Repercussion of brief hyperventilation manuever on the cerebral and systemic hemodynamic and gasometric parameters in mechanically ventilated patients

THESES

Repercussion of brief hyperventilation manuever on the cerebral and systemic hemodynamic and gasometric parameters in mechanically ventilated patients (Abstract)^* Thesis. Aracaju, 2006.

Telma Cristina Fontes Cerqueira^**

Measurements of respiratory mechanics, very important to conduct the patient with mechanical ventilation, are obtained with the relaxation of respiratory muscle in sedated or paralyzed patients or through a brief period of hyperventilation (HV), which is possible to decrease the drive ventilation of patient. However, it is known that the hyperventilation decreases the carbon dioxide arterial pressure (PaCO₂) and can induce changes in the cerebral blood flow.

This study proposes to verify the effects of this brief period of HV on the gasometric parameters, cerebral and systemic hemodynamic in 15 mechanically ventilated patients, with ventilation drive and different pathologies, except cerebral pathology, admitted in Intensive Care Unit of Vita Hospital in Curitiba-PR, being 12 males (80%) and three females (20%), mean age 61.29 (±18.97), eight clinical and seven surgical diagnosis.

The protocol consisted of a brief HV with increase by 50% from previous minute volume of patient for two minutes. The variables were recorded before, on the first minute of HV (HV1), on the second minute (HV2) and five minutes after the end of maneuver. The parameters recorded were mean blood flow velocity and pulsatility index through transcranial Doppler of the middle cerebral arteries, blood gas parameters (pH, PaCO₂, EtCO₂, HCO₃, BE, PaO₂, SatO₂ e SpO₂), besides heart rate and mean arterial pressure. The data were averaged statistically by ANOVA, Newman-Keuls and Wilcoxon tests. The normality condition of data were averaged by Kolmogorov-Smirnov. Values of p<0.05 indicate statistically significant.

The results show a decrease of mean blood flow velocity of the right (p=0.18888) and left (p=0.0071) middle cerebral arteries, mainly on the first minute of HV, estimating a decrease of cerebral blood flow (4.12% and 6.51%, of the right and left middle cerebral arteries, respectively). Five minutes after HV, there was a return to baseline values. In relation to gasometric parameters, there were a significant variation of EtCO₂ and PaCO₂ during the HV, with smaller changes of PaCO₂ in relation to EtCO₂. The pulsatility index, another gasometric parameters, heart rate and mean arterial pressure remained stable during HV.

Concluding, based on results of this study, that the maneuver of HV may be security applied and does not promote cerebral and systemic repercussion in studied patients.

Key words: hyperventilation, cerebral blood flow, transcranial Doppler.

*

Repercussão da manobra de hiperventilação breve sobre a hemodinâmica cerebral, sistêmica e alterações gasométricas em pacientes sob assistência ventilatória mecânica (Resumo). Tese de Mestrado, Universidade Federal de Sergipe, UFS (Área: Ciências da Saúde). Orientador : Carlos Umberto Pereira.

**

Address: Rua Oyapock 90/ 62, 80050-450 Curitiba PR, Brasil.

Publication Dates

• Publication in this collection
  02 Aug 2006
• Date of issue
  June 2006