Cold agglutinins complicating repair of aortic dissection using cardiopulmonary bypass and hypothermic circulatory arrest: case report and review.

Cold agglutinins (CAs) are autoantibodies that react reversibly with red blood cells (RBCs) at temperatures of, or below, the thermal amplitude for agglutination. This results in increased blood viscosity and sludging of RBC, and may impair perfusion to various organ systems. Although this phenomenon appears rarely in the clinical arena, the incidence of CA is increased substantially in cardiac surgery due to the routine use of hypothermia for organ preservation and systemic metabolic reduction. Once activated, CA are associated with microvascular occlusion, hemolysis, complement fixation, renal and hepatic insufficiency, cerebral insult, and myocardial infarction. Complications from CA may be minimized with appropriate screening, detection, and management in the perioperative period. A prototypical case is described, and pertinent issues regarding CA are reviewed.

Cardiac arrest from inadvertent overdose of lidocaine hydrochloride through an arterial pressure line flush apparatus.

IMPLICATIONS: An overdose of the antiarrhythmic drug, lidocaine hydrochloride, was inadvertently administered to a patient through an arterial pressure monitoring apparatus, resulting in cardiac asystole. This medication error demonstrates to all anesthesia care team members the importance of preventing similar occurrences.

Experience with spiral computed tomography as the sole diagnostic method for traumatic aortic rupture.

BACKGROUND: Spiral computed tomographic (CT) scan is an excellent screen for aortic trauma. Traditionally, aortography is performed when injury is suspected to confirm the diagnosis. We hypothesized that it is safe and expeditious to forgo aortography when the spiral CT demonstrates aortic injury. METHODS: Retrospective review of 54 patients undergoing aortic repair from July 1994 to December 1999. Spiral CT was the initial diagnostic study in 52 patients. Pseudoaneurysm or aortic wall defect in the presence of mediastinal hematoma was considered diagnostic. Angiography, initially routine, was later performed only when requested by the surgeon, and for all "nonnegative" studies (periaortic hematoma without detectable aortic injury). RESULTS: Twenty-six patients underwent angiography before operation (group 1). Nineteen group 1 spiral CTs were unequivocally diagnostic; 7 were nonnegative and angiography was required. Twenty-eight other patients underwent repair based on spiral CT alone (group 2). There was one false-positive result in both groups. There were no unexpected operative findings. Mean time from admission to diagnosis was 5.7+/-3.4 hours for group 1 and 1.7+/-1.7 hours for group 2 (p < 0.01). CONCLUSIONS: Operating on the basis of a diagnostic spiral CT is safe and expeditious. Aortography may be reserved for those with equivocal studies.

Fenoldopam infusion associated with preserving renal function after aortic cross-clamping for aneurysm repair.

BACKGROUND: Cross-clamping of the descending aorta during operative repairs causes sudden, significant reductions in renal function that may persist well beyond arterial clamp release. Commonly used agents, such as dopamine and mannitol, have not consistently affected renal outcome in these high-risk patients. Fenoldopam mesylate is a novel, highly selective dopamine type-1 agonist that preferentially dilates the renal and splanchnic vasculature, but has not been investigated in patients undergoing prolonged aortic clamping for whom adverse renal outcomes should be more likely. METHODS AND RESULTS: Twenty-two adult patients without significant pre-existing renal dysfunction and presenting for elective repairs of abdominal aortic aneurysms were studied. Fenoldopain mesylate was infused after obtaining baseline values ranging from 0.1 to 1.0 microg/kg/min for the first 24 hours postoperatively to maintain mean arterial pressure +/-25% baseline. Serial renal function indices, including creatinine clearance and electrolyte fractional excretions, were measured at baseline, at aortic clamping and unclamping, and post-clamp release, and were estimated through hospital discharge. Creatinine clearance fell during abdominal exploration and clamping, reaching a nadir with clamp removal. Partial recovery occurred by 2 hours after clamp removal, and returned to baseline values by postoperative day 1 and thereafter. Fractional excretions rose rapidly throughout the operative phase. Total fenoldopam dose was directly related to the baseline creatinine clearance; after clamp removal, creatinine clearance was directly related to the mean arterial pressure at the lowest dose of fenoldopam, and inversely related to the mean arterial pressure at clamp release. CONCLUSIONS: In elderly patients with severe vascular disease undergoing aneurysmal repairs, the use of a fenoldopam infusion in this open-label, uncontrolled trial was associated with a relatively rapid return of renal function to baseline values, despite profound decreases during aortic cross-clamping. Further studies will be necessary to investigate how fenoldopam infusions compare with traditional therapies.

Spinal anesthesia versus general anesthesia for hip fracture repair: a longitudinal observation of 741 elderly patients during 2-year follow-up.

The Baltimore Hip Studies, a multicenter, noninterventional, observational trial, provided an opportunity to investigate the effects of anesthetic technique on the long-term outcome of elderly patients after hip fracture repair. Detailed interviews assessing functional status and pain were conducted during the hospital stay. Out-of-hospital evaluations were repeated after the procedure at 2, 6, 12, 18, and 24 months with a portable gait and balance laboratory. Multivariate analysis was done to determine the effects of anesthetic technique on functional and other outcomes, after controlling for multiple baseline variables. Of 741 enrolled patients who completed the study, 430 and 311 patients received spinal anesthesia or general anesthesia, respectively. Subgroup analysis of three spinal anesthetics, tetracaine, lidocaine, and epinephrine, was also done. In the present large observational study, general anesthesia was at least as efficacious as spinal anesthesia, and possibly better, in affording good long-term outcome.

Pulmonary artery thromboendarterectomy: a comparison of two different postoperative treatment strategies.

UNLABELLED: Pulmonary artery thromboendarterectomy (PTE) is a potentially curative surgical procedure for chronic thromboembolic pulmonary hypertension. It is, nevertheless, associated with considerable mortality caused by postoperative complications, such as reperfusion pulmonary edema (RPE) (i.e., pulmonary infiltrates in regions distal to vessels subjected to endarterectomy) and right heart failure (RHF). However, there are no reports about the influence of different postoperative treatment strategies on complications and mortality. Therefore, we compared two different treatment strategies. In Group I (n = 33), positive inotropic catecholamines and vasodilators were avoided during termination of cardiopulmonary bypass (CPB) and thereafter, and mechanical ventilation was performed with low tidal volumes < 8 mL/kg, duration of inspiration:duration of expiration = 3:1, and peak inspiratory pressures < 18 cm H(2)O. In Group II (n = 14), positive inotropic catecholamines and vasodilators were regularly used for termination of CPB and thereafter, and ventilation was performed with high tidal volumes (10-15 mL/kg) and peak inspiratory pressures up to 50 cm H(2)O. Hemodynamics, the incidence of RPE and RHF, duration of ventilation, morbidity, and mortality were recorded. Cardiac index was comparable before surgery (2.11 +/- 0.09 vs 2.08 +/- 0.09 L. min(-1). m(-2)) and 20 min after CPB (2.26 +/- 0.09 vs 2.60 +/- 0.20 L. min(-1). m(-2)). RPE occurred in 6.1% (Group I) versus 14.3% (Group II), and RHF was observed in 9.1% (Group I) versus 21.4% (Group II). Mortality was 9.1% (Group I) versus 21.4% (Group II). Thus, the avoidance of positive inotropic catecholamines and vasodilators in combination with nonaggressive mechanical ventilation after PTE was associated with a low incidence of RPE, RHF, duration of ventilation, and mortality after PTE. IMPLICATIONS: The avoidance of positive inotropic catecholamines and vasodilators in combination with nonaggressive mechanical ventilation was associated with a low incidence of reperfusion pulmonary edema and/or right heart failure after pulmonary artery thromboendarterectomy.

Short-term outcome and predictors of adverse events following pulmonary thromboendarterectomy.

Pulmonary complications including hypoxemia, right heart failure, and prolonged ventilation may follow pulmonary thromboendarterectomy (PTE) performed via cardiopulmonary bypass (CPB) with deep hypothermic circulatory arrest. Seventeen adult patients have undergone PTE at the University of Maryland Medical System during the preceding 3 years. From these patients, clinical and hemodynamic parameters were tabulated pre-CPB, post-CPB, at admission to the intensive care unit (ICU), and prior to discontinuation of invasive monitoring in the ICU. Data on anthropometric variables, survival, and times of extracorporeal circulation, mechanical ventilation, and hospital stay were also collected. The mean values for pulmonary arterial systolic and diastolic pressures and pulmonary vascular resistance (PVR) decreased significantly from pre-CPB values after PTE (all p < 0.05). Mild mixed acidosis present at ICU admission resolved prior to discharge (p = 0.002). The length of mechanical ventilation time was positively correlated with the absolute post-CPB PVR and negatively correlated with the relative change in central venous pressure (CVP) from pre-CPB to post-CPB values (r = 0.75, p = 0.037). Of the pre-CPB anthropometric variables, only body mass index was significantly higher in nonsurvivors (p = 0.037). Pulmonary artery pressures and vascular resistance fall significantly after PTE. A lower post-CPB PVR and a relatively decreased (i.e., from pre-CPB values) CVP predict reduced length of postoperative ventilation but not of the hospital stay. Mortality appears increased in patients with a large body habitus.

Deafness and prolonged neuromuscular blockade following single-dose peritoneal neomycin irrigation.

PURPOSE: A case of deafness is reported in a patient undergoing bilateral nephrectomy after single irrigation of the peritoneal cavity with a neomycin containing solution for surgical prophylaxis. CLINICAL FEATURES: In this patient, profound, late-postoperative deafness was heralded by prolonged neuromuscular blockade and respiratory insufficiency. Additional risk factors for ototoxicity in this particular patient included the presence of end-stage renal disease requiring daily peritoneal dialysis and, possibly, the concomitant use of clonazepam and clindamycin. CONCLUSIONS: Antibiotic irrigation solutions containing neomycin may produce unwanted adverse systemic effects of deafness and prolonged neuromuscular blockade, even with only brief application within the peritoneal cavity. Concurrent end-stage renal disease, visceral inflammation from chronic dialysis and laparotomy, and the concomitant use of other medications may have contributed to these unwanted effects.

Acute effects of bilateral lung volume reduction surgery on lung and chest wall mechanical properties.

STUDY OBJECTIVES: To characterize acute changes in the dynamic, passive mechanical properties of the lungs and chest wall, elastance (E) and resistance (R), caused by lung volume reduction surgery (LVRS). DESIGN: Prospective data collection. PATIENTS: Nine anesthetized/paralyzed patients with severe emphysema. INTERVENTIONS: Bilateral LVRS. MEASUREMENTS AND RESULTS: From measurements of airway and esophageal pressures and flow during mechanical ventilation throughout the physiologic range of breathing frequency (f) and tidal volume (VT), E and R of the total respiratory system (Ers and Rrs), lungs (EL and RL), and chest wall (Ecw and Rcw) immediately before and after LVRS were calculated. After surgery, Ers, EL, Rrs, and RL were all greatly increased at each combination off and VT (p<0.05). Ecw and Rcw showed no consistent changes (p>0.05). The increases in EL were greatest in those patients with the lowest residual volumes, highest FEV1 values, and highest maximum voluntary ventilations measured 3 months preoperatively (p<0.05); the increases in RL were greatest in those patients with the lowest preoperative residual volumes (p<0.05). The largest increases in RL were in those patients with the largest decreases in residual volume and total lung capacity, measured 3 months postoperatively, caused by LVRS (p<0.05). CONCLUSION: Acute effects of LVRS are large increases in lung elastic tension and resistance; these increases need to be considered in immediate postoperative care, and can be predicted roughly from results of preoperative pulmonary function tests.

Breathing difficulties in wind instrument players.

Performance of a wind instrument requires appreciable lung volume and diaphragmatic mechanical force, skilled breath control, adequate patency and humidity of air passages, and precise coordination of the oropharyngeal cavity. Depending on the instrument class, variable rates of air flow, pressure, and duration are necessary to produce optimal tone quality. Wind players may be seriously impaired by respiratory diseases that, comparatively, might appear trivial to the nonperformer. The workplace environment should be assessed for occupational hazards when managing these patients, and smoking should be particularly discouraged. Controversy exists implicating wind instrument use in the exacerbation of respiratory disease, including bronchial, laryngeal, pharyngeal, and oral anatomic changes--a result of the constant barotrauma of performance. Asthma is the most common chronic pulmonary disorder among wind players, and therapeutic programs that include breath training and physical exercise improve symptoms, endurance, and general well-being.

Impact of pleurotomy, continuous positive airway pressure, and fluid balance during cardiopulmonary bypass on lung mechanics and oxygenation.

OBJECTIVE: To determine effects of surgical pleurotomy, continuous positive airway pressure, and fluid balance during cardiopulmonary bypass (CPB) on lung mechanical properties and indices of oxygenation. DESIGN: Prospective, descriptive, and interventional study. SETTING: Cardiothoracic service at a major university referral center. PARTICIPANTS: Eighteen anesthetized-paralyzed patients undergoing elective coronary artery bypass grafting requiring CPB. INTERVENTIONS: During CPB, continuous positive airway pressure (CPAP) was applied to nine patients, in nine others, no CPAP was applied. MEASUREMENTS AND MAIN RESULTS: From measurements of airway and esophageal pressures and flow, lung resistance and elastance were determined before sternotomy and after sternal reapproximation. Measurements were made during forced ventilation over a physiologic range of tidal volumes and frequencies, and frequency and volume dependences of lung resistance and elastance were additionally identified. In all patients, lung resistance and elastance increased after CPB, consistent with models of pulmonary edema. Multiple regression analysis showed that these increases were relatively less in patients with intact pleurae (p < 0.05) or net negative fluid balance (p < 0.05); however, no difference in these increases was noted between patients receiving CPAP and those receiving no CPAP. Increases in lung resistance were positively correlated to net fluid balance, and negatively correlated to frequency and tidal volume (p < 0.05). Increases in lung elastance were positively correlated to tidal volume (p < 0.05). Absolute change in alveolar-arterial oxygen gradient was negatively correlated with net fluid balance, whereas percentage change was positively correlated to changes in lung elastance (p < 0.05). CONCLUSIONS: These findings suggest that pleurotomy before CPB and positive fluid balance during CPB enhance postbypass pulmonary edema and/or atelectasis, as demonstrated by acute changes in respiratory mechanics and indices of oxygenation. Low levels of CPAP applied during CPB did not significantly change either mechanical properties or oxygenation.

Respiratory mechanics in the open chest: effects of parietal pleurae.

To understand how the parietal pleurae affect the mechanical behavior of the human respiratory system after the chest wall is opened by median sternotomy, we studied 18 anesthetized/paralyzed patients immediately before coronary artery bypass grafting surgery. Elastances and resistances of the total respiratory system (ETr, Rrs) were calculated from measurements of airway pressure and flow during mechanical ventilation in the frequency and tidal volume ranges of normal breathing. Elastances and resistances of the lungs (EL, RL), chest wall (Ecw, Rcw) were also estimated from measurements of esophageal pressure. Data were collected in the closed chest, after median sternotomy with the parietal pleurae intact and after the left parietal pleura was opened for internal mammary artery harvest. After sternotomy with pleurae intact (n = 14), Ers did not change but Rrs decreased (p < 0.05). Ecw (including the contribution of the pleurae) was higher than in the closed chest (p < 0.05) while EL and RL were lower (p < 0.05); Rcw did not change. Opening the left pleura (n = 10) decreased Ers (p < 0.05), but Rrs did not change. We conclude that the chest wall/pleurae compartment offers significant impedance to lung expansion after sternotomy and rib retraction, unless one pleura is opened.

Facilitation of internal jugular venous cannulation using an audio-guided Doppler ultrasound vascular access device: results from a prospective, dual-center, randomized, crossover clinical study.

OBJECTIVE: To determine the utility of an audio-guided Doppler ultrasound device in improving success and decreasing complications in cannulation of the internal jugular vein in high-risk patients. DESIGN: Prospective, randomized, crossover clinical study. SETTING: Two major university medical centers in critical care environments. PATIENTS: Seventy-six consecutive, consenting adult patients with preexisting obesity or coagulopathy requiring central venous access. INTERVENTIONS: Subjects enrolled in the study were randomized to receive either the traditional "blind" (control) technique or the ultrasonic technique. A maximum of three cannulation attempts were allowed before crossover to three attempts with the alternative technique. All cannulations were attempted via the internal jugular vein through a high/central approach. RESULTS: Patient and operator characteristics were similar between groups. The initial use of an audio-guided ultrasound device was associated with increased success of cannulation (84.4% vs. 61.4%; p < .05) and decreased need to crossover to the alternative technique. Success on the first needle pass was more likely with the ultrasound technique (56.3% vs. 29.5%; p < .05). Significant complications were greater with the control technique (carotid artery puncture 16.3% vs. 2.0% [p < .02]; any significant complication 26.5% vs. 6.1% [p < .01]). CONCLUSIONS: The use of an audio-guided Doppler ultrasound vascular access device was associated with increased success of cannulation and a decreased frequency of significant complications in a population of high-risk patients with obesity or coagulopathy.