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Biomedical subjects

P Gregorini

Publications and source records attributed to P Gregorini.

18 recordsLinked to original sources
PubMed2006

Timing of herbage allocation in strip grazing: Effects on grazing pattern and performance of beef heifers.

The timing of grazing bouts (GB) determines how cattle allot time to meet their nutritional needs. Net photosynthesis and evapotranspirational losses increase herbage nonstructural carbohydrate and DM concentrations, which may lead to longer and more intense GB at dusk. Hence, linking the grazing pattern, plant phenology, and herbage allocation time emerges as an option to manipulate the GB and nutrient intake. The objectives of this work were to analyze grazing behavior and performance of beef heifers when herbage allocation was at 0700 each morning (MHA) or at 1500 each afternoon (AHA). Two pairs of experiments were conducted during the winter and spring examining behavior and performance. Measurements were grazing, rumination, and idling times during daylight hours, and their patterns, as well as bite rate, ADG, change in BCS, and daily herbage DMI. In the behavioral experiments, 8 heifers strip-grazed annual ryegrass (Lolium multiflorum Lam.). The grazing, rumination, and idling times as well as bite rate were measured and also analyzed per time of day. In the performance experiments, 48 beef heifers strip-grazed annual ryegrass in 2 groups according to treatments. Daily DMI, ADG, and changes in BCS were analyzed. The AHA increased daily idling time (P < 0.01) and decreased grazing time (P < 0.01). The AHA concentrated grazing time in the evening, when bite rate was greater (P < 0.01). The daylight rumination time varied by time of day (P < 0.01), but total daylight rumination time did not differ (P = 0.11). With AHA, rumination time and idling time were concentrated in the morning and afternoon. In the performance experiment during the winter, there was a treatment x week effect (P < 0.01) for ADG and change in BCS. Beginning in wk 4, heifers in AHA gained 150 g of BW and 0.0145 points of BCS more than those in MHA (P < 0.05) per day. In the spring, AHA increased ADG by 549 g and 0.0145 points of BCS more than those in MHA (P < 0.05) per day during the entire 6 wk. The herbage DMI (kg/d) did not differ in winter (AHA, 5.0 vs. MHA, 4.5) or spring (AHA, 5.6 vs. MHA, 5.0). These results suggest that timing of herbage allocation alters grazing, rumination, and idling patterns; AHA leads to longer and more intense GB when herbage has greater quality, which improves cattle performance.

Animal Feed↗
PubMed1996

Comparison of four methods of automated recording of physiologic data at one minute intervals.

INTRODUCTION: This study aims to evaluate possible differences between the maximum, minimum, and mean value over each epoch, or the instantaneous value at the end of the interval, when recording physiological data at 1-minute intervals. METHODS: The mean arterial pressure (MAP), heart rate derived from the radial pulse (PULSE), end-tidal CO2 (etCO2), and the arterial O2 saturation by pulse oximeter (SpO2) were measured continuously in 10 patients during general anesthesia. Anesthesia was induced and maintained using the same technique for the first 10 minutes. At 1-minute intervals for each parameter, the maximum, minimum, and mean value (over the preceding minute), as well as the instantaneous value at the end of the recording epoch, were automatically downloaded to an electronic spreadsheet. The differences between the maximum and minimum, the maximum and mean, the mean and minimum, and the instantaneous and mean values were calculated for each patient. RESULTS: We found differences between the maximum and minimum values recorded over each interval, between the maximum and mean values, between the mean and minimum values, and between the mean and instantaneous values recorded at the end of each minute interval for all physiological parameters examined. CONCLUSIONS: From the data presented, we conclude that during the first 10 minutes of a general anesthetic, including anesthesia induction and endotracheal intubation, the values of physiologic parameters derived from different summary indices, namely the maximum, minimum, and mean values over the 1-minute interval or instantaneous at the end of the interval differ from each other. This source of error must be considered when designing systems for computerized recordkeeping of anesthesia charts and when interpreting the data stored in electronic databases.

Blood Gas Analysis↗
PubMed1996

Control of body temperature during abdominal aortic surgery.

BACKGROUND: Careful control of body temperature during anesthesia aims to prevent cardiocirculatory complications during the phase of recovery from anesthesia. Numerous studies have examined methods for warming the gases breathed by the patient, but the question of whether low flow anesthesia or heat and moisture exchanges can also influence the pattern of body temperature remains unresolved. METHODS: In this clinical trial we evaluated the mean body temperature profile measured at five points in 40 patients divided into two groups: Group I was ventilated with a non-rebreathing circuit and Group II was ventilated with a circle system using low flow rates of fresh gases. All patients were treated with a hydrophobic heat moisture exchanger. RESULTS: The results point out a significantly (P < 0.01) lower decrease in mean body temperature 40 min after the start of mechanical ventilation with the use of low flow rate anesthesia. CONCLUSIONS: This study shows that anesthesia carried out using low fresh gas flow rates and heat moisture exchanger is able to reduce the fall in mean body temperature, when compared with anesthesia carried out using high fresh gas flow rates and heat moisture exchanger.

Anesthesia↗
PubMed1993

[Computerized recording of physiologic parameters monitored during anesthesia].

STUDY OBJECTIVE: The aim of the study is to describe a multifunctional anesthesia record system PC-based, for use in operating room, and to verify the possibility of statistical analysis of some of the signals registered. DESIGN: Anesthesia records with data entered automatically were performed in 650 patients undergoing anesthesia for abdominal or thoracic surgery. A randomized trial in patients allocated into two groups was performed too. The first group was ventilated with non rebreathing system, the second group was ventilated with circle system. SETTING: Inpatient surgery clinic at a medical center. PATIENTS: 24 patients ASA I undergoing general anesthesia for laparoscopic cholecystectomy. INTERVENTIONS: The first group was ventilated with O2 = 4 1/min-1 and N2O = 6 1/min-1; the second group was ventilated with O2 = 350 ml/min-1 and N2O = 250 ml/min-1, reducing the N2O flow in order to keep FIO2 = 0.4. MEASUREMENTS: Esophageal temperature was registered every 90 sec and automatically copied on a Microsoft Excel spread sheet for statistical analysis. RESULTS: The automated anesthesia record was easy to use and different information about anesthesia and surgery were recorded. The automated analysis of the signals can be performed if no artifacts exist. With this method we found a statistical difference in the esophageal temperature between the two groups after 45 min of anesthesia. CONCLUSIONS: Computerized records capture many more data than handwritten records and give the possibility to give a rationale in their customs.

Anesthesia↗
PubMed1993

[Comparison between bacterial contamination of the circular circuit and of the non-rebreathing circle used with an antibacterial filter].

In order to evaluate whether the risk of bacterial contamination increased during low-flow anaesthesia without bacterial filter compared with non-rebreathing anaesthesia with a disposable bacterial filter, two groups of patient were studied. In the first group a disposable circle absorber system was changed once daily, thus it was used for several patients. In the second group a non-rebreathing system was connected to a disposable bacterial filter before each surgical procedure. Samples for microbiological examination were taken preoperatively from the oropharynx and postoperatively from three locations in the circle system and in the non-rebreathing system. No difference in rates of circuit contamination were observed between the two groups.

Anesthesia, Closed-Circuit↗
PubMed1992

[Effects of propofol and isoflurane on the neuromuscular block induced by atracurium].

Speed of onset, duration of action and recovery time for a bolus injection of atracurium were measured in two groups of patients. In group I anaesthesia considered of propofol, fentanyl, nitrous oxide and oxygen mixture. The induction dose of propofol was 2 mg/kg-1 followed by an infusion of 9.0 mg/kg-1/h-1 for first half hour and 4.5 mg/Kg-1/h-1 subsequently. In group II anaesthesia consisted of isoflurane, fentanyl, nitrous oxide and oxygen mixture. Isoflurane was given upon clinical needs. Speed of onset, duration of action, and recovery time for atracurium were measured in the two groups. No statistically significant differences between speed of onset and duration of action between the two groups were found. The recovery period from T1 = 10% to T1 = 70% twitch response was considerably longer with isoflurane (25 min +/- 6) than with propofol (18 min +/- 3) (p less than 0.01). Results obtained suggest that for adequate relaxation during tracheal intubation smaller doses of atracurium are not needed during isoflurane than propofol administration. Because of the longer recovery period of residual neuromuscular blockade during isoflurane anaesthesia decreasing doses of atracurium and careful monitoring of twitch depression tension are also suggested.

Adult↗
PubMed1991

[Method for the analysis of changes in mixed venous oxygen saturation in vascular surgery].

Continues monitoring of SvO2 was carried aut using an Oxi metrix pulmonary arthery catheter in 12 patients undergoing aortic surgery. Hemodynamic measurements were made before skin incision (baseline values), before aortic cross clamping, after aortic declamping and postoperatively during shivering. Hemodynamic measurements were also taken whenever SvO2 changed more than 10% from baseline value. Results showed that in clinical setting, if SvO2 do not change more than 10% from baseline values, an equilibrium exists between oxygen delivery (DO2) and oxygen consumption (VO2). As DO2 and VO2 were correlate after measuring cardiac output from the same technique, a mathematical correction of a common error for linear calculations was applied. It was also concluded that changes of SvO2 greater than 10% of baseline values should prompt the assessment of hemoglobin, cardiac output, SaO2 and oxygen demand, but changes of SvO2 less than 10% of baseline value should not prompt measurements.

Aged↗
PubMedDate not supplied

Effect of low fresh gas flow rates on inspired gas composition in a circle absorber system.

STUDY OBJECTIVE: To determine the effects of fresh gas flow on inspired gas composition during low-flow anesthesia. DESIGN: Randomized trial with 2-hour observation periods in patients assigned to one of three groups. SETTING: Inpatient surgery clinic at a medical center. PATIENTS: Thirty-six patients undergoing abdominal surgery with low-flow anesthesia. INTERVENTIONS: Fresh gas flow was given at a starting rate of 5 L/min for 6 minutes. Thereafter, the fresh gas flow setting was nitrous oxide (N2O) 1 L/min and oxygen (O2) 0.6 L/min (Group 1), N2O 0.5 L/min and O2 0.5 L/min (Group 2), and with a moderate surplus of N2O and O2 with respect to the patient's O2 consumption (Group 3). MEASUREMENTS AND MAIN RESULTS: The inspired O2 concentration (FIO2) was measured using a paramagnetic technique, and N2O levels were measured with infrared sensors; the inspired nitrogen concentration (FIN2) was calculated by the following formula: FIN2 = 1-FIO2-FIN2O, where FIN2O is the inspired N2O concentration. After 1 hour of anesthesia, FIO2 was significantly lower in Group 1 than in Groups 2 and 3 (p < 0.01), and FIN2 was significantly higher in Groups 2 and 3 than in Group 1 (p < 0.01). After 2 hours of anesthesia, FIN2 returned to normal in Group 2 but continued to increase in Group 3. FIN2O was close to 0.7% only in Group 1. CONCLUSIONS: The same initial period of denitrogenation is not adequate to denitrogenate the circle system in all cases. The lower the fresh gas flow, the longer the initial period of denitrogenation should be. Various levels of fresh gas flow for low-flow anesthesia have been suggested, but none guarantees adequate control of inspired gas composition unless flowmeters are continuously adjusted.

Aged↗