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Swen N Piper

Publications and source records attributed to Swen N Piper.

13 recordsLinked to original sources
PubMed2006

Noninvasive assessment of cardiac output using thoracic electrical bioimpedance in hemodynamically stable and unstable patients after cardiac surgery: a comparison with pulmonary artery thermodilution.

OBJECTIVE: To compare noninvasive cardiac output (CO)measurement obtained with a new thoracic electrical bioimpedance (TEB) device, using a proprietary modification of the impedance equation, with invasive measurement obtained via pulmonary artery thermodilution. DESIGN: Prospective, observational study. SETTING: Surgical intensive care unit (ICU) of a university-affiliated community hospital. PATIENTS AND PARTICIPANTS: Seventy-four adult patients undergoing elective cardiac surgery with routine pulmonary artery catheter placement. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Simultaneous paired CO and cardiac index (CI) measurements by TEB and thermodilution were obtained in mechanically ventilated patients upon admission to the ICU. For analysis of CI data the patients were subdivided into a hemodynamically stable group and a hemodynamically unstable group. The groups were analyzed using linear regression and tests of bias and precision. We found a significant correlation between thermodilution and TEB (r = 0.83; n < 0.001), accompanied by a bias of -0.01 l/min/m(2) and a precision of +/-0.57 l/min/m(2) for all CI data pairs. Correlation, bias, and precision were not influenced by stratification of the data. The correlation coefficient, bias, and precision for CI were 0.86 (n< 0.001), 0.03 l/min/m(2), and +/-0.47 l/min/m(2) in hemodynamically stable patients and 0.79 (n< 0.001), 0.06 l/min/m(2), and +/-0.68 l/min/m(2) in hemodynamically unstable patients. CONCLUSIONS: Our results demonstrate a close correlation and clinically acceptable agreement and precision between CO measurements obtained with impedance cardiography using a new algorithm to calculate CO from variations in TEB, and those obtained with the clinical standard of care, pulmonary artery thermodilution, in hemodynamically stable and unstable patients after cardiac surgery.

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PubMed2006

Total intravenous anesthesia with propofol and remifentanil is associated with a nearly twofold higher incidence in postanesthetic shivering than desflurane-fentanyl anesthesia.

BACKGROUND: Postanesthetic shivering (PAS) is a frequent side effect of general anesthesia. Previous reports on the incidence of PAS of propofol for the induction or maintenance of anesthesia have been controversial, but have not been studied in detail. The aim of the present study was to evaluate the incidence and severity of PAS in total intravenous anesthesia (TIVA) with propofol and remifentanil compared with an inhalative anesthesia. MATERIAL/METHODS: After ethics committee approval and written informed consent from the patients, 53 patients scheduled for urologic, gynecologic, or surgical operations were studied for shivering postoperatively using a five-point rating scale. They received desflurane-fentanyl based anesthesia (n=27) or TIVA with propofol and remifentanil (n=26). Hemodynamics and temperature were measured after induction of anesthesia (T0), and 5 min (T1), 15 min (T2), 30 min (T3), and 60 min (T4) after reaching the postanesthetic care unit (PACU). RESULTS: In the TIVA group, 18/26 (69.2%) patients suffered from PAS compared with 10/27 (37%) in the desflurane-fentanyl group (P<0.02). The severity of shivering was significantly higher with TIVA than with desflurane (P<0.02), whereas temperature showed no significant difference between the study groups. CONCLUSIONS: Postanesthetic shivering appears significantly more frequently and intensively after TIVA with propofol and remifentanil compared with an inhalative anesthesia with fentanyl and desflurane.

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PubMed2005

Continuous intra- and postoperative thoracic epidural analgesia attenuates brain natriuretic peptide release after major abdominal surgery.

We investigated whether blocking afferent nociceptive inputs by continuous intra- and postoperative thoracic epidural analgesia (TEA) would decrease plasma concentrations of brain natriuretic peptide (BNP) in patients who were at risk for, or had, coronary artery disease. Twenty-eight patients undergoing major abdominal surgery received either general anesthesia supplemented with a continuous thoracic epidural infusion of 1.25 mg/mL bupivacaine and 1 microg/mL sufentanil (n = 14; TEA) or general anesthesia followed by IV patient-controlled analgesia (n = 14; IV PCA). Visual analog scale pain scores, hemodynamics, plasma catecholamines, cardiac troponin T, atrial natriuretic peptide (ANP), and BNP were serially measured preoperatively, 90 min after skin incision, at arrival in the intensive care unit, and in the morning of the first, second, and third postoperative day. Dynamic visual analog scale scores were significantly less in the TEA group. TEA reduced the postoperative heart rate without affecting other hemodynamic variables. Plasma epinephrine increased perioperatively in both groups but was significantly lower in the TEA group. Baseline ANP and BNP concentrations were similar between groups (TEA 3.4 +/- 1.8 and 27.0 +/- 12.3 pg/mL; IV PCA 3.1 +/- 2.0 and 25.9 +/- 13.0 pg/mL, respectively). ANP and BNP increased perioperatively in both groups, with significantly lower postoperative BNP levels in TEA patients (TEA 92.1 +/- 31.9 pg/mL; IV PCA 161.2 +/- 44.7 pg/mL). No such difference was observed in plasma ANP concentrations. Plasma cardiac troponin T concentrations were within normal limits in both groups at all times. We conclude that continuous perioperative TEA using local anesthetics and opioids attenuated the release of BNP in patients undergoing major abdominal surgery who were at risk for, or had, coronary artery disease.

Abdomen↗
PubMed2004

The influence of allogeneic red blood cell transfusion compared with 100% oxygen ventilation on systemic oxygen transport and skeletal muscle oxygen tension after cardiac surgery.

In this study we investigated the effects of allogeneic red blood cell (RBC) transfusion on tissue oxygenation compared with those of 100% oxygen ventilation by using systemic oxygen transport variables and skeletal muscle oxygen tension (PtiO2). Fifty-one volume-resuscitated, mechanically ventilated patients with a nadir hemoglobin concentration in the range from 7.5 to 8.5 g/dL after elective coronary artery bypass grafting were allocated randomly to receive 1 unit (transfusion 1; n = 17) or 2 units (transfusion 2; n = 17) of allogeneic RBCs and ventilation with 40% oxygen or pure oxygen ventilation (100% oxygen; n = 17) and no allogeneic blood for 3 hours. Invasive arterial and pulmonary artery pressures and calculations of oxygen delivery (oxygen delivery index) and consumption indices (oxygen consumption index) were documented at 30-min intervals. PtiO2 was measured continuously by using implantable polarographic microprobes. Systemic oxygen transport variables and PtiO2 were similar between groups at baseline. The oxygen delivery index increased significantly with transfusion of allogeneic RBCs and 100% oxygen ventilation, whereas the oxygen consumption index remained unchanged. Oxygen 100% ventilation increased PtiO2 significantly (from 24.0 +/- 5.1 mm Hg to 34.2 +/- 6.2 mm Hg), whereas no change was found after transfusion of allogeneic RBCs. Peak PtiO2 values were 25.2 +/- 5.2 mm Hg and 26.3 +/- 6.5 mm Hg in the transfusion 1 and 2 groups, respectively. Transfusion of stored allogeneic RBCs was effective only in improving systemic oxygen delivery index, whereas 100% oxygen ventilation improved systemic oxygen transport and PtiO2. This improved oxygenation status was most likely due to an increase in convective oxygen transport with a large driving gradient for diffusion of plasma-dissolved oxygen into the tissue.

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PubMed2003

Diltiazem may preserve renal tubular integrity after cardiac surgery.

PURPOSE: To evaluate the influence of dopamine and diltiazem on renal function and markers for acute renal failure, including urinary alpha-glutathion s-transferase (alpha-GST), alpha-1-microglobulin (alpha(1)-MG) and N-acetyl-ss-glucosaminidase (ss-NAG) after extracorporeal circulation. METHODS: In a randomized, placebo-controlled, double-blind trial we evaluated the efficacy of dopamine (2.5 micro g x kg(-1) x min(-1)), diltiazem (2 micro g x kg(-1) x min(-1)) or placebo administered over 48 hr postoperatively to maintain renal tubular integrity in 60 elective cardiac surgery patients. alpha-GST, alpha(1)-MG, ss-NAG, and creatinine clearance were measured from urine collected during surgery (T0), the first four hours (T1), 24 hr (T2) and 48 hr (T3) postoperatively. RESULTS: Cumulative urine output in the diltiazem group (9.0 +/- 2.8 L) increased significantly compared with placebo (7.0 +/- 1.6 L), but not compared with dopamine (7.8 +/- 1.8 L). Creatinine clearance showed no significant intergroup differences. In all groups alpha(1)-MG increased from T0 to T3, but we found no significant intergroup differences. alpha-GST increased significantly from T0 to T3 in the placebo (2.1 +/- 1.8 to 11.4 +/- 8.6 micro g x L(-1)) and in the dopamine groups (2.7 +/- 1.8 to 13.6 +/- 14.9 micro g x L(-1)), but not in the diltiazem group (1.8 +/- 1.4 to 3.2 +/- 3.2 micro g x L(-1)). Forty-eight hours postoperatively alpha-GST was significantly lower in the diltiazem group than in both other groups. CONCLUSIONS: Diltiazem stimulates urine output, reduces excretion of alpha-GST and ss-NAG and may be useful to maintain tubular integrity after cardiac surgery.

Acetylglucosaminidase↗
PubMed2003

Influence of prolonged cardiopulmonary bypass times on splanchnic perfusion and markers of splanchnic organ function.

BACKGROUND: Cardiopulmonary bypass (CPB) is known to have considerable negative impact on perfusion and organ function. The effects of the duration of CPB on markers of splanchnic organ function was studied. METHODS: Consecutive patients undergoing elective aorto-coronary bypass grafting with CPB times (CPBT) of either less than 70 minutes (n = 15) or more than 80 minutes (n = 15) were prospectively studied. Splanchnic perfusion was assessed by measuring arterial and gastric mucosal PCO2 and calculating PCO2gap. Hepatic function was evaluated by monoethylglycinexylidide (MEGX) test and by measuring alpha-glutathione S-transferase (alpha-GST). Concentration of pancreatitis-associated protein was measured to assess pancreatic integrity. Measurements were performed after induction of anesthesia, at the end of surgery, 4 hours after arrival in the intensive care unit, and on postoperative day 1. RESULTS: The mean (+/- standard deviation) CPBT were 54 +/- 12 minutes and 99 +/- 16 minutes, respectively. PCO2gap increased significantly more in the group with CPBT of more than 80 minutes than in that with CPBT of less than 70 minutes, at +15 +/- 4 mm Hg versus +8 +/- 3 mm Hg, respectively, indicating reduction in splanchnic perfusion by longer CPBTs. Postoperative MEGX concentrations were significantly lower and postoperative alpha-GST concentrations were significantly higher in the group with CPBT of more than 80 minutes than in that with CPBT of less than 70 minutes. Plasma levels of pancreatitis-associated protein remained similar in both groups throughout the study period. CONCLUSIONS: In our patients with CPBT of more than 80 minutes, splanchnic perfusion and hepatocelluar integrity were moderately affected, whereas pancreatic function remained almost unchanged. Studies including a larger patient population are necessary to assess whether protective approaches would be helpful in patients undergoing complex cardiac surgery with very long CPBT.

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PubMed2002

Dolasetron, but not metoclopramide prevents nausea and vomiting in patients undergoing laparoscopic cholecystectomy.

PURPOSE: Postoperative nausea and vomiting (PONV) is one of the most frequent complications of general anesthesia. The aim of the study was to compare the antiemetic efficacy of dolasetron and metoclopramide after inhalational or i.v. anesthesia (IVA). METHODS: In a randomized, placebo-controlled, double-blinded trial we evaluated the efficacy of 12.5 mg dolasetron i.v. and 20 mg metoclopramide (MCP) i.v. in preventing PONV in 387 patients (ASA I-III) undergoing laparoscopic cholecystectomy. Patients were allocated randomly to one of three main groups: Group D (n = 129) received 12.5 mg dolasetron i.v., Group MCP (n = 129) 20 mg MCP i.v., and Group C (n = 129) saline as placebo i.v. Using a multifactorial study design, one third of each main group (n = 43) was further randomized to receive either general anesthesia with desflurane, isoflurane or IVA with propofol and remifentanil. PONV, postoperative piritramide and droperidol consumption were documented. RESULTS: Independent from the anesthesia regimen chosen, dolasetron reduced PONV (19%) significantly compared to MCP (45%) and placebo (46%). Furthermore we could show a significant difference in the incidence of PONV between IVA (28%) and isoflurane (46%), but not in comparison to desflurane (36%). Patients receiving IVA had a higher postoperative piritramide consumption compared to the two other groups. CONCLUSIONS: The results of our study suggest that dolasetron was more effective than MCP and placebo in preventing PONV. This action is independent of the anesthetic technique used.

Adult↗
PubMed2002

Dolasetron for preventing postanesthetic shivering.

UNLABELLED: We designed this study to assess the efficacy of dolasetron compared with clonidine and placebo in prophylaxis of postanesthetic shivering. We included 90 patients undergoing elective abdominal or urologic surgery. The patients were randomly assigned to one three groups (each group n = 30) using a double-blinded study protocol: Group A received 12.5 mg dolasetron, Group B 3 microg/kg clonidine, and Group C saline 0.9% as placebo. The medication was given after the induction of anesthesia. Postanesthetic shivering was judged by using a five-point scale. In the Clonidine group, 86.6% showed no shivering, whereas in the Dolasetron and Placebo groups, only 63.3% and 66.6%, respectively, were symptom free. Only clonidine, but not dolasetron, significantly reduced the incidence and the severity of shivering. We conclude that clonidine is effective in preventing shivering when given before surgery, whereas dolasetron, at the dose used, is not effective. IMPLICATIONS: Shivering, an irregular muscular fasciculation lasting longer than 15 s, is a common complication secondary to general anesthesia. We compared dolasetron with clonidine (an established antishivering drug) in the prevention of postanesthetic shivering. Dolasetron 12.5 mg was not effective.

Abdomen↗
PubMed2002

The influence of hyperoxic ventilation during sodium nitroprusside-induced hypotension on skeletal muscle tissue oxygen tension.

BACKGROUND: Increasing inspired oxygen concentrations might provide a simple and effective intervention to increase oxygen tension in tissues during controlled hypotension. To test this hypothesis, the influence of hyperoxic ventilation (100% O2) on skeletal muscle oxygen partial pressure (Ptio2) in patients receiving sodium nitroprusside-induced controlled hypotension was studied. METHODS: Forty-two patients undergoing radical prostatectomy were prospectively studied and randomly divided into three groups as follows: (1) Controlled hypotension induced by sodium nitroprusside (mean arterial blood pressure, 50 mmHg) and hyperoxic ventilation (CH-100%; n = 14); (2) controlled hypotension and ventilation with 50% O2 in nitrous oxide (CH-50%; n = 14); and (3) standard normotensive anesthesia with 50% O2 in nitrous oxide (control; n = 14). Ptio2 values were measured continuously in all patients using implantable polarographic microprobes. Arterial blood gases and lactate concentrations were analyzed in 30-min intervals. RESULTS: Surgical blood loss and transfusion requirements were significantly reduced in both groups receiving hypotensive anesthesia. During surgery, arterial partial pressure of oxy-gen and arterial oxygen content were significantly higher in patients of the CH-100% group. Baseline values of Ptio2 were comparable between the groups (CH-50%: 25.0 +/- 0.7 mmHg; CH-100%: 25.2 +/- 0.2 mmHg; control: 24.5 +/- 0.2 mmHg). After a transient increase in Ptio2 in the CH-100% group during normotension, Ptio2 values returned to baseline and remained unchanged in the control group. Ptio2 decreased significantly during the hypotensive period in the CH-50% group. The lowest mean Ptio2 values were 15.0 +/- 4.1 mmHg in the CH-50% group, 24.2 +/- 4.9 mmHg in the CH-100% group, and 23.5 +/- 3.8 mmHg in the control group. There were no significant changes in lactate plasma concentrations in any group throughout the study period. CONCLUSIONS: Hyperoxic ventilation improved skeletal muscle tissue oxygenation during sodium nitroprusside-induced hypotension. This improved local tissue oxygenation seems to be most likely due to an increase in convective oxygen transport and the attenuation of hyperoxemia-induced arteriolar vasoconstriction by sodium nitroprusside.

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PubMed2002

The heart in the elderly critically ill patient.

Cardiac complications such as myocardial infarction and congestive heart failure are the primary source of perioperative morbidity and mortality in elderly surgical patients. This is the result of structural and functional age-related changes in the heart and the vasculature and an increasing incidence of cardiovascular disorders. Appropriate perioperative management of the elderly patient should be based on the extent of functional compromise, the type and severity of pre-existing disease, and the invasiveness of the surgical procedure. Current studies suggest that appropriately administered medical therapy, particularly beta-adrenergic blockade, may reduce perioperative cardiovascular morbidity and mortality in these patients. In this article, we review changes in cardiovascular structure and function that occur with advancing age and describe perioperative medical interventions that may improve cardiac outcome in the elderly critically ill patient.

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