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Biomedical subjects

A Sidi

Publications and source records attributed to A Sidi.

At least 19 recordsLinked to original sources
PubMed2006

Treatment of ischaemic left ventricular dysfunction with milrinone or dobutamine administered during coronary artery stenosis in the presence of beta blockade in pigs.

BACKGROUND: This study examines the effects of phosphodiesterase type III (PDEIII) inhibition vs beta stimulation on global function of the left ventricle (LV) and systemic haemodynamics in a porcine model of acute coronary stenosis with beta blockade. METHODS: A total of 18 adult swine were anaesthetized. Micromanometer-tipped catheters were placed in the ascending aorta and LV. Two pairs of ultrasonic dimension transducers were placed in the subendocardium on the short axis proximal to a left anterior descending (LAD) artery occluder and the long axis of the LV. Before ischaemia, i.v. esmolol was infused to decrease baseline heart rate (HR) by approximately 25%, and all animals received an esmolol infusion (150 microg kg(-1) min(-1)). Ischaemia was produced by reducing the flow in the LAD artery by approximately 80%, from 17(4) to 3(2) ml min(-1). Animals were randomized to receive (after esmolol) one of the following: no drug, sham only (Group 1, n=6), control (C); 50 microg kg(-1) i.v. milrinone (Group 2, n=6) followed by 0.375 microg kg(-1) min(-1) (M); or incremental doses of dobutamine (Group 3, n=6) every 10 min (5, 10 and 20 microg kg(-1) min(-1)) (D). Left ventricular function data obtained included HR, arterial and LV pressures, cardiac output (CO), Emax and dP/dT. Measurements were taken during five time periods: before ischaemia (at baseline, after esmolol) and every 10 min during ischaemia (at 10, 20 and 30 min). RESULTS: The effects of beta blockade and ischaemia had a significant impact on contractility (Emax) in Group M and myocardial performance (left ventricular end-diastolic pressure, LVEDP) in all groups. Left ventricular function (Emax, CO, LVEDP and SVR) was better preserved when milrinone was added in Group M. A moderate dose of dobutamine (10 microg kg(-1) min(-1)) increased CO. Only the high dose (20 microg kg(-1) min(-1)) improved contractility (Emax), but at the expense of increased SVR. Also, LVEDP with either dose of dobutamine remained high and unchanged. CONCLUSIONS: From our limited findings, it would appear that there may, theoretically, be some benefit for using milrinone in preference to other inotropic drugs in the presence of beta blockade. Milrinone administration should be considered in patients with acute ischaemic LV dysfunction and preexisting beta blockade before using other inotropic drugs such as beta stimulants.

Adrenergic beta-Agonists↗
PubMed2006

Treatment with phosphodiesterase inhibitors type III and V: milrinone and sildenafil is an effective combination during thromboxane-induced acute pulmonary hypertension.

OBJECTIVES: To evaluate the effects of phosphodiesterase type III and V (PDEIII and PDEV) inhibition on pulmonary and systemic haemodynamics in a porcine model of acute pulmonary hypertension. METHODS: Twenty-four adult swine were anaesthetized with 1 MAC isoflurane and mechanically ventilated with an FI(O(2)) of 100%. Micromanometer-tipped catheters were placed in the ascending aorta, pulmonary artery and right ventricle. Pulmonary flow was measured with a perivascular probe using transit time ultrasound. Pulmonary hypertension was induced with a continuous infusion of the thromboxane analogue, U46619. The animals were then randomized to four groups: Group 1 (n=6) received 50 mg of sildenafil (PDEV inhibitor) diluted in water via an orogastric tube; Group 2 (n=6) received 50 microg kg(-1) of i.v. milrinone (PDEIII inhibitor); Group 3 (n=6) received sildenafil followed by milrinone; and Group 4 (n=6) received placebo via an orogastric tube. RESULTS: Pulmonary hypertension was achieved in all animals. Calculated pulmonary vascular resistance decreased by an average of 36% after sildenafil (P<0.05), 41% after milrinone (P<0.05), and 61% with both drugs combined (P<0.05). Systemic vascular resistance decreased by 37% (P<0.05) with milrinone alone, and 36% (P<0.05) with milrinone and sildenafil combined but it was preserved in the sildenafil group. Cardiac output and right ventricular dP/dT were significantly improved after milrinone or both drugs combined, but not with sildenafil. CONCLUSION: Milrinone and sildenafil are effective pulmonary vasodilators, with independent action and additive effect. Both drugs combined achieved a better haemodynamic profile, with greater pulmonary vasodilatation and increased contractility but without additional systemic vasodilatation. The systemic haemodynamic profile (systemic vasodilation, cardiac output, right ventricular dP/dT) is improved with milrinone but not with sildenafil.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2005

Preservation of static and dynamic cerebral autoregulation after mild hypothermic cardiopulmonary bypass.

BACKGROUND: Dysfunction of cerebral autoregulation might contribute to neurological morbidity after cardiac surgery. In this study, our aim was to assess the preservation of cerebral autoregulation after cardiac surgery involving cardiopulmonary bypass (CPB). METHODS: Dynamic and static components of cerebral autoregulation were evaluated in 12 patients undergoing coronary artery bypass graft surgery, anaesthetized with midazolam, fentanyl, and propofol, and using mild hypothermic CPB (31-33 degrees C). Arterial pressure (ABP), central venous pressure (CVP), and blood flow velocity in the middle cerebral artery (CBFV) were recorded. The cerebral perfusion pressure (CPP) was calculated as a difference between mean ABP and CVP. Rapid decrease of CPP was caused by a sudden change of patients' position from Trendelenburg to reverse Trendelenburg. Cerebral vascular resistance (CVR) was calculated by dividing CPP by CBFV. Index of static cerebral autoregulation (CAstat) was calculated as the change of CVR related to change of CPP during the manoeuvre. Dynamic rate of autoregulation (RoRdyn) was determined as the change in CVR per second during the first 4 s immediately after a decrease in CPP, related to the change of CPP. Measurements were obtained after induction of anaesthesia, and 15, 30, and 45 min after termination of CPB. RESULTS: No significant changes were found in CAstat or RoRdyn after CPB. Significant changes in CVR could be explained by concomitant changes in body temperature and haematocrit. CONCLUSION: Autoregulation of cerebral blood flow remains preserved after mild hypothermic CPB.

Aged↗
PubMed2004

Preliminary European results of local microwave hyperthermia and chemotherapy treatment in intermediate or high risk superficial transitional cell carcinoma of the bladder.

INTRODUCTION: Superficial bladder cancer can be treated by transurethral resection (TUR) and adjuvant intravesical therapy. Intravesical bacillus Calmette-Guérin (BCG) has been proven to be more efficacious with respect to recurrence prevention than intravesical chemotherapy, although at the cost of more severe side effects. There is a need for a new treatment modality with higher efficacy and less toxicity. The subject of this study is the efficacy of local microwave hyperthermia and chemotherapy treatment in intermediate or high risk superficial transitional cell carcinoma (TCC) of the bladder. PATIENTS AND METHODS: Ninety eligible patients received adjuvant treatment with a combination of mitomycin-C (MMC) and local microwave hyperthermia. All patients had multiple or recurrent Ta or T1 TCC of the bladder and were classified as intermediate or high risk according to EAU criteria. In total, 41 patients were BCG failures. The treatment regimen included 6 to 8 weekly sessions followed by 4 to 6 monthly sessions. Follow-up consisted of video-cystoscopy and urine cytology every 3 months. All patients were observed for 2 years. RESULTS: Kaplan-Meier analyses of the total group (N = 90) indicated that 1 year after treatment only 14.3% (SE 4.5%) of all patients experienced a recurrence. After 2 years of follow-up the risk of recurrence was 24.6% (SE 5.9%). No progression in stage and grade was observed. CONCLUSION: Microwave induced hyperthermia combined with MMC has promising value in intermediate or high risk superficial bladder cancer patients compared to literature data of BCG and/or intravesical chemotherapy, particularly where other treatments, i.e. BCG, have failed.

Adult↗
PubMed2004

Combined local bladder hyperthermia and intravesical chemotherapy for the treatment of high-grade superficial bladder cancer.

OBJECTIVES: To evaluate the effectiveness of combined local bladder hyperthermia and intravesical chemotherapy for the treatment of patients with high-grade (G3) superficial bladder cancer. METHODS: Patients with G3 bladder tumors (Stage Ta or T1) were treated with combined intravesical chemotherapy with mitomycin-C and local radiofrequency hyperthermia of the bladder wall. The patients were treated with either a prophylactic protocol (40 mg mitomycin-C) after complete transurethral resection of all tumors or with an ablative protocol (80 mg mitomycin-C) when visible tumor was seen on video-cystoscopy or bladder biopsies were positive for carcinoma in situ. RESULTS: Combined chemo-thermotherapy was administered to 52 patients with high-grade superficial bladder cancer (40 patients with Stage T1 tumor, 11 with Ta, and 3 with concomitant or isolated carcinoma in situ). At a median follow-up of 15.2 months (mean 23, range 6 to 90), no stage progression to T2 or disease-related mortality had occurred. The bladder preservation rate was 86.5%. The prophylactic protocol was administered to 24 patients. After a mean follow-up of 35.3 months, 15 patients (62.5%) were recurrence free. The bladder preservation rate was 95.8%. The ablative protocol was administered to 28 patients. Complete ablation of the tumor was accomplished in 21 patients (75%). After a mean follow-up of 20 months, 80.9% of these patients were recurrence free. The bladder preservation rate for the ablative group was 78.6%. CONCLUSIONS: Combined local bladder hyperthermia and intravesical chemotherapy has a beneficial prophylactic effect in patients with G3 superficial bladder cancer. Ablation of high-grade bladder tumors is feasible, achieving a complete response in about three quarters of the patients.

Administration, Intravesical↗
PubMed2001

Propofol/remifentanil versus propofol alone for bone marrow aspiration in paediatric haemato-oncological patients.

BACKGROUND: This prospective randomized study was designed to evaluate the effects of adding remifentanil to the standard propofol-based technique in the setting of paediatric haematology-oncology outpatient clinic. METHODS: Eighty ASA III paediatric patients treated in the outpatient haematology-oncology clinic requiring bone marrow aspiration were randomly assigned either to the propofol (P) or the propofol/remifentanil (PR) group. The quality of anaesthesia and recovery were evaluated. RESULTS: The total amount of propofol required to prevent patient movement was lower in the PR group. The time interval to eye opening and to home readiness was significantly lower in the PR group. Adverse respiratory events (RR < 10.min-1 or SpO2 < 90%) occurred significantly more in the propofol/remifentanil group. CONCLUSIONS: The addition of remifentanil improved the conditions during the procedure and reduced the total amount of propofol, as well as the time to home readiness. However, the addition of remifentanil is associated with an increased risk of respiratory depression.

Adolescent↗
PubMed2000

The American Society of Anesthesiologists' Physical Status: category V revisited.

STUDY OBJECTIVE: To determine the perioperative mortality and intraoperative morbidity according to operative procedure and postoperative period for American Society of Anesthesiologists' Physical Status (ASA-PS) V category patients. DESIGN: Retrospective chart review. SETTING: University-affiliated medical center. MEASUREMENTS AND MAIN RESULTS: The perioperative records of 111,051 consecutive anesthetized patients, from 1990 to 1997 were retrospectively reviewed. Data were collected and analyzed to determine ASA-PS classification, perioperative mortality, intraoperative morbidity, mortality according to operative procedure, and mortality postoperatively for ASA-PS V patients. At the University of Florida, 0.37% of our patients were ASA-PS V. Most had anesthesia for abdominal (26.2%), cardiothoracic (27.9%), cranial (12.3%), or diagnostic procedures (11.6%). The overall mortality rate decreased in 1993-1995 and 1995-1997, compared to 1990-1993, from 64.16 +/- 4.53 (+/-SD) to 46.7 +/- 9.5 and 56.8 +/- 1.1, respectively. The mortality rate decreased in the immediate postoperative period from 15.7 +/- 5.1 to 4.6 +/- 1.5 and 4.1 +/- 2. 8 intraoperatively, and from 42.5 +/- 1.8% to 22.1 +/- 5.1 and 26.8 +/- 1.8 within 24 hours postoperatively. The mortality rate increased from 0 +/- 0 to 7.4 +/- 3.9 and 15.5 +/- 4.9 (p < 0.05 for all), during the late postoperative period (>2 weeks, during hospitalization). Intraoperative morbidity (untoward events) was significantly higher for ASA-PS V patients than for ASA-PS IV patients only in emergency cases (11.1 +/- 4.8% vs. 5.5 +/- 1.4%). CONCLUSIONS: The ASA-PS V classification is determined subjectively rather than objectively, and can be variable within its parameters, depending on the individual interpretation of ASA classification, patient population, case severity, surgical and anesthesia factors, and the year of the study. Even though immediate perioperative mortality decreased in our patient population, late postoperative mortality increased during the same time period, possibly demonstrating a shift in mortality time rather than an absolute decrease in overall mortality. Although the ASA-PS V category was never intended to be a predictor of outcome, it correlates with perioperative mortality as well as or even better than other classifications of mortality and morbidity. The decreased mortality in the ASA-PS V patient population may be related to different factors, which are beyond the scope of this study.

Anesthesia↗
PubMed2000

[First experiences in non-enhanced spiral computed tomography for diagnosis of acute flank pain].

Acute flank pain is commonly encountered in the emergency department, and often requires imaging to establish its cause. For decades intravenous urography and sonography have been the primary media for evaluating flank pain. Recently, noncontrast spiral CT (NCSCT) has been shown to be accurate and highly successful in diagnosing cause in such cases. We evaluated its use in the diagnosis of acute flank pain. During a 7-month period, 147 such cases had NCSCT imaging immediately after initial evaluation in the emergency department. Using a spiral CT scan without oral or i.v. contrast media, 109 of 147 cases were found to have ureteral stones, and 34 others to have other urological conditions unrelated to the cause of pain; 38 CT scans were negative for ureterolithiasis and in 14 non-urological disease was diagnosed. NCSCT is a valuable diagnostic technique for patients in the emergency department with flank pain. It rapidly and accurately detects ureteral stones causing renal colic and also detects extra-urinary causes of acute flank pain.

Abdominal Pain↗
PubMed1999

Transcranial Doppler monitoring compared with invasive monitoring of intracranial pressure during acute intracranial hypertension.

OBJECTIVE: To determine whether a simple transcanial Doppler waveform variable-pulsatility difference (systolic - diastolic blood flow velocity) can serve as a measure of critical changes in cerebral perfusion. METHODS: Thirteen pigs were anesthetized (anesthesia maintained with halothane) and ventilated to maintain normoxia and normocarbia. To measure mean arterial pressure, hemoglobin, and blood gases, the right carotid artery was cannulated. The right intracranial lateral ventricle was cannulated to measure and increase intracranial pressure; the right internal jugular vein was cannulated in 8 of 13 pigs to measure jugular venous oxygen saturation and to calculate cerebral arteriovenous oxygen content difference. Intracranial pressure was also monitored continuously with a subdural bolt in the contralateral frontal region, and blood flow velocity in the middle cerebral artery was measured with a transcranial Doppler probe on the right orbital region. Intracranial pressure was increased in increments of 10 to 20 mmHg by infusing saline through the ventriculostomy catheter until the transcranial Doppler indicated that blood flow velocity had ceased, at which point all variables were allowed to return to baseline. If mean arterial pressure failed to return to baseline, epinephrine, 0.01 to 0.1 microg/kg/min, was infused. Useful data were obtained from 8 pigs and were analyzed separately for pigs that received epinephrine (n = 4) and those that did not (n = 4). RESULTS: Transcranial Doppler measurements correlated more closely with cerebral perfusion pressure = (mean arterial pressure - intracranial pressure) than with intracranial pressure. In the range of 30 to 60 mmHg, cerebral perfusion pressure correlated linearly with the pulsatility difference. The closest nonlinear correlation (third order polynomial relationship) was noted between cerebral perfusion pressure and pulsatility difference (r = 0.8, P < 0.001, n = 217), for the animals that did not receive epinephrine. When a cerebral perfusion pressure < 60 mmHg and a cerebral arteriovenous oxygen content difference > 6.5 vol% were used to define limits of abnormal, pulsatility difference was a sensitive and specific indicator of abnormality in either variable. Pulsatility difference of > 70 cm/sec had > 77.1% and 86.7% positive accuracy rate, and < 0% and 14.3% negative accuracy rate for abnormal cerebral perfusion pressure (CPP) and cerebral arterio-venous O2 (C[a-v]O2), respectively. CONCLUSIONS: In pigs with induced diffuse intracranial hypertension, noninvasive transcranial Doppler waveform monitoring of pulsatility difference can identify increased cerebral oxygen extraction and dangerously decreased cerebral perfusion pressure.

Acute Disease↗
PubMed1998

Minimally invasive surgical treatment of female stress urinary incontinence.

The purpose of this study was to evaluate the safety and efficacy of a new minimally invasive surgical procedure for the treatment of female stress urinary incontinence (SUI). Four miniature bone anchors, each attached to a suture, are inserted transvaginally into the retropubic bone using an inserter on each side of the urethra without opening the vaginal mucosa. Tying the suture on each ipsilateral side creates colposuspension, as is the aim of previously described procedures such as the Marshall-Marchetti-Krantz. Sixty-one women (mean age 52+/-SD 9.9 years) with a mean follow-up of more than 12 months (range 12-30 months) were treated for SUI. Fifty patients (82%) are dry, 7 (14%) reported great improvement and 4 are considered surgical failures. The data presented suggest that our new minimally invasive procedure provides an effective treatment for female SUI. Its main advantages over other procedures are the transvaginal approach and short operating time.

Female↗
PubMed1998

Aortic stenosis with end-stage liver disease: prioritizing surgical and anesthetic therapies.

A 48-year-old man with end-stage liver disease and aortic stenosis (AS), was being evaluated for liver transplantation. This report focuses on the question of which medical problem to correct first, the end-stage liver disease or the AS. Risk factors for surgical correction of AS and liver transplantation are reviewed and discussed, and the surgical and anesthetic management strategies for this patient are outlined.

Anesthesia, General↗
PubMed1997

False low pulse oximetry reading associated with the concomitant use of a peripheral nerve stimulator and an evoked-potential stimulator.

One of the sources of error in pulse oximetry readings is associated with an abnormal signal-to-noise ratio. The pulse oximeter distinguishes the light absorbance of arterial blood from that of other absorbers by differentiating between a constant component and a pulsating component. The pulsating component is almost exclusively the result of arteriolar bed pulsations. Because pulse oximetry is based on the assumption that arterial blood is the only pulsatile absorber, any other fluctuating phenomenon could constitute a source of error. We report a case in which a low pulse oximetry reading was associated with concomitant use of a pulse oximeter and a peripheral nerve stimulator on the same arm. Further tests conducted using a nerve stimulator and a sensory evoked potential stimulator with different amplitudes and frequencies confirmed the association and delineated the relationship between frequency and amplitude of stimulation and the degree of artificial desaturation. A theoretical explanation for this phenomenon is presented.

Electric Stimulation↗
PubMed1996

An alternative to radioactive microspheres for measuring regional myocardial blood flow, Part 1: Colored microspheres.

OBJECTIVE: To compare measurements of regional myocardial blood flow between color and radioactive microspheres. DESIGN: Prospective, randomized, controlled. SETTING: University research laboratory. PARTICIPANTS: Pigs. INTERVENTIONS: Pigs underwent constriction of the left anterior descending artery, either incremental and then 0 constriction with epinephrine, 0.5 to 3 mu/kg/min (n = 5; "variable") or only 0% and 100% constriction without epinephrine (n = 4, "single"). Radioactive and color microspheres were injected simultaneously. For variable constriction, 5 colors (3 x 10(6)/mL) were tested in random order and, for single, red and yellow (6 x 10(6)/2 mL). MEASUREMENTS AND MAIN RESULTS: Measurements of regional endocardial, epicardial, and transmural myocardial blood flow were compared by regression analysis (linear and nonlinear). With radioactive measurements as the point of reference, when regional flow was 50 to 150 mL/min/100 g, correlation was high (r = 0.85), although regression slope was low. With endocardial and epicardial flow between 30 and 100 mL/min/100 g, correlation was close (r = 0.84). Overall nonlinear correlation was higher with single than variable constriction (r = 0.72). When regional flow was less than 100 mL/min/100 g, linear correlation was r = 0.72. When transmural flow measured by color microspheres was less than 25 mL/min/100 g, correlation was high (r = 0.86) but, with endocardial or epicardial flow, low (r = 0.67). When transmural flow was greater than 100 mL/min/100 g, correlation was extremely low (r = 0.1; n = 26 data points). The overall correlations for regional endocardial and epicardial flows were also low, except in the ischemic zone. CONCLUSIONS: Color and radioactive measurements correlate well during moderate and ischemic regional myocardial blood flow, ischemic blood flow requiring a higher concentration of color microspheres. A major limitation of using color microspheres is imprecision when flow is greater than 150 mL/min 100 g.

Animals↗
PubMed1996

An alternative to radioactive microsphere for measuring regional myocardial blood flow, Part 2: Laser-Doppler perfusion monitor.

OBJECTIVE: To compare measurements of regional myocardial blood flow volume between microsphere measurement of regional flow (0.5- to 2- g tissue sampling) and a potential alternative measure, local flow (1 mm3) in the microcirculation measured by laser-Doppler perfusion monitor. DESIGN: Prospective, randomized, controlled. SETTING: University research laboratory. PARTICIPANTS: Pigs. INTERVENTIONS: After anesthetization, in 5 pigs (25 to 30 kg), the left anterior descending coronary artery was isolated and its resting flow measured by a perivascular-Doppler flowmeter. Left ventricular pressure and first time derivative of left ventricular pressure were measured. The laser-Doppler probe needle (type N) (Model ALF-21, Transonic Systems, Inc, Ithaca, NY) was inserted 2 to 3 mm into the wall of the left ventricle, parallel to the coronary artery. All 5 pigs were subjected to 0 (control), 50% , 75%, and 100% constriction of the left anterior coronary artery. MEASUREMENTS AND MAIN RESULTS: Measurements by radio-active microspheres correlated poorly with those by laser-Doppler and extremely poorly with those by perivascular Doppler flowmeter. For percent change from baseline in the constricted arterial zone, radioactive measurements correlated well with those by laser-Doppler but not those by Doppler flowmeter. Also, radioactive measurements of percent change in flow in the circumflex (nonconstricted) zone and laser-Doppler measurements in the constricted arterial zone did not correlate well. CONCLUSIONS: Laser-Doppler can be recommended for experimental research to monitor local flow. These measurements may relate to change in regional flow during normal perfusion and hypoperfusion. Before the laser-Doppler perfusion monitor can be used clinically, tissue trauma from the 0.55-mm needle needs to be evaluated.

Animals↗
PubMed1995

Left-sided stellate ganglion ablation or "rate-controlled" vagal nerve stimulation decreases regional myocardial metabolic impairment during acute ischemia in dogs.

This study was designed to see whether during ischemia a metabolic advantage results with left-sided ablation of the stellate ganglion (SGA), an available clinical technique. Its effects on hemodynamics and regional metabolism during myocardial ischemia were compared with those of electrical stimulation of the left vagus nerve (VS), a nonclinical technique, and those of a control condition (ischemia without intervention). The left anterior descending coronary artery (LADa) of 30 dogs was constricted to reduce blood flow by 50% and then 75% from that before constriction and after autonomic intervention (baseline). Electrocardiogram, left-ventricular (LV) first-time derivative (dP/dt), and systemic, LADa, and LV end-diastolic pressures were continuously recorded. Before and during each constriction, cardiac output and regional myocardial blood flow (by microspheres), blood gas tensions, pH, hemoglobin O2 saturation, lactate, glucose, sodium, and potassium concentrations were measured. During ischemia, SGA and VS each decreased heart rate, myocardial contractility (dP/dt), and filling pressures, the decrease in each variable being greater with VS. Also during ischemia, myocardial O2 delivery and consumption decreased to the same extent in the ischemic zone with VS, but the O2 delivery/consumption ratio was higher only with SGA. In addition, ischemic lactate production was lower with SGA and VS than with no autonomic intervention. It is concluded that left-sided SGA or VS to a heart rate of 80 to 90 beats per minute similarly mitigated metabolic impairment during myocardial ischemia. Although the study was only designed to compare modification of ischemia by two different techniques, the results suggest that ischemic zone O2 delivery/consumption ratio and hemodynamic stability were better with SGA.

Animals↗
PubMed1994

Midazolam's effects on myocardial load and coronary perfusion: reduced regional O2 consumption and lactate production during ischemia in dogs.

It is hypothesized that because of its potential to increase coronary flow and simultaneously decrease myocardial performance and O2 consumption, midazolam would minimize regional metabolic impairment during myocardial ischemia. Therefore, the hemodynamic and regional metabolic effects of systemic midazolam administration were compared during moderate and severe constrictions of the left anterior descending artery (LADa) to nontreated but ischemic animals in a canine model of acute coronary occlusion. In 16 anesthetized, ventilated, surgically prepared, and catheterized dogs, resting flow in the LADa was decreased by 50% and 75% for 15 minutes with 1 hour of normal flow in between. By arbitrary assignment, 7 dogs received midazolam (0.3 mg/kg and then 0.05 mg/kg/min) before thoracotomy. In all dogs, heart rate, electrocardiogram, LADa flow, left ventricular (LV) first time-derivative, and aortic, pulmonary artery, LADa, and LV pressures were measured continuously. Before and during constrictions, cardiac output by thermodilution and regional myocardial blood flow by microspheres were measured and blood was sampled for analysis. Data (mean +/- SEM) were compared within and between groups using ANOVA. Before placement of the LADa ligature, midazolam decreased heart rate and mean aortic pressure. Before ischemia, heart rate and LADa pressure were lower with midazolam than without it, but baseline metabolic variables were similar between the two groups (except for O2 consumption in the ischemic zone, which was lower with midazolam than without it). During 75% constriction with midazolam, LV end-diastolic pressure, coronary resistance, and ischemic zone O2 consumption were lower than without midazolam. Ischemic zone O2 delivery/consumption ratio was higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗