Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2003
Case ReportsTransnasal placement of biplane transesophageal echocardiography probe intraoperatively in an adolescent with congenital heart disease.
Intraoperative transesophageal echocardiography (TEE) is frequently used in children with congenital heart disease (CHD). Although transnasal TEE is being used in various settings in the adult population, there are no descriptions of its use intraoperatively in patients with CHD. This report describes the successful use of transnasal TEE after multiple unsuccessful transoral attempts in an adolescent male undergoing subaortic stenosis repair. ⋯ Transnasal transesophageal echocardiography (TEE) is being used in various settings in the adult population. The author describes its use intraoperatively in an adolescent undergoing surgery for congenital heart disease after unsuccessful transoral attempts.
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Anesthesia and analgesia · Dec 2003
Risk factors for acute lung injury after thoracic surgery for lung cancer.
Acute lung injury (ALI) may complicate thoracic surgery and is a major contributor to postoperative mortality. We analyzed risk factors for ALI in a cohort of 879 consecutive patients who underwent pulmonary resections for non-small cell lung carcinoma. Clinical, anesthetic, surgical, radiological, biochemical, and histopathologic data were prospectively collected. The total incidence of ALI was 4.2% (n = 37). In 10 cases, intercurrent complications (bronchopneumonia, n = 5; bronchopulmonary fistula, n = 2; gastric aspiration, n = 2; thromboembolism, n = 1) triggered the onset of ALI 3 to 12 days after surgery, and this was associated with a 60% mortality rate (secondary ALI). In the remaining 27 patients, no clinical adverse event preceded the development of ALI-0 to 3 days after surgery-that was associated with a 26% mortality rate (primary ALI). Four independent risk factors for primary ALI were identified: high intraoperative ventilatory pressure index (odds ratio, 3.5; 95% confidence interval, 1.7-8.4), excessive fluid infusion (odds ratio, 2.9; 95% confidence interval, 1.9-7.4), pneumonectomy (odds ratio, 2.8; 95% confidence interval, 1.4-6.3), and preoperative alcohol abuse (odds ratio, 1.9; 95% confidence interval, 1.1-4.6). In conclusion, we describe two clinical forms of post-thoracotomy ALI: 1). delayed-onset ALI triggered by intercurrent complications and 2). an early form of ALI amenable to risk-reducing strategies, including preoperative alcohol abstinence, lung-protective ventilatory modes, and limited fluid intake. ⋯ In an observational study including all patients undergoing lung surgery, we describe two clinical forms of acute lung injury (ALI): a delayed-onset form triggered by intercurrent complications and an early form associated with preoperative alcohol consumption, pneumonectomy, high intraoperative pressure index, and excessive fluid intake over the first 24 h.
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Anesthesia and analgesia · Dec 2003
Clinical TrialEndotracheal tube cuff pressure is unpredictable in children.
The use of cuffed tracheal tubes in children younger than 8 yr of age has recently increased, although cuff hyperinflation may cause tracheal mucosal damage. In this study, we sought to measure the cuff pressure (P(cuff)) after initial free air inflation (iP(cuff)) and to follow its evolution throughout the duration of 50% nitrous oxide (N(2)O) anesthesia. One-hundred-seventy-four children, aged 0 to 9 yr, fulfilling the following criteria, were studied: 1). weight of 3-35 kg; 2). ASA physical status I or II; 3). elective surgery; 4). anesthesia with tracheal intubation using a cuffed tube and lasting at least 45 min; and 5). gas mixture containing 50% N(2)O. Free air inflation results in variable iP(cuff), with hyperinflation in 39% of cases. Numerous gas removals were required to maintain P(cuff) less than 25 cm H(2)O in 85% of the patients. The number of deflations decreased with the duration of mechanical ventilation and was small after 105 min. No difference was observed among the different cuffed tube sizes. We conclude that iP(cuff) is unpredictable after free air inflation and that numerous gas removals are required to maintain P(cuff) less than 25 cm H(2)O during N(2)O anesthesia in children. ⋯ Free inflation of the tracheal tube cuff, controlled only by the palpation of the pilot balloon, is not reliable and results in extremely variable (and sometimes very high) initial cuff pressures in children. In addition, nitrous oxide anesthesia may result in cuff hyperinflation requiring numerous gas removals.
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Anesthesia and analgesia · Dec 2003
Estimating alveolar dead space from the arterial to end-tidal CO(2) gradient: a modeling analysis.
Using an original, validated, high-fidelity model of pulmonary physiology, we compared the arterial to end-tidal CO(2) gradient divided by the arterial CO(2) tension (Pa-E'CO(2)/PaCO(2)) with alveolar dead space expressed as a fraction of alveolar tidal volume, calculated in the conventional manner using Fowler's technique and the Bohr equation: (VDalv/VTalv)(Bohr-Fowler). We examined the variability of Pa-E'CO(2)/PaCO(2) and of (VDalv/VTalv)(Bohr-Fowler) in the presence of three ventilation-perfusion defects while varying CO(2) production (Vdot;CO(2)), venous admixture, and anatomical dead space fraction (VDanat). Pa-E'CO(2)/PaCO(2) was approximately 59.5% of (VDalv/VTalv)(Bohr-Fowler). During constant alveolar configuration, the factors examined (Vdot;CO(2), pulmonary shunt fraction, and VDanat) each caused variation in (VDalv/VTalv)(Bohr-Fowler) and in Pa-E'CO(2)/PaCO(2). Induced variation was slightly larger for Pa-E'CO(2)/PaCO(2) during changes in VDanat, but was similar during variation of venous admixture and Vdot;CO(2). Pa-E'CO(2)/PaCO(2) may be a useful serial measurement in the critically ill patient because all the necessary data are easily obtained and calculation is significantly simpler than for (VDalv/VTalv)(Bohr-Fowler). ⋯ Using an original, validated, high-fidelity model of pulmonary physiology, we have demonstrated that the arterial to end-tidal carbon dioxide pressure gradient may be used to robustly and accurately quantify alveolar dead space. After clinical validation, its use could replace that of conventionally calculated alveolar dead space fraction, particularly in the critically ill.
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Anesthesia and analgesia · Dec 2003
Prevention of atelectasis formation during induction of general anesthesia.
General anesthesia promotes atelectasis formation, which is augmented by administration of large oxygen concentrations. We studied the efficacy of positive end-expiratory pressure (PEEP) application during the induction of general anesthesia (fraction of inspired oxygen [FIO(2)] 1.0) to prevent atelectasis. Sixteen adult patients were randomly assigned to one of two groups. Both groups breathed 100% O(2) for 5 min and, after a general anesthesia induction, mechanical ventilation via a face mask with a FIO(2) of 1.0 for another 5 min before endotracheal intubation. Patients in the first group (PEEP group) had continuous positive airway pressure (CPAP) (6 cm H(2)O) and mechanical ventilation via a face mask with a PEEP of 6 cm H(2)O. No CPAP or PEEP was applied in the control group. Atelectasis, determined by computed radiograph tomography, and analysis of blood gases were measured twice: before the beginning of anesthesia and directly after the intubation. There was no difference between groups before the anesthesia induction. After endotracheal intubation, patients in the control group showed an increase of the mean area of atelectasis from 0.8% +/- 0.9% to 4.1% +/- 2.0% (P = 0.0002), whereas the patients of the PEEP group showed no change (0.5% +/- 0.6% versus 0.4% +/- 0.7%). After the intubation with a FIO(2) of 1.0, PaO(2) was significantly higher in the PEEP group than in the control (591 +/- 54 mm Hg versus 457 +/- 99 mm Hg; P = 0.005). Atelectasis formation is prevented by application of PEEP during the anesthesia induction despite the use of large oxygen concentrations, resulting in improved oxygenation. ⋯ Application of positive end-expiratory pressure during the induction of general anesthesia prevents atelectasis formation. Furthermore, it improves oxygenation and probably increases the margin of safety before intubation. Therefore, this technique should be considered for all anesthesia induction, at least in patients at risk of difficult airway management during the anesthesia induction.