Biomedical subjects
Publications and source records attributed to A J Layon.
We present a case of postoperative cardiac arrest caused by extrinsic occlusion of the right coronary artery by an aortic pseudoaneurysm. Extrinsic impingement upon the coronary arteries may result from several etiologies and lead to cardiac symptoms identical to those caused by intrinsic coronary disease. Extrinsic compression may be amenable to treatment with angioplasty or a combination of angioplasty and surgery.
This case report describes a patient who became asystolic after electroconvulsive therapy. The report describes the prolonged resuscitative events that lasted 54 minutes and discusses the effectiveness of chest compressions and the importance of monitoring the acid-base balance. The report also stresses the importance of being able to establish effective cardiac pacing in this patient. The updated resuscitation guidelines published by the American Heart Association are also discussed.
OBJECTIVES: To determine whether an intravenous infusion of the calcium channel blocker diltiazem was effective and safe in treating sinus tachycardia in critically ill adult patients with contraindications to beta-blockers or in whom beta-blockers were ineffective. DESIGN: Retrospective chart review. SETTING: University medical center. PATIENTS: The records of 171 surgical intensive care unit patients with sinus tachycardia treated with intravenous diltiazem were evaluated. INTERVENTIONS: In all patients with sinus tachycardia (heart rate >100 beats/min), heart rate control with intravenous diltiazem was attempted after adequate intravascular volume expansion, pain, and anxiety control. In all patients, beta-blockade either was contraindicated or (in 7%) had failed. Intravenous diltiazem was administered as a slow 10-mg bolus dose (0.1-0.2 mg/kg ideal body weight), and then an infusion was started at 5 or 10 mg/hr and increased up to 30 mg/hr, as needed, to decrease heart rate to <100 beats/min. Variables retrospectively collected included demographic data, preinfusion blood pressure, mean arterial pressure, heart rate, and preinfusion pressure-rate quotients (pressure-rate quotient = mean arterial pressure / heart rate). Intravenous bolus dose, when given, and diltiazem infusion rate and time necessary to achieve the target heart rate also were recorded. The lowest heart rate recorded within 24 hrs from the initiation of the infusion and the time necessary to achieve the lowest heart rate after beginning the infusion were recorded. MEASUREMENTS AND RESULTS: Of 171 patients studied, 97 (56%) were classified as responders. Multiple linear regression suggested that response could be predicted by age, pressure-rate quotients, baseline mean arterial pressure, and central nervous system failure. In the responders, a heart rate <100 beats/min was achieved in an average of 2 hrs, at a mean diltiazem infusion of 13.3 mg/hr. The lowest rate reached by the responders in a 24-hr period averaged 86 beats/min and was achieved in 4.8 hrs with a mean infusion rate of 14.8 mg/hr. Both target and lowest rate values were statistically different from baseline heart rate. CONCLUSION: Diltiazem was effective in achieving short-term control of heart rate in 56% of the patients, virtually without adverse effects, where beta-blockade was contraindicated or ineffective.
An approach to the airway is addressed in Table 1. A summary of induction/NMB agents and doses is given on Table 2; indications for the different agents are noted on Table 3. The central pharmacological issue is not that any one drug is universally preferred over another. Rather, it is key that one develop a thoughtful rationale for the drugs used, and a plan to get out of trouble if one is suddenly in the sinking situation of a patient with a difficult airway who cannot breathe on his or her own. The backup plan might involve the use of BVM ventilation, blind digital intubation, fiberoptic bronchoscope-aided intubation, retrograde techniques, light wand intubation, laryngeal mask airway techniques, posterior pharyngeal endotracheal tube placement ventilation, or a surgical airway. Most of these approaches are reviewed elsewhere.
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BACKGROUND: Respiratory pathogens that pass through the anesthesia breathing system potentially can infect other patients. This study was designed to determine if bacteria can pass through contemporary anesthesia breathing systems and if the environment within the machine is hostile to these organisms. METHODS: Staphylococcus aureus, Pseudomonas aeruginosa, and Mycobacterium tuberculosis were nebulized into the expiratory limb of an anesthesia breathing circuit and collected from the inspiratory and expiratory limbs in an impinger system that provided a quantitative determination of the number of organisms entering the circuit and the number that would reach the patient in the inspiratory gas. Bacteria were collected before, during, and after nebulization. A second experiment determined if a saturated solution of soda lime was bactericidal. RESULTS: When the gas flow through the circuit was interrupted for < 1 h following the nebulization period, large numbers of microorganisms (1 x 10(3) to 1 x 10(5), around 100% of the nebulized organisms) were collected from the inspiratory gas. Soda lime itself was not bactericidal for any of the organisms tested, but solutions of this material with a pH of 12 were bactericidal. CONCLUSION: Cross contamination between patients may occur unless the gas flow through the anesthesia breathing system is interrupted for > 1 h.
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A patient underwent a partial right hepatic lobectomy for adenocarcinoma of the colon metastatic to the liver. He was admitted to the surgical intensive care unit in stable condition. Six hours after surgery, the patient experienced sudden and sever hypotension, bradycardia, and systole. Differential diagnoses included acute myocardial infarction, hemorrhage from the surgical site, and pulmonary embolism. However, these complications were ruled out. We believe that an allergic reaction to vitamin K and its potential side effects are discussed.
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A patient with a history of spina bifida and cerebral palsy was anesthetized for an ileal conduit. The procedure was uneventful until penetration of the abdominal cavity, immediately after which the patient suffered severe hypotension and her peak inspiratory pressure doubled. The patient's skin became flushed and the capnogram tracing was consistent with bronchospasm. The patient was treated with phenylephrine hydrochloride (Neo-Synephrine), and then epinephrine. This was followed with an epinephrine infusion, intravenous (i.v.) methylprednisolone sodium succinate (Solu-Medrol), inhaled albuterol sulfate, and diphenhydramine hydrochloride (Benadryl) i.v.. The patient responded to these interventions and the procedure was completed without further incident. A diagnosis of latex allergy was made based on the patient's clinical status, underlying diseases, and positive postoperative radioallergosorbent test (RAST). Anesthesiologists must be able to diagnose the signs and symptoms of allergic reactions in patients under anesthesia. This article will review the types of hypersensitivity reactions involved, define the risk groups, and examine the treatment protocols available for latex allergy.
BACKGROUND AND PURPOSE: Age may influence cost or effectiveness of treatment for subarachnoid hemorrhage (SAH). This study examined the effect of age on both. METHODS: Patients (n = 219) who underwent craniotomy for intracranial aneurysm and SAH over 6 years at one tertiary care center were divided in two ways by age: single advanced age (< 65 years and > or = 65 years) and decade of age (23 to 39, 40 to 49, 50 to 59, 60 to 69, and 70 to 81 years). Data recorded for each patient included numbers of procedures and complications in the surgical intensive care unit (SICU), number of days in the SICU and the hospital, costs for SICU and ward care, total cost (SICU plus ward costs), and the Acute Physiology and Chronic Health Evaluation (APACHE) II score at admission and discharge, the Hunt-Hess grade at admission and immediately preoperatively, and quality of life score, a measure of outcome. Mortality rates by age group were calculated. RESULTS: The only variable significantly affected by decade of age was mortality rate, which increased as decade of age increased (3% to 17%). With the 65-year comparison, mortality rate, cost, APACHE II score at admission and discharge, days before operation, and days in the SICU were significantly higher for age > or = 65 years. CONCLUSIONS: Whereas mortality is higher for the older age group, quality of life scores appear acceptable for those who survive. Even though the hospital costs of treating elderly patients for SAH may be higher than those for younger patients, this should not be used to justify withholding care from the elderly.
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Autonomy is a central ethical principle of medical practice. The physician's autonomy is usually expressed in concert with the other, overriding, ethic of medical care: beneficence. The autonomy of patients, however, has had a growing influence on medical decision-making and can complicate the process. One area where this is especially true is the manner in which cardiopulmonary resuscitation is disallowed: the do-not-resuscitate (DNR) order. Cardiopulmonary resuscitation initially was a therapy automatically instituted in emergencies because it was life-saving. Data began to show, however, that this drastic measure was not always effective. Therefore, its use began to be limited through DNR orders, and policies about DNR orders have been developed to ensure it, in turn, is instituted properly. Besides being used when CPR is futile, the DNR order also serves as a formal means of accounting for a patient's autonomy. Data show, however, that patients are not routinely consulted on this issue even though they want to discuss it. In these cases, quality of life, a patient's subjective evaluation, serves as the basis of a DNR order and makes mandatory communication between physician and patient. Such communication, however, can be obstructed by social values about life and death and the urgent nature of medical care in these situations. To show how such communication ought to be incorporated into medical decision-making, one of the most difficult situations is examined hypothetically: the patient who has a DNR order but who consents to undergo anaesthesia and surgery. In these cases, frequent communication between physician and patient about each therapy and its effect most often will resolve dilemmas.
In carbon monoxide (CO) poisoning, the mortality and morbidity risk does not always correlate with the level of carboxyhemoglobin (COHb). Recent studies confirm that the mitochondrial cytochrome portion of the respiratory chain is susceptible to CO toxicity at concentrations traditionally considered nontoxic. These laboratory findings correlate with subtle neurologic symptoms detected by psychometric studies in individuals many days from the time of acute intoxication. Additionally, in the pregnant patient, a time lag for both uptake and elimination of CO between the mother and fetus has been demonstrated, with the fetus at risk for hypoxia even when the mother's blood level of CO is nontoxic. Hyperbaric oxygen (HBO) therapy in pregnant patients has not been shown to have adverse effects on the fetus. We present a case of CO intoxication in late pregnancy treated with HBO therapy without adverse consequences.
Cardiopulmonary bypass (CPB) does not appear to cause excessive maternal risk, but the potential for fetal complications is of great concern. In general, operative intervention should be delayed until at least the second trimester. When this is not possible, ethical issues arise and a clash of maternal autonomy versus "fetal rights" ensues. This conflict is further complicated by maternal status changes that may accompany valvular disease or develop after CPB. The case described herein summarizes and discusses these conflicts.
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OBJECTIVE: Some physicians and academicians have suggested that limiting selected healthcare resources to the elderly will help curtail the rising cost of health care in the United States. In order to test this hypothesis in a specific medical context, we compared the cost of caring for younger (< 65 yrs) patients with that of caring for older (> or = 65 yrs) patients who underwent craniotomy for treatment of brain tumors. DESIGN: Prospective collection and review of data on patients undergoing craniotomy for tumor in our institution between February 1989 and December 1991. SETTING: University teaching hospital. METHODS: Patients were divided into two groups: those < 65 yrs, and those > or = 65 yrs. Demographics, severity of illness, length of stay, hospital and surgical intensive care unit (ICU) costs and charges, ICU complications, procedures, and outcome variables were analyzed. RESULTS: Of 3,265 ICU patients admitted during the study period, data on 123 (3.8%) undergoing craniotomy for brain tumor were analyzed. There were no differences between the patient groups in length of ICU stay or hospital stay, final outcome at discharge from the hospital, quality of life, or hospital or ICU costs, despite the fact that elderly patients had a greater number of procedures and complications per patient, and higher Acute Physiology and Chronic Health Evaluation II (APACHE II) severity of illness scores on admission and discharge than younger patients. CONCLUSIONS: The assertion that the elderly may, under certain conditions, consume more healthcare resources and benefit less from them than younger patients must be tested for accuracy with regard to specific disease states. In the context of the disorder studied herein, the elderly do as well as the young. Without specific study of specific pathologic processes or surgical procedures, using age to limit access to resources remains an unsubstantiated, ideologic concept, rather than a scientifically proven cost-saving measure.