[Development of continuous monitoring of spontaneous respiration in the postoperative phase. 2. Cutaneous oxygen and carbon dioxide partial pressures following i.v. bolus application of fentanyl, buprenorphine, naloxone and amiphenazole in healthy adult subjects]. / Entwicklung eines kontinuierlichen Monitorings der Spontanatmung in der postoperativen Phase. Teil 2. Kutane Sauerstoff- und Kohlendioxidpartialdrücke nach i.v. Bolusapplikation von Fentanyl, Buprenorphin, Naloxon und Amiphenazol bei gesunden erwachsenen Versuchspersonen.

METHODS: In an attempt to develop a noninvasive monitoring technique for patients in the early postoperative period, cutaneous O2 and CO2 pressures (pctO2, pctCO2) were monitored in ten healthy adult volunteers of both sexes (5 male, 5 female, age 29 +/- 5 years, weight 68 +/- 11 kg) who received, in several sessions after a 60-min equilibration period, i.v. bolus doses of fentanyl (3 micrograms/kg and, 60 min later, another 1.5 micrograms/kg), buprenorphine (3 and 1.5 micrograms/kg), naloxone (1.8 and 0.9 micrograms/kg), and the respiratory analeptic amiphenazole (2 and 1 mg/kg) as well as combinations of fentanyl/amiphenazole or buprenorphine/naloxone in the aforementioned dosages. Data were collected and stored by a personal computer using the TCM3 system with a combination electrode for simultaneous measuring of pctO2 and pctCO2 (TINA, Radiometer) at 30-s intervals. The overall observation period was 240 min. Means, standard deviations, and ranges were calculated for individual data and data pooled for 15-min intervals. Groups were compared by means of Student's t-test and analysis of variance. RESULTS: Following i.v. fentanyl 3 micrograms/kg, pctO2 decreased and pctCO2 increased rapidly and statistically significantly. The changes were of similar intensity after the first and second doses (1.5 micrograms/kg) and normalized about 60 min after each injection. In contrast, following i.v. buprenorphine (3 and 1.5 micrograms/kg) the cutaneous partial pressures changed continuously and progressively during the observation period and did not reach the control values after 240 min. Naloxone and amiphenazole injections had no obvious influence on the time course of the blood gas tensions. If opiates and antagonists were combined, neither the fentanyl/amiphenazole group nor the buprenorphine/naloxone group differed significantly from the respective opiate groups. DISCUSSION AND CONCLUSION: As was discussed in detail in a previous communication, monitoring of opiate-induced respiratory depression must be nonstimulant and, preferably, noninvasive. Whereas the precision and/or limitations of monitoring partial oxygen saturations by pulse oximetry is well documented in the literature, knowledge of the value of cutaneous partial pressure monitoring is still limited and controversial for the adult patient population. The present study was performed to define the usefulness of cutaneous blood gas analysis in healthy volunteers receiving opiate dosages well known in recovery room patients. It is concluded that continuous monitoring of pctO2 and pctCO2 can indeed detect opiate-induced respiratory depression in adults. The well-known difference in respiratory pattern for fentanyl and buprenorphine could easily be determined. It was confirmed that naloxone and amiphenazole in the dosage range studied do not influence spontaneous respiration in healthy adults. Thus, the authors are convinced that continuous monitoring of cutaneous partial pressures of oxygen and carbon dioxide is sensitive enough to be used, in combination with pulse oximetry, in a monitoring concept for patients recovering from surgery and anaesthesia. Results in patients undergoing conventional pain management or patient-controlled analgesia with relatively high opiate dosages will be presented in following papers. Concerning the controversy about clinically relevant interactions between fentanyl and amiphenazole or buprenorphine and naloxone, the present study did not confirm any useful antagonism. Whether this is due to limitations of cutaneous monitoring, the difference between volunteers and patients, or pharmacological reasons must be evaluated in further investigations.

[Development of a method of continuous monitoring of spontaneous respiration in the postoperative phase. 1. Normal values for cutaneous pO2- and pCO2-partial pressure together with pulse oximetry determined oxygen saturation in healthy young volunteers]. / Entwicklung eines kontinuierlichen Monitorings der Spontanatmung in der postoperativen Phase. Teil 1. Normalwertbereiche für kutane pO2- und pCO2-Partialdrücke sowie pulsoxymetrisch bestimmte Sauerstoffsättigungen bei gesunden jungen Erwachsenen.

METHODS: Twenty-eight healthy volunteers of both sexes (14 male, 14 female, age 31 +/- 7 years, weight 70 +/- 12 kg) breathing room air were monitored for cutaneous partial pressures of oxygen and carbon dioxide (pctO2, pctCO2) and partial oxygen saturation (psO2) as determined by pulse oximetry. Data triplets were collected and stored by a personal computer at 30-s intervals during a 4-h resting period to establish a confidence range for the devices in use (TCM 3 with a combination electrode E 5270, and Pulse Oximeter, Radiometer). This data range was intended to be used in later noninvasive, continuous respiratory studies with postoperative patients. Means, standard deviations, and ranges were calculated for individual data and data pooled from 15-min intervals. Data distribution over time was calculated for 30-min intervals. RESULTS: Contrary to the saturation data delivered by pulse oximetry, the pctO2 and pctCO2 readings needed about 15 min to stabilize. The mean +/- SD of a total of 12,600 pctO2 measurements (77.2 +/- 10.9 mmHg) could not simply be compared with arterial normal values, whereas the pctCO2 measurements (39.9 +/- 3.6 mmHg) fit well with arterial data from the literature. Interestingly, pctCO2 values in unmedicated healthy adults were not uniformly distributed, suggesting individual differences in either skin permeability of central regulation of respiration. Additionally, the pctO2 readings were characterized by serious inter-subject variability, which confirms earlier studies that pctO2 is not suitable for routine monitoring procedures in adults, the mean +/- SD of a total of 4500 psO2 measurements was 94.9 +/- 1.6%. A statistically significant correlation was found between pctO2 and psO2 (r = 0.358). Cutaneous carbon dioxide readings of greater than 50 mmHg were observed in only 0.06% of all 12,600 data sets (maximum 51.3 mmHg; 28 volunteers), desaturations (less than 90%) in only 0.24% of all 4,500 saturation measurements (minimum 86%; 10 volunteers). DISCUSSION AND CONCLUSION: Monitoring of spontaneous respiration in the recovery room is regarded as essential to prevent serious complications resulting from surgery and anesthesia. This has become particularly true with newer analgesic techniques like spinal opiates or patient-controlled analgesia. Since minor degrees of opiate-induced respiratory depression are easily influenced by external stimulation, it is mandatory that any monitoring of spontaneous respiration must be nonstimulant, and prefereably noninvasive. The present communication is the first of a series of investigations to develop of monitoring technique for postoperative patients. Because normal values for the parameters studied are either lacking or dependent on the monitoring devices in use, the present paper defined the respective data ranges. It is concluded that pulse oximetry and pctCO2 measurement are both useful and sensitive for continuous, non-invasive respiratory monitoring in adults, whereas pctO2 measurements are of lesser value. Results in volunteers treated with opiates and postoperative patients under patient-controlled analgesia using the above mentioned equipment will be reported in following publications.

Diagnostic value of transesophageal echocardiography in cardiac surgery.

The aim of this study was to assess the diagnostic value of intraoperative 2-D color Doppler transesophageal echocardiography (ITEE) for the surgeon and anesthesiologist in patients undergoing coronary bypass surgery or heart valve replacement. Information given by ITEE in 100 cardiac operations was documented. We judged the ITEE information, considering to what extent it was not to be obtained by other methods and to what extent it influenced the operation itself. The value was classified as dispensable (0), informative (1), valuable (2), or essential (3). In 50 consecutive patients with heart-valve replacement (25 aortic valve prostheses, 25 mitral valve prostheses) ITEE was 38 x (0), 8 x (1), 4 x (2). In 50 consecutive patients undergoing coronary artery bypass graft surgery it was 33 x (0), 11 x (1), 4 x (2), 2 x (3). The two essential diagnoses referred to undetected vein graft occlusions. Information classified as valuable mainly referred to left and right ventricular function or valvular and prosthetic valve function when difficulties occurred during and after extracorporeal circulation. In conclusion, information given by ITEE, although generally regarded as dispensable in the procedures considered, was valuable in 10% of cases and in 2% even essential.

Muscle relaxation in patients with Duchenne's muscular dystrophy. Use of vecuronium in two patients.

Cumulative 50% and 90% neuromuscular blocking doses of vecuronium were determined in two 4-yr-old boys with Duchenne's muscular dystrophy. Vecuronium 20 micrograms kg-1 was required for 50% twitch depression in both patients. The 90% blocking doses were 43 and 57 micrograms kg-1. Although these data do not indicate a greater than normal sensitivity to vecuronium, the recovery time (75-25% block) of twitch tension was three to almost six times as long as in normal children. The evoked compound EMG, additionally recorded in one patient, reflected almost the same dose-response relationship as twitch tension, yet the EMG recovered faster than the twitch. The present findings do not exclude an increased sensitivity to neuromuscular blocking drugs in a larger population of patients with muscular dystrophy. Thus, the titration of the individual neuromuscular blocking dose with the aid of a nerve stimulator is mandatory. During a previous anaesthetic, cardiac arrest and acute rhabdomyolysis had occurred in one patient. The substitution of suxamethonium by vecuronium, or probably any other non-depolarizing myoneural blocking drug of intermediate or short duration of action, may help to avoid this complication.