Changes in body temperature during profound hypothermic cardiopulmonary bypass in adult patients undergoing aortic arch reconstruction

Purpose Our aim was to characterize changes in body temperatures during profound hypothermic cardiopulmonary bypass (CPB) conducted with the sternum opened.Methods In ten adult patients who underwent profound hypothermic (20°C) CPB for aortic arch reconstruction, pulmonary arterial temperature (PAT), nasopharyngeal temperature (NPT), forehead deep-tissue temperature (FHT), and urinary bladder temperature (UBT) were recorded every 1min throughout the surgery. In addition, the CPB venous line temperature (CPBT), a reasonable indicator of mixed venous blood temperature during CPB and believed to best reflect core temperature during stabilized hypothermia on CPB, was recorded during the period of total CPB.Results PAT began to change immediately after the start of cooling or rewarming, closely matching the CPBT (r = 0.98). During either situation, the other four temperatures lagged behind PAT (P 0.05); however, NPT followed PAT more closely than the other three temperatures (P 0.05). During stabilized hypothermia, PAT, NPT, and FHT, but not UBT, closely matched the CPBT, with gradients of less than 0.5°C.Conclusion During induction of profound hypothermia and its reversal on total CPB with the heart in situ, a PA catheter thermistor, presumably because of its placement immediately behind the superior vena cava, would provide a reliable measure of the mixed venous blood temperature. During stabilized profound hypothermia, PAT, NPT, and FHT, but not UBT, serve as a reliable index of core temperature.This work was presented, in part, at the 50th annual meeting of the Japanese Society of Anesthesiologists, Yokohama, May 29–31, 2003, and at the annual meeting of the American Society of Anesthesiologists, San Francisco, USA, October 11–15, 2003.     

Cardiovascular causes of airway compression

Compression of the paediatric airway is a relatively common and often unrecognized complication of congenital cardiac and aortic arch anomalies. Airway obstruction may be the result of an anomalous relationship between the tracheobronchial tree and vascular structures (producing a vascular ring) or the result of extrinsic compression caused by dilated pulmonary arteries, left atrial enlargement, massive cardiomegaly, or intraluminal bronchial obstruction. A high index of suspicion of mechanical airway compression should be maintained in infants and children with recurrent respiratory difficulties, stridor, wheezing, dysphagia, or apnoea unexplained by other causes. Prompt diagnosis is required to avoid death and minimize airway damage. In addition to plain chest radiography and echocardiography, diagnostic investigations may consist of barium oesophagography, magnetic resonance imaging (MRI), computed tomography, cardiac catheterization and bronchoscopy. The most important recent advance is MRI, which can produce high quality three-dimensional reconstruction of all anatomic elements allowing for precise anatomic delineation and improved surgical planning. Anaesthetic technique will depend on the type of vascular ring and the presence of any congenital heart disease or intrinsic lesions of the tracheobronchial tree. Vascular rings may be repaired through a conventional posterolateral thoracotomy, or utilizing video-assisted thoracoscopic surgery (VATS) or robotic endoscopic surgery. Persistent airway obstruction following surgical repair may be due to residual compression, secondary airway wall instability (malacia), or intrinsic lesions of the airway. Simultaneous repair of cardiac defects and vascular tracheobronchial compression carries a higher risk of morbidity and mortality.     

Perioperative hypertension due to undiagnosed aortic coarctation: are current standards of care adequate?

A 12-year-old male presented for a superficial parotidectomy for chronic parotitis. The patient had an unremarkable past medical history and was admitted on the day of surgery for his procedure without further anaesthetic or surgical review. During the patient's intraoperative course, higher than expected blood pressures were noted and treated with clonidine. After further high blood pressure readings in the postoperative care unit, close surveillance of blood pressures for the following 24 h was arranged. The hypertension was ongoing, and further examination and investigation confirmed the diagnosis of coarctation of the aorta. We examine the possible reasons for failure to diagnose this patient's hypertension preoperatively and suggest that there is a need for greater surveillance of blood pressures in the paediatric population presenting for surgery. A discussion of the significance of hypertension in paediatrics and recommendations for minimum standards of care to address shortcomings in the diagnosis and treatment of paediatric hypertension are proposed.     

Scanning electron microscopy of aortic medial changes in aortic ascending dilatation

The study of cystic cavities and collagen fibers fragmentation is useful to for a better knowledge of pathogenesis and surgical therapy of medial ascending aortic degeneration. Thus, the aim of this study was to describe by scanning electron microscopy the surfaces and shape of the cysts, measure their area, and identify microcystic spaces related to this degenerative disease. Scanning electron microscopy analysis was performed in 16 out of 36 patients who underwent surgery for ascending aorta dilatation with associated aortic valve disease. The aortic medial wall showed a cribrose appearance at low magnification (×50-100) and the intima was effuse. At high magnification (×500-2000), small cavities (clefts) lined by normal or fragmented elastic fibers and large cavities (pseudocystes) with anfractuous borders lined by fragmented elastic fibers and smooth muscle cells were observed. Furthermore, in the outer media wall microvessels lined by endothelium were also observed. These changes were lacking or less pronounced in normal aorta. SEM allows one to better identify the pathological cavities and to differentiate them from microvessels. These pathological cavities are more numerous and larger in the convexity than in the concavity of the aorta in according to our previous morphological and morphometric findings in asymmetrical aorta dilatation.     

Evaluation of recurrent nerve paralysis due to thoracic aortic aneurysm and aneurysm repair

OBJECTIVES: We sought to clarify the relationship between the outcome of recurrent laryngeal nerve paralysis with the characteristics of the thoracic aortic aneurysm and the surgical procedure used in each patient. METHODS: Nine patients who developed recurrent nerve paralysis (nonsurgical paralysis) due to a thoracic aortic aneurysm alone and 14 patients who underwent artificial vessel replacement for thoracic aortic aneurysm and developed recurrent nerve paralysis postoperatively (surgical paralysis) were evaluated. RESULTS: In the patients with nonsurgical paralysis, the aneurysms were similar in size to those of other patients who underwent surgery of the thoracic aorta and were invariably located near the aortic arch. Aneurysm shape was not associated with nerve paralysis. Surgical paralysis was alleviated in two patients. Surgical paralysis was observed in 9% of those who underwent surgery of the thoracic aorta. Vocal cord mobility recovered in 4 of the 11 patients with surgical paralysis who underwent follow-up. Symptoms were alleviated by rehabilitation in many patients who did not recover vocal cord mobility. The positions of the artificial vessel anastomoses are thought to be closely related to the outcome of paralysis. CONCLUSION: Recurrent nerve paralysis reduced not only the patient's quality of life but also survival by leading to disorders including aspiration pneumonia. Therefore, early rehabilitation should be performed, and surgical treatment should be considered, if necessary, for patients with recurrent nerve paralysis.     

Surgical outcome following treatment of isolated subaortic obstruction

Surgical and nonsurgical patients with isolated subaortic stenosis (SAS) were compared to determine the important factors contributing to the timing of surgical intervention. This study reviews 49 consecutive patients (27 surgical and 22 nonsurgical) aged 1.8 to 15.9 years with isolated SAS. The preoperative peak left ventricular outflow tract (LVOT) gradient in surgical patients was significantly higher than the gradient in nonsurgical patients (59.0±30.4 vs 22.77± 13.9 mm Hg, P=.0001). The progression in LVOT gradient analyzed by echo Doppler was significantly higher in the surgical group compared with the nonsurgical group (10.48±9.7 vs 1.56±6.5 mm Hg/y, P=.007). Repeat surgical intervention was required in 22% of patients in the surgical group for recurrence of SAS, and 4% needed a third surgery. The progression in the severity of aortic regurgitation (AR) was not significantly different in the surgical and nonsurgical groups. There was a significant association between the development of AR and patients undergoing surgery (P=.045). AR may not be a reliable indication for early operative intervention in isolated SAS as there was no significant difference in its progression with surgical and nonsurgical patients. Asymptomatic patients with isolated SAS may warrant surgical intervention on the basis of progression of LVOT gradient, rather than the development or progression of AR.     

Sedation in children undergoing CT scan or MRI: effect of time-course and tolerance of rectal chloral hydrate

The aim of this paper was to describe the time-course of the sedative effect of rectal chloral hydrate (75 mg/kg) in children undergoing CT scan or MRI. Twenty children (2.13 +/- 1.43 years old) were administered 75 mg/kg chloral hydrate rectally (chloralhydrat-rectiole rectal formulation, Dr Mann-Pharma Lab, Berlin, Germany), before a CT scan or an NMR imaging. Sedation was measured at specific times using a sedation score of 1-6. Patients were continuously monitored for respiratory and heart rate, systolic and diastolic blood pressures, and oxygen saturation. About 82.35 and 94.11% of the patients had a score of sedation > or = 3 within 15 and 30 min, respectively. The mean time to effective sedation (score > or = 3) was of 0.30 +/- 0.14 h (median time, 0.25 h). The mean duration of effective sedation (score > or = 3) was 1.29 +/- 1.05 h (median duration, 0.75 h). A total of 93.1% of the X-ray sections were obtained without artifact and sedation was considered by radiologists to be efficient for 83.3% of the procedures. This sedation procedure appeared efficient and safe during ambulatory CT scan and NMR imaging. The long-term effect of chloral hydrate, however, remains to be evaluated.     

Blood loss and transfusion in elective abdominal aortic aneurysm surgery

BACKGROUND: Intraoperative blood loss and transfusion are known determinants of mortality and morbidity of elective abdominal aortic aneurysm (AAA) repair. The present study analysed the pattern of blood loss and transfusion and evaluated the risk factors of blood loss during open repair of infrarenal AAA. METHODS: Blood loss, transfusion and fluid replacement during elective open repair operation for patients with infrarenal AAA were correlated to demographic data, operative findings and procedural information. RESULTS: A total of 129 patients with a mean age of 71 years was analysed. The mean blood loss was 1000 +/- 887 mL (200-6000 mL). Blood transfusion, with a mean transfusion volume of 400 +/- 591 mL (0-3000 mL), was required in 46% of patients. Univariate analysis showed that bodyweight, renal impairment, low haemoglobin and platelet counts, iliac artery involvement, large aneurysm, bifurcated graft, large graft diameter, prolonged aortic clamp time and long operation time were associated with a higher blood loss. A haemoglobin level of <10.5 g/dL (relative risk (RR): 4.6), platelet count <130 x 10(9)/L (RR: 3.9), aortic clamp time >50 min (RR: 15), total operation time >200 min (RR: 11) and type of graft (RR: 3.5) were identified as independent determinants of blood loss on multivariate analysis. CONCLUSION: Intraoperative blood loss in elective infrarenal aneurysm surgery is influenced by patients' haematological parameters, distal involvement of aneurysm and degree of difficulty of operation.