Emeritus Faculty - University Medical Line, Anesthesiology, Perioperative and Pain Medicine
MD, University of Utrecht, Medicine (1975)
PhD, University of Maastricht, Physiology (1988)
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Cardiovascular Pharmacology, Cardiovascular Physiology,
Neurophysiology and Monitoring,
This study was undertaken to compare the effect of deep hypothermic circulatory arrest, compared with moderate hypothermia, on the plasma concentrations and pharmacokinetic profile of vancomycin, administered as prophylaxis, in patients undergoing cardiac surgery with cardiopulmonary bypass.Two groups of adult cardiac surgery patients were prospectively studied. One group consisted of 12 patients undergoing valvular surgery with moderate hypothermia, and another group was of 12 patients undergoing surgery with the use of profound hypothermic circulatory arrest. Vancomycin was administered before skin incision, and plasma levels were measured at regular intervals for 24h.The plasma concentrations of vancomycin showed a similar pattern in both groups. The pharmacokinetic profile showed a three-compartment model in both groups.The dosing of vancomycin, if used as antibiotic prophylaxis, does not need to be adjusted in cardiac surgery patients when undergoing profound hypothermic circulatory arrest, since the plasma concentrations and pharmacokinetic profile are similar to patients with moderate hypothermia. The pharmacokinetic profile, consisting of three compartments, was not changed by the differences in temperature.
View details for DOI 10.1016/j.ejcts.2010.03.029
View details for Web of Science ID 000285221700018
View details for PubMedID 20663677
Chronic rejection, manifested pathologically as airway fibrosis, is the major problem limiting long-term survival in lung transplant recipients. Airway hypoxia and ischemia, resulting from a failure to restore the bronchial artery (BA) circulation at the time of transplantation, may predispose patients to chronic rejection. To address this possibility, clinical information is needed describing the status of lung perfusion and airway oxygenation after transplantation.To determine the relative pulmonary arterial blood flow, airway tissue oxygenation and BA anatomy in the transplanted lung was compared with the contralateral native lung in lung allograft recipients.Routine perfusion scans were evaluated at 3 and 12 months after transplantation in 15 single transplant recipients. Next, airway tissue oximetry was performed in 12 patients during surveillance bronchoscopies in the first year after transplant and in 4 control subjects. Finally, computed tomography (CT)-angiography studies on 11 recipients were reconstructed to evaluate the post-transplant anatomy of the BAs.By 3 months after transplantation, deoxygenated pulmonary arterial blood is shunted away from the native lung to the transplanted lung. In the first year, healthy lung transplant recipients exhibit significant airway hypoxia distal to the graft anastomosis. CT-angiography studies demonstrate that BAs are abbreviated, generally stopping at or before the anastomosis, in transplant airways.Despite pulmonary artery blood being shunted to transplanted lungs after transplantation, grafts are hypoxic compared with both native (diseased) and control airways. Airway hypoxia may be due to the lack of radiologically demonstrable BAs after lung transplantation.
View details for DOI 10.1164/rccm.200910-1573OC
View details for Web of Science ID 000280206700014
View details for PubMedID 20339145
View details for PubMedCentralID PMC3269232
Delirium is a neurobehavioral syndrome caused by the transient disruption of normal neuronal activity secondary to systemic disturbances.The authors investigated the effects of postoperative sedation on the development of delirium in patients undergoing cardiac-valve procedures.Patients underwent elective cardiac surgery with a standardized intraoperative anesthesia protocol, followed by random assignment to one of three postoperative sedation protocols: dexmedetomidine, propofol, or midazolam.The incidence of delirium for patients receiving dexmedetomidine was 3%, for those receiving propofol was 50%, and for patients receiving midazolam, 50%. Patients who developed postoperative delirium experienced significantly longer intensive-care stays and longer total hospitalization.The findings of this open-label, randomized clinical investigation suggest that postoperative sedation with dexmedetomidine was associated with significantly lower rates of postoperative delirium and lower care costs.
View details for Web of Science ID 000267537700004
View details for PubMedID 19567759
Endoleaks after stent-graft repair of aortic dissections are poorly understood but seem substantially different from those seen after aneurysm repair. We studied anatomic and clinical factors associated with endoleaks in patients who underwent stent-graft repair of complicated type B aortic dissections.From 2000 to 2007, 37 patients underwent stent-graft repair of acute (< or =14 days; n=23), subacute (15 to 90 days; n=10) or chronic (>90 days; n=4) complicated type B aortic dissections using the Gore Thoracic Excluder (n=17) or TAG stent-grafts (n=20) under an investigator-sponsored protocol. Endoleaks were classified as imperfect proximal seal, flow through fenestrations or branches, or complex (both). Variables studied included coverage of the left subclavian artery, aortic curvature, completeness of proximal apposition, dissection chronicity, and device used. Endoleaks were found during follow-up (mean, 22 months) in 59% of patients, and they were associated with coverage of the left subclavian artery (complex, P<0.001), small radius of curvature (type 1 and complex, P=0.05), and greatest length of unapposed proximal stent graft (complex, P<0.0001). During follow-up, 10 endoleaks resolved spontaneously, 6 required reintervention for false lumen dilatation, and 2 were stable without clinical consequences.Endoleaks are common after stent-graft repair of aortic dissection and may lead to false lumen enlargement necessitating reintervention. Anatomic complexities such as acute aortic curvature and covered side branches were associated with endoleaks, illustrating the need for dissection-specific device development.
View details for DOI 10.1161/CIRCINTERVENTIONS.108.819722
View details for PubMedID 20031703
We sought to assess the effects of cardiopulmonary bypass and profound hypothermic circulatory arrest on plasma cefazolin levels administered for antimicrobial prophylaxis in cardiovascular surgery.Four groups (10 patients per group) were prospectively studied: vascular surgery without cardiopulmonary bypass (group A), cardiac surgery with a cardiopulmonary bypass time of less than 120 minutes (group B), cardiac surgery with a cardiopulmonary bypass time of greater than 120 minutes (group C), and cardiac surgery with cardiopulmonary bypass and profound hypothermic circulatory arrest (group D). Subjects received cefazolin at induction and a second dose before wound closure. Arterial blood samples were obtained preceding cefazolin administration, at skin incision, hourly during the operation, and before redosing. Cefazolin plasma concentrations were determined by using a radial diffusion assay, with Staphylococcus aureus as the indicator microorganism. Cefazolin plasma concentrations were considered noninhibitory at 8 microg/mL or less, intermediate at 16 mug/mL, and inhibitory at 32 microg/mL or greater.In group A cefazolin plasma concentrations remained greater than 16 microg/mL during the complete surgical procedure. In group B cefazolin plasma concentrations diminished to 16 microg/mL or less in 30% of the patients but remained greater than 8 microg/mL. In group C cefazolin plasma concentrations decreased to less than 16 microg/mL in 60% of patients and were less than 8 microg/mL in 50% of patients. In group D cefazolin plasma concentrations reached 16 microg/mL in 66% of the patients but decreased to 8 microg/mL in only 1 patient.For patients undergoing cardiac surgery with a cardiopulmonary bypass time of greater than 120 minutes, a single dose of cefazolin before skin incision with redosing at wound closure does not provide targeted antimicrobial cefazolin plasma levels during the entire surgical procedure. Patients undergoing profound hypothermic circulatory arrest are better protected, but the described protocol of prophylaxis is not optimal.
View details for DOI 10.1016/j.jtcvs.2005.11.047
View details for PubMedID 16733167
We describe a patient with a history of hemangiopericytoma, who had hemoptysis develop due to a pseudoaneurysm of the thoracic aorta from an intrathoracic metastasis. Stent-graft repair successfully excluded the aneurysm from the aorta. Transesophageal echocardiography showed to be an important guide for correct placement of the device.
View details for DOI 10.1016/j.athoracsur.2005.07.016
View details for Web of Science ID 000238027600059
View details for PubMedID 16731179
Acute heart failure has become a major medical issue in the western population. Because mortality is still as high as 50%, the treatment of these patients has been the focus of many studies. A new approach has recently been proposed, including B-type natriuretic peptide as a medication. The purpose of this review is to discuss these new developments.Recent studies have shown that plasma levels of B-type natriuretic peptide may serve as a marker for the severity of acute decompensated heart failure. Nesiritide, which is the recombinant equivalent of B-type natriuretic peptide, is a vasodilator, acting by increasing cyclic guanosine 3', 5'-monophosphate in the vascular smooth muscle cells. It is mainly considered to be an alternative for nitroglycerin, because it has fewer side-effects, and its activity is more prolonged. Treatment with nesiritide has shown fewer arrhythmias and a lower mortality rate compared with dobutamine and milrinone. In cardiac surgery, nesiritide is mainly administered to patients awaiting heart transplantation, but intraoperatively the doses of nesiritide and anesthetics must be adjusted because of a potential interaction. A few anecdotal reports have shown the advantageous effects of nesiritide in the early post-bypass period.Anesthesiologists will be confronted with increasing numbers of patients with heart failure, who require new forms of medication. Nesiritide is a promising new tool, and its application, which is still mainly restricted to the preoperative period, will probably soon be extended to the early post-bypass period.
View details for PubMedID 16534321
The choice of anesthetics for vascular surgical patients is not only determined by the kind and extent of the surgical procedure but also by patient comorbidities. Frequently, patients have a history of hypertension, peripheral vascular and coronary artery disease,cerebrovascular disease, and renal impairment. The goal of the chosen anesthetic technique is to protect organ function, mainly of the brain and the heart. In some instances regional anesthesia might be preferred, but no difference in outcome between the two techniques has been shown conclusively. Vascular emergencies are particularly challenging for the anesthesiologist, but in recent years the development of stent graft insertion has improved the short-term outcome in many of these procedures.
View details for PubMedID 15182868
The authors evaluated the ability of visible light spectroscopy (VLS) oximetry to detect hypoxemia and ischemia in human and animal subjects. Unlike near-infrared spectroscopy or pulse oximetry (SpO2), VLS tissue oximetry uses shallow-penetrating visible light to measure microvascular hemoglobin oxygen saturation (StO2) in small, thin tissue volumes.In pigs, StO2 was measured in muscle and enteric mucosa during normoxia, hypoxemia (SpO2 = 40-96%), and ischemia (occlusion, arrest). In patients, StO2 was measured in skin, muscle, and oral/enteric mucosa during normoxia, hypoxemia (SpO2 = 60-99%), and ischemia (occlusion, compression, ventricular fibrillation).In pigs, normoxic StO2 was 71 +/- 4% (mean +/- SD), without differences between sites, and decreased during hypoxemia (muscle, 11 +/- 6%; P < 0.001) and ischemia (colon, 31 +/- 11%; P < 0.001). In patients, mean normoxic StO2 ranged from 68 to 77% at different sites (733 measures, 111 subjects); for each noninvasive site except skin, variance between subjects was low (e.g., colon, 69% +/- 4%, 40 subjects; buccal, 77% +/- 3%, 21 subjects). During hypoxemia, StO2 correlated with SpO2 (animals, r2 = 0.98; humans, r2 = 0.87). During ischemia, StO2 initially decreased at -1.3 +/- 0.2%/s and decreased to zero in 3-9 min (r2 = 0.94). Ischemia was distinguished from normoxia and hypoxemia by a widened pulse/VLS saturation difference (Delta < 30% during normoxia or hypoxemia vs. Delta > 35% during ischemia).VLS oximetry provides a continuous, noninvasive, and localized measurement of the StO2, sensitive to hypoxemia, regional, and global ischemia. The reproducible and narrow StO2 normal range for oral/enteric mucosa supports use of this site as an accessible and reliable reference point for the VLS monitoring of systemic flow.
View details for Web of Science ID 000221551300018
View details for PubMedID 15166566