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Spinal Epidural Hematoma Associated with Epidural Anesthesia: Complications of Systemic Heparinization in Patients Receiving Peripheral Vascular Thrombolytic Therapy Curtis Dickman;Steven Shedd;Robert Spetzler;Andrew Shetter;Volker Sonntag; Anesthesiology

The aims of this stady were: to investigate a possible significant relation between the size of the tidal volume during constant volume ventilation and the rate of change of the alveolar-arterial oxygen tension gradient (AaDO2): to determine whether hypothermia significantly affects this relationship; and to test the accuracy of correction factors previously proposed for the effect of temperature on the oxygen tension of fully saturated blood. Ten patients were surface cooled to 30° C. for over 24 hours. Anesthesia consisted of pentobarbital sodium and d-tubocurarine. Constant volume pulmonary ventilation with 100 per cent oxygen was provided by a piston pump. A significant relationship (P < 0.01) was found between the size of the constant tidal volume and the rate of increase or decrease of the AaDO2. This relation showed little evidence of being affected by hypothermia per se. The accuracy of previously determined temperature correction factors for oxygen tension was confirmed.

An enclosed gas-filled space in the body will expand if gas within it is less soluble than the gas respired. Blood arriving at such a space can discharge a greater quantity of the soluble gas into the space than that blood can take up, assuming the tension gradient of each gas is equal. This results from the greater capacity of blood for the more soluble agent. When air was placed in the intestinal lumens of 3 dogs and nitrous oxide respired, intestinal gas volume increased 75 to 100 per cent in two hours and 100–200 per cent in four hours. Similarly, 300 ml. of air placed in the pleural space doubled in volume in 10 minutes, tripled in 45 minutes, and in one dog quadrupled in two hours. Nitrous oxide concentrations rose concomitantly in both the intestinal and pleural spaces. With cither gas in the intestine or in the pleural space, no volume changes were seen when the animal respired oxygen and halothane alone. These results suggest that nitrous oxide is relatively contraindicated in cases of intestinal obstruction or pneumothorax.

A detailed review of the published literature on systematic studies on anesthetic deaths after 1950 is made in this article. According to the author the high estimate of errors in all these studies resulted from failure to entertain the possibility of any cause of death other than anesthetic error. The myth that anesthetic drugs are different from all other drugs, and that they are absolutely safe unless someone errs, is to be dispelled. Drugs used in clinical anesthesia are potent and potentially lethal, and have primary desired actions, and unwanted side effects. The role of anesthesia in surgical mortality is greater than anyone has yet imagined; risks are not completely preventable because patients do not respond to drugs with stereotyped responses, but, at times, with adverse responses.

This case illustrates the effect of abnormal pseudocholinesterase on the metabolism and actions of chloroprocaine in a postpartum patient. The patient apparently could not adequately metabolize chloroprocaine which may have led to excessive somnolence intraoperatively. It also led to a prolonged chloroprocaine block (normally the block would last only 45-60 minutes) of 3 hours as well as to detectable serum chloroprocaine 5 hours after administration. Abnormal pseudocholinesterase was verified by the prolonged apnea following subsequent succinylcholine administration and by the fact that her dibucaine number at 6 weeks postpartum was indicative of a homozygote for the atypical cholinesterase variant or a heterozygote with 1 gene for the atypical variant and one for the silent variant. This case suggests that an abnormal reaction to chloroprocaine can occur in a patient with atypical cholinesterase and that an abnormal reaction to chloroprocaine has clinical implications beyond a prolonged epidural block. An abnormal reaction to chloroprocaine should alert the anesthesiologist to the possibility of a pseudocholinesterase deficiency which should suggest that the subsequent use of succinylcholine may result in a prolonged neuromuscular blockade.

No standard outcome measures exist to evaluate the effect of interventions intended to improve the quality of anesthesia care. The authors established a clinically practical definition of outcome, and used it to assess the effect of feedback of information about complications and the effect of pulse oximetry on the rate and severity of important anesthesia-related problems encountered in the operating room (OR) and recovery room (RR). On admission to the RR, the patient's anesthetist documented Recovery-Room-Impact Events (RRIE), defined as an "unanticipated, undesirable, possibly anesthesia-related effect that required intervention, was pertinent to recovery-room care, and did or could cause at least moderate morbidity." Following a control period with no feedback of data, intense feedback of grouped (anonymous) RRIE rates was provided. Later, pulse oximeters were introduced to all anesthetizing locations. Among 12,088 patients (71% of all RR admissions), 18% had at least one RRIE in the OR or RR. The most common RRIEs were hypotension (4.4%), arrhythmia (3.9%), hypertension (1.5%), intubation difficulties (0.8%), hypoventilation (0.8%), and hypovolemia (0.6%). Feedback of information produced no demonstrable change in the rate of RRIEs. Although significantly fewer patients experienced RRIEs (15.6% vs. 12.4%, P less than 0.0001), hypotensive RRIEs (5.2% vs. 3.8%, P = 0.0003), and hypovolemic RRIEs (0.88% vs. 0.42%, P = 0.0017) following the introduction of pulse oximetry in the OR, confounding factors prevent establishment of a cause-and-effect relationship. Quality assurance may require more direct intervention and individual feedback to be effective. Still, the RRIE measure requires minimal effort at low cost and encourages improved transmission of information at the time of admission to recovery-room care.

The mechanism of injury to the brachial plexus which follows certain operative positions was studied in 15 cadavers by dissection and in five patients by radial artery pulse tracings. In particular the “hands up” and common supine positions were studied. Stretch was shown to be the most likely mecha

An increase in cerebrospinal fluid pressure incurs in dogs and humans anesthetized with nitrous oxide after air has been injected into the cerebral ventricles. The mechanism for the increase in pressure is felt to be due to the difference in blood solubility between nitrous oxide and nitrogen. Nitro

Hospital admissions in Seattle over an 11-year period were reviewed to determine the risk of precipitating respiratory paralysis by barbiturates in patients with undiagnosed porphyria. There were 66 cases of porphyria with 163 hospital admissions, an incidence of 1 in 7,088 admissions. The group rec