RESUMEN

OBJECTIVE: To assess the accuracy of aortic valve area (AVA) calculations using the continuity equation with data obtained from the double envelope (DE) (simultaneously obtained left ventricular outflow tract [V1]) and aortic valve [V2] velocities) during intraoperative transesophageal echocardiography (TEE). DESIGN: Prospective study; measurements were performed on-line. SETTING: University hospital. PARTICIPANTS: Cardiac and noncardiac surgical patients (n = 75) with recent aortic valve assessment (<3 months) undergoing general anesthesia or endotracheal intubation. INTERVENTIONS: Intraoperative AVA was measured by the continuity equation using the DE technique (DE/TEE) and by planimetry (PL/TEE). Left ventricular outflow tract diameter was obtained from midesophageal views, whereas subvalvular (V1) and valvular (V2) velocities were obtained simultaneously using continuous-wave Doppler from transgastric views. V1 was also obtained using pulsed-wave Doppler. Measurements were compared with AVA obtained preoperatively by the Gorlin equation during cardiac catheterization (G/CATH) or by transthoracic echocardiography using the traditional continuity equation (C/TTE) (nonsimultaneously obtained V1 and V2). MEASUREMENTS AND MAIN RESULTS: A DE was obtained in 73 of 75 patients (97%). Four patients had atrial fibrillation at the time of the examination, whereas the rest were in sinus rhythm. PL/TEE was performed in 54 of 71 patients with sinus rhythm (76%). Agreement was good between DE/TEE and G/CATH (mean bias, 0.02 cm(2) [SD, 0.24 cm(2)]), and C/TTE (mean bias, -0.05 cm(2) [SD, 0.16 cm(2)]). Agreement was not as good between PL/TEE and G/CATH (mean bias, -0.07 cm(2) [SD, 0.28 cm(2)]) and C/TTE (mean bias, -0.13 cm(2) [SD, 0.30 cm(2)]). V1 obtained by pulsed-wave Doppler and with DE closely agreed (mean bias, 0.01 m/sec [SD, 0.05 m/sec]). CONCLUSION: TEE evaluation of native AVA using the DE technique is feasible and in good agreement with that obtained by C/TTE and G/CATH. Compared with DE/TEE, PL/TEE did not agree as well. Use of DE/TEE should simplify the continuity equation and may minimize errors resulting from beat-to-beat variability in stroke volume.

Asunto(s)

RESUMEN

BACKGROUND: The ability of intravenous lidocaine to prevent intubation-induced bronchospasm is unclear. The authors performed a prospective, randomized, double-blind, placebo-controlled trial to test the ability of intravenous lidocaine and inhaled albuterol to attenuate airway reactivity after tracheal intubation in asthmatic patients undergoing general anesthesia. METHODS: Sixty patients were randomized to receive either 1.5 mg/kg intravenous lidocaine or saline, 3 min before tracheal intubation. An additional 50 patients were randomized to receive 4 puffs of inhaled albuterol or placebo 15-20 min before tracheal intubation. Anesthesia was induced with propofol. Immediately after intubation and at 5-min intervals, transpulmonary pressure and airflow were recorded, and lower pulmonary resistance (RL) was calculated. Isoflurane was administered after the initial two measurements to assess reversibility of bronchoconstriction. A bronchoconstrictor response to intubation was defined as RL greater than or equal to 5 cm H2O. l-1. s-1 in the first two measurements after intubation and RL subsequently decreasing by 50% or more after isoflurane. RESULTS: The lidocaine and placebo groups were not different in the peak RL before administration of isoflurane (8.2 cm H2O. l-1. s-1 vs. 7.6 cm H2O. l-1. s-1) or frequency of airway response to intubation (lidocaine 6 of 30 vs. placebo 5 of 27). In contrast, the albuterol group had lower peak RL (5.3 cm H2O. l-1. s-1 vs. 8.9 cm H2O. l-1. s-1; P < 0.05) and a lower frequency of airway response (1 of 25 vs. 8 of 23; P < 0.05) than the placebo group. CONCLUSIONS: Inhaled albuterol blunted airway response to tracheal intubation in asthmatic patients, whereas intravenous lidocaine did not.

Asunto(s)

RESUMEN

OBJECTIVE: To determine if intraoperative magnesium supplementation would be associated with a reduction in postoperative atrial tachyarrhythmias (POAT) in patients undergoing coronary artery bypass grafting (CABG) surgery without cardiopulmonary bypass (off-pump CABG surgery). DESIGN: Retrospective study. SETTING: University Medical Center. PARTICIPANTS: Patients who had undergone off-pump CABG surgery (n = 124). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The charts of 124 patients who had undergone off-pump CABG surgery (64 by anterior thoracotomy and 60 by median sternotomy) were retrospectively reviewed. Demographic data and perioperative care were recorded and compared among patients who did and did not experience POAT and among patients who did and did not receive intraoperative magnesium supplementation. Logistic regression analysis was used to assess the association between magnesium supplementation and incidence of POAT, controlling for other covariables. Of the 124 patients, 16 had a prior history of atrial or ventricular arrhythmias and/or were receiving antiarrhythmic medications. Medical records of the remaining 108 patients were reviewed. Twenty-four patients (22%) had POAT. Forty-two patients (39%) received intraoperative magnesium. In patients receiving intraoperative magnesium, the incidence of POAT was significantly decreased (12% v 29%; p = 0.03). In these patients, initial postoperative serum magnesium was significantly higher (2.37 mEq/L v 1.86 mEq/L; p < 0.01). In patients not receiving intraoperative magnesium, 35% had hypomagnesemia (serum magnesium < 1.8 mEq/L) compared with 9% of patients receiving magnesium (p < 0.01). Patients who received intraoperative magnesium and beta-adrenergic blockers had a lower incidence of POAT (5%) than patients who received only one (19%) or neither (33%) (p < 0.05). CONCLUSIONS: Intraoperative magnesium supplementation is associated with a decrease in POAT after off-pump CABG surgery. The combination of a beta-blocker and magnesium may reduce POAT further. It is recommended that intraoperative magnesium supplementation be part of the care of patients undergoing off-pump CABG surgery.

Asunto(s)

RESUMEN

UNLABELLED: The conventional continuity equation uses nonsimultaneous measurements of blood flow velocities through the left ventricular outflow tract and across the aortic valve to calculate aortic valve area (AVA). We have noted that both velocities can be simultaneously obtained from continuous wave (CW) Doppler analysis (double-envelope [DE]). We hypothesize that prosthetic AVA can be calculated by using the DE technique, during transesophageal echocardiography (TEE). Prosthetic AVA was calculated in 41 of 45 patients immediately after aortic valve replacement by using the DE/AVA technique. Left ventricular outflow tract diameter was obtained from an esophageal view, while subvalvular (V(1)) and valvular (V(2)) peak velocities were simultaneously obtained from transgastric views by using CW Doppler. Prosthetic AVA and V(1)/V(2) ratio (Doppler velocity index) were calculated. V(1) was also measured by using pulse wave Doppler, as is conventionally done. Twenty-three Carbomedic (CM) and 18 Carpentier-Edwards (CE) AVA were evaluated. DE/AVAs for CM and CE valves correlated and agreed with that reported by the manufacturer (CM r(2) = 0.91, mean bias -0.25 cm(2) [SD 0.18]; CE r(2) = 0.73, mean bias -0.02 cm(2) [SD 0.27]). Calculated Doppler velocity index values agree with available data (mean bias 0.03 [SD 0.05]). The V(1) obtained by using the DE method was nearly identical to the V(1) obtained by using pulse wave (r(2) = 0.95, mean bias 0.02 m/s [SD 0.04 m/s]). TEE assessment of prosthetic AVA using the DE technique agrees with data reported by the manufacturer. Obtaining subvalvular and valvular velocities from the same CW Doppler trace may simplify the continuity equation and help avoid errors caused by beat-to-beat changes in blood flow. Quantitative prosthetic aortic valve assessment can be performed, on-line, with TEE by using the DE technique. IMPLICATIONS: Quantitative assessment of prosthetic aortic valve area can be performed on-line by using transesophageal echocardiography using the double envelope technique.

Asunto(s)

RESUMEN

OBJECTIVE: To investigate the effect of heparin-coated pulmonary artery catheters (HPACs) on activated coagulation time (ACT) drawn through a non-heparin-coated introducer sheath. DESIGN: A prospective, observational study. SETTING: University teaching hospital. PARTICIPANTS: Patients scheduled for surgical procedures requiring cardiopulmonary bypass. INTERVENTIONS: With institutional review board approval, 63 patients without prior coagulopathy undergoing procedures requiring cardiopulmonary bypass were studied. Jugular venous and radial arterial ACTs were measured before and immediately after insertion of an HPAC. Additional measurements were obtained 1 hour later and 4 minutes after completion of protamine infusion. MEASUREMENTS AND MAIN RESULTS: The ACT drawn from the introducer after placement of an HPAC was 48 seconds greater than the ACT drawn before the HPAC was placed (p < 0.0001). This difference was still present 1 hour later but not after the administration of protamine or in blood drawn at any time from another site. Baseline ACTs drawn from radial arterial catheters, kept patent using a heparin flush system, resulted in elevated measurements, despite withdrawing seven times the deadspace before taking a sample. CONCLUSIONS: Blood obtained from an introducer with an HPAC in situ provides a spuriously high ACT. ACTs drawn from catheters kept patent using heparin flush also result in prolonged measurements. Baseline ACT measurement from an introducer should be obtained before placement of the HPAC.

Asunto(s)

RESUMEN

OBJECTIVE: To determine predictors of systolic anterior motion and left ventricular outflow tract obstruction (SAM/LVOTO) after mitral valve repair (MVRep) in patients with myxomatous mitral valve disease. BACKGROUND: Mechanisms for the development of SAM/LVOTO after MVRep have been described; however, predictors of this complication have not been explored. We hypothesize that pre-MVRep transesophageal echocardiography (TEE) can predict postrepair SAM/ LVOTO. METHODS: Using TEE, the lengths of the coapted anterior (AL) and posterior (PL) leaflets and the distance from the coaptation point to the septum (C-Sept) were measured before and after MVRep in 33 patients, including 11 who developed SAM/LVOTO (Group 1) and 22 who did not (Group 2). RESULTS: Group 1 patients had smaller AL/PL ratios (0.99 vs. 1.95, p < 0.0001) and C-Sept distances (2.53 vs. 3.01 cm, p = 0.012) prior to MVRep than those in Group 2. Resolution of SAM/LVOTO was associated with increases in AL/PL ratio and C-Sept distance. This reflects a more anterior position of the coaptation point in those who developed SAM/ LVOTO. CONCLUSIONS: These data suggest that TEE analysis of the mitral apparatus can identify patients likely to develop SAM/LVOTO after MVRep for myxomatous valve disease. The findings are consistent with the concept that SAM of mitral leaflets is due to anterior malposition of slack mitral leaflet portions into the LVOT. The position of the coaptation point of the mitral leaflets is dynamic and a potential target and end point for surgical designs to prevent SAM/LVOTO post MVRep.

Asunto(s)

RESUMEN

OBJECTIVE: The authors hypothesized that changes in surgical procedures for minimally invasive direct coronary artery bypass grafting (MIDCAB) have led to changes in anesthetic management with a resultant decrease in the complexity of care. DESIGN: Retrospective observational study. SETTING: University teaching hospital. PARTICIPANTS: Review of the records of 60 patients who underwent MIDCAB surgery. MEASUREMENTS AND MAIN RESULTS: Data included preoperative demographics, perioperative anesthetic management, and postoperative cardiac and noncardiac issues and complications. Two groups were formed: in group I, a coronary stabilizer (CS) was not used, and in group II, it was. With the exception of a greater incidence of those with no preoperative comorbidities in group II (CS), there were no differences between the two groups with respect to demographics or preoperative variables. A surgical design called H-graft was used in a greater number of group II (CS) patients, whereas a direct anastomosis was performed in the majority of group I patients. Use of pharmacologically induced bradycardia/asystole has not been performed after the introduction of the CS. The use of central venous catheters (instead of pulmonary artery catheters) and single-lumen (v double-lumen) endotracheal tubes was greater in group II (CS) patients. Despite changes in intraoperative management, there was no significant change in the incidence of postoperative complications, intensive care unit stay, and hospital stay between groups I and II. New-onset atrial fibrillation was the most common postoperative complication (13 of 56 patients; 23%). Three of 24 patients (12.5%) who received intraoperative magnesium experienced atrial fibrillation compared with 10 of 32 patients (31%) who did not receive magnesium. CONCLUSIONS: The complexity of anesthetic technique has decreased since the onset of MIDCAB surgery. The decrease in complexity may be related to changes in surgical design and technology.

Asunto(s)

RESUMEN

PURPOSE: Accurate haemodynamic assessment during surgical repair of scoliosis is crucial to the care of the patient. The purpose of this study was to compare transoesophageal echocardiography (TEE) with central venous pressure monitoring in patients with spinal deformities requiring surgery in the prone position. METHODS: Twelve paediatric patients undergoing corrective spinal surgery for scoliosis/kyphosis in the prone position were studied. Monitoring included TEE, intra-arterial and central venous pressure monitoring (CVP). Haemodynamic assessment was performed prior to and immediately after positioning the patient prone on the Relton-Hall table. Data consisted of mean arterial blood pressure (mBP), heart rate (HR), CVP, left ventricular end-systolic and end-diastolic diameters (LVESD and LVEDD respectively) and fractional shortening (FS). Right ventricular (RV) function and tricuspid regurgitation (TR) were assessed qualitatively. Analysis was performed using descriptive statistics, Student's t test, sign rank, and correlation analysis. RESULTS: There was an increase in CVP (8.7 mmHg to 17.7 mmHg; P < .01), and decreases in LVEDD (37.1 mm to 33.2 mm; P < .05), and mean blood pressure (75.0 mmHg to 65.7 mmHg; P < .05) when patients were placed in the prone position. Fractional shortening, LVESD, and HR did not change from the supine to the prone position. Right ventricular systolic function and tricuspid regurgitation were unchanged. CONCLUSION: These data indicate that the CVP is a misleading monitor of cardiac volume in patients with kyphosis/scoliosis in the prone position. This is consistent with previous studies. In this clinical situation, TEE may be a more useful monitoring tool to assess on-line ventricular size and function.

Asunto(s)

RESUMEN

PURPOSE: The purpose of this study was to determine factors associated with abnormal coagulation in the setting of intrauterine fetal death (IUFD). METHODS: We reviewed the charts of 238 patients diagnosed with IUFD over ten years. Data included demographics, co-existing obstetric disease and coagulation studies. A coagulation score was assigned based on the platelet count, prothrombin time, activated partial thromboplastin time and plasma fibrinogen concentration. Approximately 90% of the study population had coagulation scores < 4. A score of > or = 4 was considered abnormal. RESULTS: Complete coagulation analysis was available in 183/238 patients (77%) within 24 hr of delivery. One hundred and sixty-four of these (89.6%) had a coagulation score, < 4 and 19 had a score > or = 4 (10.4%). No relationship between the coagulation score and age, parity, gestational age at delivery, and number of days the dead fetus remained in utero was found. A coagulation score > = or 4 was associated with the presence of a pregnancy-related disease (P < 0.05), notably abruption (P < 0.001) and uterine perforation (P < 0.05). Four patients without co-existing disease (3.2%), had a coagulation score > or = 4. CONCLUSION: In most pregnancies complicated by fetal demise, the fetus and placenta are delivered within one week of fetal demise. The previously reported severe coagulation disturbances are largely eliminated by early delivery. Our study shows that coagulation abnormalities occur in some patients with uncomplicated IUFDs (3.2%) and that this number rises in the presence of abruption or uterine perforation.

Asunto(s)

RESUMEN

OBJECTIVE: To determine the ability of transesophageal echocardiography to accurately identify or exclude left atrial thrombi. DESIGN: Prospective cohort study. SETTING: University hospital. PATIENTS: 231 consecutive patients having transesophageal echocardiography before elective repair or replacement of the mitral valve or excision of a left atrial tumor. Fifty-six percent of patients had a history of atrial fibrillation, and 17% had a history of thromboembolism. MEASUREMENT: Identification of left atrial thrombi during transesophageal echocardiographic examination and comparison with direct near-simultaneous visualization during cardiac surgery. RESULTS: Transesophageal echocardiography identified 14 left atrial thrombi in 14 patients (6%). Thrombus size range from 3 to 80 mm. Surgery confirmed 12 of 14 thrombi (86%), including 9 thrombi confined to the left appendage. No additional thrombi were found on direct inspection of the atria (sensitivity, 100% [95% CI, 74% to 100%]; specificity, 99% [CI, 97% to 99.9%]; positive predictive value, 86% [12/14]; negative predictive value, 100% [217/217]; for a population that had a 5.2% prevalence of thrombi). All 12 surgically confirmed thrombi were identified by two independent observers. Neither thrombus seen by only a single observer on transesophageal echocardiography was confirmed during direct inspection of the atria at surgery. CONCLUSION: Transesophageal echocardiography is highly accurate for identifying left atrial thrombi and can be used clinically to exclude left atrial thrombi.

Asunto(s)

RESUMEN

The objective of this study was to compare the haemodynamic and myocardial effects of pipecuronium and pancuronium in patients undergoing coronary artery bypass grafting (CABG) during benzodiazepine/sufentanil anaesthesia. Twenty-seven ASA III-IV patients received lorazepam (1-3 mg) po and midazolam ( < 0.1 mg.kg-1) i.v. before induction of anaesthesia with sufentanil (3-8 micrograms.kg-1) was administered to facilitate tracheal intubation. According to random allocation, each patient received either pipecuronium (150 micrograms.kg-1) or pancuronium (120 micrograms.kg-1) after sternotomy but before heparinization. Mean arterial pressure, central venous pressure (CVP), pulmonary artery pressure (PAP), ST segment position and ECG (leads III, V5, AVF) were monitored continuously throughout the procedure. Thermodilution determinations of CO in triplicate were made immediately before, and at two and five minutes after muscle relaxant administration. Multiplane transoesophageal echocardiography (TEE, midpapillary short axis views of the left ventricle) images were continuously recorded from ten minutes before until ten minutes after muscle relaxant administration and graded by two experienced echocardiographic readers. Heart rate, MAP and CO increased after administration of pancuronium (by 13.6 beats.min-1, 10.8 mmHg and 1.0 L.min-1 respectively) but not after pipecuronium (P < 0.05). Evidence of myocardial ischaemia was not detected in any patients using ECG ST segment analysis or TEE assessment of left ventricular wall motion. We conclude that pancuronium caused increases in HR, MAP and CO but that neither pancuronium nor pipecuronium caused myocardial ischaemia.

Asunto(s)

Asunto(s)