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Biomedical subjects

F Mertzlufft

Publications and source records attributed to F Mertzlufft.

86 records · Page 5Linked to original sources
PubMed1989

Failure of opioids to affect excitation and contraction in isolated ventricular heart muscle.

The opioid agonists morphine (selective for mu-receptors) and ethylketocyclazocine (selective for kappa-receptors), at concentrations evoking strong effects in neuronal structures, did not significantly affect the configuration of the intracellularly recorded action potential and the force of contraction in ventricular heart muscle isolated from guinea pigs, rabbits and man. These results suggest that any changes of heart functions in vivo in response to opioid-like drugs are probably not mediated postsynaptically at the myocardial cell membrane but rather presynaptically, influencing the release of noradrenaline and/or acetylcholine from the nerve terminals.

Acetylcholine↗
PubMed1989

Hyperoxic intubation apnoea: an in vivo model for the proof of the Christiansen-Douglas-Haldane effect.

The Christiansen-Douglas-Haldane effect, commonly known as the HALDANE effect, describes the dependence of the CO2 binding of blood on the degree of oxygenation of haemoglobin. Under the physiological conditions of an "open" system between blood and alveoli the partial pressure of arterial CO2, after CO2 delivery to the alveoli for example, can only range below the value of mixed venous blood. However, during the unphysiological circumstances of a "closed" system, e.g. the state of hyperoxic apnoea, i.e. oxygen uptake and lacking CO2 delivery, the paCO2 cannot only approximate the mixed venous value but must even exceed it. Without the Haldane effect coming into force, a rapid adjustment of arterial to mixed venous pCO2 would have to be expected during apnoea, due to the lacking CO2 delivery. If however, as a consequence of adequate preoxygenation (a high alveolar pO2) and failure to eliminate CO2 (i.e. the CO2 concentration remains constant) a sufficient oxygenation of blood takes place during the passage through the lung capillaries, then this leads to a rightwards shift of the CO2 binding curve--the Haldane effect. The resulting increase in pCO2 as shown here, actually leads to an arterial-mixed venous CO2 partial pressure difference of 2.8 +/- 1.8 mmHg, where pvCO2 decreases paCO2. The results described substantiate for the first time the existence of the Haldane effect under clinical conditions, too.

Apnea↗
PubMed1989

Accuracy of delivered versus preset minute ventilation of portable emergency ventilators.

The accuracy of delivered minute volume (VE) ventilation of portable emergency ventilators (PEV) was evaluated. Five PEV from three manufacturers were adapted to an artificial lung for varying compliance and resistance. Each PEV was tested in the "no airmix" (pure oxygen) and "airmix" (approximately 60% oxygen) setting at different frequencies and VE. Measurement of delivered VE (VEdel) was made using a pneumotachograph and digital integration of the flow values greater than 1 min (maximal error +/- 2%). Maximal inspiratory pressure (Pinsp) was measured with a transducer. Two PEV from one manufacturer produced severe hyperventilation when used at low VE (i.e., in children). Two other PEV from another manufacturer produced less marked hyperventilation, but revealed unexpected hypoventilation during conditions of higher inspiratory pressures (i.e., in adults with reduced compliance). The prototype PEV that was tested also revealed less marked hyperventilation with small decreases (down to -10% of the VE at higher Pinsp values). Further investigation is needed before this prototype goes into production. Manufacturers should redefine predicted values or machine settings or indicate that use of these devices may produce results which are not in accordance with the machine settings. Until adjustments are made, ventilation should be monitored when possible by measurement of end-tidal PCO2 or systemic arterial blood gases.

Adult↗
PubMed1989

[The status of arterial and mixed venous blood gases in the initial phase of intubation apnea. Studies on the Christiansen-Douglas-Haldane effect].

The Christiansen-Douglas-Haldane effect describes the reduced CO2 binding capacity of oxygenated as compared to deoxygenated hemoglobin on the basis of its increased acidity. This study describes the development of the above effect during the first 2 min of hyperoxic intubation apnea. METHODS. After institutional approval 12 patients (NYHA III, ASA IV) scheduled for coronary-artery bypass grafting were studied after written informed consent. Routine monitoring measures included invasive arterial and pulmonary-arterial pressure monitoring. Pulse oximetry (Nellcor N 101) was also used during intubation apnea. Premedication consisted of flunitrazepam 2.0 mg p.o. the evening before operation and another 2.0 mg p.o. 90-120 min before induction of anesthesia. Following standardized preoxygenation induction of anesthesia was performed with 20-25 micrograms/kg fentanyl and 0.1 mg/kg pancuronium. After cessation of spontaneous respiration, controlled ventilation was continued with 100% oxygen until intubation. Thirteen arterial (a) and mixed-venous (v) blood samples were drawn sequentially immediately before and during the first 2 min of apnea and analyzed using Corning 150 pH/blood gas analyzer and a Corning 2500 CO-oximeter. RESULTS. As shown in Table 1 and Fig. 1, paO2 decreased from 485 +/- 100 mmHg before apnea to 376 +/- 68 mmHg after 2 min of apnea while pvO2 remained constant at 47-50 mmHg. Arterial oxygen saturation (saO2) showed stable values greater than 97% while svO2 slightly increased from 81.9% to 82.4% until the end of apnea. A biphasic increase was observed in paCO2 from 41.2 +/- 3.4 mmHg before to 54.5 +/- 3.9 mmHg at the end of apnea. An increase in pvO2 during apnea was linear from 45.7 +/- 3.9 mmHg to 51.9 +/- 4.0 mmHg. After 28.5 s of apnea paCO2 exceeded pvCO2 due to the Haldane effect ("pCO2 reversal"). During apnea, pHa decreased biphasically from 7.40 +/- 0.03 to 7.31 +/- 0.02. The speed of decrease was 0.106 pH units/min (5-35 s) in the 1st and 0.023 pH units/min in the 2nd min of apnea; pHv decreased almost linearly from 7.37 +/- 0.03 mmHg (5s) to 7.33 +/- 0.02 mmHg (115s). After 20.66 s of apnea pHa exceeded pHv ("pH reversal"); pH-reversal occurred earlier than pCO2 reversal (p less than = 0.05). CONCLUSIONS. During early hyperoxic apnea, venoarterial pH and pCO2 reversal can be observed due to the Christiansen-Douglas-Haldane effect. pH reversal starts earlier than pCO2 reversal. Reversal time is dependent on arterial-mixed-venous pCO2 difference (avDpCO2) before apnea, arterial-mixed-venous O2 saturation difference (avDsO2) and cardiac output. The amount of reversal is dependent on avDsO2, i.e. the pH difference of arterial and m

Aged↗
PubMed1989

[The use of pulse oximetry in the perioperative monitoring of pediatric patients at risk using the surgical correction of a laparoschisis as an example].

Pulse oximetry has been recently introduced into anesthetic practice as an additional monitoring technique. In contrast to other methods (ECG, inspection, auscultation, blood gas analysis), it immediately detects an impending lack of oxygen, whatever its cause. Therefore, especially in pediatric risk patients, precious time can be saved. This is illustrated during the perioperative period for correction of gastroschisis. Even with a critical look at the mishaps of this method - overestimation of true O2 saturation (sO2) and partial O2 saturation (psO2) and overestimation of hemoglobin derivatives--pulse oximetry seems superior to the established monitoring techniques in the perioperative period. Therefore, we believe pulse oximetry to be an useful tool for additional monitoring, especially in pediatric risk patients. It is a suitable continuous and noninvasive in vivo technique for the early detection of hypooxygenation. Due to the special disadvantages of the method, we consider it advisable to perform control measurements with a CO-oximeter from time to time.

Abdominal Muscles↗
PubMed1989

[The Oxytron: a new device for administering oxygen in the spontaneously breathing patient].

The Oxytron (Weinmann, Hamburg, FRG) electronic oxygen conserver (patent pending) is a new device designed to deliver precise amounts of oxygen at the optimum point in the breathing cycle via a nasal cannula. In 200 Oxytron the delivered volume of oxygen was 35 +/- 5 ml within 150-200 ms at the beginning of the inspiratory phase of the respiratory cycle. Four different settings are possible: setting 1 provides one insufflation every 4th breath; setting 2 provides one insufflation every 2nd breath; setting 3 provides three insufflations every 4 breaths; and setting 4 provides an insufflation with every breath. These settings provide approx. The equivalent of 1-4 l oxygen per minute on a continuous flow basis. Both clinical experience and literature reports show variations in savings, with an average ratio of approx. 6:1 to 7:1. In the clinical evaluation, the following advantages were found: easy handling, exact oxygen delivery, increased oxygen saving and increased oxygen delivery with increasing respiratory rate. Due to the lack of any alarm system monitoring disconnection or failure of oxygen supply must be considered a disadvantage.

Anesthesia↗
PubMed1989

[The washout behavior of isoflurane following balanced anesthesia and its effect on postoperative oxygen supply].

Few studies have described the pharmacokinetics and pharmacodynamics of isoflurane (I) during the postoperative recovery room stay. In this study the influence of balanced anesthesia with I on the postoperative course was investigated by studying pulmonary washout of I and its effect on arterial oxygen saturation. METHODS. Following institutional approval and informed consent, 50 patients (ASA I and II) scheduled for lateral fenestration for intervertebral disc herniation participated; all had no previous record of cardiopulmonary problems. Induction of anesthesia was achieved with intravenous alcuronium 0.03 mg/kg, fentanyl 0.003 mg/kg, thiopental 5 mg/kg, and succinylcholine 1.5 mg/kg followed by alcuronium 0.09 mg/kg before changing to the prone position. Anesthesia was maintained with controlled ventilation in a rebreathing system (fresh gas flow FGF) = 3.01/min, FIO2 = 0.3 in N2O, plus 0.8 Vol.-% cIet = 1.3 MAC). Near the end of surgery I was discontinued and IGI was increased to 61/min O2 for 10 min. Patients then returned to breathing ambient air. Extubation was carried out as soon as a minimum tidal volume of 400 ml was obtained. End tidal I concentration (cIet; Vol.-%) was measured by infrared absorption (Normac, Datex) and O2 saturation by pulse oximetry (Biox III, Ohmeda). Datum point of the pulmonary I-washout curve was the mean end-tidal I concentration obtained 15 min before terminating I (cIAW). Effects of duration of anesthesia, Broca index, and amount of I administered (tidal volume x inspiratory I concentration x min; ml) on I-washout were assessed. A pulse-oximetric O2 saturation of less than 90% was regarded as hypoxygenation. RESULTS. Mean duration of anesthesia for both males and females was 85 +/- 25 min, mean Broca index 102 +/- 13. The amount of I administered with the inspiratory volume was 5.661 +/- 2.194 1 I (1.0 +/- 0.4 Vol.-%). Mean I-regression (Fig. 3) was 236 x 10(-5) Vol.-%/min (Figs. 1 and 3). Mean I-washout 60 min after extubation was 44.6 +/- 15.2% of the administered amount. Adequate spontaneous breathing began a mean of 17 min after the end of I exposure, corresponding to 20% cIet of washout. All patients were extubated after a mean of 22 min at a mean etI of 17% of washout. After extubation, pulse oximetry indicated hypoxygenation in 18 patients (= 36%) during 2 periods (Fig. 4): (1) at a mean cIet of 0.1 Vol.-% (= 15% of washout) after a mean of 8 min; and (2) at a mean cIet of 0.08 Vol.-% (= 12% of washout) a mean of 19 min following extubation. Further episodes of hypoxygenation occurred as much as 40 min post-extubation. (ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1988

Prolonged anaesthesia with isoflurane and halothane. Effects on hepatic function.

Hepatic function was assessed pre-operatively and on the first and sixth postoperative days in 40 healthy patients who underwent prolonged maxillofacial surgery with isoflurane or halothane anaesthesia. No major changes were observed in hepatic enzymes or bilirubin. One-stage prothrombin time and Factor VII concentrations decreased on the first postoperative day and this change was more pronounced in the halothane group. The results support the use of isoflurane rather than halothane for prolonged anaesthesia in respect of the synthesising function of the liver.

Anesthesia, Inhalation↗
PubMed1988

[Effect of different pre-oxygenation procedures on arterial oxygen status].

There are different opinions regarding efficiency, duration, and techniques of preoxygenation. It was the aim of our study to systematically investigate the effectiveness of different preoxygenation methods by means of arterial blood gas parameters (paO2, SaO2, and CaO2). METHODS. After receiving informed consent, 80 patients undergoing coronary bypass grafting (NY-HA II-III, ASA III-IV, mean age 57 years) were randomized in eight groups, each with a different preoxygenation technique (Table 1). During normocapnic preoxygenation (Table 2), the following parameters were compared: duration of preoxygenation (3 vs. 5 min), manner of holding the face mask (tightly fitting vs. one digit away from mouth and nose), and oxygen flow (6 vs. 10 l/min) via anesthesia circuit system. Arterial blood gases were analyzed with a Corning 170 pH/blood gas analyzer and a Corning 2500 CO-oximeter. For statistical analysis Student's t-test was used. P less than or equal to 0.01 was considered to be significant (*). RESULTS. As Fig. 1 shows, the different preoxygenation techniques affected paO2 values differently: oxygen flow had a greater influence than duration of preoxygenation. Most important was the manner of holding the face mask. With a tightly fitting mask, preoxygenation was more effective than with the face mask one digit away from mouth and nose, independent of preoxygenation time and oxygen flow (Table 3). The SaO2 (Fig. 2) increased in the same manner with the different preoxygenation techniques from 94.0% to 97.5% (Table 3); CaO2 (Fig. 3) was influenced in a similar way (16.7 ml/dl to 17.4 ml/dl).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Gas Analysis↗
PubMedDate not supplied

Prevalence and persistence of heparin/platelet factor 4 antibodies in patients with heparin coated and noncoated ventricular assist devices.

Thromboembolism is a major complication in patients with ventricular assist devices (VAD). Anticoagulation with heparin, coumarin, and anti-platelet agents, particularly the development of biocompatible surfaces such as inner pseudo-endothelial layers or a coating with heparin, are intended to reduce these complications. However, the administration of heparin can lead to heparin induced thrombocytopenia type II (HIT II). Predominantly heparin/platelet factor 4 (HPF4) antibodies are responsible for the development of HIT II. The goal of the present investigation was to assess the prevalence of these antibodies in patients with heparin coated and noncoated VADs. Fifty-five patients were enrolled in the investigation. A heparin coated system was implanted in 30 patients, and a noncoated system was implanted in 25 patients. Antibodies were evaluated before, on days 7 and 14, and 3 months after implantation. Testing was performed with the Heparin/Platelet factor 4 enzyme-linked immunosorbent assay (ELISA) (Stago, France). In 40 of the 55 patients, the formation of HPF4 antibodies was observed (73%). In 35 of these patients (88%), HPF4 antibodies were present before surgery. There were no differences between the groups. In 11 patients (equal from both groups), the antibodies disappeared after termination of systemic heparinization. We conclude that in a rather high percentage of patients with VADs HPF4 antibodies are found. This finding may be explained by the repetitive and prolonged exposure of these patients to heparin. Immobilized heparin, as presently used in the carmeda coating, seems not to influence the formation and persistence of HPF4 antibodies. Further studies will have to prove whether HPF4 antibodies contribute to thromboembolic complications in these patients.

Adult↗