Anesthesia and analgesia
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Anesthesia and analgesia · Sep 2000
Clinical TrialThe hemodynamic and metabolic effects of tourniquet application during knee surgery.
We evaluated the effects of tourniquet application on the cardiovascular system and metabolism in 10 young men undergoing knee surgery with general anesthesia. The duration of inflation was from 75 to 108 min. Heart rate, mean arterial pressure, cardiac index (CI) by pulse contour method, and systemic vascular resistance were measured before, during, and after tourniquet inflation. pH, PaO(2), PaCO(2), and lactate blood concentrations were also measured. VO(2) and VCO(2) were assessed every minute from tracheal intubation up to 15 min after tourniquet deflation and VO(2) in excess of the basal value over the 15 min after deflation (VO(2)exc) was calculated. Mean arterial pressure increased 26% (P: < 0.05) during inflation and returned to basal values after deflation. CI did not change immediately after inflation; although, thereafter, it increased 18% (P: < 0.05). Five minutes after deflation, CI further increased to a value 40% higher than the basal value. Therefore, systemic vascular resistance increased 20% suddenly after inflation (P: < 0.05) and decreased 18% after deflation (P: < 0.05). VO(2) and VCO(2) remained stable during inflation and increased (P: < 0.05) after deflation. VO(2)exc depended on duration of tourniquet inflation time (Tisch) (P: < 0.05). After deflation, PaCO(2) and lactate increased (P: < 0.05) while Tisch increased. We conclude that tourniquet application induces modifications of the cardiovascular system and metabolism, which depend on tourniquet phase and on Tisch. Whether these modifications could be relevant in patients with poor physical conditions is not known. ⋯ The clinical effects of tourniquet application were evaluated in 10 young men undergoing knee surgery. Our data indicate that tourniquet application causes hemodynamic and metabolic changes which may become clinically relevant after a long period of tourniquet inflation, particularly in patients with concomitant cardiovascular diseases.
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Anesthesia and analgesia · Sep 2000
Case ReportsGeneral anesthesia in a patient on long-term amphetamine therapy: is there cause for concern?
Amphetamines are powerful, sympathomimetic amines that, when used chronically, can profoundly effect a patient's cardiovascular stability during anesthesia and surgery. Amphetamines are the third most widely abused class of drugs in the United States. They also have legitimate medical use for attention deficit disorder with hyperactivity, exogenous obesity, and narcolepsy. We report a case of a patient with a 40-yr history of chronic amphetamine use having undergone two general anesthesias without complication.
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Anesthesia and analgesia · Sep 2000
Clinical TrialAging reduces the efficacy of the simulated epidural test dose in anesthetized adults.
Aging is associated with reduced beta-adrenergic responsiveness. However, the age-related effects on hemodynamic changes and effectiveness of a simulated epidural IV test dose have not been defined during general anesthesia. We studied 20 (140 total) consecutive patients (ASA physical status I) assigned in each of the following age groups after endotracheal intubation and during stable end-tidal sevoflurane 2% and 67% nitrous oxide anesthesia (in yr): 10s, 20s, 30s, 40s, 50s, 60s, and 70s. Each group first received normal saline 3 mL IV, followed 4 min later by 1.5% lidocaine 3 mL plus 15 microg epinephrine (1:200,000) IV for 5 s. Heart rate (HR) and systolic blood pressure (SBP) were continuously monitored for 4 min after saline administration and the test dose injections. None receiving IV saline and all patients receiving IV test dose in age groups 10s to 50s developed HR increases > or = 10 bpm, whereas 17 and 13 patients met this HR criterion in age groups 60s and 70s (85% and 65% sensitivities), respectively. There was a significant inverse correlation between the maximum HR increase and the age (P: < 0.001 by Spearman's rank correlation). However, none receiving saline and all patients receiving IV test dose in all age groups developed SBP increases of 15 mm Hg, resulting in 100% efficacy based on the SBP criterion. We conclude that during stable sevoflurane anesthesia administration (a) the efficacy based on the HR criterion for detecting accidental intravascular injection of the epidural test dose is age-dependent, (b) the HR criterion may be clinically applicable only in patients <60 yr of age, and (c) the SBP criterion is effective for all age groups studied. ⋯ To determine whether an epidurally administered local anesthetic has been unintentionally injected into a blood vessel, a small dose of epinephrine is often added to a local anesthetic. We found that an increase in systolic blood pressure > or = 15 mm Hg is a more useful indicator than an increase in heart rate > or = 10 bpm in the patients > or = 60 yr old during stable sevoflurane anesthesia administration.
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Anesthesia and analgesia · Sep 2000
Case ReportsDownbeat nystagmus associated with intravenous patient-controlled administration of morphine.
This case documents a patient who developed dizziness with downbeating nystagmus while receiving a relatively large dose of IV patient-controlled analgesia morphine. Although there have been case reports of epidural morphine with these symptoms and signs, this has not been previously documented with IV or patient-controlled analgesia morphine.