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Biomedical subjects

John Butterworth

Publications and source records attributed to John Butterworth.

At least 19 recordsLinked to original sources
PubMed2007

Lower extremity paralysis after thoracotomy or thoracic epidural: image first, ask questions later.

BACKGROUND: When an epidural catheter is present, new motor deficits will often be attributed to a local anesthetic effect, potentially delaying imaging studies, or to an epidural hematoma, ignoring other mechanisms of spinal cord injury. METHODS: A 69-yr-old female patient undergoing thoracotomy received a preoperative thoracic epidural for postoperative analgesia. RESULTS: Intraoperatively, there was bleeding near the costovertebral junction. Hemorrhage was controlled with cellulose gauze and bone wax. Paralysis developed postoperatively and was initially misdiagnosed as a local anesthetic effect when, in fact, it was caused by an extradural deposit of cellulose gauze and bone wax. CONCLUSIONS: We emphasize the need for prompt, definitive imaging when new lower extremity weakness develops after thoracotomy or thoracic epidural analgesia.

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PubMed2006

Perioperative management of chronic heart failure.

Heart failure (HF) is one of the few cardiac conditions that is increasing. Despite a better understanding of how hormones and other signaling systems underlie the pathophysiology, and despite improved outcomes from pharmacologic therapy, many HF patients receive no effective treatment. Patients with HF commonly require medical diagnosis and management in operating rooms and critical care units; thus anesthesiologists are obliged to remain up-to-date both with advances in outpatient (chronic) medical management and with inpatient treatments for acute exacerbations of HF. Accordingly, we reviewed angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-adrenergic receptor blockers, and aldosterone antagonists because these drugs prolong life and are included in current clinical practice guidelines for treating patients with chronic HF. We also reviewed the implications of chronic HF for patients undergoing surgery and anesthesia and discuss how best to provide intensive treatment for acute exacerbations of symptoms, such as might be caused by excessive intravascular volume, inappropriate drug "holidays," or worsening of the underlying cardiac disease.

Adrenergic beta-Antagonists↗
PubMed2006

Local anesthetic-induced cardiac toxicity: a survey of contemporary practice strategies among academic anesthesiology departments.

Though new local anesthetics (LA), effective test-dosing, and new regional anesthetic techniques may have improved the safety of regional anesthesia, the optimal management plan for LA-induced cardiac toxicity remains uncertain. Accordingly, we evaluated current approaches to LA cardiotoxicity among academic anesthesiology departments in the United States. A 19-question survey regarding regional anesthesia practices and approaches to LA cardiac toxicity was sent to the 135 academic anesthesiology departments listed by the Society of Academic Anesthesiology Chairs-Association of Anesthesiology Program Directors. Ninety-one anonymously completed questionnaires were returned, at a response rate of 67%. The respondents were categorized into groups according to the number of peripheral nerve blocks (PNBs) performed each month: >70 PNBs (38%), 51-70 PNBs (13%), 31-50 PNBs (20%), 11-30 PNBs (23%), and <10 PNBs (6%). Anesthesia practices administering >70 PNBs were 1.7-times more likely to use ropivacaine (NS), 3.9-times more likely to consider lipid emulsion infusions for resuscitation (P = 0.008), and equally as likely to have an established plan for use of invasive mechanical cardiopulmonary support in the event of LA cardiotoxicity (NS) than low-PNB volume centers. We conclude that there are differences in the management and preparedness for treatment of LA toxicity among institutions, but the safety implications of these differences are undetermined.

Academic Medical Centers↗
PubMed2005

Attempted control of hyperglycemia during cardiopulmonary bypass fails to improve neurologic or neurobehavioral outcomes in patients without diabetes mellitus undergoing coronary artery bypass grafting.

OBJECTIVE: Hyperglycemia worsens outcomes in critical illness. This randomized, double-blind, placebo-controlled clinical trial tested whether insulin treatment of hyperglycemia during cardiopulmonary bypass would reduce neurologic, neuro-ophthalmologic, and neurobehavioral outcomes after coronary artery bypass grafting. METHODS: Three hundred eighty-one nondiabetic patients undergoing isolated coronary artery bypass grafting were given infusions of insulin or placebo when their blood glucose concentration exceeded 100 mg/dL during cardiopulmonary bypass. The primary outcome measure was the combined incidence of new neurologic, neuro-ophthalmologic, or neurobehavioral deficits or neurologic death observed at 4 to 8 days postoperatively. This same measure was assessed secondarily at 6 weeks and 6 months. Length of hospital stay was also compared as a secondary assessment. RESULTS: The 2 groups were well matched at baseline. The insulin-treated group had significantly lower blood glucose concentrations during bypass. Sixty-six percent of subjects in the insulin-treated group and 67% of subjects in the control group demonstrated a new or worsening neurologic, neuro-ophthalmologic, or neurobehavioral deficit or neurologic death at the 4- to 8-day assessment. Outcomes were also similar in the 2 groups at 6 weeks (37% and 39% incidence, respectively) and 6 months (30% and 25%, respectively). Median lengths of stay were 7 and 6 days, respectively, in the treatment and control groups. None of these outcome differences was statistically significant. CONCLUSION: Attempted control of hyperglycemia during cardiopulmonary bypass had no significant effect on the combined incidence of neurologic, neuro-ophthalmologic, or neurobehavioral deficits or neurologic death and failed to shorten the length of hospital stay. These results do not contradict those of other studies showing that aggressive control of hyperglycemia in the postoperative period will improve outcome.

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PubMed2004

Failure of argatroban anticoagulation during off-pump coronary artery bypass surgery.

Heparin-induced antibodies create vexing problems during cardiac surgery. Although alternative medications have been used for intraoperative anticoagulation, the results have been sufficiently variable that no one medication is recommended. In our case, due to the poor reversibility of the antithrombin agents, argatroban was chosen as a heparin substitute due to its short half-life and its anticoagulation assessment using the activated clotting time (ACT). Unfortunately, our experience was that argatroban does not provide adequate anticoagulation during off-pump coronary bypass surgery, even when the ACT is maintained at more than 380 sec.

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PubMed2004

Intrathecal morphine reduces infarct size in a rat model of ischemia-reperfusion injury.

UNLABELLED: Systemically-administered morphine reduces infarct size in rat models of myocardial ischemia-reperfusion. We sought to determine whether much smaller doses of spinally-administered morphine offer a similar cardioprotective benefit. Barbiturate-anesthetized, open-chested, Wistar rats with chronic indwelling thoracic intrathecal catheters were instrumented for hemodynamic measurements and subjected to 30 min of coronary occlusion and 90 min of reperfusion. Myocardial infarct size was determined using triphenyl-tetrazolium staining. Rats were randomly assigned to receive intrathecal (IT) 0.9% saline (vehicle), IV morphine (0.3 mg/kg) plus IT saline, small-dose IT morphine (0.3 microg/kg), or large-dose IT morphine (3 microg/kg) 20 min before occlusion. IV and both doses of IT morphine reduced infarct size, defined as area of necrosis expressed as a percentage of area at risk (%AN/AAR), as compared with vehicle. The %AN/AAR group means were as follows: IV (n = 7), 30% +/- 6%; IT(small-dose) (n = 9), 30% +/- 5%; IT(large-dose) (n = 9), 18% +/- 4%; and vehicle (n = 10), 47% +/- 5%. There were no significant differences in infarct size among the morphine-pretreated rats. During ischemia-reperfusion, heart rate was unchanged from baseline in the IT(large-dose) group, whereas in the IT(small-dose), IV and vehicle groups, significant declines in heart rate occurred. Changes in arterial blood pressure were similar among groups. These results indicate that IT morphine reduces infarct size in rats, and this benefit is as great as that provided by IV morphine administration. IMPLICATIONS: Our findings suggest that spinally-administered morphine provides a previously unrecognized cardioprotective benefit. In anesthetized rats subjected to ischemia-reperfusion injury, we show that very small doses of intrathecal morphine reduce infarct size in rats, and this benefit is as great as that provided by much larger doses of IV morphine.

Animals↗
PubMed2003

Severe acute visceral pain from varicella zoster virus.

UNLABELLED: Varicella zoster virus infection often will not present in the characteristic dermatomal distribution of vesicles in patients who have undergone bone marrow transplantation. We cared for a 51-yr-old man with severe abdominal pain after bone marrow transplantation for non-Hodgkin's lymphoma. The diagnosis of varicella zoster was not entertained until he developed a diffuse vesicular rash several days after the onset of pain. We report this case to alert others who may be consulted regarding pain management options for similar oncology patients. IMPLICATIONS: We report a patient with lymphoma, prior bone marrow transplant, and acute visceral pain for whom IV opioids in large doses proved inadequate. An interventional pain management technique was considered until characteristic varicella vesicles appeared over the patient's trunk. We report this case to alert others who treat oncology patients that the diagnosis of visceral zoster should be considered when patients who have undergone bone marrow transplantation present with severe visceral pain.

Abdomen↗
PubMed2002

Rapid disappearance of protamine in adults undergoing cardiac operation with cardiopulmonary bypass.

BACKGROUND: Despite long use of protamine in cardiac operations, neither protamine concentrations nor pharmacokinetics have been reported in patients. METHODS: Twenty-eight patients (age, 26 to 80 years) undergoing various cardiac surgical procedures gave their consent to receive 250 mg of protamine sulfate administered intravenously by an infusion pump during 5 minutes. Protamine was administered at the usual intraoperative time after separation from cardiopulmonary bypass for reversal of heparin. Timed arterial blood samples were obtained after protamine infusion. Blood plasma was subjected to solid-phase extraction and high-performance liquid chromatography. Total (free + heparin-bound) protamine concentration versus time data were subjected to pharmacokinetic modeling. RESULTS: Twenty-six patients completed the study. Total plasma protamine concentrations declined rapidly. Model-independent pharmacokinetic analysis revealed median (range) values as follows: volume of distribution, 5.4 L (0.82 to 34 L); clearance, 1.4 L/min (0.61 to 3.8 L/min); and half-life, 4.5 min (1.9 to 18 min). Schwarz-Bayesian criterion identified a two-compartment exponential model with adjustment for weight in the central compartment volume of distribution as performing better than other compartmental or Michaelis-Menten models. CONCLUSIONS: Protamine has a very short (approximately 5 minutes) half-life after a single 250-mg dose in adult patients. This short half-life could underlie recurrent anticoagulation after initial apparent reversal of heparin.

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PubMed2002

Ulnar nerve injury and perioperative arm positioning.

Primum non nocere. Hippocrates included this admonition in Epidemics, Book I, Second Constitution, to do good or "to do no harm." However, even the most conscientious health care provider will encounter unexpected and serious adverse medical events. This discussion focuses on one relatively common, often perplexing, and usually unexplained perioperative complication: ulnar neuropathy. Perioperative ulnar neuropathy has received increased scientific attention because it accounts for one third of all nerve injury claims in the American Society of Anesthesiologists (ASA) Closed Claims Study database. In addition, these injuries may result in chronic pain or paresthesia, employment disability, catastrophic economic damages, and malpractice litigation. We will explore the current understanding of perioperative ulnar nerve dysfunction by summarizing the relevant scientific literature and information within the ASA closed-claims database, describing the epidemiologic features of perioperative nerve injuries, discussing relevant clinical investigations and recommendations for safe arm positioning during anesthesia, and reviewing the medico-legal issues inevitably intertwined with this topic, particularly the doctrine of res ipsa loquitur.

Anesthesia↗
PubMed2002

Intraoperative insulin therapy does not reduce the need for inotropic or antiarrhythmic therapy after cardiopulmonary bypass.

OBJECTIVE: To determine whether attempted glucose control through intraoperative insulin therapy reduces the need for inotropic or antiarrhythmic therapy after cardiopulmonary bypass (CPB). DESIGN: Post hoc analysis of a randomized, masked clinical trial of insulin therapy for prevention of neurobehavioral deficits. SETTING: Single university hospital. PARTICIPANTS: Nondiabetic patients undergoing elective coronary artery bypass graft surgery (n = 381). INTERVENTIONS: Patients received either insulin infusions in an attempt to maintain blood glucose at 80 to 120 mg/dL (n = 188) or placebo (saline; n = 193). Inotropic therapy was defined as the initiation of vasoactive support with epinephrine or amrinone infusions or mechanical support with the initiation of an intra-aortic balloon pump in the operating room or within 12 hours postoperatively. Antiarrhythmic therapy was defined as cardioversion, antiarrhythmic medications, or pacing. MEASUREMENTS AND MAIN RESULTS: Of patients, 64 in the placebo group and 71 in the insulin group required inotropic support after CPB (p = not significant). The use of cardioversion (55 in placebo group v 61 in insulin group), antiarrhythmic medications (64 in placebo group v 76 in insulin group), and pacing (118 in placebo group v 117 in insulin group) was similar between groups. Inotropic drug support was associated with age >60 years, female gender, reduced preoperative ejection fraction, history of angina, and increased duration of CPB. CONCLUSION: Intraoperative insulin therapy did not reduce the use of inotropic or antiarrhythmic support after cardiac surgery with CPB. The lack of benefit may be due to the inability to prevent hyperglycemia during the physiologic stress of CPB or a tribute to the effectiveness of modern myocardial preservation techniques.

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