ABSTRACT
A ventilação artificial em pacientes neurocirúrgicos apresenta aspectos técnicos específicos como a hiperventilação e aplicação de pressão expiratória final positiva (PEEP). As medidas geralmente utilizadas para proteção pulmonar, tais como altos níveis de PEEP, baixos volumes correntes, elevadas frequências respiratórias e hipercapnia permissiva podem ser danosas em pacientes com doença neurológica. A influência da ventilação mecânica sobre os parâmetros hemodinâmicos, notadamente sobre a pressão intracraniana (PIC) e a pressão de perfusão cerebral (PPC), tem sido foco de diversos estudos, embora os resultados permaneçam controversos. No centro da discussão, destaca-se o papel da PEEP e suas implicações nessa população. A partir dos dados disponíveis na literatura, ainda que controversos, existe a tendência a se inferir que o uso da PEEP em níveis baixos a moderados pouco provavelmente causará aumento significativo da PIC na grande maioria dos casos. Enquanto a vasoconstrição cerebral induzida pela hipocapnia por hiperventilação reduz efetivamentea a PIC, o risco de diminuir o fluxo sanguíneo cerebral (FSC) abaixo do seu limite crítico sempre foi foco de preocupação clínica e investigação científica. Faltam dados na literatura acerca do uso de manobras de recrutamento alveolar em pacientes neurocirúrgicos. Estratégias de proteção pulmonar devem ser sempre respeitadas, mas simultaneamente devem-se otimizar a PPC e PIC. A monitorização da ventilação é de suma importância, visto que há forte influência dos parâmetros respiratórios na fisiologia cerebral.
The mechanical ventilation in neurological patients indicates some aspects related to the techniques used, such as hyperventilation and the application of positive end-expiratory pressure (PEEP). The measures generally adopted for lung protective ventilation, such as high levels of PEEP, low tidal volume, elevated respiratory frequency, and permissive hypercapnia can be damaging for patients with neurological disesases. The influence of mechanical ventilation on hemodynamic parameters, such as intracranial pressure (ICP) and cerebral perfusion pressure (CPP) has been the focus of many studies, even though the results are still controversial. The role of PEEP and its implications in neurological patients is in evidence. Based on data available in the literature, albeit controversial, there is a tendency toinfer that the use of PEEP at low to moderate levels is unlikely to cause a significantincrease in ICP. While cerebral vasoconstriction induced by hypocapnia reduces effectively ICP, the risk of reducing cerebral blood flow (CBF) to a critical condition level was always a clinical concern and a subject of scientific investigation. There are few data about lung recruitment maneuver in this patient population.Lung protection strategiesshould alwaysbe respected, butsimultaneouslyoptimizeCPPandICP. Monitoring ofventilationisof paramountimportance, since there is a stronginfluenceof respiratory parametersin brainphysiology.
ABSTRACT
OBJECTIVE: Aneurysmal subarachnoid hemorrhage puts patients at high risk for the development of pituitary insufficiency. We evaluated the incidence of pituitary dysfunction in these patients and its correlation with clinical outcome. METHODS: Pituitary function was tested in 66 consecutive patients in the first 15 days after aneurysmal subarachnoid hemorrhage. The following were measured in all patients: thyroid-stimulating hormone, free thyroxine, triiodothyronine, luteinizing hormone, follicle-stimulating hormone, total testosterone (in males), estradiol (in females), prolactin, serum cortisol, plasma adrenocorticotropic hormone, growth hormone and insulin growth factor. RESULTS: The endocrine assessment was made at a mean of 7.4 days (standard deviation ±6.6) after subarachnoid hemorrhage. Forty-four (66.7%) female and 22 (33.3%) male patients were evaluated. Thirty-nine patients (59.1%) had some type of pituitary dysfunction. Follicle-stimulating hormone/luteinizing hormone deficiency was the most frequent disorder (34.8%), followed by growth hormone/insulin growth factor (28.7%), adrenocorticotropic hormone (18.1%) and thyroid-stimulating hormone (9%). Seventeen (25.7%) patients showed deficiencies in more than one axis. A greater incidence of hormone deficiency was observed in patients with a Glasgow Coma Scale score ≤13 (t test, p = 0.008), Hunt-Hess grade ≥4 (t test, p<0.001), or Fisher grade 4 (t test, p = 0.039). Hormone deficiency was not significantly associated (p>0.05) with increased hospitalization or clinical outcome. CONCLUSION: Pituitary dysfunction was identified in a substantial portion of patients with previous aneurysmal subarachnoid hemorrhage, but no association was found between this dysfunction and poor clinical outcome. .