Continuous positive airway pressure for treatment of respiratory complications after abdominal surgery: a systematic review and meta-analysis

OBJECTIVE: We evaluated the potential benefit of continuous positive airway pressure (CPAP) to prevent postoperative pulmonary complications (PPCs), atelectasis, pneumonia, and intubation in patients undergoing major abdominal surgery. SUMMARY BACKGROUND DATA: PPCs are common during the postoperative period and may be associated with a high morbidity rate. Efficacy of CPAP to prevent PPCs occurrence is controversial. METHODS: Medical literature databases were searched for randomized controlled trials examining the use of CPAP versus standard therapy in patients undergoing abdominal surgery. The meta-analysis estimated the pooled risk ratio and the number needed to treat to benefit (NNTB) for PPCs, atelectasis, and pneumonia. RESULTS: The meta-analysis was carried out over 9 randomized controlled trials. Overall, CPAP significantly reduced the risk of (1) PPCs (risk ratio, 0.66; 95% confidence interval [CI], 0.52-0.85) with a corresponding NNTB of 14.2 (95% CI, 9.9-32.4); (2) atelectasis (risk ratio, 0.75; 95% CI, 0.58-0.97; NNTB, 7.3; 95% CI, 4.4-64.5); (3) pneumonia (risk ratio, 0.33; 95% CI, 0.14-0.75; NNTB, 18.3; 95% CI, 14.4-48.8). In all cases the variation in risk ratio attributable to heterogeneity was negligible, although there was some evidence of publication bias. CONCLUSIONS: This systematic review suggests that CPAP decreases the risk of PPCs, atelectasis, and pneumonia and supports its clinical use in patients undergoing abdominal surgery.     

Modulation of synaptic transmission by nicotine and nicotinic antagonists in hippocampus

Using rat hippocampal slices, we studied the effects of nicotine and three antagonists of neuronal nicotinic receptors on excitatory and inhibitory transmission. We report that nicotine at concentrations between 0.5 and 100 microM enhanced excitatory synaptic responses and increased the size of the presynaptic fiber volley. This effect was reproduced by three neuronal nicotinic receptor antagonists: dihydro-beta-erythroidine, methyllycaconitine and mecamylamine. In contrast, nicotine, but not nicotinic antagonists, produced a dual effect on inhibition: nicotine enhanced gamma-aminobutyric-acid A (GABA(A)) receptor-mediated synaptic responses at low concentration (0.5 microM) and blocked them at high concentration (100 microM). We conclude that the excitatory effects of nicotine are reproduced by nicotinic receptor antagonists, thereby suggesting that these effects might be mediated through receptor desensitization. These results also indicate that nicotine differentially affects GABAergic inhibition at low and high concentrations-effects that are not reproduced by antagonists.     

Effect of a gonadotrophin-releasing hormone analogue on lung function in lymphangioleiomyomatosis

BACKGROUND: Lymphangioleiomyomatosis (LAM), a multisystem disease occurring primarily in women, is characterized by cystic lung destruction, and kidney and lymphatic tumors, caused by the proliferation of abnormal-appearing cells (ie, LAM cells) with a smooth muscle cell phenotype that express melanoma antigens and are capable of metastasizing. Estrogen receptors are present in LAM cells, and this finding, along with reports of disease progression during pregnancy or following exogenous estrogen administration, suggest the involvement of estrogens in the pathogenesis of LAM. Consequently, antiestrogen therapies have been employed in treatment. The goal of this prospective study was to evaluate the efficacy of triptorelin, a gonadotrophin-releasing hormone analogue, in 11 premenopausal women with LAM. METHODS: Patients were evaluated at baseline and every 3 to 6 months thereafter, for a total of 36 months. Hormonal assays, pulmonary function tests, 6-min walk tests, high-resolution CT scans of the chest, and bone mineral density studies were performed. RESULTS: Gonadal suppression was achieved in all patients. Overall, a significant decline in lung function was observed; two patients underwent lung transplantation 1 year after study enrollment, and another patient was lost to follow-up. Treatment with triptorelin was associated with a decline in bone mineral density. CONCLUSIONS: Triptorelin appears not to prevent a decline in lung function in patients with LAM. Its use, however, may be associated with the loss of bone mineral density.     

Different growth factor activation in the right and left ventricles in experimental volume overload

Mechanical factors play a key role in activation of cardiac growth factor response in hemodynamic overload, and both cooperate in myocardial remodeling. The present study was performed to investigate whether a different growth factor response is activated in the right and left ventricles in aortocaval fistula and its effects on regional myocardial adaptation. Relations between regional growth factor expression (angiotensin II, insulin-like growth factor-I, and endothelin-1), myocyte shape changes, and collagen deposition were investigated at mRNA and peptide levels in adult pigs after the creation of an aortocaval fistula distal to the renal arteries (n=15) and in sham-operated animals (n=15). The role of angiotensin II was investigated by the administration of angiotensin-converting enzyme inhibitor or angiotensin II receptor antagonist. In the left ventricle, pure volume overload was accompanied by persistent increase of insulin-like growth factor-I mRNA expression, peptide concentration (2.2-fold versus sham at 3 months, P<0.05), and significant increase of myocyte length (+29% at 3 months, P<0.05). Conversely, the mixed pressure-volume overload faced by the right ventricle resulted in significant regional overexpression of all growth factors investigated (angiotensin II, insulin-like growth factor-I, and endothelin-1), with corresponding increase of myocyte diameter and length and collagen deposition (+117% at 3 months). Collagen accumulation in the right ventricle as well as the increase in right ventricular end-diastolic pressure at the 3-month observation were inhibited by angiotensin II antagonism. The left and right ventricles respond differently to aortocaval fistula, and local growth factor expression is closely related to the regional myocardial adaptation.