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Biomedical subjects

A D Ivankovich

Publications and source records attributed to A D Ivankovich.

At least 19 recordsLinked to original sources
PubMed2000

The use of a ketamine-propofol combination during monitored anesthesia care.

UNLABELLED: Supplemental analgesics are commonly used to enhance analgesia and improve patient comfort during procedures performed under local anesthesia and sedation. Because the use of ketamine as an analgesic adjunct to propofol sedation has not been well established, we evaluated its impact on analgesia, sedation, and recovery after ambulatory surgery. One hundred female outpatients undergoing breast biopsy procedures under local anesthesia participated in this randomized, double-blinded, placebo-controlled study. After premedication with midazolam, 2 mg IV, patients received an infusion of a solution containing propofol (9.4 mg/mL) in combination with either placebo (saline) (Group 1) or ketamine, 0.94 mg/mL (Group 2), 1.88 mg/mL (Group 3), or 2.83 mg/mL (Group 4). The sedative infusion rate was varied to maintain a deep level of sedation (Observer Assessment of Alertness/Sedation score 4) and normal respiratory and hemodynamic functions. Sufentanil, 2.5 microg IV, "rescue" boluses were used as needed to treat patients' responses (if any) to local anesthetic infiltration or surgical stimulation. Ketamine produced a dose-dependent reduction in the "rescue" opioid requirements. However, there was an increase in postoperative nausea and vomiting, psychomimetic side effects, and delay in discharge times with the largest ketamine dosage (Group 4). The adjunctive use of ketamine during propofol sedation provides significant analgesia and minimizes the need for supplemental opioids. The combination of propofol (9.4 mg/mL)/ketamine (0.94-1.88 mg/mL) provides effective sedation/analgesia during monitored anesthesia care. IMPLICATIONS: Ketamine, when used in subhypnotic dosages, may be an useful adjuvant to propofol sedation.

Adult↗
PubMed2000

Magnesium sulfate potentiates morphine antinociception at the spinal level.

UNLABELLED: Intrathecal magnesium sulfate coinfusion with morphine increases antinociception in normal rats; however, because magnesium also delays the onset of tolerance, it is not clear whether this additional antinociception is a result of potentiated analgesia or tolerance abatement. We examined the antinociceptive interaction of intrathecal (IT) bolus magnesium sulfate and morphine in morphine naive rats and those with mechanical allodynia after a surgical incision. After intrathecal catheter implantation, rats were given preinjections of magnesium or saline, followed by injections of morphine or saline. In morphine naïve rats, IT bolus magnesium sulfate 281 and 375 microg followed by IT morphine 0.25 or 0.5 nmol enhanced peak antinociception and area under the response versus time curve two-to-three-fold in the tail-flick test as compared with morphine alone. Likewise, in rats with incisional pain, IT bolus magnesium sulfate 188 and 375 microg followed by morphine 0.5 nmol reduced mechanical allodynia, whereas morphine 0.5 nmol alone did not. This study suggests that IT magnesium sulfate potentiates morphine at a spinal site of action. IMPLICATIONS: Magnesium sulfate potentiates morphine analgesia when coadministered intrathecally in normal rats, and in an animal model of mechanical allodynia after a surgical incision. These results suggest that intrathecal administration of magnesium sulfate may be a useful adjunct to spinal morphine analgesia.

Analgesics, Opioid↗
PubMed2000

Comparison of epidural butamben to celiac plexus neurolytic block for the treatment of the pain of pancreatic cancer.

OBJECTIVE: To compare pain relief in metastatic pancreatic cancer patients between neurolytic celiac plexus block (NCPB) and epidural 5% butamben suspension (EBS), a material-based delivery system of a local anesthetic that produces a long-lasting differential nerve block. DESIGN: Open-label patient-selected parallel groups. SETTING: Urban tertiary care medical center. PATIENTS: Twenty-four adult patients with metastatic pancreatic cancer experiencing pain uncontrolled by systemic opioids who were referred to a multidisciplinary pain clinic for interventional therapy. INTERVENTIONS: Antecrural NCPB-block with ethanol and epidural 5% butamben suspension injections. MEASURES: Subjective global pain relief assessments on a 0-100% scale were made weekly for 4 weeks and then monthly. Change in opioid use postintervention. RESULTS: Eight patients had a single NCPB and three patients had two NCPB. Four of the former and two of the latter had successful pain relief defined to be a more than 75% reduction in pain when compared with pretreatment maintained for more than 4 weeks or until death (if less than 4 weeks). Thirteen patients received EBS in divided doses. Eleven patients received a cumulative EBS dose of 5 grams, one patient received a cumulative EBS dose of 2.5 grams, and one patient received a cumulative EBS dose of 8.75 grams. Nine of the eleven patients and each of the other two patients had successful pain relief. The overall incidence (85% EBS vs. 55% NCPB), the duration of successful pain relief, and the percent reduction in opioid use did not differ between the two groups. There were no serious complications. CONCLUSION: EBS appears to be a safe and effective alternative to NCPB in the treatment of pancreatic cancer pain.

Adult↗
PubMed2000

Long-term testing of an intracranial pressure monitoring device.

OBJECT: Long-term monitoring of intracranial pressure (ICP) is limited by the lack of an implantable sensor with low drift. The goal of this study was to demonstrate that a new capacitive transducer system will produce accurate and stable ICP records over extended periods. METHODS: Intracranial pressure sensors were implanted into the frontal white matter of four dogs. In addition, a fluid-filled catheter was placed in the cisterna magna (CM) to measure cerebrospinal fluid (CSF) pressure. The animals were tested using standard physiological maneuvers such as jugular vein compression, head elevation, and CSF withdrawal from and saline injection into the CM to verify that the ICP sensor precisely matched CSF pressure changes. The mean ICP pressure and CM pressure were compared for months to demonstrate that the transducer system produced minimal drift over time. The change in the ICP sensor record closely duplicated that of the CSF waveform in the CM in response to well-known physiological stimuli. More important, mean ICP pressure remained within 3 mm Hg of CM pressure for months, with a mean difference of less than 0.3 mm Hg. Histological examination of the dog brains revealed only minimal tissue reaction to the presence of the sensor. CONCLUSIONS: The authors demonstrate a new implantable solid-state sensor that reliably measures ICP for months, with minimal drift. The clinical application of this sensor and its telemetry is for long-term monitoring of patients with head injury, mass lesions, and hydrocephalus.

Animals↗
PubMed1999

Aprotinin pretreatment diminishes postischemic myocardial contractile dysfunction in dogs.

UNLABELLED: We evaluated the effect of aprotinin, administered before the onset of acute regional myocardial ischemia, on reversible contractile dysfunction induced by ischemia and reperfusion in pentobarbital-anesthetized dogs. Animals were randomized to receive either aprotinin 30,000 kallikrein inactivator units (KIU)/kg and 7000 KIU x kg(-1) x hr(-1) (n = 8) or equivalent volumes of 0.9% sodium chloride (n = 7) IV 60 min before a 15-min interruption of circumflex coronary artery blood flow and then reperfusion. There were no intra- or intergroup differences in hemodynamic variables or regional myocardial mechanics (sonomicrometry) before onset of ischemia. Immediately before reperfusion, systolic dysfunction characterized by significantly decreased percent systolic shortening was present in the circumflex coronary artery area of both study groups. After reestablishment of perfusion, aprotinin animals had preserved percent systolic shortening whereas saline animals exhibited regional systolic dysfunction. Regional myocardial contractility as assessed by the slope Mw of the preload recruitable stroke work relation was preserved during reperfusion in animals who received aprotinin but depressed in the control group. We conclude that functional recovery from myocardial ischemia-reperfusion injury at normothermia is improved by IV administration of aprotinin before the onset of acute regional myocardial ischemia in physiologically intact dogs. IMPLICATIONS: Administration of clinically relevant doses of aprotinin IV before the onset of regional myocardial ischemia, in contrast to control conditions, preserved regional systolic function and contractility at baseline values after reestablishment of myocardial perfusion in dogs.

Animals↗
PubMed1998

Antinociceptive potentiation and attenuation of tolerance by intrathecal co-infusion of magnesium sulfate and morphine in rats.

UNLABELLED: N-methyl-D-aspartate (NMDA) antagonists, such as MK801, delay the development of morphine tolerance. Magnesium, a noncompetitive NMDA antagonist, reduces postoperative morphine requirements. The present study was designed to evaluate the effects of intrathecal co-administration of magnesium sulfate with morphine on antinociceptive potentiation, tolerance, and naloxone-induced withdrawal signs. Magnesium sulfate (40-60 microg/h) co-administration for 7 days, similar to MK801 (10 nmol/h), prevented the decline in antinociceptive response compared with morphine (20 nmol/h). Magnesium sulfate (60 microg/h) produced no antinociception, but co-infused with morphine (1 nmol/h), it resulted in potentiated antinociception compared with morphine throughout the 7-day period. Probe morphine doses after 7-day infusions demonstrated a significantly greater 50% effective dose value for morphine 1 nmol/h (109.7 nmol) compared with saline (10.9 nmol), magnesium sulfate 60 microg/h (10.9 nmol), and magnesium sulfate 60 microg/h plus morphine 1 nmol/h (11.2 nmol), which indicates that magnesium had delayed morphine tolerance. Morphine withdrawal signs after naloxone administration were not altered by the co-infusion of magnesium sulfate. Cerebrospinal fluid magnesium levels after intrathecal magnesium sulfate (60 microg/h) for 2 days increased from 17.0 +/- 1.0 microg/mL to 41.4 +/- 23.6 microg/mL, although serum levels were unchanged. This study demonstrates antinociceptive potentiation and delay in the development of morphine tolerance by the intrathecal coinfusion of magnesium sulfate and morphine in the rat. IMPLICATIONS: The addition of magnesium sulfate, an N-methyl-D-aspartate antagonist, to morphine in an intrathecal infusion provided better analgesia than morphine alone in normal rats. These results suggest that intrathecal administration of magnesium sulfate may be a useful adjunct to spinal morphine analgesia.

Analgesia↗
PubMed1998

Intrathecal bupivacaine reduces pruritus and prolongs duration of fentanyl analgesia during labor: a prospective, randomized controlled trial.

UNLABELLED: Pruritus is a frequent complication (40%-100%) of intrathecal (IT) fentanyl 25 microg (F) for labor analgesia. The addition of IT bupivacaine 2.5 mg (B) to F has been reported in a nonrandomized series to have a 17.3% incidence of pruritus. This study prospectively evaluated the incidence and distribution of pruritus in laboring parturients receiving IT F + B. Sixty-five laboring parturients were randomly assigned to receive IT F, B, or F + B as part of a combined spinal-epidural technique. Visual analog scores, sensory level, motor strength, and pruritus were recorded before injection and at intervals thereafter. When present, the distribution of pruritus was evaluated. The duration of analgesia was determined as the time from IT drug administration until the patient requested supplemental analgesia. The median duration of analgesia in the F, B, and F + B groups was 62.5, 55.0, and 94.5 min, respectively. Compared with F alone, the combination of F + B led to a decreased frequency of pruritus (36.4% vs 95%). The incidence of facial pruritus (25%) was same in the F + B and F groups; however, the occurrence of pruritus distributed over the rest of the body was significantly more frequent in the F compared with the F + B group. The combination of F + B prolongs the duration of labor analgesia compared with IT F or B alone. F + B also leads to a decreased incidence of pruritus, except in the facial region. IMPLICATIONS: When administered intrathecally with fentanyl 25 microg in laboring parturients, bupivacaine 2.5 mg attenuates the frequency of pruritus on all parts of the body except the face. This combination also results in a rapid onset and prolonged duration of labor analgesia compared with either drug alone.

Adult↗
PubMed1996

Intrathecal clonidine and tizanidine in conscious dogs: comparison of analgesic and hemodynamic effects.

Intrathecal delivery of alpha(2)-adrenergic agonists produces an analgesic effect. However, hemodynamic side effects limit their clinical usage. To more fully characterize the effects on heart rate and arterial blood pressure of alpha(2)-adrenergic agonists, clonidine and tizanidine were injected intrathecally in conscious dogs. Both compounds produced a potent inhibition of thermal foot-withdrawal latencies at 1000 micrograms, which was blocked by the alpha(2)-adrenergic antagonist yohimbine. Tizanidine (250-500 micrograms) did not change heart rate. Clonidine (500 -2000 micrograms) and tizanidine (1000-2000 micrograms) decreased heart rate. The tizanidine effect was inhibited by yohimbine and the alpha(2)/imidazoline antagonist idazoxan, as well as the parasympathetic blocker glycopyrrolate. No drug completely inhibited the clonidine-induced bradycardia. Clonidine had a biphasic effect on arterial blood pressure, a decrease at 500 micrograms and an increase at 2000 micrograms. Tizanidine decreased arterial blood pressure at all doses. The results indicate that, while the analgesic effects of both drugs are similar, the hemodynamic responses differ. While the decrease in heart rate with tizanidine is consistent with alpha(2)-adrenergic binding and vagal action, the bradycardia induced by clonidine is more complex. In addition, the increased arterial blood pressure with high doses of clonidine, which is suggestive of a peripheral vasoconstrictive effect, does not occur with tizanidine.

Adrenergic alpha-Agonists↗
PubMed1996

Preoperative airway assessment: predictive value of a multivariate risk index.

Using readily available and objective airway risk criteria, a multivariate model for stratifying risk of difficult endotracheal intubation was developed and its accuracy compared to currently applied clinical methods. We studied 10,507 consecutive patients who were prospectively assessed prior to general anesthesia with respect to mouth opening, thyromental distance, oropharyngeal (Mallampati) classification, neck movement, ability to prognath, body weight, and history of difficult tracheal intubation. After induction of anesthesia, the laryngeal view during rigid laryngoscopy was graded and the ability of experienced anesthesia personnel to ventilate via a mask was determined. Poor intubating conditions (laryngoscopy Grade IV) and inability to achieve adequate mask ventilation were identified in 107 (1%) and 8 (0.07%) cases, respectively. Logistic regression identified all seven criteria as independent predictors of difficulty with laryngoscopic visualization. A composite airway risk index (derived from nominalized odds ratios calculated from the multivariate model) as well a simplified (0 = low, 1 = medium, 2 = high) risk weighting exhibited higher positive predictive value for laryngoscopy Grade IV at scores with similar sensitivity to Mallampati class III, as well as higher sensitivity at scores with similar positive predictive value. Compared to Mallampati class I fewer false-negative predictions were observed at a risk index value of 0. We conclude that improved risk stratification for difficulty with visualization during rigid laryngoscopy (Grade IV) can be obtained by use of a simplified preoperative multivariate airway risk index, with better accuracy compared to oropharyngeal (Mallampati) classification at both low- and high-risk levels.

Adult↗
PubMed1996

Aspirin does not increase allogeneic blood transfusion in reoperative coronary artery surgery.

While preoperative aspirin (ASA) therapy does not increase allogeneic transfusion in elective primary coronary artery bypass grafting (CABG) operations, the impact of ASA consumption on transfusion in cardiac operations with greater risk of bleeding has not been investigated. We examined the influence of ASA consumption on mediastinal drainage and allogenic transfusion in 317 patients undergoing reoperative CABG surgery. Patients receiving ASA or ASA containing medications within 7 days preoperatively (n = 215) had similar perioperative characteristics but were older and had smaller red cell volumes than control patients not receiving ASA (n = 102). All patients received aminocaproic acid, but autotransfusion of mediastinal blood or platelet rich plasma, aprotinin, or desmopressin were not used. No significant differences were observed between ASA and control groups with respect to postoperative hematocrit, mediastinal drainage, frequency of reexploration for excessive bleeding, amount of allogeneic packed red blood cell, fresh frozen plasma, platelet concentrate or cryoprecipitate transfusion, or the fraction of patients receiving any allogeneic blood product. There was no difference in mediastinal drainage when stratified by timing of most recent ASA ingestion. Multiple linear regression identified duration of cardiopulmonary bypass (CPB), internal mammary artery harvesting, chronic preoperative steroid therapy and use of an intraaortic balloon pump (IABP) as significant predictors of mediastinal drainage. Logistic regression demonstrated that female gender, prolonged duration of CPB, advanced age, use of IABP, and a negative history of smoking were significant independent predictors of blood product transfusion. There was no significant interaction of preoperative heparin therapy with ASA on transfusion demonstrated by univariate or multivariate analyses. These results indicate that preoperative ASA ingestion is not an important determinant of mediastinal drainage or allogeneic transfusion, even after repeat CABG operations, and that surgical and patient characteristics are more important predictors of these outcomes.

Age Factors↗
PubMed1995

Effects of phenylephrine or volume loading on right ventricular function in patients undergoing myocardial revascularization.

The acute effects of phenylephrine (PHE) administration or intravascular volume loading on right ventricular (RV) function were examined in 34 patients undergoing elective coronary artery surgery. After anesthetic induction with sufentanil and midazolam, 20 patients received PHE to treat hypotension and increase systemic arterial pressure 20% above baseline values. PHE effectively restored arterial pressure without changing stroke index (SI), although RV ejection fraction (RVEF) declined (41.3% to 37.6%) with concomitant increases in RV end-diastolic volume index (RVEDVI) (86.3 to 97.5 mL/m2) and RV end-systolic volume index (51.8 to 63.4 mL/m2). In the first 6 to 8 hours after surgery, 18 patients received intravascular volume expansion with 5% albumin when the clinical perfusion state was inadequate and accompanied by pulmonary artery occlusion pressure (PAOP) less than 15 mmHg and a hemoglobin level greater than 8 g/dL. Volume loading with 500 mL of albumin increased SI(27.0 to 31.8mL/m2), PAOP (12.2 to 15.4 mmHg) and RVEDVI (69.0 to 86.5 mL/m2), although RVEF declined (39.3% to 37.6%). Baseline values of RVEF and SI (but not PAOP or right atrial pressure [RAP]) were lower in 9 of 18 patients who exhibited declines in RVEF after volume loading, and RAP was a poor indicator of RVEDVI (r = 0.17). RVEDVI (but not RAP or PAOP) had significant correlation with SI during volume loading. There was no relationship between the presence of hemodynamically significant right coronary artery stenoses requiring revascularization or other perioperative factors with the response to PHE before revascularization or to volume loading after revascularization.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Angiotensin-converting enzyme inhibitors increase vasoconstrictor requirements after cardiopulmonary bypass.

Preoperative use of angiotensin-converting enzyme (ACE) inhibitors is common and has been associated with hypotension at separation from cardiopulmonary bypass (CPB). This study prospectively examined the influence of chronic preoperative ACE inhibitor use and other perioperative factors on the incidence of vasoconstrictor therapy required to maintain systolic blood pressure at more than 85 mm Hg despite a normal cardiac output after CPB in 4301 adults undergoing elective coronary artery and/or valve surgery. Hypothermic, nonpulsatile CPB and either opioid or ketamine-benzodiazepine anesthesia were common features of the operations. At least two vasoconstrictor infusions (phenylephrine, norepinephrine, or dopamine) were required for low perfusion pressure despite adequate cardiac output after CPB in 7.7% of 519 ACE-inhibited patients and 4.0% of 3782 patients not receiving ACE inhibitors (P = 0.0001). In the first 4 h after arrival in the intensive care unit, the need for vasoconstrictor infusions to treat hypotension with adequate cardiac output did not differ, although more ACE-inhibited patients (6.4%) exhibited low values of systemic vascular resistance (< 600 dyne.s.cm-5) than patients not receiving ACE inhibitors (2.8%; P = 0.0002). Logistic regression analysis identified preoperative ACE inhibitor use, congestive heart failure, poor left ventricular function, duration of CPB, reoperative surgery, age, and opioid anesthesia as independent risk factors for requiring > or = 2 vasoconstrictor infusions after CPB. No other preoperative drug therapy significantly altered this outcome.

Aged↗
PubMed1994

Postthoracotomy pain management using continuous epidural analgesia in 1,324 patients.

Continuous epidural analgesia consisting of an opioid with or without a local anesthetic agent is a commonly employed technique for pain relief after thoracotomy. In this study, we prospectively evaluated the use of continuous epidural analgesia in 1,324 patients undergoing elective thoracotomy between 1987 and 1993. Epidural pain management was continued for 1 to 3 postoperative days. Patients experienced excellent pain relief, with mean visual analog pain scores of 2.4, 1.7, and 1.4 on postoperative days 1, 2, and 3, respectively. Side effects occurred most frequently in the first 24 hours postoperatively; the incidence of pruritus was 14.1%; nausea, 11.2%; hypotension, 4.3%; sedation, 3.3%; and numbness, 1.1%. Respiratory depression (< 8 breaths per minute) occurred in 1 patient who received 16 mg of supplemental morphine sulfate over a 2-hour period. The incidence of inadequate analgesia (a visual analog pain score of 7 or more persisting for 1 to 2 hours after an epidurally administered bolus) was 3.8%. The results from this study support the use of standard protocols for dosing guidelines, the treatment of inadequate analgesia, and the management of side effects. Daily evaluation by a team member of the postoperative analgesia services section of the Department of Anesthesiology enhances patient care and minimizes adverse effects.

Adult↗
PubMed1994

Evaluation of coagulation during cardiopulmonary bypass with a heparinase-modified thromboelastographic assay.

Thromboelastography (TEG) is a useful method of assessing perioperative coagulation function in patients undergoing cardiac surgery. The presence of significant amounts of heparin in blood samples, however, prevents determination of changes in coagulation function by TEG or introduces artifactual error if samples contain heparin that is not present in vivo. For these reasons, whole blood coagulation function monitoring with TEG has not been feasible during cardiopulmonary bypass (CPB) with heparin anticoagulation. In this study, data obtained from 42 volunteers are presented to describe the effects of heparinase on TEG variables in the presence and absence of heparin. These data indicate that heparinase does not affect TEG parameters of whole blood not containing heparin and reverses the TEG effects of low levels of heparin contamination. Subsequently, 51 patients undergoing coronary artery surgery were studied using a modified TEG assay that incorporates in vitro application of heparinase to allow measurement of TEG parameters before, during, and after CPB. Heparinase-modified TEG assays facilitated diagnosis of heparin contamination in preoperative blood samples and permitted baseline TEG evaluation in patients receiving preoperative heparin infusions. Heparinase-modified TEG assays revealed declines in alpha and MA values during CPB, which persisted and significantly correlated with values after protamine infusion (alpha: r = 0.77, P = 0.001; MA: r = 0.78, P = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Bioimpedance hemodynamics compared to pulmonary artery catheter monitoring during orthotopic liver transplantation.

Simultaneous cardiac output measurements were obtained using bioimpedance (BI) and thermodilution (TD) methods in 10 patients undergoing orthotopic liver transplantation (OLT). BI and TD data were collected during five intraoperative phases of OLT. Linear regression revealed significant correlation between BI and TD (r = 0.8, P = 0.001) with a slope of regression of 0.64. Bias analysis demonstrated a negative of BI (-0.26) when compared with TD.Sv-O2 correlated poorly with cardiac index determined by TD (r = 0.41) or BI (r = .47). BI is an accurate reproducible method for measuring cardiac output and may be a useful adjunct to the pulmonary artery catheter for hemodynamic monitoring during OLT.

Adult↗