Biomedical subjects
Publications and source records attributed to M J Matjasko.
This article focuses on recent developments in anesthesiology, including the expanded perioperative role of the anesthesiologist and the value these services add to an integrated delivery system by improving efficiencies and providing significant cost savings. Research activities are concerned with specific receptor mechanisms of drug action, as well as mechanisms of cell injury and post ischemia death.
Anesthetic care for patients with traumatic brain injury involves an integration of cerebral resuscitation, resuscitation of other vital organs, the provision of "anesthesia," and the prevention of harmful physiologic responses to surgery. Adverse responses to surgery such as hypertension, tachycardia, coughing, and straining can increase intracranial pressure (ICP). Airway manipulations can aggravate spinal cord injury as well as increase ICP. Anesthetic agents can exacerbate hemodynamic instability, increase cerebral blood volume and ICP, and produce respiratory depression. Cerebral resuscitation during surgery resembles that in the preoperative and postoperative periods. ICP measurement and jugular venous saturation monitoring may help define end-points for cerebral resuscitation. Various anesthetic techniques and agents have distinct advantages and disadvantages. The choice of agents and techniques is determined by the nature and severity of the patient's injuries and by pre-existing medical problems. The investigation of drugs that might protect against cerebral ischemia has included anesthetic agents but none appear to be uniformly effective. Intraoperative hypothermia is also being investigated as a cerebral protectant.
BACKGROUND: With rapid technological advances in anesthesiology, we are acquiring an ever increasing number of auditory alarm systems in the operating room the value of which depend on the hearing acuity of the anesthesiologist monitoring the patient. Presbycusis, the effect of aging on the auditory system, characteristically results in a bilaterally symmetric neurosensory high-frequency hearing loss ( > 2,000 Hz). In this study we attempt to assess the impact of this common hearing disorder on alarm detection. METHODS: We measured air conduction hearing acuities of 188 anesthesiologists who volunteered to participate. Subjects were divided into six age groups (25-34, 35-44, 45-54, 55-64, and > 75 yr of age). Abnormal audiograms were compared to the intensity and frequency of alarms in our operating room to determine which alarms were out of hearing range. Subjects with a history of chronic or excessive noise exposure were excluded from the study. The median hearing threshold for each age group of study subjects was compared to the median hearing threshold of similar age groups in the general population. RESULTS: Overall, 66% of the subjects had an abnormal audiogram, and 7% had one or more alarm intensities less than their detectability threshold (14% unilateral, 86% bilateral). Median hearing threshold was worse than the general population for men and women less than 55 yr of age. Hearing acuity worse than the general population occurred at the lower frequencies while acuity at the higher frequencies was equal or slightly better. However, inability to hear alarms occurred only with those alarms that have frequencies of 4,000 Hz or greater. CONCLUSIONS: Although high-frequency hearing acuity of individuals in our study was better than that of the general population, hearing deficits at high frequencies were of the magnitude to interfere with alarm detection. Also background noise levels vary greatly in different operating rooms. These two problems create a hindrance to alarm detection for certain anesthesiologists. From our data we conclude that the aging human ear may not be capable of accurately detecting some auditory alarms in the operating room. Alarm design should consider hearing acuity because high-frequency alarms may go undetected.
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Microcomputer generation of an automated record without complexity or operator intervention is desirable in many circumstances. We developed a microcomputer system specifically designed for simplified automated collection of cardiorespiratory data in research and clinical environments. We tested the system during possible extreme clinical conditions by comparison with a patient simulator. Ranges used were heart rate of 35-182 beats per minute, systemic blood pressures of 65-147 mmHg and venous blood pressures of 14-37 mmHg, all with superimposed respiratory variation of 0-24 mmHg. We also tested multiple electrocardiographic dysrhythmias. The results showed that there were no clinically relevant differences in vascular pressures, heart rate, and other variables between computer processed and simulator values. Manually and computer recorded physiological variables were compared to simulator values and the results show that computer values were more accurate. The system was used routinely in 21 animal research experiments over a 4 month period employing a total of 270 collection periods. The file system integrity was tested and found to be satisfactory, even during power failures. Unlike other data collection systems this one (1) requires little or no operator intervention and training, (2) has been rigorously tested for accuracy using a wide variety of extreme patient conditions, (3) has had computer derived values measured against a standardized reference, (4) is reliable against external sources of computer failure, and (5) has screen and printout presentations with quick and easily understandable formats.
A double-blinded randomized prospective study was performed to determine whether alkalinization of lidocaine decreases the pain of intradermal injection and if a larger intravenous catheter (16 gauge) causes more discomfort on insertion than a smaller (20 gauge) catheter when intradermal anesthesia has been used. In a random manner, 100 patients received skin wheals with commercially prepared lidocaine or lidocaine with the addition of sodium bicarbonate before the insertion of a 16- or 20-gauge intravenous catheter. Visual analogue pain scores were obtained after the skin wheal was placed and after the intravenous catheter was inserted. There was no statistically significant difference in pain scores between the two local anesthetic solutions. However, the catheter insertions pain scores were slightly, but statistically significantly larger in the 16-gauge group regardless of local anesthetic solution used. The addition of sodium bicarbonate to commercially prepared lidocaine does not decrease the pain associated with an intradermal skin wheal. There is a slight increase in patient discomfort upon insertion of a large-bore intravenous catheter, even with the prior use of local anesthetic.
The most sensitive method of venous air embolism (VAE) detection in clinical use is the precordial Doppler detector. Because the Doppler detector may provide false-positive and false-negative data, many clinicians rely on end-tidal gas measurements for verification of VAE in the operating room. End-tidal nitrogen (ETN2) increases soon after experimental VAE are small enough to cause minimal changes in blood pressure; however, decreases in end-tidal CO2 (ETCO2) are more sensitive. A large VAE causes hemodynamic instability, and the effect of low cardiac output on ETN2 has not been evaluated. This study was done to compare the changes in ETN2 and ETCO2 during large bolus and infusion VAE. Five mongrel dogs were anesthetized, intubated, and ventilated (FIO2 1.0, PaCO2 38 +/- 4 (SD) mm Hg). The animals were studied in the supine position; anesthesia and paralysis were maintained with a constant infusion of thiamylal and pancuronium. Maintenance fluids were administered at 5 ml kg-1 h-1. Mean arterial and pulmonary arterial pressures (PAP) and ETN2 and ETCO2 were displayed on a strip chart recorder. The dogs underwent both bolus and infusion VAE in separate experiments 10 to 14 days apart. The air emboli were given in random order by automated syringe over 1 minute (infusion) (1 to 2.5 ml kg-1 min-1) or by hand injection over 5 seconds (bolus) (1 to 2.5 ml kg-1). Changes in precordial Doppler sounds occurred in all animals at all doses. The peak increase in PAP and decrease in ETCO2 were significant after all air doses. ETN2 changes were biphasic. The peak increase was significant after all air doses; the peak decrease was significant in 37 of 40 bolus and infusion VAE episodes, occurred within 1 to 3 minutes, and lasted 20 to 30 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)
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The authors describe their use of a Doppler flow detector in the treatment of carotid-cavernous fistulas to monitor the ocular bruit, the clinical sign usually used to detect obliteration of the fistula. In seven procedures the Doppler ultrasonic flow detector has yielded satisfactory proof that the flow sounds were no longer audible, and that the surgery was successful.
The right heart and great veins can be the harbinger of septic and aseptic thromboemboli, which can result in a spectrum of clinical syndromes. This report presents five distinct clinical scenarios of thromboembolization, the occurrence of which in the central circulation resulted in life-threatening sepsis and hemodynamic and pulmonary insufficiency. Recommendations for therapeutic intervention and a review of the literature also are presented.
STUDY OBJECTIVE: To determine whether the levels of serum myoglobin and the occurrence of fasciculations and postoperative symptoms following a single dose of succinylcholine are modified by the prior administration of midazolam. DESIGN: Randomized, double-blind, placebo-controlled study. SETTING: Outpatient surgical service of a university hospital. PATIENTS: 69 ASA physical status I and II healthy, adult female outpatients undergoing laparoscopy (for diagnosis or tubal ligation) with general anesthesia that included succinylcholine. INTERVENTIONS: Patients received pretreatment of either a saline placebo (Group 1, n = 31) or intravenous midazolam 0.03 mg/kg (Group 2, n = 38) 5 minutes before succinylcholine. MEASUREMENTS AND MAIN RESULTS: Serum myoglobin prior to pretreatment and at 5 (t5) and 30 (t30) minutes after succinylcholine was determined by radioimmunoassay. Pain was assessed by telephone interview 24 to 36 hours postoperatively. Baseline myoglobin levels ranged from 14 to 69 ng/ml; the 5- and 30-minute samples varied widely (range, 16 to 900 ng/ml). The rise was 3 or more SDs above the baseline mean in 23% and 42% of Group 1 at t5 and t30, respectively, and in 21% and 35% of Group 2 at t5 and t30, respectively. The differences between groups were not significant. The frequency of fasciculations (77% in Group 1, 87% in Group 2), postoperative sore throat (64% in Group 1, 57% in Group 2), and myalgias (44% in Group 1, 51% in Group 2) also was not significantly different between groups. CONCLUSIONS: Midazolam had no effect on myoglobin level or postoperative symptoms following succinylcholine.
STUDY OBJECTIVE: To present our preliminary experience using three doses of an equimilligram mixture of 1% tetracaine and 0.75% bupivacaine in 8.25% dextrose for spinal anesthesia in patients undergoing peripheral vascular surgery. SETTING: Operating and recovery rooms at a university medical center. PATIENTS: 60 patients who received femoral popliteal or femoral distal bypass with spinal anesthesia. INTERVENTIONS: All patients had intravenous cannulae inserted and received lactated Ringer's solution. There were no bolus infusions of fluid preanesthesia. Fluid administration occurred at a rate of 8 to 15 ml/kg/hr, with additional fluid and inotropic drugs administered to treat hypotension. Oxygen (O2) was delivered by nasal cannula, and peripheral O2 saturation was monitored. Blood pressure (BP) was monitored every 1 to 5 minutes using an automatic BP device, and ECG was displayed continually. MEASUREMENTS AND MAIN RESULTS: Initially, 8 patients received a dose of 15 mg of each drug combined with 0.2 mg of epinephrine injected in a 20-degree head-up tilt. Because the duration of anesthesia was prolonged, subsequent patients received 12 mg of each drug mixed with 0.2 mg of epinephrine for cases in which an extended duration was predicted and 10 mg of each drug plus epinephrine for proximal first-time bypasses. With mixtures of 15 mg, 12 mg, and 10 mg of each drug plus epinephrine, a mean duration of approximately 300 minutes of surgically acceptable anesthesia was obtained. As the dose was decreased, the SD increased. There was a 0% failure rate for the spinal anesthetics at doses of 15 mg and 12 mg of each drug and a 19.5% failure rate at a dose of 10 mg of each drug. In each case, the rapid onset of a sensory blockade regressed in a standard and predictable fashion. The decline in BP and the use of inotropic and vasoconstrictive drugs were comparable to those in previously published reports of spinal anesthetics using single drug techniques with smaller doses. In none of the patients were there any untoward cerebrovascular or neurologic events, nor were there any clinically evident episodes of coronary insufficiency. CONCLUSION: Spinal anesthesia using bupivacaine and tetracaine mixed in a single-injection technique can last 5 hours at the T12 level without added untoward effects when compared with lower-dose spinal anesthetics.