Lellouche François, Qader Siham, Taille Solenne, Lyazidi Aissam, Brochard Laurent
INSERM U 651, Université PARIS XII, Service de Réanimation Médicale, AP-HP, Hôpital Henri Mondor, 51 av. du Maréchal de Lattre de Tassigny, 94010 Créteil, France.
Intensive Care Med. 2006 Jul;32(7):1014-21. doi: 10.1007/s00134-006-0192-8. Epub 2006 May 23.
In mechanically ventilated patients with induced hypothermia, the efficacy of heat and moisture exchangers and heated humidifiers to adequately humidify the airway is poorly known. The aim of the study was to assess the efficacy of different humidification devices during moderate hypothermia.
Prospective, cross-over randomized study.
Medical Intensive Care Unit in a University Hospital.
Nine adult patients hospitalized after cardiac arrest in whom moderate hypothermia was induced (33 degrees C for 24[Symbol: see text]h).
Patients were ventilated at admission (period designated "normothermia") with a heat and moisture exchanger, and were randomly ventilated during hypothermia with a heat and moisture exchanger, a heated humidifier, and an active heat and moisture exchanger.
Core temperature, inspired and expired gas absolute and relative humidity were measured. Each system demonstrated limitations in its ability to humidify gases in the specific situation of hypothermia. Performances of heat and moisture exchangers were closely correlated to core temperature (r (2)[Symbol: see text]=[Symbol: see text]0.84). During hypothermia, heat and moisture exchangers led to major under-humidification, with absolute humidity below 25[Symbol: see text]mgH(2)O/l. The active heat and moisture exchanger slightly improved humidification. Heated humidifiers were mostly adequate but led to over-humidification in some patients, with inspiratory absolute humidity higher than maximal water content at 33 degrees C with a positive balance between inspiratory and expiratory water content.
These results suggest that in the case of moderate hypothermia, heat and moisture exchangers should be used cautiously and that heated humidifiers may lead to over-humidification with the currently recommended settings.
在接受机械通气并进行诱导低温治疗的患者中，热湿交换器和加热湿化器对气道进行充分湿化的效果尚不清楚。本研究的目的是评估不同湿化设备在中度低温期间的效果。
前瞻性、交叉随机研究。
大学医院的医学重症监护病房。
9例心脏骤停后住院的成年患者，对其进行中度低温诱导（33℃持续24小时）。
患者入院时使用热湿交换器进行通气（称为“正常体温”期），在低温期间随机使用热湿交换器、加热湿化器和主动热湿交换器进行通气。
测量核心温度、吸入气和呼出气的绝对湿度和相对湿度。每个系统在低温的特定情况下对气体进行湿化的能力都存在局限性。热湿交换器的性能与核心温度密切相关（r² = 0.84）。在低温期间，热湿交换器导致严重的湿化不足，绝对湿度低于25mgH₂O/l。主动热湿交换器略微改善了湿化效果。加热湿化器大多是合适的，但在一些患者中导致了过度湿化，吸气绝对湿度高于33℃时的最大含水量，吸气和呼气含水量之间存在正平衡。
这些结果表明，在中度低温的情况下，应谨慎使用热湿交换器，并且按照目前推荐的设置，加热湿化器可能会导致过度湿化。
