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Biomedical subjects

Michael D Sharpe

Publications and source records attributed to Michael D Sharpe.

8 recordsLinked to original sources
PubMed2005

Acute paralysis following "a bad potato": a case of botulism.

PURPOSE: Intensivists often encounter patients with respiratory failure as a result of neuromuscular disease, however, acute neuro-muscular syndromes are less common. We present a case of food borne Clostridium botulism and discuss the diagnostic and therapeutic considerations. CLINICAL FINDINGS: A 35-yr-old healthy male presented with abdominal pain and blurred vision 12 hr after ingesting a "bad" potato. During the next 17 hr, the patient demonstrated a gradual descending paralysis which ultimately resulted in no cranial nerve function and 0/5 strength in all extremities. Sensation was intact. The patient required intubation and mechanical ventilation. His blood count, biochemical profile, computerized tomography and magnetic resonance imaging of the head were normal. A lumbar puncture revealed no abnormalities. Due to the rapid deterioration and presentation of 'descending' paralysis, botulism was suspected. The patient was treated empirically with botulinum anti-toxin. Samples of blood, stool and gastric contents were cultured for the presence of Clostridium botulinum and its toxin and these tests were positive for botulinum toxin A 12 days later. The patient's neuromuscular function gradually improved over a prolonged period of time. Six and one-half months after his initial presentation, the patient was discharged home after completing an aggressive rehabilitation program. CONCLUSIONS: Botulism is a rare syndrome and presents as an acute, afebrile, descending paralysis beginning with the cranial nerves. If suspected, botulinum anti-toxin should be considered, particularly within the first 24 hr of onset of symptoms. Confirmation of the presence of botulinum requires days therefore the diagnosis and management rely on history and physical examination.

Acute Disease↗
PubMed2004

Treatment of refractory status epilepticus with inhalational anesthetic agents isoflurane and desflurane.

BACKGROUND: Refractory status epilepticus (RSE) is defined as continued seizures after 2 or 3 antiepileptic drugs have failed. Several intravenous agents have been used for RSE; however, problems occur with their toxicity and/or effectiveness. OBJECTIVE: To report our experience with inhalational anesthesia (IA) in patients who were refractory to other antiepileptic drugs. DESIGN, SETTING, AND PARTICIPANTS: Retrospective review during a 4-year period of patients with RSE treated with isoflurane and/or desflurane. MAIN OUTCOME MEASURE: Efficacy of IA on therapy in terminating RSE. RESULTS: Seven patients (4 male) aged 17 to 71 years received 7 to 15 (mean, 10) antiepileptic drugs in addition to IAs. The IAs were initiated after 1 to 103 (mean, 19) days of RSE and were used for a mean +/- SD 11 +/- 8.9 days. All patients received isoflurane, and 1 patient in addition received desflurane anesthesia 21 days after the onset of RSE for a total of 19 days. Regardless of seizure type, isoflurane and desflurane consistently stopped epileptic discharges with adequate, sustained electroencephalographic burst suppression within minutes of initiating IA therapy. Four patients had good outcomes, 3 died (1 of acute hemorrhagic leukoencephalitis, 1 of bowel infarction, and 1 of toxic encephalopathy, who remained in a persistent vegetative state until death 5.5 months after the onset of seizures). Complications during IA therapy included hypotension (7/7), atelectasis (7/7), infections (5/7), paralytic ileus (3/7), and deep venous thrombosis (2/7). No patient developed renal or hepatic dysfunction. CONCLUSIONS: Isoflurane and desflurane adequately suppressed RSE in all cases. Complications were common, but mortality and long-term morbidity were related to the underlying disease and duration of RSE. Prolonged use of isoflurane and desflurane is well tolerated.

Adolescent↗
PubMed2004

The apnea test for brain death determination: an alternative approach.

INTRODUCTION: Problems associated with the standard apnea test relate to overshooting or undershooting the target PaCO2, potentially compromising the viability of organs for transplantation or invalidating the test. MATERIALS AND METHODS: In 60 adult patients, the authors used an alternative method using exogenously administered CO2 and measurement of end-tidal CO2. RESULTS: All patients achieved an adequate respiratory stimulus (mean increase in PaCO2 was 28+/-3 mmHg, postapnea test pH was 7.20+/-.02). There was a clinically insignificant reduction in arterial blood pressure during testing, but no other complications occurred. Multiple regression analysis demonstrated a correlation between the predicted PaCO2 (predicted from the end-tidal CO2) and measured PaCO2 (64+/-9 versus 67+/-9; r=.75169, p<0.0001). CONCLUSION: Exogenously administered CO2 as an alternative method for the standard apnea test was a reliable and safe method, with minimal complications that offers several advantages over the standard method.

Adolescent↗
PubMed2003

Efficacy and safety of itraconazole prophylaxis for fungal infections after orthotopic liver transplantation: a prospective, randomized, double-blind study.

BACKGROUND: There is significant morbidity and mortality related to fungal infections in the solid-organ transplant population. METHODS: A prospective, randomized, double-blind, placebo-controlled, restricted sequential design trial was performed in 71 adults undergoing orthotopic liver transplantation. Patients were randomly assigned to receive either itraconazole (5.0 mg/kg orally, preoperatively, 2.5 mg/kg orally, two times a day, postoperatively) or placebo. Therapy continued for a maximum of 56 days or until patient was discharged from hospital or met a predefined endpoint. Measurements included incidence of fungal colonization, superficial or systemic fungal infections requiring systemic therapy, adverse events, and mortality rate. RESULTS: This trial design supported the superiority of itraconazole in preventing fungal infections; nine patients in the placebo group (24%; 95% confidence interval, 0.118-0.412) and one patient in the itraconazole group (4%; 95% confidence interval, 0.001-0.204) developed fungal endpoints requiring therapy with amphotericin B (P=0.04, Fisher's exact test). At the time of enrollment, fungal colonization occurred in 40% and 37% of itraconazole and placebo patients (P=0.43), respectively. Adverse events were reported by 97% and 100% of the intraconazole and placebo groups, respectively, and one itraconazole and six placebo-group patients died within the study period. There was no relation to trial medication for serious adverse events. CONCLUSION: Prophylaxis with itraconazole reduces fungal infections in patients undergoing orthotopic liver transplantation and is well tolerated.

Administration, Oral↗
PubMed2003

Bench-to-bedside review: microvascular dysfunction in sepsis--hemodynamics, oxygen transport, and nitric oxide.

The microcirculation is a complex and integrated system that supplies and distributes oxygen throughout the tissues. The red blood cell (RBC) facilitates convective oxygen transport via co-operative binding with hemoglobin. In the microcirculation oxygen diffuses from the RBC into neighboring tissues, where it is consumed by mitochondria. Evidence suggests that the RBC acts as deliverer of oxygen and 'sensor' of local oxygen gradients. Within vascular beds RBCs are distributed actively by arteriolar tone and passively by rheologic factors, including vessel geometry and RBC deformability. Microvascular oxygen transport is determined by microvascular geometry, hemodynamics, and RBC hemoglobin oxygen saturation. Sepsis causes abnormal microvascular oxygen transport as significant numbers of capillaries stop flowing and the microcirculation fails to compensate for decreased functional capillary density. The resulting maldistribution of RBC flow results in a mismatch of oxygen delivery with oxygen demand that affects both critical oxygen delivery and oxygen extraction ratio. Nitric oxide (NO) maintains microvascular homeostasis by regulating arteriolar tone, RBC deformability, leukocyte and platelet adhesion to endothelial cells, and blood volume. NO also regulates mitochondrial respiration. During sepsis, NO over-production mediates systemic hypotension and microvascular reactivity, and is seemingly protective of microvascular blood flow.

Hemodynamics↗
PubMed2003

Translaryngeal tracheostomy: experience of 340 cases.

OBJECTIVE: To describe the authors' initial experience with a new and innovative dilational translaryngeal tracheostomy bedside technique. STUDY DESIGN: A prospective documentation of 340 patients who received an elective translaryngeal tracheostomy in a multidisciplinary, tertiary care intensive care unit during a 45-month period. RESULTS: All translaryngeal tracheostomy procedures but one were completed successfully; one was aborted because of bleeding from a thyroid vein. Minor perioperative complications occurred in 42% of patients, which caused no adverse effects. The most common complication was arterial desaturation occurring in 17% of patients; this was short-lived, and the lowest saturation was 79%. Blood loss was minimal (<5 mL) in all but one case, despite an elevated international normalized ratio (INR) and partial thromboplastin time in 42% and 41% of patients, respectively, and a low platelet count in 13% of patients. CONCLUSIONS: Translaryngeal tracheostomy is a safe and reliable technique and can also be used in patients with unstable cervical spines and bleeding diathesis. It has become the authors' procedure of choice for an elective bedside tracheostomy in the intensive care unit.

Documentation↗
PubMed2002

Effect of a maldistribution of microvascular blood flow on capillary O(2) extraction in sepsis.

Inherent in the remote organ injury caused by sepsis is a profound maldistribution of microvascular blood flow. Using a 24-h rat cecal ligation and perforation model of sepsis, we studied O(2) transport in individual capillaries of the extensor digitorum longus (EDL) skeletal muscle. We hypothesized that erythrocyte O(2) saturation (SO(2)) levels within normally flowing capillaries would provide evidence of either a mitochondrial failure (increased SO(2)) or an O(2) transport derangement (decreased SO(2)). Using a spectrophotometric functional imaging system, we found that sepsis caused 1) an increase in stopped flow capillaries (from 10 to 38%, P < 0.05), 2) an increase in the proportion of fast-flow to normal-flow capillaries (P < 0.05), and 3) a decrease in capillary venular-end SO(2) levels from 58.4 +/- 20.0 to 38.5 +/- 21.2%, whereas capillary arteriolar-end SO(2) levels remained unchanged compared with the sham group. Capillary O(2) extraction increased threefold (P < 0.05) and was directly related to the degree of stopped flow in the EDL. Thus impaired O(2) transport in early stage sepsis is likely the result of a microcirculatory dysfunction.

Animals↗