Correction to: Inert gas narcosis in scuba diving, different gases different reactions.

The original version of this article unfortunately contained a mistake.

Inert gas narcosis in scuba diving, different gases different reactions.

PURPOSE: Underwater divers face several potential neurological hazards when breathing compressed gas mixtures including nitrogen narcosis which can impact diver's safety. Various human studies have clearly demonstrated brain impairment due to nitrogen narcosis in divers at 4 ATA using critical flicker fusion frequency (CFFF) as a cortical performance indicator. However, recently some authors have proposed a probable adaptive phenomenon during repetitive exposure to high nitrogen pressure in rats, where they found a reversal effect on dopamine release. METHODS: Sixty experienced divers breathing Air, Trimix or Heliox, were studied during an open water dive to a depth of 6 ATA with a square profile testing CFFF measurement before (T0), during the dive upon arriving at the bottom (6 ATA) (T1), 20 min of bottom time (T2), and at 5 m (1.5 ATA) (T3). RESULTS: CFFF results showed a slight increase in alertness and arousal during the deep dive regardless of the gas mixture breathed. The percent change in CFFF values at T1 and T2 differed among the three groups being lower in the air group than in the other groups. All CFFF values returned to basal values 5 min before the final ascent at 5 m (T3), but the Trimix measurements were still slightly better than those at T0. CONCLUSIONS: Our results highlight that nitrogen and oxygen alone and in combination can produce neuronal excitability or depression in a dose-related response.

Epidemiology and clinical outcome of Healthcare-Associated Infections: a 4-year experience of an Italian ICU.

BACKGROUND: Due to their impact on the outcome, hospital-acquired infections (HAIs) in ICUs represent a critical issue of patients' assistance. This study describes microbiological and clinical findings of a surveillance program covering 4 years in an Italian ICU. METHODS: Patients staying for >48 hours were prospectively followed until discharge or death. For each patient, infections after admissions, duration of device exposure and causal pathogens were noted. A multivariable logistic regression analysis concerning ICU mortality was made. RESULTS: Incidence density rates were 23.14 VAPs, 6.6 CLABSIs and 5.45 CAUTIs (per 1000 device-days) with an increase in yearly rates during the study period (P<0.001). Use of invasive devices was significantly longer among infected patients (P<0.001, for each), whose proportion was higher among medical admissions (P=0.009). The most frequent source of infection was the lung (78%), followed by bloodstream (23%). MSSA was the most frequently isolated pathogen (26%) but Gram-negatives were found in 86.1% of infected patients, with a high degree of resistance to carbapenems (27.5% for Klebsiella pneumoniae). APACHE score, immunosuppression, duration of mechanical ventilation, surgical admission and abdominal infections were independent predictors of ICU mortality (P<0.001; P<0.001; P=0.006; P=0.027; P=0.006, respectively). CONCLUSION: Our infection rates are higher than those reported by other studies. The use of devices and a medical admission share a significant relationship with infection presence. A greater degree of organ failure and the development of an abdominal sepsis are risk factors for mortality.

Comparison of triple-lumen central venous catheters impregnated with silver nanoparticles (AgTive®) vs conventional catheters in intensive care unit patients.

BACKGROUND: Silver-impregnated central venous catheters (CVCs) have been proposed as a means for preventing CVC colonization and related bloodstream infections (CRBSIs). AIM: To evaluate the efficacy of CVCs impregnated with silver nanoparticles in a large group of critically ill patients. METHODS: A prospective, randomized clinical trial was conducted in five intensive care units (ICUs). Three hundred and thirty-eight adult patients requiring CVCs between April 2006 and November 2008 were randomized to receive AgTive silver-nanoparticle-impregnated (SC) or conventional (CC) CVCs. Primary endpoints were CVC colonization (growth of ≥15 colony-forming units from the catheter tip) and incident CRBSIs (meeting the definitions of the Centers for Disease Control and Prevention). Infection-free time (days from initial CVC insertion to initial blood culture positivity) and ICU mortality rates were measured as secondary endpoints. FINDINGS: The SC group (N = 135) and CC group (N = 137) were similar in terms of clinical and laboratory parameters at baseline, reasons for ICU admission, complications during CVC insertion, and total time with CVC (mean ± standard deviation; SC 13 ± 24 vs CC 15 ± 37 days). No significant intergroup differences were found in CVC colonization rates (SC 32.6% vs CC 30%; P = 0.7), CRBSI incidence rates (3.36 infections per 1000 catheter-days in both groups), infection-free times (SC 13 ± 34 vs CC 12 ± 12 days; P = 0.85) or ICU mortality (SC 46% vs CC 43%; P = 0.7). CONCLUSION: In critically ill patients, use of AgTive(®) silver-nanoparticle-impregnated CVCs had no significant effect on CVC colonization, CRBSI incidence or ICU mortality. These CVCs cannot be recommended as an adjunctive tool for control of CRBSIs.

The Bonfils fiberscope: a clinical evaluation of its learning curve and efficacy in difficult airway management.

BACKGROUND: This study evaluated the use of the Bonfils fiberscope by analyzing its learning curve, efficacy and safety during airway management. METHODS: This was a prospective observational study where five anesthetists, with differing levels of experience, were asked to use the Bonfils rigid fiberscope (Karl Storz) for a six-month period. They used the scope when performing endotracheal intubations in patients undergoing general anesthesia. The patients were excluded if various clinical indicators predicted that they might be difficult to intubate. The patient's head was kept in the neutral position to simulate the intubation of a trauma patient. Direct laryngoscopy with a Macintosh blade was performed to assign a Cormack and Lehane grade prior to attempting laryngoscopy with the Bonfils fiberscope. After intubating the patient with the Bonfils fiberscope, intubation time and any complications or failures noted after the procedure were recorded. RESULTS: The study included 216 patients, three of which were failed intubations. No complications occurred during the study period. The median intubation time was 21.4 s. The learning curve improved significantly after 20 intubations (P<0.05) and was affected by the operator's experience and aptitude with endoscopic viewing. Seventeen patients were deemed to have "unpredicted" difficult airways: 15 subjects with a Cormack grade 3 (6.9%) and two subjects with a Cormack 4 (0.9%). Median time to intubation in subjects with a Cormack <3 was 16 s (95% CI=10-29 s), and in subjects with a Cormack ≥3, it was 15 s (CI 95%=15-18 s) with P=0.703. CONCLUSION: The Bonfils fiberscope is an efficient, easy to use and safe device for endotracheal intubation.

Prospective multicenter study on epidemiology of acute kidney injury in the ICU: a critical care nephrology Italian collaborative effort (NEFROINT).

Acute kidney injury (AKI) is an independent risk factor for mortality in critically ill patients whose epidemiology has been made unclear in the past by the use of different definitions across various studies. The RIFLE consensus definition has provided a unifying definition for AKI leading to large retrospective studies in different countries. The present study is a prospective observational multicenter study designed to prospectively evaluate all incident admissions in 10 Intensive Care Units (ICUs) in Italy and the relevant epidemiology of AKI. A simple user-friendly web-based data collection tool was created with the scope to serve for this study and to facilitate future multicenter collaborative efforts. We enrolled 601 consecutive patients into the study; 25 patients with End-Stage Renal Disease were excluded leaving 576 patients for analysis. The median age was 66 (IQR 53-76) years, 59.4% were male, while median SAPS II and APACHE II scores were 43 (IQR 35-54) and 18 (IQR 13-24), respectively. The most common diagnostic categories for ICU admission were: respiratory (27.4%), followed by neurologic (17%), trauma (14.4%), and cardiovascular (12.1%). Crude ICU and hospital mortality were 21.7% and median ICU length of stay was 5 days (IQR 3, 14). Of 576 patients, 246 patients (42.7%) had AKI within 24 hours of ICU admission while 133 developed new AKI later during their ICU stay. RIFLE-initial class was Risk in 205 patients (54.1%), Injury in 99 (26.1%) and Failure in 75 (19.8%). Progression of AKI to a worse RIFLE class was seen in 114 patients (30.8% of AKI patients). AKI patients were older, with higher frequency of common risk factors. 116 AKI patients (30.6%) fulfilled criteria for sepsis during their ICU stay, compared to 33 (16.7%) of non-AKI patients (P<0.001). 48 patients (8.3%) were treated with renal replacement therapy (RRT) in the ICU. Patients were started on RRT a median of 2 (IQR 0-6) days after ICU admission. Among AKI patients, they were started on RRT a median of 1 (IQR 0-4) days after fulfilling criteria for AKI. Median duration of RRT was 5 (IQR 2-10) day. AKI patients had a higher crude ICU mortality (28.8% vs. non-AKI 8.1%, P<0.001) and longer ICU length of stay (median 7 days vs. 3 days [non-AKI], P<0.001). Crude ICU mortality and ICU length of stay increased with greater severity of AKI. Two hundred twenty five patients (59.4% of AKI patients) had complete recovery of renal function, with a SCr at time of ICU discharge which was ≤120% of baseline; an additional 51 AKI patients (13.5%) had partial renal recovery, while 103 (27.2%) had not recovered renal function at the time of death or ICU discharge. Septic patients had more severe AKI, and were more likely to receive RRT with less frequency of renal function recovery. Patients with sepsis had higher ICU mortality and longer ICU stay. The study confirms previous analyses describing RIFLE as an optimal classification system to stage AKI severity. AKI is indeed a deadly complication for ICU patients where the level of severity correlated with mortality and length of stay. The tool developed for data collection resulted user friendly and easy to implement. Some of its features including a RIFLE class alert system, may help the treating physician to collect systematically AKI data in the ICU and possibly may guide specific decision on the institution of renal replacement therapy.

Extended-spectrum beta-lactamases Klebsiella pneumoniae: multimodal infection control program in intensive care units.

INTRODUCTION: The aims of our study were to investigate a nosocomial spread of an extended-spectrum fl-lactamases-Klebsiella pneumoniae cluster at a University teaching hospital in Italy, to describe, and to monitor the implementation of a multimodal infection control program in two mixed ICUs. METHODS: During the 1 October 2005-30 September 2006 period, 79 colonized patients have been identified. Isolates were genotyped by pulsed-field gel electrophoresis (PFGE). A mutimodal infection control program with monitoring of alcohol-based hand rub was performed in Intensive Care Units (ICU A and ICU B). RESULTS: The epidemiological investigation and PFGE showed a horizontal transmission of the same PFGE genotype, with the isolation of the outbreak strain on the hand of one healthcare operator. Alcohol based hand rub was adopted in ICUA on 18 March 2006, in addition to hand washing with plain or antiseptic soap. ICU B did not change its hand hygiene habits. Following the implementation of the program, the incidence density rate (IDR) in ICU A fell down from 4.50 to 1.68/1000 patient days. DISCUSSION AND CONCLUSIONS: Our findings confirm the important role of personnel in cross-transmission. Moreover the inbuilt control group involuntarily offered by the delaying of the intervention in ICU B has given the opportunity to verify the epidemiological association between the actual implementation of infection control practices and the outbreak control.

Behavior of B-type natriuretic peptide during mechanical ventilation and spontaneous breathing after extubation.

BACKGROUND: The behavior of B-type natriuretic peptide (BNP) is assessed during mechanical ventilation (MV) and spontaneous breathing after extubation in critical patients. METHODS: Thirty patients admitted in the Intensive Care Unit (ICU) were enrolled. BNP, fluid balance (FB), airway pressure (AP) and dobutamine infusion needing (DP) were registered in three stages: T0, admission to ICU; T1, before extubation; T2, 24 h after extubation. RESULTS: Patients with congestive heart failure (CHF) had BNP values higher than other patients. The value of BNP during MV was greater than normal in all patients. The cut-off to discriminate patients with heart failure during MV was 286 pgxmL(-1)(sensitivity: 86%; specificity: 90%). The increase of BNP during MV directly correlated with FB and inversely correlated with AP and DP. The plasmatic level of BNP remained higher than normal values 24 h after extubation. CONCLUSIONS: The underlying disease of an ICU patient seems to play a relevant role for BNP production and is probably linked to different aspects of therapeutic approach required by the patient. Our data suggest a cut-off value of BNP higher than the usual is necessary to discriminate mechanically-ventilated patients without CHF. This study should be repeated with an enlarged population.

Improvement of the ventilator associated pneumonia rate with infection control practices in an Italian ICU.

BACKGROUND: To assess the impact of an intervention to improve respiratory infection control practices and reduce the ventilator associated pneumonia (VAP) rate in an intensive care unit, at the request of the ICU staff. DESIGN: prospective surveillance before-after study. Baseline VAP rates were determined over a 4-month period of active surveillance without an infection control program (period 1) and compared to VAP rates following implementation of an infection control program (period 2). The ICU staff requested the implementation of infection control practices. SETTING: Intensive Care Unit (ICU) at a university teaching hospital in Italy. PATIENTS: A total of 185 patients admitted to the ICU were included in the study. RESULTS: PATIENTS assessed during period 1 were similar to patients assessed during period 2 with regard to age, sex, origin, type of admission and mortality. PATIENTS who were admitted during period 2 had significantly lower simplified acute physiology scores (SAPS) II and acute physiology and chronic health evaluation (APACHE) II scores than patients admitted during period 1 (P<0.05). During period 1, there were 27 cases of VAP, and the incidence rate was 36.9/1000 MV-days. During period 2, the VAP rate decreased significantly (P=0.049): there were only 17 cases of VAP, and the incidence rate was 22.5/1,000 MV-days, with a rate-ratio of 0.61. CONCLUSION: Despite our short study period, the results appear to be encouraging and show a measurable impact on the incidence of VAP.

Sufentanil-propofol vs remifentanil-propofol during total intravenous anesthesia for neurosurgery. A multicentre study.

BACKGROUND: In a randomised, prospective multi-centre study, we compared the intraoperative and postoperative effects of two opioids: sufentanil and remifentanil, in combination with propofol in two groups of patients undergoing neurosurgery. METHODS: After Local Ethics Committee approval and informed consent obtaining, 69 patients undergoing neurosurgery for supratentorial tumours, between 18 and 75 years of age were randomised to receive either sufentanil or remifentanil in combination with propofol. Intraoperative and postoperative haemodynamic variables, recovery times (time to eye opening and to extubation), the incidence of postoperative respiratory depression, pain, nausea and vomiting were also evaluated. The Short Orientation-Memory-Concentration Test was used to evaluate cognitive function at 15, 45 and 180 min after emergence from anesthesia. RESULTS: There were no significant differences between the groups in the duration of surgery and anesthesia, mean arterial pressure, heart rate, time to eye opening or extubation. The incidence of vomiting, respiratory depression and shivering was similar in both groups. Postoperative pain requiring supplemental analgesics was significantly lower in the sufentanil group (P<0.05). Although there were no significant differences between the groups in postoperative behavioural examinations by Rancho Los Amigos Test, patients anesthetised with sufentanil had significantly better Short Orientation-Memory-Concentration Test values at 15 and 180 min postoperatively (P<0.05). CONCLUSION. We conclude that remifentanil and sufentanil are suitable adjunct to propofol for total intravenous anesthesia (TIVA). Patients receiving sufentanil have reduced analgesic requirements and better cognitive function postoperatively than those who received remifentanil.

The ability of PiCCO versus LiDCO variables to detect changes in cardiac index: a prospective clinical study.

BACKGROUND: Both PiCCO and LiDCO can provide dynamic preload parameters, pulse pressure variation (PPV) and stroke volume variation (SVV). The PiCCO device also provides a measure of intrathoracic blood volume index (ITBVI). We investigated the agreement between SVV and PPV, as well as the reliability of LiDCO- and PiCCO-measured SVV, PPV and ITBVI, in detecting fluid responsiveness before and after fluid challenge (FC). METHODS: We performed a prospective clinical study in University Hospital ICU. Nine adult ICU patients with cardiovascular instability were enrolled in the study. All patients were sedated and mechanically ventilated with intermittent positive pressure ventilation. The PiCCO and LiDCO systems were both connected to each patient. The PiCCO pulse waveform system was joined by a 5-French (Fr) thermistor-tipped arterial catheter inserted into the femoral artery. LiDCO measurements were performed through radial artery pulse contour analysis. Fluid challenge was performed using a rapid infusion of 7 mL/kg of 6% hydroxyethylstarch over 30 min. RESULTS: Measurements of CI, ITBVI, SVV, and PVV were made using both techniques before and after FC. Pre-FC cardiac index (CI) measurements were similar with both devices, although the reading was higher after FC with the PiCCO device (P<0.001). The correlation coefficient between PiCCO-CI and LiDCO-CI was 0.85 (95% CI: 0.69 to 0.93; P<0.001); for P-PPV and L-PPV, it was 0.74 (95% CI: 0.49 to 0.88; P<0.001). Only ITBV had a significant correlation with LiDCO-CI or PiCCO-CI. CONCLUSION: We found a narrow bias but less accurate precision in cardiac index values measured by a radial artery-site LiDCO catheter and a femoral artery-site PiCCO catheter, with poor agreement between radial and femoral-derived SVV and PPV measurements. ITBVI proved to be the best predictor of fluid responsiveness. The SVV does not seem to be reliable for preload optimization in ICU patients.

Fluid challenge in patients submitted to spinal block.

AIM: The practice of routinely prehydrating patients by infusing a colloid solution for prevention of spinal anesthesia-induced hypotension has been challenged recently. The aim of the study was to evaluate the influence of a 15 mL/kg pre-emptive bolus of colloids (6% hydroxyhethyl starch) on heart rate (HR), mean arterial blood pressure (MAP), cardiac index (CI) in patients submitted to subarachnoid block with hyperbaric bupivacaine 0.5%, 0.2 mg/kg for orthopedic surgery of the lower limb. METHODS: Patients were monitored by a Model Flow method. Forty patients (ASA I-II) scheduled to undergo to spinal anesthesia for elective orthopedic surgery of the lower limb were enrolled in the study. The 20 patients in Group A were treated with a preanesthetic infusion of 15 mL/kg of hydroxyhaethyl starch 6%, Group B (20 untreated patients) was the control group. HR, MAP, CI were collected at T0 (first relevation); T1 (after 5 min from the spinal block); T2 (after 10 min); T3 (after 15 min); T4 (after 20 min); T5 (after 25 min); T6 (after 30 min); T7 (after 35 min). RESULTS: Our data show that MAP value is higher in treated patients than in control group (ANOVA: P<0.001) and at T1 in Group B MAP was lower than at T0 (P<0.05). HR and CI trend appear similar in the 2 groups. Our results show that heart rate is not affected by colloid infusion. This may be due to the substantial cardiovascular stability of the selective spinal anesthesia, which does not activate a clinical relevant compensatory vagal effect. Fluid prehydration would expand the vascular space and hence compensate for the reduction in systemic vascular resistance, although MAP reduction following the induction of spinal anesthesia is present in both treated and control groups. CONCLUSION: Our data show that despite to fluid challenge, we could not prevent MAP decrease in Group A, even if it is more marked in Group B.

Successful early voriconazole treatment of Aspergillus infection in two non immunocompromised patients in Intensive Care Unit.

We report two cases of respiratory Aspergillus infection that occurred in patients admitted to the Intensive Care Unit of a teaching hospital during renovation works and treated with new triazole voriconazole (Vfend). The first patient was affected with cerebral hemorrhage, the second with polytrauma and both developed Aspergillus Pneumonia during their ICU stay. Bronchoalveolar lavage, dosage with anti-Aspergillus antibodies, antigen measurements and galactomannan research with Sanofi Platelia were performed. Therapy was carried out with voriconazole for 12 days. Chest X-ray and laboratory tests showed complete resolution after 12 days of therapy; clinical symptoms were negative after 4 days. Aspergillus infection can be observed frequently in non-immunocompromised patients during ward renovation or in hospitals near building areas. Since treatment is often unsuccessful, we preferred to immediately employ new agents to reduce the impact of this disease.

Spectral entropy assessment with auditory evoked potential in neuroanesthesia.

OBJECTIVE: The assessment of the level of anesthesia is a very hard task, since no gold standard has stood out in the past three decades. Middle Latency Auditory Evoked Potential (MLAEP) is one of the most popular neurophysiological tools for anesthesia monitoring. Recently, Spectral Entropy (SpEn) has been introduced: it provides two different parameters, State Entropy (SE) and Response Entropy (RE). The aim of this prospective study is to check SpEn end-point, comparing it to MLAEPs in neurosurgical anesthesia. METHODS: Twenty patients submitted to elective supratentorial neurosurgery for removal of a temporal-parietal meningioma were included in the study. SpEn and MLAEPs were simultaneously monitored using the M-entropy module S/5 (GE Health Care, Helsinki, Finland) and Alaris Medical System AEP-ARX index monitor (AAI) (Kidemosevej, Denmark), respectively. RESULTS: Four thousand and sixty four data points of SE, RE and AAI were recorded and ROC curves comparing AAI to RE and SE showed a highly significant (p<0.0001) area under the curve. The RE and SE cut-off values (showing maximal sensitivity with maximal specificity) to discriminate anesthesia from awake or consciousness sedation were 61 and 58, respectively. However, in a group of data points, low AAI was associated to high SpEn (577 data points for RE and 770 for SE) and vice versa (31 data points for RE and 43 for SE). The prediction probability for SE was 0.977 and for RE was 0.968. CONCLUSIONS: Our results suggest that SpEn is as effective as AAI. SIGNIFICANCE: Our results show that SpEn is able to discriminate between the levels of wakefulness and surgical anesthesia. However, the meaning of data showing a discrepancy between AAI and SpEn is not yet clear and calls for further study.

Correlation between hyperglycemia and mortality in a medical and surgical intensive care unit.

AIM: The aim of this study was to assess the correlation between hyperglycemia and mortality in a group of patients admitted to a medical and surgical ICU and to evaluate if the association between hyperglycemia and reason of ICU admission significantly worsens patients' outcomes. METHODS: A retrospective clinical study was conducted in the ICU of a University Hospital. Four-hundred and twelve adult patients admitted to our ICU were enrolled. The blood glucose level was measured at the time of admission and daily at 2-4 h intervals. When the glucose level exceeded 180 mg/dL, an insulin bolus or a continuous infusion were performed to maintain the glucose level at or below 180-200 mg/dL. RESULTS: Analysing the mean blood glucose levels of patients with the receiver operating characteristic (ROC) curve, it resulted that the blood glucose level of 141.7 mg/dL had higher sensitivity (76%) and specificity (56.5%) to discriminate the probability of death. In other words, in patients in whom the mean blood glucose levels were greater than 141.7 mg/dL, the probability of death was higher (26.62%) than in the group of patients in whom a strict blood glucose control was maintained (13.55%) (P = 0.0017). CONCLUSIONS: A strict blood glucose control seems to be crucial, even in a medical and surgical ICU. The need for intensive insulin therapy, even by means of continuous infusion of insulin, to obtain the normalization of blood glucose levels, appears essential.

Haemodynamic modifications after unilateral subarachnoid anaesthesia evaluated with transthoracic echocardiography.

AIM: The aim of the study is the evaluation through transthoracic echocardiography of the haemodynamic modifications due to unilateral subarachnoid anaesthesia with bupivacaine 0.5% given for orthopaedic surgery. METHODS: In this prospective study, at the University Hospital Orthopedics surgical theater, 20 patients underwent orthopaedic surgery on the lower limbs. Unilateral spinal block was performed with hyperbaric bupivacaine 0.5%, 8 mg after a fluid challenge with saline solution 0.9%. Transthoracic echocardiography was performed and cardiac output was calculated from the left ventricular outflow tract (LVOT) with a recently validated technique. Cardiac output, stroke volume, ejection fraction, heart rate, mean arterial pressure were evaluated. These parameters were obtained before anaesthesia (t1), 5 minutes after anaesthesia (t2) and 16 minutes after anaesthesia (t3). RESULTS: Systolic, mean and diastolic arterial pressures after 5 min and 16 min from anaesthesia significantly decreased if compared to basal time (p<0.05 and p<0.001 respectively) while cardiac index (p<0.001) and ejection fraction (p<0.05) decreased only after 16 min from subarachnoid anaesthesia. CONCLUSION: Despite the fluid challenge we can not prevent a significant fall in the blood pressure and a decrease of the left ventricular function calculated with the decrease of cardiac output and of the left ventricular ejection fraction.

A new and feasible model for predicting operative risk.

BACKGROUND: Although the POSSUM (Physiological and Operative Severity Score for the enumeration of Mortality and Morbidity) score can be used to calculate operative risk, its complexity makes its use unfeasible in the immediate clinical setting. The aim of this study was to create a new model, based on ASA status, to predict mortality. METHODS: Data were collected in two hospitals. All types of surgery were included except for cardiac surgery and Caesarean delivery. Age, sex and preoperative information, including the presence of cardiocirculatory and/or lung disease, renal failure, diabetes mellitus, hepatic disease, cancer, Glasgow Coma Score, ASA grade, surgical diagnosis, severity of the procedure and type of surgery (elective, urgent or emergency), were recorded for each patient. The model was developed using a data set incorporating data from 1936 surgical patients, and validated using data from a further 1849 patients. Forward stepwise logistic regression was used to build the model. Goodness of fit was examined using the Hosmer-Lemeshow test and receiver operating characteristic (ROC) curve analyses were performed on both data sets to test calibration and discrimination. In the validation data set, the new model was compared with POSSUM and P-POSSUM for both calibration and discrimination, and with ASA alone to compare discrimination. RESULTS: The following variables were included in the new model: ASA status, age, type of surgery (elective, urgent, emergency) and degree of surgery (minor, moderate or major). Calibration and discrimination of the new model were good in both development and validation data sets. This new model was better calibrated in the validation data set (Hosmer-Lemeshow goodness-of-fit test: chi(2)=6.8017, P=0.7440) than either P-POSSUM (chi(2)=14.4643, P=0.1528) or POSSUM, which was not calibrated (chi(2)=31.8147, P=0.0004). POSSUM and P-POSSUM had better discrimination than the new model, although this was not statistically significant. Comparing the two ROC curves, the new model had better discrimination than ASA alone (difference between areas, 0.077, SE 0.034, 95% confidence interval 0.012-0.143, P=0.021). CONCLUSIONS: This new, ASA status-based model is simple to use and can be performed routinely in the operating room to predict operative risk for both elective and emergency surgery.