Lung volumes, respiratory mechanics and dynamic strain during general anaesthesia.

BACKGROUND: Driving pressure (ΔP) represents tidal volume normalised to respiratory system compliance (CRS) and is a novel parameter to target ventilator settings. We conducted a study to determine whether CRS and ΔP reflect aerated lung volume and dynamic strain during general anaesthesia. METHODS: Twenty non-obese patients undergoing open abdominal surgery received three PEEP levels (2, 7, or 12 cm H2O) in random order with constant tidal volume ventilation. Respiratory mechanics, lung volumes, and alveolar recruitment were measured to assess end-expiratory aerated volume, which was compared with the patient's individual predicted functional residual capacity in supine position (FRCp). RESULTS: CRS was linearly related to aerated volume and ΔP to dynamic strain at PEEP of 2 cm H2O (intraoperative FRC) (r=0.72 and r=0.73, both P<0.001). These relationships were maintained with higher PEEP only when aerated volume did not overcome FRCp (r=0.73, P<0.001; r=0.54, P=0.004), with 100 ml lung volume increases accompanied by 1.8 ml cm H2O-1 (95% confidence interval [1.1-2.5]) increases in CRS. When aerated volume was greater or equal to FRCp (35% of patients at PEEP 2 cm H2O, 55% at PEEP 7 cm H2O, and 75% at PEEP 12 cm H2O), CRS and ΔP were independent from aerated volume and dynamic strain, with CRS weakly but significantly inversely related to alveolar dead space fraction (r=-0.47, P=0.001). PEEP-induced alveolar recruitment yielded higher CRS and reduced ΔP only at aerated volumes below FRCp (P=0.015 and 0.008, respectively). CONCLUSIONS: During general anaesthesia, respiratory system compliance and driving pressure reflect aerated lung volume and dynamic strain, respectively, only if aerated volume does not exceed functional residual capacity in supine position, which is a frequent event when PEEP is used in this setting.

Quantitative risk assessment of human campylobacteriosis by consumption of salad cross-contaminated with thermophilic Campylobacter spp. from broiler meat in Argentina.

Here, we developed a quantitative risk assessment for thermophilic Campylobacter spp. related to the consumption of salad prepared alongside broiler meat. The assessment considered initial contamination levels, cross-contamination and decontamination events during the broiler slaughter process and distribution, and storage and consumption patterns in Argentina and other Latin American countries. The model predicted an infection risk of 3.32×10(-4) per serving. This estimation was variable according to the dose-response model used. Considering the number of chickens slaughtered annually in Argentina, the estimated number of people who could suffer campylobacteriosis related to poultry meat consumption was, on average, 484,304. The risk of human campylobacteriosis was most sensitive to the probability of infection from a Campylobacter (r=0.72), the number of Campylobacter spp. per serving (r=0.40), the frequency of washing the cutting board (r=-0.31), the preparation of raw poultry before salad using the same cutting board (r=0.14), and the frequency of hand washing (r=-0.14). The most sensitive stages of the process identified through the risk assessment can be used as a basis for measures of risk management. Public campaigns on hygiene habits during food preparation at home should focus on the importance of washing the cutting board before preparing raw and ready-to-eat foods and of washing the hands during food preparation.

Human pancreatic secretory trypsin inhibitor in the assessment of the severity of acute pancreatitis. A comparison with C-reactive protein.

We assessed the ability of serum human pancreatic secretory trypsin inhibitor (hPSTI) to establish the severity of acute pancreatitis and compared it in this respect to that of serum C-reactive protein (CRP). Of 26 patients studied with acute pancreatitis, 16 had mild pancreatitis, and 10, severe disease. Initial studies were performed at onset of the disease in 20 patients, on the second day of illness in two, and on the third day of illness in the remaining four. In all, serum hPSTI and CRP concentrations were determined on admission and daily for the following 5 days using commercial kits; Ranson's score was evaluated within the first 48 h of admission. Sixty-three healthy subjects and 31 patients with nonpancreatic acute abdomen were also studied. Values of 70 ng/ml for serum hPSTI and 10 mg/dl for serum CRP were taken as limits to distinguish severe from mild-to-moderate acute pancreatitis. When assessed within the first 24 h of pain, serum hPSTI correctly classified 71% of the patients with severe acute pancreatitis, whereas serum CRP did so for 29%. In subsequent days, the two markers showed a similar sensitivity in predicting severe acute pancreatitis. Serum hPSTI and CRP were alike in excluding a diagnosis of severe acute pancreatitis. Ranson's score correctly identified 50% of patients with severe illness and 63% of patients with mild pancreatitis. This study indicates that, when assessed within 24 h of pain onset, serum hPSTI is a better predictor of the severity of acute pancreatitis than serum CRP or Ranson's criteria.

Human pancreas-specific protein/procarboxypeptidase B: a useful serum marker of acute pancreatitis.

The aim of this study was to evaluate the serum behavior of human pancreas-specific protein/procarboxypeptidase B (hPASP/PCPB) in the early phases of acute pancreatitis, and to calculate its sensitivity and specificity in comparison with those of serum amylase and lipase in the diagnosis of this illness. Twenty-six acute pancreatitis patients were studied; the pancreatitis was of biliary origin in 11, due to alcohol abuse in 8, and due to other causes in 7. Sixteen patients had mild pancreatitis and 10 the severe form of the disease. Thirty-one patients with nonpancreatic acute digestive diseases were also studied. Serum concentrations of hPASP/PCPB, amylase and lipase were determined in all subjects on admission to the study as well as daily for the following 5 days in acute pancreatitis patients. All patients with acute pancreatitis had abnormally high serum hPASP/PCPB, amylase and lipase concentrations on the first day of admission. On the sixth day of the disease, 76% of acute pancreatitis patients had abnormally high serum concentrations of hPASP/PCPB, whereas only 48% (p < 0.05) had elevated serum amylase and lipase. No differences in serum levels of hPASP/PCPB, amylase or lipase were found between patients with alcoholic pancreatitis and those with other etiological forms of the disease, or between those with mild and severe forms of pancreatitis. The specificity of the three serum pancreatic protein assays, calculated on the 31 patients with nonpancreatic acute digestive diseases, was 90% for both hPASP/PCPB and lipase, 75% for amylase.(ABSTRACT TRUNCATED AT 250 WORDS)