Biomedical subjects

C David Mazer

Publications and source records attributed to C David Mazer.

23 records · Page 2Linked to original sources

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↗

PubMed2002

Survey of the members of the cardiovascular section of the Canadian Anesthesiologists' Society on the use of perioperative transesophageal echocardiography - a brief report.

PURPOSE: Transesophageal echocardiography (TEE) is a useful diagnostic and monitoring tool in the operating room. In the United States, an increasing number of centres are training anesthesiologists to preform intraoperative TEE. In Canada, TEE has been slow to gain acceptance as an intraoperative monitor and little information is available on its use by the anesthesiologists across the country. METHODS: We surveyed all members of the cardiovascular section of the Canadian Anesthesiologists' Society, to find out how many perform TEE, how they acquired their skills and how they use TEE in their practice. RESULTS: The response rate was 48.4%. Most respondents were Canadian-trained cardiac anesthesiologists working in university centres. 91% of respondents stated that their centres offer intraoperative TEE services. Of those services, 35.1% were provided by anesthesiologists only, 13% by cardiologists only, and 51.9% by both. 53.8% of respondents have certification in intraoperative TEE (NBE/SCA, ASE or Provincial College). 90% of respondents use equipment that is less than five years old and multiplane probes are used by almost everyone. There was strong support for Canadian-based continuing medical education events in perioperative TEE. CONCLUSION: TEE appears to be available in most cardiac centres in Canada and anesthesiologists are actively involved in providing intraoperative TEE services, using state-of-the-art equipment. Many anesthesiologists have formal training in TEE.

Anesthesiology↗

PubMed2002

Right heart obstruction from a balloon-like sinus of Valsalva aneurysm in a patient with Down syndrome.

A 40-year-old man with Down syndrome presented with right heart failure. He was markedly obese and had severe developmental delay. There was marked edema and an early diastolic sound. Transthoracic echocardiography suggested a right heart mass. Transesophageal echocardiography revealed an unruptured balloon-like sinus of Valsalva aneurysm within the right atrium that obstructed the tricuspid orifice. The patient died in hospital of mixed obstructive and/or septic shock.

Adult↗

PubMedDate not supplied

Successful treatment using recombinant factor VIIa for severe bleeding post cardiopulmonary bypass.

PURPOSE: To describe a case of persistent and excessive bleeding following an aortic valve and ascending aorta replacement that was successfully managed with recombinant factor VIIa (rFVIIa). The postulated mechanisms for rFVIIa are discussed. CLINICAL FEATURES: A 75-yr-old female with no preoperative coagulopathy underwent a tissue aortic valve replacement and supracoronary ascending aorta replacement for severe aortic stenosis and an ascending aortic aneurysm. Following surgery, she bled in excess of 200 mL x hr(-1) despite a nearly normal platelet count and nearly normal coagulation parameters. The patient was surgically re-explored twice in seven hours, and despite the presence of near normal in vitro coagulation parameters, the patient continued to bleed. Multiple units of fresh frozen plasma, platelets and cryoprecipitate were administered empirically. We then administered a single 6-mg (107 microg x kg(-1)) iv dose of rFVIIa. Following the administration of rFVIIa, blood loss decreased to a total of 440 mL over the next 12 hr. CONCLUSIONS: This case describes the use of rFVIIa for intractable bleeding postcardiovascular surgery in the presence of nearly normal laboratory markers of coagulation. Further controlled laboratory and clinical studies are required to define the role of rFVIIa in patients undergoing cardiovascular surgery.

Aged↗