospectively studied 12 COPD patients (group A), on long-term therapy (for at least 4 consecutive months, range 4-18 months) with an oral steroid, deflazacort, 15 mg.d-1. The subjects were strictly matched, with regard to age, sex, height, weight, forced expiratory volume in one second (FEV1), residual volume (RV), arterial oxygen tension (PaCO2), arterial carbon dioxide tension (PaCO2) and pH, with 12 COPD patients (Group B) who had never taken oral steroids. To assess respiratory muscle strength, we measured maximal inspiratory (MIP) and expiratory (MEP) pressures, while mouth occlusion pressure (P0.1) was employed to assess neuromuscular drive; ventilatory pattern and airway impedence were also evaluated. Effectiveness of ST was confirmed by the plasmatic levels of endogenous cortisol. No significant differences were observed between the two groups with regard to MIP (A 72.2 +/- 9.7 vs B: 70 +/- 7.2 cmH2O) and MEP (A 91.6 +/- 10.5 vs B 94.4 +/- 7.6 cmH2O) whilst P0.1 was significantly higher in group A (2.6 +/- 0.3 cmH2O) than in group B (1.8 +/- 0.1 cmH2O). No significant differences were found among all the ventilatory parameters, but the impedence was significantly higher in group A.(ABSTRACT TRUNCATED AT 250 WORDS)     

The use of continuous i.v. sedation is associated with prolongation of mechanical ventilation

STUDY OBJECTIVE: To determine whether the use of continuous i.v. sedation is associated with prolongation of the duration of mechanical ventilation. DESIGN: Prospective observational cohort study. SETTING: The medical ICU of Barnes-Jewish Hospital, a university-affiliated urban teaching hospital. PATIENTS: Two hundred forty-two consecutive ICU patients requiring mechanical ventilation. INTERVENTIONS: Patient surveillance and data collection. MEASUREMENTS AND RESULTS: The primary outcome measure was the duration of mechanical ventilation. Secondary outcome measures included ICU and hospital lengths of stay, hospital mortality, and acquired organ system derangements. A total of 93 (38.4%) mechanically ventilated patients received continuous i.v. sedation while 149 (61.6%) patients received either bolus administration of i.v. sedation (n=64) or no i.v. sedation (n=85) following intubation. The duration of mechanical ventilation was significantly longer for patients receiving continuous i.v. sedation compared with patients not receiving continuous i.v. sedation (185+/-190 h vs 55.6+/-75.6 h; p<0.001). Similarly, the lengths of intensive care (13.5+/-33.7 days vs 4.8+/-4.1 days; p<0.001) and hospitalization (21.0+/-25.1 days vs 12.8+/-14.1 days; p<0.001) were statistically longer among patients receiving continuous i.v. sedation. Multiple linear regression analysis, adjusting for age, gender, severity of illness, mortality, indication for mechanical ventilation, use of chemical paralysis, presence of a tracheostomy, and the number of acquired organ system derangements, found the adjusted duration of mechanical ventilation to be significantly longer for patients receiving continuous i.v. sedation compared with patients who did not receive continuous i.v. sedation (148 h [95% confidence interval: 121, 175 h] vs 78.7 h [95% confidence interval: 68.9, 88.6 h]; p<0.001). CONCLUSION: We conclude from these preliminary observational data that the use of continuous i.v. sedation may be associated with the prolongation of mechanical ventilation. This study suggests that strategies targeted at reducing the use of continuous i.v. sedation could shorten the duration of mechanical ventilation for some patients. Prospective randomized clinical trials, using well-designed sedation guidelines and protocols, are required to determine whether patient-specific outcomes (eg, duration of mechanical ventilation, patient comfort) can be improved compared with conventional sedation practices.     

Short-term effects of nasal proportional assist ventilation in patients with chronic hypercapnic respiratory insufficiency

Proportional assist ventilation (PAV) has recently been proposed as a mode of synchronized partial ventilatory support. This study evaluates the short-term effects of nasal PAV on arterial blood gases in stable patients with chronic hypercapnia. Forty two patients (30 with chronic obstructive pulmonary disease (COPD) and 12 with restrictive chest wall disease (RCWD) due to kyphoscoliosis) underwent a 1 h run of nasal PAV. Randomly, two levels of assistance were performed: 1) PAV was set at a level corresponding to volume assist (VA) and flow assist (FA) at 80% of the individual values of elastance (Ers) and resistance (Rrs) obtained with the "runaway" method; and 2) VA and FA were set at a value corresponding to the difference between the patients' individual Ers and Rrs and normal values of Ers and Rrs. Arterial blood gases and dyspnoea (by visual analogue scale (VAS)) were evaluated in all patients during unsupported ventilation and 60 min of PAV. PAV was well tolerated and resulted in significant improvement in arterial oxygen tension (Pa,O2), arterial carbon dioxide tension (Pa,CO2) (6.8+/-0.8 to 7.4+/-1.4 and 7.2/-0.9 to 6.8+/-0.9 kPa, respectively) and VAS (29+/-23 to 20+/-18%). The effects of PAV were not different in the two groups of diseases nor in the two groups of settings. Different settings of nasal proportional assist ventilation are well tolerated and may improve gas exchange and dyspnoea in patients with stable hypercapnic respiratory insufficiency.     

The C-terminal region of the Escherichia coli UvrC protein, which is homologous to the C-terminal region of the human ERCC1 protein, is involved in DNA binding and 5''-incision

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.     

Controlled expiration in mechanically-ventilated patients with chronic obstructive pulmonary disease (COPD)

In patients with severe chronic obstructive pulmonary disease (COPD), lung emptying may be affected by flow limitation. We tested the hypothesis that the airway compression leading to flow limitation can be counteracted by controlling the expiratory flow. The effects of an external resistor on lung emptying were studied in six patients with COPD, who were mechanically ventilated whilst sedated and paralysed. Respiratory mechanics were obtained during ventilatory support with and without the resistor. Airway compression was assessed using the interruptor method. For the study, a turbulent resistor was applied with the highest resistance level that did not increase the end-expiratory lung volume. At this resistance level, external positive end-expiratory pressure (PEEP) was generated in all patients. As total PEEP levels remained unchanged at both settings during the controlled expiration, the levels of intrinsic PEEP were significantly decreased from 0.96+/-0.30 to 0.53+/-0.19 kPa (mean+/-SD). Comparison of the expiratory flow-volume curves at both settings revealed that, during the controlled expiration, the flows were significantly decreased during the first 40% of the expired volume and significantly increased during the last 60%. As the end-expiratory lung volumes remained unchanged during both settings, these increments in flow indicated a decrease in effective resistance. Airway compression was observed during unimpeded expirations in all patients using the interruptor method. During the application of the resistor, airway compression was no longer detectable. In patients with chronic obstructive pulmonary disease receiving ventilatory support, the application of an external resistor could decrease effective expiratory resistance by counteracting airway compression, without increments in end-expiratory lung volume.     

The need for inotropic support in a subgroup of infants with severe life-threatening respiratory syncytial viral infection

BACKGROUND: We experienced an unusual complication of life-threatening respiratory syncytial viral disease cardiovascular compromise. Life-threatening respiratory syncytial virus (RSV) infection has predominancy involved with ventilatory support for respiratory distress and/or failure. We performed a retrospective chart review of 20 consecutive infants admitted to the pediatric intensive care unit (PICU) for impending respiratory failure. METHODS: Seventeen required ventilatory support. As part of the infants' initial assessment, blood pressure, distal perfusion [capillary refill time (CRT) > or = 3 sec], decreased peripheral pulses, and peripheral mottling were used to determine cardiovascular compromise. These infants received volume resuscitation either at the referring facility or the PICU until euvolemia was obtained, as determined by central venous pressure (CVP) monitoring (between 3 to 7 cm H20). Nine of the 20 infants did not respond to volume resuscitation alone and required vasopressor support in the form of: Dopamine (7 patients, 5-10 micrograms/kg/min), Dobutamine (2 patients, 5-7 micrograms/kg/min), and one who expired required both Epinephrine (600 ng/kg/min) and Dopamine (10 micrograms/kg/min). The mean ages of these 9 patients were 6.2 +/- 3.4 weeks (range 3-12 weeks), the mean duration of ventilation was 7.2 +/- 4.1 days (range 4-12 days). The mean duration of pharmacologic support was 69.7 +/- 47 hours (range 14-168 hours). The mean ages of RSV+ infants not requiring inotropic support was 19.4 +/- 27.4 weeks (range 1-90 weeks), and mean duration of ventilation was 5.5 +/- 5.9 days (range 2-20 days). RESULTS: The inotrope treated patients were weaned from pharmacologic support prior to extubation, without any hemodynamic deficits. Our experience with this rather high incidence of hemodynamic complications during this RSV epidemic was unexpected. CONCLUSION: These results substantiate the fact that younger patients with RSV disease are at both greater risk for pulmonary complications and cardiovascular deterioration and may thus benefit from pharmacologic support.     

Pressure support ventilation in adult respiratory distress syndrome: short-term effects of a servocontrolled mode

PURPOSE: To assess the short-term effects of pressure support ventilation in adult respiratory distress syndrome (ARDS), we studied 17 patients with moderate to severe ARDS using mandatory rate ventilation (MRV), a servocontrolled mode of PSV having respiratory rate as the targeted parameter. MATERIALS AND METHODS: Based on the duration of ARDS, the patients were divided into two groups: Group 1, early ARDS (duration up to 1 week), 10 patients; Group 2, intermediate ARDS (duration between 1 and 2 weeks). The patients were initially ventilated with assisted mechanical ventilation then with MRV, and finally with controlled mechanical ventilation. After a 20-minute period allowed for stabilization in each mode, ventilatory variables, gas exchange, hemodynamics, and patient's inspiratory effort were evaluated. RESULTS: During MRV blood gases, airway pressures and hemodynamic variables remained within acceptable limits in all patients. Compared with assisted mechanical ventilation, during MRV, patients of group 1 decreased their VT and V (from 0.64 +/- 0.04 to 0.42 +/- 0.03 L/sec) and increased their TI/TT (from 0.39 +/- 0.03 to 0.52 +/- 0.03). f did not change. PAO2 - PaO2 and QS/QT decreased (from 306 +/- 16 to 269 +/- 15 mm Hg, and from 20.2 +/- 1.4 to 17.5 +/- 1.1, respectively), while PaCO2 increased (from 44 +/- 3 to 50 +/- 3 mm Hg). On the contrary, patients of group 2 increased their VT (from 0.69 +/- 0.02 to 0.92 +/- 0.09 L), decreased their f (from 22.3 +/- 0.5 to 19.3 +/- 0.3 b/min), although they did not change their V and TI/TT. PAO2 - PaO2 and QS/QT remained stable. PaCO2 diminished (from 39 +/- 3 to 34 +/- 3 mm Hg). Pressure support level was higher in group 2 than in group 1 (29.4 +/- 3.0 v 19.8 +/- 2.9 cm H2O). CONCLUSIONS: We conclude that (1) PSV delivered by MRV may adequately ventilate patients with moderate to severe ARDS, preserving gas exchange and hemodynamics, at least for the short period tested; (2) early and intermediate ARDS respond in a different manner to MRV in terms of breathing pattern, gas exchange, and level of pressure assistance; and (3) patients with early ARDS are those who have an improvement in intrapulmonary oxygenation probably due, at least in part, to alveolar recruitment augmented by active diaphragmatic contraction.     

Relation between chemosensitivity and the ventilatory response to exercise in chronic heart failure

OBJECTIVES: This study sought to establish the chemosensitivity of patients with chronic heart failure. BACKGROUND: The ventilatory response to exercise is often increased in patients with chronic heart failure, as characterized by the steeper regression slope relating minute ventilation to carbon dioxide output. We hypothesized that the sensitivity of chemoreceptors may be reset and may in part mediate the exercise hyperpnea seen in this condition. METHODS: Hypoxic and peripheral hypercapnic chemosensitivity were studied in 38 patients with chronic heart failure (35 men, 3 women; mean [+/-SE] age 60.2 +/- 1.3 years; radionuclide left ventricular ejection fraction 25.7 +/- 2.3%) and 15 healthy control subjects (11 men, 4 women; mean age 54.9 +/- 3.0 years) using transient inhalations of pure nitrogen and single breaths of 13% carbon dioxide, respectively. The change in chemosensitivity during mild exercise (25 W) was assessed in the first 15 patients and all control subjects. Central hypercapnic chemosensitivity was also characterized in 25 patients and 10 control subjects by the rebreathing of 7% carbon dioxide in 93% oxygen. Cardiopulmonary exercise testing was performed in all subjects. RESULTS: Maximal oxygen consumption was 16.6 +/- 0.9 versus 29.7 +/- 2.2 mol/kg per min (p < 0.0001), and the ventilation-carbon dioxide output regression slope was 37.2 +/- 1.5 versus 26.5 +/- 1.4 (p < 0.0001) in patients and control subjects, respectively. Hypoxic and central hypercapnic chemosensitivity were enhanced in patients (0.707 +/- 0.076 vs. 0.293 +/- 0.056 liters/min per % arterial oxygen saturation [SaO2], p = 0.0001 and 3.15 +/- 0.41 vs. 2.02 +/- 0.25 liters/min per mm Hg, p = 0.025, respectively) and correlated significantly with the ventilatory response to exercise. Hypoxic chemosensitivity was augmented during exercise in patients and in control subjects but remained higher in the former (1.530 +/- 0.27 vs. 0.685 +/- 0.12 liters/min per %SaO2, p = 0.01). The peripheral hypercapnic chemosensitivity of patients at rest and during exercise was similar to that in control subjects, consistent with its lesser contribution to overall carbon dioxide chemosensitivity. CONCLUSIONS: Enhanced hypoxic and central hypercapnic chemosensitivity may play a role in mediating the increased ventilatory response to exercise in chronic heart failure.