Search PubMed⌕ Search

Biomedical subjects

C David Mazer

Publications and source records attributed to C David Mazer.

At least 19 recordsLinked to original sources
PubMed2006

Increased expression of HIF-1alpha, nNOS, and VEGF in the cerebral cortex of anemic rats.

This study tested the hypothesis that specific hypoxic molecules, including hypoxia-inducible factor-1alpha (HIF-1alpha), neuronal nitric oxide synthase (nNOS), and vascular endothelial growth factor (VEGF), are upregulated within the cerebral cortex of acutely anemic rats. Isoflurane-anesthetized rats underwent acute hemodilution by exchanging 50% of their blood volume with pentastarch. Following hemodilution, mean arterial pressure and arterial Pa(O(2)) values did not differ between control and anemic rats while the hemoglobin concentration decreased to 57 +/- 2 g/l. In anemic rats, cerebral cortical HIF-1alpha protein levels were increased, relative to controls (1.7 +/- 0.5-fold, P < 0.05). This increase was associated with an increase in mRNA levels for VEGF, erythropoietin, CXCR4, iNOS, and nNOS (P < 0.05 for all), but not endothelial NOS. Cerebral cortical nNOS and VEGF protein levels were increased in anemic rats, relative to controls (2.0 +/- 0.2- and 1.5 +/- 0.4-fold, respectively, P < 0.05 for both). Immunohistochemistry demonstrated increased HIF-1alpha and VEGF staining in perivascular regions of the anemic cerebral cortex and an increase in the number of nNOS-positive cerebral cortical cells (3.2 +/- 1.0-fold, P < 0.001). The nNOS-positive cells costained with the neuronal marker, Neu-N, but not with the astrocytic marker glial fibrillary acidic protein (GFAP). These nNOS-positive neurons frequently sent axonal projections toward cerebral blood vessels. Conversely, VEGF immunostaining colocalized with both neuronal (NeuN) and astrocytic markers (GFAP). In conclusion, acute normotensive, normoxemic hemodilution increased the levels of HIF-1alpha protein and mRNA for HIF-1-responsive molecules. nNOS and VEGF protein levels were also increased within the cerebral cortex of anemic rats at clinically relevant hemoglobin concentrations.

Anemia↗
PubMed2006

Two-year outcomes, health care use, and costs of survivors of acute respiratory distress syndrome.

RATIONALE: Little is known about the long-term outcomes and costs of survivors of acute respiratory distress syndrome (ARDS). OBJECTIVES: To describe functional and quality of life outcomes, health care use, and costs of survivors of ARDS 2 yr after intensive care unit (ICU) discharge. METHODS: We recruited a cohort of ARDS survivors from four academic tertiary care ICUs in Toronto, Canada, and prospectively monitored them from ICU admission to 2 yr after ICU discharge. MEASUREMENTS: Clinical and functional outcomes, health care use, and direct medical costs. RESULTS: Eighty-five percent of patients with ARDS discharged from the ICU survived to 2 yr; overall 2-yr mortality was 49%. At 2 yr, survivors continued to have exercise limitation although 65% had returned to work. There was no statistically significant improvement in health-related quality of life as measured by Short-Form General Health Survey between 1 and 2 yr, although there was a trend toward better physical role at 2 yr (p = 0.0586). Apart from emotional role and mental health, all other domains remained below that of the normal population. From ICU admission to 2 yr after ICU discharge, the largest portion of health care costs for a survivor of ARDS was the initial hospital stay, with ICU costs accounting for 76% of these costs. After the initial hospital stay, health care costs were related to hospital readmissions and inpatient rehabilitation. CONCLUSIONS: Survivors of ARDS continued to have functional impairment and compromised health-related quality of life 2 yr after discharge from the ICU. Health care use and costs after the initial hospitalization were driven by hospital readmissions and inpatient rehabilitation.

Adult↗
PubMed2006

Case report: profound hypotension associated with labetalol therapy in a patient with cerebral aneurysms and subarachnoid hemorrhage.

PURPOSE: Labetalol is an effective antihypertensive medication frequently used to treat systemic hypertension in acute care settings, including the management of hypertension associated with a subarachnoid hemorrhage. We present a case of profound hypotension, refractory to inotropic and vasopressor therapy following an iv infusion of labetalol. CLINICAL FEATURES: Initiation of an iv labetalol infusion resulted in good blood pressure control in a patient suffering from a Fisher grade 3 subarachnoid hemorrhage with an initial Glascow coma scale of 14/15 and mild hydrocephalus. Progressive deterioration of neurological symptoms and evidence of worsening hydrocephalus preceded the sudden development of profound hypotension (60/35 mmHg) and bradycardia with a minimum heart rate of 40 beats.min(-1). Initial resuscitative efforts included administration of intravascular fluid, hypertonic saline, atropine, adrenalin (more than 10 mg in divided doses) and noradrenalin. These measures restored the blood pressure to 80/45 with a HR of 98 beats.min(-1). Intraoperative placement of an intraventricular drain released cerebrospinal fluid under pressure with an initial intracranial pressure of 15 cm H(2)O. A combination of adrenalin, noradrenalin, dopamine and vasopressin infusions were required to restore the blood pressure to 130/65 mmHg after an additional two hours. All inotropic and vasopressor support was weaned off after the 14th hr (about two drug half-lives). The patient was awake and responsive the following day, with no obvious neurological consequences. No evidence of neurological injury, drug administration error or myocardial dysfunction was documented. CONCLUSION: The episode of profound hypotension which occurred after initiating a labetolol infusion required maximal combined vasopressor therapy to restore the blood pressure suggesting that this patient demonstrated an extreme sensitivity to labetalol. Combination therapy with adrenergic and nonadrenergic agonists may be required for optimal treatment of profound hypotension associated with labetalol-induced vasoplegia.

Antihypertensive Agents↗
PubMed2006

Effect of oxygen affinity and molecular weight of HBOCs on cerebral oxygenation and blood pressure in rats.

PURPOSE: This study assessed the effect of oxygen affinity and molecular weight (MW) of o-raffinose cross-linked hemoglobin based oxygen carriers (HBOCs) on cerebral oxygen delivery and mean arterial blood pressure (MAP) following hemorrhage and resuscitation in rats. METHODS: Isoflurane anesthetized rats (n = 6-7 per group) underwent 30% hemorrhage and resuscitation with an equivalent volume of one of three different HBOCs: 1) High P50 Poly o-raffinose hemoglobin (Poly OR-Hb, P50 = 70 mmHg); 2) High P50 > 128 Poly OR-Hb (MW > 128 kDa, P50 = 70 mmHg) and 3) Low P50 > 128 Poly OR-Hb (MW >128 kDa, P50 = 11 mmHg). Hippocampal cerebral tissue oxygen tension, regional cerebral blood flow (rCBF), MAP, total hemoglobin concentration and arterial blood gases were measured. Data analysis by two-way ANOVA and post hoc Tukey tests determined significance (P < 0.05, mean +/- SD). RESULTS: Hippocampal tissue oxygen tension increased in all HBOC groups following resuscitation. The rCBF remained unchanged after HBOC resuscitation in all groups. Following resuscitation, the peak MAP was higher in the High P50 Poly OR-Hb group (152 +/- 13 mmHg) when compared to either the Low or High P50 large MW, (> 128 kDa) HBOC group (119 +/- 15 mmHg or 127 +/- 18 respectively, P < 0.05 for both). CONCLUSIONS: O-raffinose polymerized HBOC, with or without lower MW components, maintained cerebral tissue oxygen delivery following hemorrhage and resuscitation in rats. The higher MW HBOCs showed a decrease in peak MAP, which did not alter oxygen delivery. No significant effect of oxygen affinity on cerebral tissue oxygen tension or blood flow was observed.

Animals↗
PubMed2006

Factors affecting perioperative transfusion decisions in patients with coronary artery disease undergoing coronary artery bypass surgery.

BACKGROUND: A high proportion of patients having cardiac bypass surgery receive erythrocyte transfusions. Decisions about when to transfuse patients having surgery for coronary artery disease may impact on erythrocyte utilization and patient morbidity and mortality. There are no published data about the factors that influence physicians' decisions to transfuse erythrocytes to these patients. The objectives of this study were to determine the hemoglobin concentration for transfusion and the factors that influence physicians' perioperative transfusion decisions for coronary artery bypass patients. METHODS: The authors conducted a cross-sectional study using pretested, self-administered, mailed questionnaires sent in 2004 to all cardiac surgeons and anesthesiologists in Canada who participate in coronary artery bypass surgery. The questionnaire included four intraoperative and four postoperative vignettes. Factors assessed included patient age, sex, cardiac index, and myocardial ischemia. RESULTS: The response rates were 70% (345 of 489) for the intraoperative and 61% (297 of 489) for the postoperative case scenarios. The mean hemoglobin concentrations for transfusion were 7.0 g/dl for the intraoperative case scenarios and 7.2 g/dl for the postoperative case scenarios. Older age, the presence of myocardial ischemia, and a low cardiac index were factors that increased the hemoglobin concentration for transfusion (P < 0.0001). Physicians ranked myocardial ischemia as the most significant factor affecting their transfusion decisions. CONCLUSIONS: Factors such as the presence of a low cardiac index, myocardial ischemia, and older age increase the hemoglobin concentrations at which physicians transfuse coronary bypass surgery patients. Future studies are required to elucidate whether transfusions based on these variables affect patient morbidity and mortality.

Adult↗
PubMed2006

Treatment of pulmonary hypertension with selective pulmonary vasodilators.

PURPOSE OF REVIEW: Pulmonary vasodilators are important in the management of pulmonary hypertension. Although systemic vasodilators may be effective in lowering pulmonary artery pressure, systemic vasodilation is the main limitation to dose titration. This review summarizes the latest research and developments in pulmonary vasodilators in the management of acute and chronic pulmonary hypertension. RECENT FINDINGS: Nitric oxide, the prototype of selective pulmonary vasodilators, remains an effective option in the management of pulmonary hypertension; however, cost and complexity of administration have led to consideration of other pulmonary vasodilators. Animal research suggests that nitric oxide may have an important role in the prevention of pulmonary hypertension after cardiopulmonary bypass. Experience with phosphodiesterase inhibitors, as monotherapy or as part of combination therapy, suggests that these agents improve cardiopulmonary hemodynamics and can be considered as alternatives and/or adjuncts to nitric oxide. Prostacyclins are a versatile class of pulmonary vasodilator as they have been shown to improve pulmonary hemodynamics administered intravenously or via inhalation. Endothelin receptor antagonists have been shown to be effective for long-term management of pulmonary hypertension. Several gene therapy strategies are currently undergoing evaluation. SUMMARY: Selective pulmonary vasodilation can be achieved through delivery of vasodilators directly to the lungs or targeting pulmonary specific processes. Several therapeutic options are available that demonstrate selectivity for the pulmonary vasculature. These agents can facilitate optimization of cardiopulmonary hemodynamics.

Calcium Channel Blockers↗
PubMed2005

Natural course of left atrial thrombi after bioprosthetic mitral valve replacement in a patient with heparin-induced thrombocytopenia.

Left atrial (LA) clots involving prosthetic mitral valves are unusual complications of heparin-induced thrombocytopenia (HIT), and little is known about their natural history. A 73-year-old woman underwent bioprosthetic mitral valve replacement, which was complicated by atrial fibrillation and LA thrombus due to HIT. She was treated medically and followed up for 18 months. The present case provides unique insights into the natural history of HIT-related LA thrombus involving a bioprosthetic valve. It highlights the importance of having a high index of suspicion for this condition and avoiding the use of warfarin early in the course of the condition.

Aged↗
PubMed2004

A multicenter risk index for atrial fibrillation after cardiac surgery.

CONTEXT: Atrial fibrillation is a common, but potentially preventable, complication following coronary artery bypass graft (CABG) surgery. OBJECTIVES: To assess the nature and consequences of atrial fibrillation after CABG surgery and to develop a comprehensive risk index that can better identify patients at risk for atrial fibrillation. DESIGN, SETTING, AND PARTICIPANTS: Prospective observational study of 4657 patients undergoing CABG surgery between November 1996 and June 2000 at 70 centers located within 17 countries, selected using a systematic sampling technique. From a derivation cohort of 3093 patients, associations between predictor variables and postoperative atrial fibrillation were identified to develop a risk model, which was assessed in a validation cohort of 1564 patients. MAIN OUTCOME MEASURE: New-onset atrial fibrillation after CABG surgery. RESULTS: A total of 1503 patients (32.3%) developed atrial fibrillation after CABG surgery. Postoperative atrial fibrillation was associated with subsequent greater resource use as well as with cognitive changes, renal dysfunction, and infection. Among patients in the derivation cohort, risk factors associated with atrial fibrillation were advanced age (odds ratio [OR] for 10-year increase, 1.75; 95% confidence interval [CI], 1.59-1.93); history of atrial fibrillation (OR, 2.11; 95% CI, 1.57-2.85) or chronic obstructive pulmonary disease (OR, 1.43; 95% CI, 1.09-1.87); valve surgery (OR, 1.74; 95% CI, 1.31-2.32); and postoperative withdrawal of a beta-blocker (OR, 1.91; 95% CI, 1.52-2.40) or an angiotensin-converting enzyme (ACE) inhibitor (OR 1.69; 95% CI, 1.38-2.08). Conversely, reduced risk was associated with postoperative administration of beta-blockers (OR, 0.32; 95% CI, 0.22-0.46), ACE inhibitors (OR, 0.62; 95% CI, 0.48-0.79), potassium supplementation (OR, 0.53; 95% CI, 0.42-0.68), and nonsteroidal anti-inflammatory drugs (OR, 0.49; 95% CI, 0.40-0.60). The resulting multivariable risk index had adequate discriminative power with an area under the receiver operating characteristic (ROC) curve of 0.77 in the validation sample. Forty-three percent (640/1503) of patients who had atrial fibrillation after CABG surgery experienced more than 1 episode of atrial fibrillation. Predictors of recurrent atrial fibrillation included older age, history of congestive heart failure, left ventricular hypertrophy, aortic atherosclerosis, bicaval venous cannulation, withdrawal of ACE inhibitor or beta-blocker therapy, and use of amiodarone or digoxin (area under the ROC curve of 0.66). Patients with recurrent atrial fibrillation had longer hospital stays and experienced greater infectious, renal, and neurological complications than those with a single episode. CONCLUSIONS: We have developed and validated models predicting the occurrence of atrial fibrillation after CABG surgery based on an analysis of a large multicenter international cohort. Our findings suggest that treatment with beta-blockers, ACE inhibitors, and/or nonsteroidal anti-inflammatory drugs may offer protection. Atrial fibrillation after CABG surgery is associated with important complications.

Aged↗
PubMed2004

Comparison of bolus remifentanil versus bolus fentanyl for induction of anesthesia and tracheal intubation in patients with cardiac disease.

OBJECTIVE: Large bolus-dose remifentanil may be advantageous for use during induction of anesthesia because of its short duration of effect. Currently, there are little data on the use of large bolus-dose remifentanil because of reports of severe bradycardia and hypotension. The purpose of this study is to compare the hemodynamic effects of bolus remifentanil versus fentanyl with glycopyrrolate for induction of anesthesia in patients with heart disease. DESIGN: A randomized, double-blinded study. SETTING: A tertiary-care academic medical center. PARTICIPANTS: One hundred patients for coronary artery bypass or valvular surgery. INTERVENTION: Subjects received either (1) remifentanil, 5 microg/kg, with glycopyrrolate, 0.2 mg, or (2) fentanyl, 20 microg/kg, with 0.2 mg of glycopyrrolate, and both groups also received midazolam, 70 microg/kg, for induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: Heart rate, mean arterial pressure, systemic vascular resistance, and cardiac output were similar between the 2 groups during induction of anesthesia and tracheal intubation. The incidence of adverse events such as bradycardia (remifentanil 10%, fentanyl 10%), hypotension (remifentanil 16%, fentanyl 10%), and ischemia (remifentanil 0%, fentanyl 2%) were also similar. A greater percentage of patients in the remifentanil group lost consciousness within 1 minute of opioid administration (86% v 66%, p = 0.034). CONCLUSION: Remifentanil with glycopyrrolate is associated with rapid and predictable clinical anesthetic effect, cardiac stability, and the ability to blunt the hemodynamic responses to tracheal intubation. Bolus remifentanil may be a feasible alternative to bolus fentanyl for induction of anesthesia in patients with heart disease because of its short duration of action and its ability to blunt the hemodynamic responses to tracheal intubation.

Adjuvants, Anesthesia↗
PubMed2004

Increased cerebral tissue oxygen tension after extensive hemodilution with a hemoglobin-based oxygen carrier.

Transfusion of anemic patients with hemoglobin-based oxygen carriers (HBOCs) may improve cerebral oxygen delivery. Conversely, cerebral vasoconstriction, associated with HBOC transfusion, could limit optimal cerebral tissue oxygenation. We hypothesized that hemodilution with a HBOC would maintain cerebral tissue oxygenation, despite the occurrence of cerebral vasoconstriction. Isoflurane-anesthetized rats (100% oxygen) underwent direct measurement of mean arterial blood pressure (MAP), caudate tissue oxygen tension (P(Br)o(2)), and regional cortical cerebral blood flow (rCBF) before and after 50% of the estimated blood volume (30 mL/kg) was exchanged with either an HBOC (hemoglobin raffimer; Hemolink) or pentastarch (n = 6). Hemodilution with hemoglobin raffimer caused a transient increase in P(Br)o(2) from 24.9 +/- 13.3 mm Hg to 32.2 +/- 19.1 mm Hg (P < 0.05), a sustained increase in MAP, and no change in rCBF. Arterial blood oxygen content was maintained despite an increase in methemoglobin and reduced oxygen saturation. Hemodilution with pentastarch caused a transient increase in MAP, no change in P(Br)o(2), and a sustained increase in rCBF (P < 0.05), whereas the hemoglobin concentration and oxygen content were significantly reduced. Hemodilution with hemoglobin raffimer augmented P(Br)o(2) and prevented the increase in rCBF observed after similar hemodilution with pentastarch. These data suggest that transfusion with hemoglobin raffimer may help to maintain cerebral oxygenation during severe anemia.

Animals↗
PubMed2003

One-year outcomes in survivors of the acute respiratory distress syndrome.

BACKGROUND: As more patients survive the acute respiratory distress syndrome, an understanding of the long-term outcomes of this condition is needed. METHODS: We evaluated 109 survivors of the acute respiratory distress syndrome 3, 6, and 12 months after discharge from the intensive care unit. At each visit, patients were interviewed and underwent a physical examination, pulmonary-function testing, a six-minute-walk test, and a quality-of-life evaluation. RESULTS: Patients who survived the acute respiratory distress syndrome were young (median age, 45 years) and severely ill (median Acute Physiology, Age, and Chronic Health Evaluation score, 23) and had a long stay in the intensive care unit (median, 25 days). Patients had lost 18 percent of their base-line body weight by the time they were discharged from the intensive care unit and stated that muscle weakness and fatigue were the reasons for their functional limitation. Lung volume and spirometric measurements were normal by 6 months, but carbon monoxide diffusion capacity remained low throughout the 12-month follow-up. No patients required supplemental oxygen at 12 months, but 6 percent of patients had arterial oxygen saturation values below 88 percent during exercise. The median score for the physical role domain of the Medical Outcomes Study 36-item Short-Form General Health Survey (a health-related quality-of-life measure) increased from 0 at 3 months to 25 at 12 months (score in the normal population, 84). The distance walked in six minutes increased from a median of 281 m at 3 months to 422 m at 12 months; all values were lower than predicted. The absence of systemic corticosteroid treatment, the absence of illness acquired during the intensive care unit stay, and rapid resolution of lung injury and multiorgan dysfunction were associated with better functional status during the one-year follow-up. CONCLUSIONS: Survivors of the acute respiratory distress syndrome have persistent functional disability one year after discharge from the intensive care unit. Most patients have extrapulmonary conditions, with muscle wasting and weakness being most prominent.

APACHE↗
PubMed2003

Hemodilutional anemia is associated with increased cerebral neuronal nitric oxide synthase gene expression.

Severe hemodilutional anemia may reduce cerebral oxygen delivery, resulting in cerebral tissue hypoxia. Increased nitric oxide synthase (NOS) expression has been identified following cerebral hypoxia and may contribute to the compensatory increase in cerebral blood flow (CBF) observed after hypoxia and anemia. However, changes in cerebral NOS gene expression have not been reported after acute anemia. This study tests the hypothesis that acute hemodilutional anemia causes cerebral tissue hypoxia, triggering changes in cerebral NOS gene expression. Anesthetized rats underwent hemodilution when 30 ml/kg of blood were exchanged with pentastarch, resulting in a final hemoglobin concentration of 51.0 +/- 1.2 g/l (n = 7 rats). Caudate tissue oxygen tension (Pbr(O(2))) decreased transiently from 17.3 +/- 4.1 to 14.4 +/- 4.1 Torr (P < 0.05), before returning to baseline after approximately 20 min. An increase in CBF may have contributed to restoring Pbr(O(2)) by improving cerebral tissue oxygen delivery. An increase in neuronal NOS (nNOS) mRNA was detected by RT-PCR in the cerebral cortex of anemic rats after 3 h (P < 0.05, n = 5). A similar response was observed after exposure to hypoxia. By contrast, no increases in mRNA for endothelial NOS or interleukin-1beta were observed after anemia or hypoxia. Hemodilutional anemia caused an acute reduction in Pbr(O(2)) and an increase in cerebral cortical nNOS mRNA, supporting a role for nNOS in the physiological response to acute anemia.

Anemia↗
PubMed2003

Hypercapnia increases cerebral tissue oxygen tension in anesthetized rats.

PURPOSE: To test the hypotheses that deliberate elevation of PaCO(2) increases cerebral tissue oxygen tension (PBrO(2)) by augmenting PaO(2) and regional cerebral blood flow (rCBF). METHODS: Anesthetized rats were exposed to increasing levels of inspired oxygen (O(2)) or carbon dioxide (CO(2); 5%, 10% and 15%, n = 6). Mean arterial blood pressure (MAP), PBrO(2) and rCBF were measured continuously. Blood gas analysis and hemoglobin concentrations were determined for each change in inspired gas concentration. Data are presented as mean +/- standard deviation with P < 0.05 taken to be significant. RESULTS: The PBrO(2) increased in proportion to arterial oxygenation (PaO(2)) when the percentage of inspired O(2) was increased. Proportional increases in PaCO(2) (48.7 +/- 4.9, 72.3 +/- 6.0 and 95.3 +/- 15.4 mmHg), PaO(2) (172.2 +/- 33.1, 191.7 +/- 42.5 and 216.0 +/- 41.8 mmHg), and PBrO(2) (29.1 +/- 9.2, 49.4 +/- 19.5 and 60.5 +/- 23.0 mmHg) were observed when inspired CO(2) concentrations were increased from 0% to 5%, 10% and 15%, respectively, while arterial pH decreased (P < 0.05 for each). Exposure to CO(2) increased rCBF from 1.04 +/- 0.67 to a peak value of 1.49 +/- 0.45 (P < 0.05). Following removal of exogenous CO(2), arterial blood gas values returned to baseline while rCBF and PBrO(2) remained elevated for over 30 min. The hypercapnia induced increase in PBrO(2) was threefold higher than that resulting from a comparable increase in PaO(2) achieved by increasing the inspired O(2) concentration (34.9 +/- 14.5 vs 11.4 +/- 5.0 mmHg, P < 0.05). CONCLUSION: These data support the hypothesis that the combined effect of increased CBF, PaO(2) and reduced pH collectively contribute to augmenting cerebral PBrO(2) during hypercapnia.

Animals↗
PubMed2003

Dynamic characteristics of cerebral lipid microemboli: videomicroscopy studies in rats.

UNLABELLED: Cerebral lipid microemboli (LME) may cause postoperative cognitive dysfunction after orthopedic and cardiovascular surgery. In 13 anesthetized rats, we created a cranial window to study LME using orthogonal polarization spectral imaging videomicroscopy. All rats received 0.2 mL of human marrow fat, obtained from surgical waste during arthroplasty, injected into the superior vena cava. Five rats died within seconds of this injection, despite resuscitation efforts. Seven minutes later, we injected an additional 0.1 mL in 6 of the 8 surviving rats. We observed the videomicroscopy for 1 h in all 8 rats. Arterial blood pressure (BP) was continuously measured. No LME were observed in the first 7 min (n = 8); however, within seconds of the additional 0.1 mL injection, mean BP decreased from 79 +/- 31 mm Hg to 28 +/- 12 mm Hg (n = 6; P < 0.02). Epinephrine and crystalloid infusion increased BP to 161 +/- 9 mm Hg and 20-100 LME were seen within 5 min. LME changed shape and fragmentation, erosion, and streaming patterns were noted, with transient arteriolar occlusion (10-220 s). Increasing BP resulted in reperfusion of occluded arterioles. No venous LME were noted. Postmortem, brain and lung LME were found with no patent foramen ovale. This model may be useful in studying cerebral LME. IMPLICATIONS: Marrow lipid may pass through the lung during orthopedic surgery, creating cerebral lipid microemboli (LME). We created a cranial window in rats to study LME flowing through pial-cortical vessels. Cerebral LME appeared after resuscitation from hypotension and vessel occlusion was transient. This model may be useful in studying cerebral LME.

Animals↗
PubMed2002

PVC tracheal tubes exert forces and pressures seven to ten times higher than silicone or armoured tracheal tubes--an in vitro study.

PURPOSE: Many types of tracheal tubes (TT) including silicone, polyvinylchloride (PVC) and armoured have been used for blind tracheal intubation (TI) via the intubating laryngeal mask airway (ILMA) and may cause trauma to the airway. We examined the maximal in vitro forces and pressures exerted by the tip of various TT as it exits the ILMA. METHODS: Silicone, PVC and armoured TT were studied. A #5 ILMA was secured on a wooden platform. With the use of a Harvard pump, force was applied to push the TT through the ILMA at 0.34 cm*sec(-1). Forces exerted to push the TT and forces exerted by the TT tips on distal objects were calculated using proximal and distal pressure manometres. The areas of contact between the distal TT tips and the distal objects were measured by planimetry of an imprint. The final pressures exerted by the TT tips on a fixed distal object were calculated by dividing the forces exerted by the areas of contact. RESULTS: When compared to silicone and armoured TT, PVC TT exerted seven to ten times higher forces and pressures on distal objects. (P < 0.05). Heating PVC TT and inserting PVC TT with reverse curvature to the ILMA did not decrease the forces and pressures exerted by the distal tip. CONCLUSION: The high forces and pressures exerted by PVC TT may theoretically contribute to increased morbidity to patients' airway and esophagus. Caution should be exercised before attempting blind TI via the ILMA with a PVC TT.

Intubation, Intratracheal↗