2005 Annual Scientific Meeting - CLICK FOR PROGRAMME

Obesity and arterial hypertension do not influence the haemodynamic and BIS response to a large remifentanil bolus

 Ferreira DA, Nunes CS, Lobo F, Amorim P, Antunes LM

Serviço de Anestesiologia, Hospital Geral de Santo António, Porto, Portugal; CECAV- UTAD, Vila Real, Portugal

Introduction

Remifentanil (Remi) is safely used as an analgesic drug in neurosurgical procedures. When combined with propofol (Prop), bradicardia and hypotension usually occurs.¹ Nevertheless, large Remi doses are sometimes required to abolish undesirable haemodynamic responses to acute noxious stimuli as head-pins placement. We analyzed the bispectral index and haemodynamic effects of a Remi bolus under general anaesthesia with Prop and Remi in three groups of neurosurgical patients: patients with hypertension, obese patients and patients without hypertension and obesity.

Methods

GROUP 1: Neurosurgical patients non-obese and non-hypertense, Glasgow 15. GROUP 2: Neurosurgical patients with diagnosed hypertension, Glasgow 15. GROUP 3: Obese (BMI>32 in women and >31 in men) neurosurgical patients, Glasgow 15. All groups received a 2 µg/kg Remi bolus under TIVA in a period free from stimuli. TCI was used with Schnider² for Prop and Minto³ for Remi. BIS, haemodynamic data, neuromuscular activity (NMT) and EtCO2 were collected from A-2000XP BIS and AS/3 Datex monitors every 5 s using RugLoopII®. Data was analyzed at the starting time of Remi bolus (T0), 30, 60, 90 and 120 (T120) s after. BIS baseline at T0 was the average of the 12 previous measurements; BIS data at each time point after the bolus was the average of three consecutive measurements. Analysis of variance and multiple comparisons tests were used for statistical analysis; data expressed has mean±SD.

Results

GROUP 1: 10 patients, 42±14 years (20-69), body mass index (BMI) 23±1.9, ASA I-II, 9 females. When awake, mean arterial pressure (MAP) was 93±7.1 mmHg and heart rate (HR) was 73±12 bpm. GROUP 2: 10 patients, 60±11 years (47-74), BMI 24.5±2.5, ASA II, 8 females. When awake, MAP was 114.2±10.4 mmHg and HR was 78±8 bpm. GROUP 3: 10 patients, 52±14 years (18-69), BMI 35.2±4.4, ASA I-III, 7 females. When awake, MAP was 103.9±11.8 mmHg and HR was 72±10 bpm. In all groups, BIS, MAP and HR decreased significantly from T0 to T120. No statistical differences were observed between groups in BIS, HR, NMT, EtCO2, Remi and Prop predicted effect-site concentrations at any time point.

Table: BIS, MAP (mmHg) and HR (bpm) data at T0 (baseline) and at T120 for patients in Groups 1 (G1), 2 (G2) and 3 (G3). Decrease (%) in BIS and in MAP from baseline to T120 for the same groups. Within groups comparisons: ^ªP<0.05; ^ªªP<0.01; Between groups comparisons: *P<0.01.

Discussion

No significant differences in the percentage of variation of BIS, MAP and HR were observed in obese and hypertensive patients, when compared to Group 1. We conclude that remifentanil is a safe drug to be used by bolus in obese and hypertensive patients during neurosurgical anaesthesia.

Acknowledgements

The authors wish to acknowledge the Portuguese Foundation for Science and Technology (Lisbon, Portugal) for their financial support under project POSC/EEA-SRI/57607/2004.

References

1.       Br J Anaesth 2000, 84: 578-583

2.       Anesthesiology, 1998, 88:1170-82

3.       Anesthesiology, 1997, 86:24-33.