Oximetry in pulseless disease

992 zyxwvutsrqpo zyxwvutsrqp zyxwvu Correspondence coat.’ Jeffreys’s explanation was that a very much smaller quantity of heat was ‘lost by the lungs in respiration, partly in raising a cold air up to blood heat, and in part in the form a latent heat carried off in the vapour exhaled.2 Jeffreys, who was no mean physicist, recognised, from a consideration of the physical principles involved, that for efficient heat transfer both a good conductive material and a cascade mechanism were needed. His heat and moisture exchanger consisted of from eight to 12 closely woven lattices of very fine silver wire, each insulated from the next.’ He took the unusual step of patenting it in his concern to ensure the accurate manufacture of the device, and to protect it from less effective imitations. Mapleson and his colleagues, in their investigation of condense-humidifiers, supported, albeit unwittingly, Jeffreys’s stipulation that for maximal effect the lattices, or gauzes, should be thermally isolated from one another, and about 10 layers thick.4 The limitations of the Portex device, therefore, argue against its failure to conform in its design to the principles established by Jeffreys. Craigo wer, St Andrews Close, London NI2 8BA References D. ZUCK zyxwv 1. ZUCK D, Julius Jeffreys-pioneer of humidification. Proceedings of the History of Anaesthesia Society. (in press) 2. JEFFREYS J. On artificial climates for the restoration and preservation of health. London Medical Gazette 1842: 3 0 431. 3. JEFFREYS J. On artificial climates for the restoration and preservation of health. London Medical Gazette 1842; 3 0 291. 4. MAPLESON WW, MORGANJG, HILLARDEK. Assessment of condenser humidifiers with special reference to a multiplegauze model. British Medical Journal 1963; I: 300-5. zyxwvutsrq zyxwvu zyxwvutsr Inhaled opiates The ‘recent interest’ in the delivery of opiates by nebuliser (Anaesthesia 1990; 4 5 449) is rather longstanding. Beigel’ wrote his treatise in 1866 ‘On Inhalation’! This deals with the application of nebulised solutions in the treatment of various chest diseases, which was a novel approach at the time designed to get the drug to the site of action. He, (although not the beneficiary of our present knowledge of pharmacokinetics) comments ‘It must be borne in mind that besides the local effect of the spray, absorption takes place also, and that medicaments are even much more readily absorbed through the mucous membranes than they are by internal application-a fact which must be taken into consideration when the dose is to be decided upon.’ The pharmacopoeia of suggested drugs for inhalation is rather limited, but it includes the following: ‘9. Tincture of opium, from five to twenty minims (approximately 3-12 mg morphine) to one ounce of water, is very often beneficially applied, when it is our aim to rid the patient of a troublesome cough, be it a symptom of phthisis or of any other pathological process of the respiratory organs, provided that no phenomen exists preventing the application of opium in general.’ It will be interesting to observe how the story unfolds this time around, and I can d o no better than to close with the end of Beigel’s treatise. ‘He who expects wonders from that mode of treatment (nebulised drugs) will soon be disappointed: he who recommends it as an infallible one, will prove a false prophet; but an unprejudiced application of the atomizer will lead to a conviction that the invention of Sales-Girons has been a most valuable addition to therapeutics.’ Queen Elizabeth Hospital, Edgbaston, Birmingham BIS 2TH Reference I . BETGEL H. On Inhalation, as a means of local treatment of the organs of respiration by atomized ,fluids and gases. London: Robert Hardwicke, 1866. A reply We would like to thank Dr Harrison for drawing attention to the historical aspects of our paper. Interest in the delivery of opiates in this manner is recent in the anaesthetic literature, but the concept is indeed a very old one as Dr Harrison points out. Opiates were used by religious cults in the Eastern Mediterranean area as early as 5000 years ago,’ and a n opium pipe dating from the 12th century BC found in Cyprus2 indicates that their administration by inhalation is a t least 3000 years old. We agree entirely with Dr Harrison that in general terms the technique is not new, and also with his 19th century source Beigel, in that we should not have unrealistic hopes of any treatment until it has been thoroughly investigated. To this end, we hope our application of a pharmacokinetic and pharmacodynamic approach to the use of fentanyl in this manner is a step along that path. Royal Injirmary. Edinburgh EH3 9YW M.H. WORSLEY C. CLARK References 1. Encyclopaedia Britannica, 15th edn. Chicago: 1988; 1 3 242. 2. KARAGEORGHIS V. A 12th century BC opium pipe from Kition. Antiquity 1976; 5 0 125-9. G.R. HARRISON Oximetry in pulseless disease We report the use of a pulse oximeter in two patients with pulseless disease to monitor arterial oxygen saturation and systolic blood pressure. A 30-year-old female, who was known to have aortoarteritis presented with chronic suppurative otitis media for mastoidectomy under general anaesthesia. Examination revealed bilaterally weak carotid pulsations and absent pulses in both the arms. The pulses in the lower limbs were palpable, and blood pressure of 140/96 mmHg was recorded. A pulse oximeter (Ohmeda Biox 3700) was used to monitor the systolic pressure in the upper limb. The finger probe of an oximeter, when placed on the right hand, showed a distinct plethysmographic waveform with oxygen saturation (Spo,) of 92-95%. The pulse oximeter was judged to be functioning accurately once the pulse rate Correspondence displayed by the oximeter and cardioscope corresponded. An appropriate size blood pressure cuff connected to a mercury manometer was placed on same arm. The cuff was manually inflated in 2-5-mmHg increments till the plethysmographic waveform disappeared and the reading recorded. The cuff was then inflated to 250 mmHg and gradually deflated until the waveform reappeared on the oximeter and the monometer reading recorded at this point. The average of the two recordings was taken as systolic blood pressure in the upper arm. This technique to measure the systolic blood pressure was adopted in the intra-operative and postoperative periods. A 45-year-old male, known to have aorto-arteritis presented to the ICU in grade IV coma and with irregular breathing (rate 44/minute). All the peripheral pulses and left carotid pulse were absent. Therefore, measurement of systolic blood pressure by conventional techniques was not possible. Management included ventilatory support and general supportive care. The pulse oximeter was used to zyx 993 monitor systolic blood pressure (as described above) during his 9-day stay in the ICU. It is technically difficult to obtain reliable estimates of systolic blood pressure in these patients. Ramanathan et al.’ observed a pulsatile blood flow in clinically nonpulsatile arteries in patients with Takayasu’s syndrome. We too observed the plethysmographic waveform on the oximeter in the limbs with weak or absent pulses. zyxwvu zyxwvu zyxwv zyxwvu Guru Teg Bahadur Hospital, Shardara, Delhi, India R. CHAWLA V. KUMARVEL K.K. GIRDHAR A.K. SETHI A. BHATTACHARYA Reference 1. RAMANATHAN S, GUPTAU, CHALON J, TURNDORF H. Anesthetic considerations in Tdkayasu arteritis. Anesthesia and Analgesia 1919; 58: 241-9. Noncardiogenic pulmonary oedema after attempted suicide by hanging Acute pulmonary oedema after an attempted suicide by hanging was reported earlier,’ but it was not defined by the recent diagnostic criteria for adult respiratory distress syndrome (ARDS).’ This is a case report of a patient who could not be saved despite best possible supportive care and monitoring where these criteria were used. A 25-year-old woman was brought to the casualty department of our Institute within 25 minutes of rescue by her family from an attempted suicide by hanging. The exact duration of hanging was not known. She was unconscious with normal sized pupils that were sluggisly reacting to light. There was dusky cyanosis in the peripheries; her respiratory rate was 22/minute. Her arterial blood pressure was 80/60 mmHg and her heart rate 140 beats/minute. There was no evidence of upper airway obstruction but there were crepitations at both lung bases. There was an ecchymotic mark over the anterior aspect of the neck. Her trachea was inhutated with a 7.5-sized Portex cuffed nasotracheal tube and manual ventilation of the lungs was started with an Ambu bag with 100% oxygen. This resuscitation improved her arterial blood pressure to 110/70 mmHg. The patient was transferred to the respiratory intensive care unit (RICU) and connected to a Cape 2600 intensive care ventilator with Ao, of 1.0. Pink frothy secretions were observed through the transparent tracheal tube within a few minutes. The airway pressure was 4.5 kPa. Hypoxaemia (Pao, 5.7 kPa) and metabolic acidosis was demonstrated on arterial blood gas analysis (sample I ) . Furosemide 60 mg, 100 mmol NaHCO, were given intravenously and 1.0 kPa PEEP was applied. Improvement (sample 2) resulted. A chest radiograph showed pulmonary oedema with densities in all four lung quadrants. A radiograph of the neck was normal. A bedside two-dimensional echocardiograph revealed normal ventricular size, normal sized pulmonary veins, fair left ventricular function and normal valves. 12-lead electrocardiography (ECG) revealed sinus tachycardia. Four hours after admission to RICU, there was systolic hypotension (70 mmHg) which failed to respond to a fluid challenge. PEEP was deceased to 0.6 kPa and a dopamine infusion was commenced at a rate of (5 pg/kg)/minute which resulted in improvement of systolic pressure to 110 mmHg. The patient regained consciousness the next morning (approximately 8 hours after admission to RICU) with no apparent neurological deficit. She continued to receive dopamine infusion at a rate of 5 to 8 (pg/kg)/minute to maintain her systolic blood pressure between 90 to 100 mmHg. The chest X ray was not changed. Arterial Paoz ranged between 22 and 24 kPa (samples 4, 5 and 6) with an Flo, of 0.8 and PEEP 0.6 kPa. Cardiac arrest occurred on the morning of the third day from when she was resuscitated. The Ao, was increased to 1 and dopamine infusion rate to 12 (pg/kg)/minute after this episode. Sample 7 (after cardiac arrest) revealed a Pao, of 8.3 kPa. Bedside two-dimensional echocardiography again showed no regional wall motion abnormalities, mild diastolic dysfunction, normal function of the valves, and overall good left ventricular function. Sinus tachycardia continued. PEEP was increased to 1 .O kPa since an Flo, 1 .O had failed to improve arterial oxygenation (sample 8). Severe pulmonary oedema persisted on X ray. She was resuscitated after five more episodes of cardiac arrest, but she succumbed on the sixth occasion. Monitoring during management in RICU consisted of continuous ECG, direct arterial blood pressure, inspired oxygen concentration, end tidal CO,, central venous pressure and urine output monitoring. Intravenous fluids (crystalloids) were administered according to CVP, arterial blood pressure and urine output. This case illustrates the occurrence of 4 R - X after an attempted suicide by hanging. The recent expanded criteria2 for ARDS using chest X ray, hypoxaemia and PEEP scores were used (see Table). Cardiac failure was excluded by use of bedside two-dimensional echocardiography. The pathogenesis of pulmonary oedema appears to be similar to that after relief of acute airway obstruction.’ Acute upper airway obstruction during hanging results in a large increase in subatmospheric pressure which may be transmitted to the interstitial peribronchial and perivascular spaces; this disrupts the integrity of the pulmonary capillaries. The high subatmospheric transpulmonary pressure would enhance venous return, while simultaneously fluid therapy would increase the preload and consequently the pulmonary vascular pressure. These cardiovascular haemodynamics are opposed during expiration by the relatively high positive transpulmonary pressure. The expiratory component of acute upper airway obstruction thus acts as a form of retard, akin to PEEP, which exerts a protective effect in the patient. The haemodynamic consequences produced by an abrupt zyxwvuts