Désaturation artérielle en oxygène et maintien de l’oxygénation pendant l’intubation

CXC Chemokine Receptor Type 4 Antagonism Ameliorated Allograft Fibrosis in Rat Kidney Transplant Model

OBJECTIVES

In this study, we evaluated the effects of CXC chemokine receptor type 4 and stromal cell-derived factor 1 signaling in the progression of chronic allograft nephropathy in a rat model.

MATERIALS AND METHODS

Experimental rats were divided into 3 groups: Lewis-to-Lewis isograft transplant (group A), Fisher 344 rat-to-Lewis allograft transplant with immunosuppressant cyclosporine (group B), and Fisher 344 rat-to-Lewis allograft transplant treated with cyclosporine and the CXC chemokine receptor type 4 antagonist AMD3100 (1 mg/kg/d) (group C). On day 90 after the operation, renal graft function, proteinuria, and histologic Banff score were measured. The expression levels of transforming growth factor β1 and collagen IV were determined by quantitative real-time polymerase chain reaction.

RESULTS

Renal function and urinary protein were increased in allografts of groups B and C compared with isografts of group A. The Banff score was significantly decreased in the AMD3100-treated animals (group C), with renal fibrosis being reduced. In addition, overexpressed levels of transforming growth factor β1 and collagen IV in group B allografts were significantly reduced versus that shown with treatment with the CXC chemokine receptor type 4 antagonist in group C.

CONCLUSIONS

Together, these data strongly implicate that CXC chemokine receptor type 4 antagonism alleviated renal interstitial fibrosis in long-term surviving allografts by down-regulating expression of transforming growth factor β1.

How to preoxygenate in operative room: healthy subjects and situations "at risk"

Intubation is one of the most common procedures performed in operative rooms. It can be associated with life-threatening complications when difficult airway access occurs, in patients who cannot tolerate even a slight hypoxemia or when performed in patients at risk of oxygen desaturation during intubation, as obese, critically-ill and pregnant patients. To improve intubation safety, preoxygenation is a major technique, extending the duration of safe apnoea, defined as the time until a patient reaches an arterial saturation level of 88% to 90%, to allow for placement of a definitive airway. Preoxygenation consists in increasing the lung stores of oxygen, located in the functional residual capacity, and helps preventing hypoxia that may occur during intubation attempts. Obese, critically-ill and pregnant patients are especially at risk of reduced effectiveness of preoxygenation because of pathophysiological modifications (reduced functional residual capacity (FRC), increased risk of atelectasis, shunt). Three minutes tidal volume breathing or 3-8 vital capacities are recommended in general population, mostly allowing achieving a 90% end-tidal oxygen level. Recent studies have indicated that in order to maximize the value of preoxygenation (i.e, oxygenation stores) obese and critically-ill patients can benefit from the combination of breathing 100% oxygen and non-invasive positive pressure ventilation (NIV) with end-expiratory positive pressure (PEEP) in the proclive position (Trendelenburg reverse). Recruitment manoeuvres may be of interest immediately after intubation to limit the risk of lung derecruitment. Further studies are needed in the field of preoxygenation in pregnant women.

[Effectiveness of preoxygenation using the head-up position and noninvasive ventilation to reduce hypoxaemia during intubation]

OBJECTIVE

The purpose of this article was to present an update of the preoxygenation management in morbidly obese adults, parturient women and hypoxemic critically-ill patients.

DATA SOURCES

All references obtained from the medical database Medline related to the area and more specifically during the last five years were reviewed.

DATA SYNTHESIS

Preoxygenation decreases the risk of hypoxia and should be optimized when the standard technique appears to be less effective as in morbidly obese adults, parturient women and critically-ill patients. The head-up position and noninvasive ventilation may be useful during preoxygenation probably because of the increase of ventilation and alveolar recruitment. The effectiveness of preoxygenation (when defined as the duration of the desaturation safety period) is enhanced in the head-up position as compared to supine position in the obese patient but not in parturient women. Noninvasive ventilation improves preoxygenation in the hypoxemic critically-ill patient but not in the obese patient. Neither the head-up position nor the noninvasive ventilation improve preoxygenation in parturient women.

CONCLUSION

Further studies are required to investigate other methods attempting to improve preoxygenation and prevent hypoxemia during intubation.