A. Eugene Pflug

The Effects of Postoperative Peridural Analgesia on Pulmonary Therapy and Pulmonary Complications

Effects of continuous postoperative pain relief produced by peridural block with bupivacaine on effectiveness of postoperative pulmonary therapy, incidence of pulmonary complications, and duration of convalescence were evaluated. Patients receiving morphine for postoperative analgesia served as controls. Forty patients scheduled for upper abdominal or hip-fracture operations were studied for 72 hours. They were divided into four equal groups: postoperative peridural analgesia with pulmonary therapy, peridural analgesia without pulmonary therapy, morphine analgesia with pulmonary therapy, and morphine analgesia without pulmonary therapy. Preoperative and postoperative variables compared were: chest x-rays, arterial blood gases, calculated alveolar-arterial Po2 differences (A-aDo2), vital capacity (VC), peak expiratory Bow rate (PEFR), and duration of convalescence. Patients receiving pulmonary therapy combined with either morphine or peridural analgesia postoperatively did not have a decreased incidence of atelectasis, improvement in blood-gas values, or shorter convalescence times compared with control values (no pulmonary therapy). Twelve of 20 patients in the morphine group and seven of 20 patients in the peridural analgesia group showed x-ray evidence of atelectasis 72 hours after operation. Twenty-four hours postoperatively, the morphine group had decreased arterial blood gases (Pao2 Paco2), vital capacity, and peak expiratory flow rate, and an increase in A-aDo2 compared with preoperative levels. Corresponding values in the peridural analgesia group did not reveal a significant improvement over the morphine group. The mean convalescence time of peridural analgesia patients was three days shorter than that of the patients receiving morphine (4.8 ± 0.2 vs. 7.8 ± 0.6, P < 0.005).

Arterial-venous differences of plasma catecholamines in man

To investigate the relationship between forearm venous levels of catecholamines and systemic levels, simultaneous arterial and forearm vein blood samples were obtained from 14 subjects undergoing elective dental procedures and assayed with a sensitive and specific radioenzymatic assay. Baseline venous levels of norepinephrine were greater than arterial levels (305 +/- 30 pg/ml versus 221 +/- 18; +/- SEM, p less than .005). Conversely, arterial epinephrine levels were higher than venous (132 +/- 17 pg/ml versus 80 +/- 10; p less than .005). There was a significant relationship between arterial and venous levels of both norepinephrine (r = .77, p less than .01) and epinephrine (r = .67, p less than .01). The arterial-venous epinephrine difference increased from the baseline value of 44 +/- 14 pg/ml to 108 +/- 16 (p less than .005) by 3 min after subcutaneous injection of epinephrine (18 microgram), but the arterial-venous difference returned to 65 +/- 24 by 5 min after injection (p = NS versus baseline). These findings indicate that under the conditions of this study, forearm tissues produced more norepinephrine than they removed, but removed more epinephrine than they produced. Baseline venous and arterial levels were related; when epinephrine production was augmented, there was a short time lag for the venous epinephrine increase.

Prevention of post-anaesthesia shivering

SummaryThis study involves ventilation of the lungs with warmed humidified anaesthetic gases during prolonged elective abdominal operations. Tympanic, oesophageal and toe temperatures were compared between twenty warmed and twenty un-warmed patients at various times during operation and recovery. Fifty per cent (10/20) unwarmed patients shivered in the recovery room, while none of the warmed patients shivered. Our data indicate that pulmonary ventilation with warm humidified anaesthetic gases provides heat transfer by the lungs, preventing hypothermia during operation and post-anaesthesia shivering is prevented by maintaining the patient normothermic in both the operating room and the recovery room.RésuméAu cours ďinterventions abdominales électives de longue durée, nous avons utilisé des gaz anesthésiques humidifiés et réchauffés pour ventiler 20 de nos malades. Nous avons comparé les températures tympaniques, oesophagiennes et cutanées (gros orteil) de ces 20 malades à celles de 20 malades subissant des interventions du même genre et ventilés avec des gaz anesthésiques non chauffés. Cinquante pour cent (10/20) des malades non réchauffés par des gaz ont présenté du tremblement dans la salle de réveil. Aucun des malades ayant reçu des gaz chauds n’a tremblé.Nos résultats indiquent qu’une ventilation pulmonaire utilisant des gaz anesthésiques chauds et humidifiés permet un transfert de température au niveau du poumon et prévient l’hypothermie en cours de chirurgie, et que le tremblement post-opératoire est évité par le maintien du malade en normothermie.

Sequence of return of neurological function and criteria for safe ambulation following subarachnoid block (Spinal anaesthesic)

SummaryTwenty-three adult men were studied during and after subarachnoid block anaesthesia for elective surgery. Measurements were obtained of mean arterial pressure and pulse, both supine and after standing for five minutes, core body (tympanic) and peripheral skin (toe) temperatures and blood flow in the leg. Time of measurements included one hour after the injection of tetracaine and after regression of the block. Results obtained indicate that the sequence of return of neurological activity following tetracaine subarachnoid block is sympathetic nervous system activity, pinprick sensation, somatic motor function followed by proprioception in the feet. This progression provides the basis for recommended criteria which indicate when it is safe for patients who have had subarachnoid block anaesthesia to become ambulatory. These criteria include: (I) return of pinprick sensation in the peri-anal area (sacral 4-5); (2) plantar flexion of the foot (while supine) at pre-anaesthetic levels of strength; and (3) return of proprioception in the big toe, always provided that the patient is not hypovolaemic or sedated.RéSUMéLes auteurs ont soumis 23 adultes consentants à une étude visant à déterminer ľordre de retour des fonctions sympathiques, sensitives et motrices, après anesthésie sous-arachnoïdienne et à rechercher des critères permettant à ces patients de reprendre la station debout en toute sécurité. A ces fins, ils ont effectué des mesures de fréquence cardiaque et de pression artérielle moyenne en position couchée et après cinq minutes de station debout, de température centrale (tympanique) et cutanée périphérique (gros orteil), ainsi que des mesures de débit sanguin au membre inférieur. Ces mesures ont été faites durant et après le bloc, à ľexception des mesures en station debout qui n’ont été effectuées que lorsque les critères de récupération du bloc étaient satisfaits.Les résultats indiquent la séquence suivante dans le retour des fonctions neurologiques après bloc sous-arachnoïdien à la tetracaine: activité sympathique, sensibilité à la piqure ďaiguille, motricité et, enfin, proprioception au niveau des pieds. Cette séquence ďévénements permet de préciser les critères nous indiquant le moment où nous pouvons permettre avec sécurité aux patients de redevenir ambulants après rachi-anesthésie.Ces critères incluent: (1) Retour de la sensibilité à ľaiguille dans la région péri-anale (S4-S5). (2) Flexion plantaire du pied en position couchée et ceci au niveau de force préanesthésique. (3) Retour de la fonction proprioceptive au gros orteil. Tout ceci en autant que le malade n’est pas sous sédation ou hypovolémique.

Effects of anesthesia and surgical stress on insulin secretion in man

Surgical stress with inhalation anesthesia is associated with increased circulating catecholamines, hyperglycemia, and impaired insulin secretion. These changes do not occur during surgical stress with spinal anesthesia, suggesting that they are neurally mediated due to pain initiated afferents from the site of tissue trauma. Inhalation anesthesia alone was found to suppress basal insulin levels and the insulin response to intravenous glucose with no significant increase in plasma norepinephrine and a decrease in plasma epinephrine. Thus, these changes in insulin secretion are not attributable to adrenergic mechanisms. In the postoperative period, however, suppressed insulin secretion was found to be correlated with elevated plasma epinephrine concentrations and may, therefore, be mediated by adrenergic mechanisms. Thus, these findings indicate that impaired insulin secretion during surgical stress may have two etiologies--one related to the type of anesthesia used and the other due to adrenomedullary stimulation due to pain.

Spinal anesthesia: bupivacaine versus tetracaine.

The clinical effects of equal hyperbaric doses of bupivacaine HCI and tetracaine HCI were studied and compared in 99 adult men undergoing spinal anesthesia for similar surgical procedures. The spinal anesthetic agents were used in random order in various dosages. Comparisons were made of (1) amount of anesthetic agent used, (2) elapsed time for onset of analgesia, (3) elapsed time for obtaining maximum anesthesia, (4) cephalad dermatome level of anesthesia, (5) incidence of motor blockade, and (6) duration of anesthesia. Results with the 2 drugs in equal dose, volume, and specific gravity were almost identical. However, tetracaine provided a motor block in a significantly greater number of patients than did bupivacaine (100 versus 42%, p<0.001) when both drugs were used at the 9.75-mg dose level.

Neurohumorally induced cardiac dysrhythmias during nitrous oxide-oxygen-thiopental anesthesia

Barbiturate, nitrous oxide, and oxygen are commonly used by the oral and maxillofacial surgeon to anesthetize the ambulatory oral surgery patient. The authors report three cases of ventricular dysrhythmia occurring from surgical stimulation during nitrous oxide-oxygen-thiopental anesthesia. These dysrhythmias were most likely mediated via direct neural stimulation of cardiac sympathetic nerves. Concomitant with adrenergic stimulation, a rise in the arterial plasma norepinephrine level was documented, along with an increase in the rate-pressure product. Immediate recognition and treatment of ventricular dysrhythmia is mandatory to preclude further serious cardiovascular complications or death.