British Journal of Anaesthesia 1992; 69: 143-147
THE LARYNGEAL MASK AIRWAY FOR INTRAOCULAR SURGERY: EFFECTS ON INTRAOCULAR PRESSURE AND STRESS RESPONSES K. LAMB, M. F. M. JAMES AND P. K. JANICKI
SUMMARY
KEY WORDS Anaesthesia: ophthalmic. Equipment: laryngeal mask airway. Eye: intraocular pressure.
Tracheal intubation is performed routinely during general anaesthesia in patients undergoing intraocular surgery to secure a clear airway, to allow good surgical access and to facilitate ventilation of the lungs for control of PaCOf. However, intubation is associated with tachycardia, hypertension [1] and an increase in intraocular pressure [2]. Many techniques have been tried to attenuate this response but to date none has been completely successful [1]. The Brain laryngeal mask airway (LMA) has been shown to be an effective means of securing a clear airway in fasted patients for elective surgery [3]. Its insertion requires neither visualization of the cords nor penetration of the larynx, making placement less stimulating than tracheal intubation [4] and it may provoke less sympathetic response and catecholamine release. Therefore, during insertion of the LMA there is less likelihood of a pressor response or
PATIENTS AND METHODS
The study was approved by the Human Ethics Committee of the University of Cape Town and informed patient consent obtained. Twenty ASA I and II patients undergoing intraocular surgery were allocated randomly to receive a LMA (group 1) or T T (group 2). Any patient with oesophageal reflux or respiratory disease was excluded from the study. All patients received premedication with temazepam 0.3 mg kg"1 orally 1 h before operation. Before induction of anaesthesia, a vein in both arms was cannulated and 5 ml of venous blood withdrawn for measurement of plasma concentrations of catecholamines. Intraocular pressure was measured in the non-operated eye using a Perkins hand-held applanation tonometer after instillation of 0.5% amethocaine drops and fluorescein dye. Data were recorded at the times shown in table I. Monitoring consisted of continuous ECG, noninvasive arterial pressure, end-tidal carbon dioxide partial pressure, neuromuscular transmission by train-of-four stimulation, end-tidal enflurane partial pressure (Ohmeda Agent Monitor) and pulse oximetry. After determination of baseline data, the lungs were preoxygenated. Alfentanil 7 ug kg"1 was given K. LAMB*, F.R.C.ANAES., M. F. M. JAMES, PH.D., F.R.C.ANAES.,
P. K. JANICKI, M.D., PH.D., Department of Anaesthesia, University of Cape Town Medical School, Observatory 7925, Cape, South Africa. Accepted for Publication: February 25, 1992. 'Present address: Department of Anaesthetics, Victoria Infirmary, Glasgow. Correspondence to M.F. M.J.
Downloaded from http://bja.oxfordjournals.org/ by guest on March 22, 2016
Trachea/ intubation, performed routinely during general anaesthesia in patients undergoing intraocular surgery, may have adverse effects on cardiovascular function and intraocular pressure. This study assessed the suitability of the laryngeal mask airway (LMA) as a substitute for trachea/ intubation. Intraocular and systemic pressor effects, heart rate changes and catecho/amine concentrations were measured in two groups of 10 patients receiving standardized anaesthesia with either a trachea/ tube (TT) or a LMA. There were significantly smaller changes in the pressor responses to insertion and in concentrations of catecholamines at critical times in the anaesthetic sequence in the LMA group. Mean (SEM) rate-pressure product was significantly smaller in the LMA group compared with the TT group after both insertion (8276 (730) vs 13307 (1348), ?
THE LARYNGEAL MASK AIRWAY FOR INTRAOCULAR SURGERY: EFFECTS ON INTRAOCULAR PRESSURE AND STRESS RESPONSES K. LAMB, M. F. M. JAMES AND P. K. JANICKI
SUMMARY
KEY WORDS Anaesthesia: ophthalmic. Equipment: laryngeal mask airway. Eye: intraocular pressure.
Tracheal intubation is performed routinely during general anaesthesia in patients undergoing intraocular surgery to secure a clear airway, to allow good surgical access and to facilitate ventilation of the lungs for control of PaCOf. However, intubation is associated with tachycardia, hypertension [1] and an increase in intraocular pressure [2]. Many techniques have been tried to attenuate this response but to date none has been completely successful [1]. The Brain laryngeal mask airway (LMA) has been shown to be an effective means of securing a clear airway in fasted patients for elective surgery [3]. Its insertion requires neither visualization of the cords nor penetration of the larynx, making placement less stimulating than tracheal intubation [4] and it may provoke less sympathetic response and catecholamine release. Therefore, during insertion of the LMA there is less likelihood of a pressor response or
PATIENTS AND METHODS
The study was approved by the Human Ethics Committee of the University of Cape Town and informed patient consent obtained. Twenty ASA I and II patients undergoing intraocular surgery were allocated randomly to receive a LMA (group 1) or T T (group 2). Any patient with oesophageal reflux or respiratory disease was excluded from the study. All patients received premedication with temazepam 0.3 mg kg"1 orally 1 h before operation. Before induction of anaesthesia, a vein in both arms was cannulated and 5 ml of venous blood withdrawn for measurement of plasma concentrations of catecholamines. Intraocular pressure was measured in the non-operated eye using a Perkins hand-held applanation tonometer after instillation of 0.5% amethocaine drops and fluorescein dye. Data were recorded at the times shown in table I. Monitoring consisted of continuous ECG, noninvasive arterial pressure, end-tidal carbon dioxide partial pressure, neuromuscular transmission by train-of-four stimulation, end-tidal enflurane partial pressure (Ohmeda Agent Monitor) and pulse oximetry. After determination of baseline data, the lungs were preoxygenated. Alfentanil 7 ug kg"1 was given K. LAMB*, F.R.C.ANAES., M. F. M. JAMES, PH.D., F.R.C.ANAES.,
P. K. JANICKI, M.D., PH.D., Department of Anaesthesia, University of Cape Town Medical School, Observatory 7925, Cape, South Africa. Accepted for Publication: February 25, 1992. 'Present address: Department of Anaesthetics, Victoria Infirmary, Glasgow. Correspondence to M.F. M.J.
Downloaded from http://bja.oxfordjournals.org/ by guest on March 22, 2016
Trachea/ intubation, performed routinely during general anaesthesia in patients undergoing intraocular surgery, may have adverse effects on cardiovascular function and intraocular pressure. This study assessed the suitability of the laryngeal mask airway (LMA) as a substitute for trachea/ intubation. Intraocular and systemic pressor effects, heart rate changes and catecho/amine concentrations were measured in two groups of 10 patients receiving standardized anaesthesia with either a trachea/ tube (TT) or a LMA. There were significantly smaller changes in the pressor responses to insertion and in concentrations of catecholamines at critical times in the anaesthetic sequence in the LMA group. Mean (SEM) rate-pressure product was significantly smaller in the LMA group compared with the TT group after both insertion (8276 (730) vs 13307 (1348), ?
