Effects of fluid and dobutamine treatment on renal function during partial superior mesenteric artery occlusion and reperfusion.

OBJECTIVE: We compared the effects of dobutamine, fluid resuscitation and their combination on renal function during experimental intestinal ischaemia and reperfusion. MATERIALS AND METHODS: Superior mesenteric artery (SMA) blood flow was reduced to 30% from the baseline for 120 minutes in 24 anaesthetized pigs (ischaemic group); 24 pigs (sham group) served as non-ischaemic controls. The animals were further assigned into four treatment arms. In the control arms, the animals were given only basic fluid therapy. In the fluid therapy arms, pulmonary capillary wedge pressure (PCWP) was maintained at 10 mmHg with intravenous fluids. In the dobutamine treatment arm, dobutamine hydrochloride was infused at a dose of 10 microg/min/kg. In the combined dobutamine-fluid therapy arms, dobutamine at 10 microg/min/kg was given and PCWP was maintained at 10 mmHg with fluids. At 120 minutes, the occluder was released in all study groups and the animals were followed for an additional 60 minutes. Renal function was evaluated by means of serum and urine creatinine. urine volume and creatinine clearance. Systemic and regional haemodynamics as well as intramucosal pH, intramucosal-arterial pCO2 gradient, and portal venous-arterial lactate gradient were measured. RESULTS: In the ischaemic groups, diuresis increased and serum and urine creatinine decreased significantly in fluid (p < 0.01, p < 0.01 and p < 0.05, respectively) and dobutamine-fluid (p < 0.01, p < 0.001 and p < 0.001, respectively) treated groups during SMA ischaemia. After SMA reperfusion, diuresis decreased in control group (p < 0.05) and in animals treated with dobutamine alone (p < 0.01). In addition, urine creatinine increased in dobutamine treated group (p < 0.05), and creatinine clearance decreased in control group (p < 0.01). Renal function and diuresis during the SMA occlusion and reperfusion did not differ between ischaemic and sham groups. All fluid treated groups had lower serum creatinine during SMA occlusion than control groups (p < 0.001). CONCLUSIONS: Intestinal ischaemia caused by partial SMA occlusion did not influence renal function. On the contrary, SMA reperfusion resulted in a significant impairment of renal function both in ischaemic and sham operated animals. The impairment was most obvious in control groups and in animals treated with dobutamine alone.

Effects of dobutamine on splanchnic tissue perfusion during partial superior mesenteric artery occlusion.

OBJECTIVE: To evaluate the effects of dobutamine and fluid treatment on splanchnic hemodynamics and tissue oxygenation during partial superior mesenteric artery occlusion. DESIGN: Prospective, open randomized, full-factorial design. SETTING: University research laboratory. SUBJECTS: Forty-eight female pigs. INTERVENTIONS: In 24 anesthetized pigs (ischemic group), superior mesenteric artery (SMA) blood flow was reduced to 30% from the baseline for 120 mins; 24 pigs (sham group) served as nonischemic controls. The animals were further assigned into four treatment arms. In the control arm, the animals were administered only basic fluid therapy. In the fluid therapy arm, pulmonary artery occlusion pressure was maintained at 10 mm Hg with fluids. In the dobutamine treatment arm, dobutamine hydrochloride was infused at a dose of 10 microg/min/kg. In the combined dobutamine-fluid therapy arm, dobutamine at 10 microg/min/kg was administered and pulmonary artery occlusion pressure was maintained at 10 mm Hg with fluids. MEASUREMENTS AND MAIN RESULTS: Systemic and regional hemodynamics and oxygen transport, as well as jejunal intramucosal pH, intramucosal-arterial PCO2 gradient, and portal venous-arterial lactate gradient were measured. Ischemia did not modify the effects of fluids or dobutamine on systemic hemodynamics and oxygen transport. Dobutamine-treated animals had a higher cardiac index compared with control animals (218 +/- 22 vs. 135 +/- 13 mL/min/kg; p = .012), and the effect was enhanced when dobutamine was combined with fluid treatment (365 +/- 23 mL/ min/kg; p = .019). Fluid treatment alone did not influence cardiac index, whereas it increased SMA blood flow compared with control groups (15 +/- 2 vs. 12 +/- 2 mL/min/kg; p = .023). Dobutamine also decreased the proportion of SMA blood flow of cardiac output compared with control groups (6 +/- 1 vs. 9% +/- 1%; p = .024). Other treatments had no effect on SMA blood flow. Ischemia increased intramucosal-arterial Pco2 gradient to 54.8 +/- 10.7 torr (7.31 +/- 1.43 kPa) (p = .002 vs. sham control) and decreased intramucosal pH to 7.13 +/- 0.06 (p = .028 vs. sham control). In the ischemic animals, dobutamine without fluid therapy reduced intramucosal pH further to 7.00 +/- 0.09 (p = .023 vs. ischemic control) and increased portal venous-arterial lactate gradient (p = .033). CONCLUSIONS: Dobutamine alone worsened splanchnic tissue perfusion during partial superior mesenteric artery occlusion. As compared with fluid treatment alone, the combination of fluid and dobutamine therapy did not improve tissue perfusion.

Systemic and regional effects of experimental gradual splanchnic ischemia.

PURPOSE: We evaluated the effects of gradual intestinal ischemia on systemic and regional haemodynamics and oxygen transport. MATERIALS AND METHODS: Superior mesenteric artery (SMA) blood flow was decreased by 40%, 70%, and 100% for 60-minute periods and thereafter released in 12 pigs. Hemodynamic changes were monitored continuously, and the intestinal perfusion was evaluated by changes in portal vein-arterial lactate gradient, intramucosal pH, tonometric Pco2, tonometric-portal vein Pco2 gradient, and regional oxygen extraction. RESULTS: Local signs of intestinal hypoperfusion developed during the SMA occlusion. Intramucosal pH and portal vein pH decreased from 7.18 +/- 0.04 to 6.81 +/- 0.04 (P < .01) and from 7.36 +/- 0.01 to 7.25 +/- 0.03 (P < .05), respectively. Intramucosal Pco2 and tonometric-portal vein Pco2 gradient increased from 12.4 +/- 1.3 to 21.2 +/- 1.8 kPa (P < .01) and from 6.0 +/ 1.3 to 14.0 +/- 1.9 kPa (P < .05), respectively. Portal vein-arterial lactate gradient and splanchnic oxygen extraction increased from 0.02 +/- 0.07 to 2.32 +/- 0.47 mmol/L (P < .01) and from 0.44 +/- 0.03 to 0.60 +/- 0.03 (P < .05), respectively. Systemic changes observed during the SMA occlusion were reduction of cardiac index (161 +/- 12 to 114 +/- 8 mL/min/kg, P < .01) and pulmonary capillary wedge pressure (4 +/- 1 to 3 +/- 1 mm Hg) and increase in heart rate (124 +/- 5 to 173 +/- 11 beats/ min, P < .01) and mean arterial pressure (79 +/- 3 to 104 +/- 5 mm Hg, P > .01). Systemic oxygen extraction increased (P > .05), arterial pH increased (P < .05), and arterial lactate decreased (P < .01) during the SMA occlusion. Splanchnic ischemia defined as an increase in portal vein-arterial lactate gradient above mean +2 SD of the baseline occurred at 93 +/- 15 minutes corresponding 70% SMA occlusion. CONCLUSION: We conclude that signs of tissue hypoperfusion started to develop at 70% SMA occlusion and that regional tissue hypoperfusion in the splanchnic region may develop without any systemic signs of oxygen supply/demand mismatch.

Comparison of tropisetron, droperidol, and saline in the prevention of postoperative nausea and vomiting after gynecologic surgery.

This study was performed to compare the efficacy of tropisetron, droperidol, and saline in the prevention of postoperative nausea and vomiting (PONV) and to compare the possible adverse effects of these drugs in gynecologic incontinence surgery. Using a randomized, double-blind study design, we studied 150 women undergoing gynecologic incontinence surgery with standardized general anesthesia. At the end of surgery, the patients received either tropisetron 5 mg, droperidol 1.25 mg, or 0.9% saline intravenously (i.v.). As a rescue antiemetic, the patients received metoclopramide 10 mg i.v.. The episodes of nausea, retching, and vomiting; the need for rescue treatment; and the type and severity of adverse events were recorded at four occasions during the 48-h observation period. Pain, anxiety, drowsiness, and general satisfaction were also evaluated on a linear numerical scale of 0-10. Complete response (no PONV within the 48-h observation period) occurred similarly in the study groups (tropisetron 25%, droperidol 22%, and placebo 18%). Tropisetron and droperidol had no effect on the incidence of nausea and retching. However, the incidence of vomiting was significantly less in the tropisetron group than in the placebo group (tropisetron 19%, droperidol 45%, and placebo 57%). The number of emetic episodes (retching and/or vomiting) per patient within 48 h was significantly decreased under tropisetron when compared with placebo (tropisetron 2.5 +/- 3.4, droperidol 4.2 +/- 6.1, placebo 5.9 +/- 7.1). With regard to adverse events, the patients in the droperidol group had significantly more anxiety than the placebo group (2-6 h postoperatively), more drowsiness than the tropisetron and placebo groups (0-2 h postoperatively), and more dissatisfaction than the tropisetron (0-6 h postoperatively) and placebo groups (2-6 h postoperatively). We conclude that tropisetron given 5 mg i.v. during anesthesia in gynecologic incontinence surgery effectively prevents vomiting but not nausea and retching, while 1.25 mg i.v. droperidol fails to prevent any of these emetic symptoms and results in adverse events.

Clinicians' opinions on alarm limits and urgency of therapeutic responses.

To survey the routine use of bedside multivariable monitors in monitoring cardiac postoperative patients, 23 experienced anesthesiologists and cardiac surgeons were first asked to list which variables and what limit alarms they used. Then they defined to what extent the variables' values were allowed to deviate before therapeutic actions were needed. Typically, limit alarms were applied to heart rate and end-tidal CO2. For clinical assessment of a patient's state, the clinicians usually observed the heart rate and the systemic arterial blood pressures, but placed less emphasis on the pulmonary arterial pressures. Clinicians had similar opinions on alert limits for monitoring less extensive physiological deviations and on alarm limits for warning of a critical situation. Person-to-person tolerance of suboptimal monitored values varied. No correlation was found between the limit values and how long these values were tolerated without therapeutic response. However, the inquiry provided information on setting limits for alerts and alarms, and on experienced clinicians' decision-making during postoperative intensive care of cardiac patients.

Alarm-inducing variability in cardiac postoperative data and the effects of prealarm delay.

OBJECTIVE: Our objective was to study the distribution of invasively measured hemodynamic data to enhance the reliability of patient monitor alarm systems. METHODS: Monitoring data were collected, preprocessed off-line, and analyzed in 10 postcardiac surgery patients. The data were studied statistically to estimate the probability distributions, the probability of alarm at various probability levels in these distributions, the effect of the prealarm delay to the alarm probability, and the effect of preprocessing the monitoring data using one- or multidimensional median filtering. RESULTS: Fifteen percent of all registered values fell outside of commonly applied alarm limits. Doubling the prealarm delay from 5 to 10 sec reduced the mean alarm rate by 26%. A further decrease of 8% in the alarm rate was observed when a multidimensional vector median filter was used to remove the variable value interdependencies. CONCLUSIONS: Brief excursions beyond clinically optimal alarm limits were frequent and can occur without leading to significant degradation of the patient's state. Preprocessing can decrease the alarm rate effectively. Multidimensional preprocessing may produce more reliable alarms than one-dimensional processing.

A knowledge-based alarm system for monitoring cardiac operated patients--assessment of clinical performance.

An intelligent alarm system for the postoperative monitoring of cardiac surgery patients, which did not require any manual data entries, was tested in two phases. A clinician monitored at bedside the patients' recovery and verified clinically abnormal physiological states. After the first test with ten patients, the system's rulebase was upgraded and then tested with an additional 15 patients. The alarm system employed two PC/ATs and was programmed to give notice of four pathological states (hyperdynamic state, hypovolemic state, hypoventilation and left ventricular failure) at two levels of urgency (alarm and alert levels). The monitoring lasted 5.4 +/- 1.7 hours per patient (mean +/- S.D.), totalling 134.7 hours. The system alarmed 27 times during the first and 73 times during the second phase of the testing. The sensitivity of the alarms was 100% in both phases, and the specificities increased from 20.0% to 73.9% and from 59.1% to 70.0% for the alarms and the alerts, respectively. This computerized decision support system based exclusively on data available in the automatically collected data base had a low false positive rate and gave early warnings about pathological states in the homogeneous group of adult postoperative cardiac patients.

A knowledge-based alarm system for monitoring cardiac operated patients--technical construction and evaluation.

A knowledge-based alarm system for intensive care monitoring was designed, built, tested on-line, and evaluated. The system is a functional prototype of a highly specific patient monitor providing alarms on hypovolemia, hyperdynamic state, left ventricular failure and hypoventilation. These intelligent alarm functions aim to maintain the quality of patient monitoring even if nurses' attention is temporarily reduced or focused elsewhere. The alarm system has an electronic access to data available in a multichannel patient monitor and the patient data management system of the intensive care unit. Median filtering, trend estimation, and rule-based reasoning are applied when processing the measured variables and estimating the patient's state.

Ultrasound-facilitated central venous cannulation.

OBJECTIVE: To compare the conventional method for cannulation of the internal jugular vein with the ultrasound-aided technique. DESIGN: Prospective, randomized trial. SETTING: Medical and surgical patients requiring central cannulation in a university hospital. PATIENTS: Consecutive medical and surgical patients in whom central venous cannulation was indicated. INTERVENTIONS: Cannulation of the internal jugular vein was performed by one anesthesiologist. During the first 6 months, the ultrasound-aided technique (n = 29) was used, and during the second 6 months, the conventional technique (n = 27) was applied. MEASUREMENTS AND MAIN RESULTS: The venous lumen was reached with fewer punctures (1.2 +/- 0.5 vs. 3.3 +/- 3.0 punctures per patient) and the cannulation time was shorter (35 +/- 19 vs. 198 +/- 211 secs) while using the ultrasound-aided technique. The ultrasound-aided method showed that the large-bore (diameter greater than 2.0 mm) needles invariably perforated the medial wall of the internal jugular vein, increasing the risk of perforating the adjacent carotid artery. CONCLUSIONS: Ultrasound guidance reduces both the duration of time and the number of punctures required to cannulate the internal jugular vein. The Seldinger technique appears safer for catheterization of the internal jugular vein.

Development of an expert system for haemodynamic monitoring: computerized symbolization of on-line monitoring data.

The development of intelligent alarm systems for intensive care benefits from the transformation of data from a quantitative to a qualitative mode. We constructed a computerized algorithm for the symbolization of on-line monitoring data of heart rate, systemic arterial, pulmonary arterial and central venous pressures, as well as central and peripheral temperatures. We tested the ability of the algorithm to symbolize the levels of the parameters and to detect significant long-term trends in ten adult patients admitted to the intensive care unit after cardiac surgery. The estimations of an experienced clinician were taken as the 'gold standard'. The symbolization of the levels of the monitored parameters was in agreement with the clinician in 99.4% of the estimations. The algorithm detected 93.0% of the trends correctly and also estimated their reliability. The clinician considered its estimations to be accurate in 96.2% of cases. On the other hand, the clinician considered unreliable 2.4% of all the trends detected and classified as reliable by the algorithm. The computerized algorithm for the symbolization of real-time monitoring data performed efficiently enough for its further use in expert systems for intelligent monitoring.

Frequency and reliability of alarms in the monitoring of cardiac postoperative patients.

Postoperative monitoring of cardiac operated patients requires appropriately functioning monitor alarms as well as intensive nursing activity. The limit alarms can be used for detection of life-threatening situations and monitoring of physiological changes in the patient's state. We studied the significance and the frequency of audible alarms during the postoperative intensive care of ten cardiac patients. Of 1307 occasions when such an alarm was activated during the study period of approximately 26 hours per patient, only 139 (10.6%) were significant. The highest proportion of significant audible limit alarms was found during the immediate postoperative period. Heart rate alarms were more reliable than alarms of the other parameters monitored in the study. Possibilities for improving the physiological monitoring and alarm system are discussed.

Double blind comparison of transdermal hyoscine and placebo for the prevention of postoperative nausea.

Transdermal hyoscine (Scopoderm, Ciba-Geigy) has been compared with placebo in 283 female patients. The hyoscine patch had no significant effect on postoperative nausea or vomiting. In contrast with earlier studies, there was no correlation between previous experiences of nausea (motion, pregnancy or surgery related) and nausea caused by the surgery or anaesthetic in this study. No correlation was found between nausea or vomiting and the type of operation.

Venous sequelae after intravenous propofol ('Diprivan')--a comparison with methohexitone in short anaesthesia.

Propofol, in emulsion formulation, was compared with methohexitone for short duration anaesthesia with the main emphasis on acute and long-term venous tolerance. Flunitrazepam and fentanyl were given to all the patients. Fifty-two female patients undergoing short gynaecological procedures were randomly allocated to two groups to receive propofol or methohexitone as the intravenous anaesthetic agent. The dose of propofol was 2.0 mg/kg at induction with an average total dose of 2.58 mg/kg and the dose of methohexitone was 1.5 mg/kg and 2.20 mg/kg, respectively. Propofol or methohexitone were given through a 1.0 mm Teflon indwelling cannula in a superficial vein of one hand. All other drugs were given through a similar cannula in the other hand. There were no significant differences in acute or late tolerance between the propofol and methohexitone or control (all other drugs) groups. Because there was no thrombophlebitis following either drug the venous tolerance of both drugs can be regarded as good. Moreover this type of short anaesthesia was characterized with fast recovery and high patient acceptance.