Acta anaesthesiologica Scandinavica
-
Acta Anaesthesiol Scand · Jan 1976
ReviewThe effect of respiratory frequency on pulmonary function during artificial ventilation. A review.
This is a review of previous studies on the effects of variations between 12 and 24 breaths per minute in ventilation frequency during artificial ventilation, minute ventilation being constant. The total material consisted of 66 healthy subjects investigated under anaesthesia with artificial ventilation and 43 patients investigated during prolonged respiratory treatment. An increase in ventilation frequency resulted in an increased ratio of dead space to tidal volume (VD/VT) and in diminished alveolar ventilation with a subsequent elevation of Paco2. ⋯ Cardiac output was increased, as was venous admixture. Pao2 was slightly reduced. The more efficient gas exchange occurring at a low ventilation frequency makes this setting preferable in the treatment of patients with chronic obstructive lung disease, whereas a high ventilation frequency, by improving cardiac output, may be advantageous in patients with circulatory failure.
-
Acta Anaesthesiol Scand · Jan 1976
Anesthetic management of posterior fossa surgery in the sitting position.
From the surgical aspect, the sitting position gives good surgical access to the operative site, improves venous drainage, gives a better view of facial area for monitoring evoked responses from cranial nerve stimulation and allows for better ventilation. Conversely, the sitting position can present complications such as air emboli, postural hypotension and serious cardiac arrhythmias due to surgical stimulation of cranial nerves and brainstem. This paper presents our clinical experience in 180 neurosurgical procedures on the posterior fossa in the sitting position. ⋯ Surgical stress also accounted for the 13 patients (7%) having frequent premature ventricular extrasystoles. One case of profound hypotension and another case of virtual cardiac standstill were noted during the use of the bipolar electrocautery at or near the fifth nerve exit from brainstem. Additional hemodynamic data, the physiopathology, diagnosis and treatment of air embolism is discussed.
-
Capnography and measurement of the respiratory minute volume were carried out on normal, conscious subjects during breathing of pure O2 via a Mapleson C modification of a Magill attachment, with and without continuous gas evacuation. The measurements were performed in two series, with intermittent discharge and with continuous evacuation. ⋯ The measurements indicated CO2 accumulation at a flow below 200% of the respiratory minute volume. There was no significant difference between the systems with and without evacuation.
-
Exact placement is an essential prerequisite for long-term use of a central venous catheter. Reported data show an extremely wide range of catheteral misplacements: from less than 1% to more than 60%. Some approaches appear to be less advantageous than others, but the highest rates of misplacement occur in the cubital, external jugular and saphenous veins. ⋯ The total frequency for pure loop formation was 2.9%. The authors discuss numerous reported data on catheter malpositioning, according to the specific techniques used, and compare them with thier own results. The relatively low incidence in the present series is possibly due to the high proportion of cases where the supraclavicular subclavian approach was used, the omission of the sphrenous/femoral and cubital techniques, and to pre-determining the length of the inserted catheteral segments.
-
Acta Anaesthesiol Scand · Jan 1976
Anesthesia for cesarean section IV: placental transfer and neonatal elimination of bupivacaine following epidural analgesia for elective cesarean section.
Epidural analgesia with bupivacaine was used for elective cesarean section, and repeated maternal and neonatal blood samples were collected over 24 h for calculation of drug concentration. A gas-chromatogrphic micro-method was used for the analysis. The aim of this investigation was to evaluate the placental transfer and the elimination rate of the drug. ⋯ The fetal-maternal ratio of concentrations at delivery was higher than in previous studies, most probably due to the protein-binding characteristics of bupivacaine and the dosage used. The biological half-life of the rapid phase of elimination (alpha-phase) in the newborn was shorter than in the mother (P less than 0.002), indicating a more rapid distribution process. The half-life of the slow phase of elimination (beta-phase) in the newborn was of the same magnitude as in the mother, indicating that neonatal elimination processes of bupivacaine may be well developed at birth.