Optimizing intensive care capacity using individual length-of-stay prediction models

Introduction  

Effective planning of elective surgical procedures requiring postoperative intensive care is important in preventing cancellations and empty intensive care unit (ICU) beds. To improve planning, we constructed, validated and tested three models designed to predict length of stay (LOS) in the ICU in individual patients.     

Multicenter randomized comparison of xenon and isoflurane on left ventricular function in patients undergoing elective surgery

BACKGROUND: Volatile anesthetics are commonly used for general anesthesia. However, these can induce profound cardiovascular alterations. Xenon is a noble gas with potent anesthetic and analgesic properties. However, it is uncertain whether xenon alters myocardial function. The aim of this study was therefore to investigate left ventricular function during anesthesia with xenon compared with isoflurane. METHODS: The authors performed a randomized multicenter trial to compare xenon with isoflurane with respect to cardiovascular stability and adverse effects in patients without cardiac diseases scheduled for elective surgery. Two hundred fifty-nine patients were enrolled in this trial, of which 252 completed the study according to the protocol. Patients were anesthetized with xenon or isoflurane, respectively. Before administration of the study drugs and at four time points, the effects of both anesthetics on left ventricular function were investigated using transesophageal echocardiography. RESULTS: Global hemodynamic parameters were significantly altered using isoflurane (P < 0.05 vs. baseline), whereas xenon only decreased heart rate (P < 0.05 vs. baseline). In contrast to xenon, left ventricular end-systolic wall stress decreased significantly in the isoflurane group (P < 0.05 vs. baseline). Velocity of circumferential fiber shortening was decreased significantly in the xenon group but showed a more pronounced reduction during isoflurane administration (P < 0.05 vs. baseline). The contractile index (difference between expected and actually measured velocity of circumferential fiber shortening) as an independent parameter for left ventricular function was significantly decreased after isoflurane (P < 0.0001) but unchanged using xenon. CONCLUSIONS: Xenon did not reduce contractility, whereas isoflurane decreased the contractile index, indicating that xenon enables favorable cardiovascular stability in patients without cardiac diseases.     

Lung clearance of intratracheally instilled 99mTc-tobramycin using pulmonary surfactant as vehicle

1. The use of pulmonary exogenous surfactant as a vehicle for intratracheally administered antibiotics to improve local antimicrobial therapy has been proposed. The present study investigated lung clearance rates in the rat of intratracheally instilled technetium labelled tobramycin with and without the addition of surfactant to the antibiotic solution. 2. The influence of surfactant on 99mTc-tobramycin lung clearance rates was studied dynamically with a gamma-camera in anaesthetized spontaneously breathing animals and in mechanically ventilated animals. 3. The results show that instillation of 99mTc-tobramycin with use of surfactant as vehicle significantly increases 99mTc-tobramycin lung clearance compared to instillation of 99mTc-tobramycin solution alone (P=0.006 between the two spontaneously breathing groups of animals and P=0.02 between the two ventilated groups of animals, ANOVA for repeated time measurements). The half life (t1/2) of composite clearance curves in spontaneous breathing animals was 147 min for animals receiving 99mTc-tobramycin versus 61 min for animals receiving 99mTc-tobramycin with surfactant. In mechanically ventilated animals this was 163 min versus 51 min, respectively. 4. It is concluded that exogenous surfactant, used as vehicle for intratracheally instilled 99mTc-tobramycin, increases lung clearance rate of 99mTc-tobramycin in rats.     

Treatment of ventilation-induced lung injury with exogenous surfactant

OBJECTIVE: It has been demonstrated that pulmonary surfactant plays a role in the pathophysiology of ventilation-induced lung injury (VILI). Therefore, we investigated whether exogenous surfactant might restore lung function and lung mechanics in an established model of VILI. DESIGN: Prospective, randomized, animal study. SETTING: Experimental laboratory of a university. SUBJECTS: Twenty-four adult male Sprague-Dawley rats. INTERVENTIONS: First, a group of six animals were killed immediately after induction of anesthesia and used as healthy controls. Then, in 18 rats, VILI was induced by increasing peak inspiratory pressure (PIP) to 45 cmH2O without positive end-expiratory pressure (PEEP) for 20 min. Thereafter, animals were randomly divided into three groups of six animals each: one group was killed immediately after VILI and served as VILI-control. In the other two groups, ventilator settings were changed to a PIP of 30 cmH2O and a PEEP of 10 cmH2O, and a respiratory rate of 40 bpm. One group received a bolus of surfactant and the other group received no treatment. MEASUREMENTS AND RESULTS: Blood gas tension and arterial blood pressures were recorded every 30 min for 2 h. After the study period, a pressure-volume curve was recorded. Then, a broncho-alveolar lavage (BAL) was performed to determine protein content, minimal surface tension, and surfactant composition in the BAL fluid. Oxygenation, lung mechanics, surfactant function and composition were significantly improved in the surfactant-treated group compared to the ventilated and non-ventilated control groups. CONCLUSION: We conclude that exogenous surfactant can be used to treat VILI.     

Bronchoalveolar lavage with a diluted surfactant suspension prior to surfactant instillation improves the effectiveness of surfactant therapy in experimental acute respiratory distress syndrome (ARDS)

Objective: To assess whether bronchoalveolar lavage (BAL) with a diluted surfactant suspension prior to surfactant instillation prevents the only transient improvement in lung function as reported after surfactant instillation in severe acute respiratory distress syndrome (ARDS). Design: Randomized, prospective, experimental study. Setting: Laboratory and animal facility of a large university. Materials: Adult male Sprague-Dawley rats (280 ± 30 g). Interventions: All animals underwent repetitive whole lung saline lavage to induce acute lung injury. Then, animals were randomly divided into seven study groups: the first group received surfactant (150 mg/kg) within 10 min after the last lavage (early treatment), whereas in the other six groups mechanical ventilation was continued for 3 h before treatment (late treatment). Treatment consisted of: surfactant instillation at a dose of 150 mg/kg; at a dose of 250 mg/kg; BAL with saline; BAL with a diluted surfactant suspension (2.5 mg/ml); BAL with saline, immediately followed by surfactant instillation (150 mg/kg) and BAL with a diluted surfactant suspension (2.5 mg/kg), immediately followed by surfactant instillation (150 mg/kg). Measurements and results: Blood gases were measured for 6 h and then BAL was performed to measure the protein concentration and surface tension properties. Mean PaO₂ values increased immediately after surfactant instillation to pre-lavage values but remained stable only in the group that received surfactant immediately after the lavage procedure and the group that underwent BAL with a diluted surfactant suspension prior to surfactant instillation. Conclusion: BAL with a diluted surfactant suspension prior to surfactant instillation at a later time point in lung injury resulted in a stable improvement of lung function. This improvement is comparable with the results seen after surfactant instillation immediately after lung lavage.     

Comparison of three perioperative fluid regimes for laparoscopic donor nephrectomy

Background Pneumoperitoneum (PP), as used for laparoscopic procedures, impairs stroke volume, renal blood flow, glomerular filtration rate and urine output. This study investigated whether perioperative fluid management can abolish these negative effects of PP on hemodynamics. Methods Twenty-one patients undergoing laparoscopic donor nephrectomy (LDN) were randomized into three groups: group 1 received overnight infusion and received a bolus of colloid before induction of anesthesia, followed by a bolus just before PP; group 2 received overnight infusion and a colloid bolus before anesthesia; group 3 served as controls and received only infusion during operation. All three groups received the same total amount of crystalloids and colloids until nephrectomy. Data analysis of the donor included; mean arterial pressure (MAP), stroke volume (SV), left ventricular ejection time (LVETc), perioperative urine output and renal function measured as the creatinine clearance (CrCl) until one-year post-operative. Results SV was significantly higher in group 1 compared to controls for all measurements. In the control group SV significantly decreased after changing from the supine to lateral position whereas there was no change in SV in both pre-hydrated groups. In all groups, MAP decreased after induction of anesthesia, and restored to pre-anesthetic values during PP. CrCl decreased in the control group during PP, but not in the other groups. From two days postoperative, CrCl was comparable between the three study groups. Conclusion Overnight infusion and a bolus of colloid just before PP attenuate hemodynamic compromise from PP. This study was performed at the Department of Anesthesiology, Erasmus University Medical Center Rotterdam and was financially supported by this Department     

Pulmonary surfactant as vehicle for intratracheally instilled tobramycin in mice infected with Klebsiella pneumoniae.

1. The use of pulmonary surfactant has been proposed as a vehicle for antibiotic delivery to the alveolar compartment of the lung. This study investigated survival rates of mice with a respiratory Klebsiella pneumoniae infection treated intratracheally with tobramycin using a natural exogenous surfactant preparation as vehicle. 2. At day 1 after infection, animals were injected intratracheally with 20 microliters of the following solutions: (1) a mixture of surfactant (500 micrograms) and tobramycin (250 micrograms); (2) tobramycin (250 micrograms) alone; (3) surfactant (500 micrograms) alone; and (4) NaHCO3 buffer (control, sham-treatment). A fifth group received no treatment (control). Deaths were registered every 12 h for 8 consecutive days. 3. The results show an increased survival in the group receiving the surfactant-tobramycin mixture compared to the group receiving tobramycin alone (P < 0.05), the group receiving surfactant alone (P < 0.01) and the control groups (P < 0.01). It is concluded that intratracheal instillation of surfactant-tobramycin is superior to tobramycin alone in protecting animals from death due to a respiratory Klebsiella pneumoniae infection.