PubMed Health⌕ Search

Biomedical subjects

C M Stiles

Publications and source records attributed to C M Stiles.

10 recordsLinked to original sources
PubMed1990

Respiratory mechanics in anesthetized young patients with kyphoscoliosis. Immediate and delayed effects of corrective spinal surgery.

To our knowledge, the effects of corrective spinal surgery on total respiratory mechanics and its components in anesthetized patients with kyphoscoliosis have not been previously reported in detail. We studied 13 patients with kyposcoliosis; their mean (+/- SD) age was 24.7 +/- 2.1 years; eight underwent anterior and posterior spinal fusions (AF and PF, respectively) two weeks apart (group A), four underwent PF alone (group B), and one had a three-stage procedure. Mean total respiratory elastance (Ers), static and dynamic lung elastance (Est,L and Edyn,L, respectively), chest wall elastance (Ew), and lung resistance (RL) were derived according to previously described methodology. In group A, Ers and Ew increased by 39 percent and 58 percent, respectively, following AF and by 20 percent and 129 percent following PF, while Est,L and Edyn,L did not change or declined following PF. Lung resistance increased 19 percent and 41 percent by the end of AF and PF, respectively, in group A. In group B, Ew more than doubled, resulting in a 39 percent increase in Ers. Increases in Ers, Ew, and respiratory flow resistance observed at the time of spinal corrective surgery for kyphoscoliosis may result from rib cage trauma and changes in airway caliber related to microatelectasis and uneven distribution of mechanical properties within the lungs. Spinal correction results in immediate and short-term deterioration of respiratory mechanics measured under anesthesia.

Adolescent↗
PubMed1989

Respiratory elastic load compensation in anesthetized patients with kyphoscoliosis.

To evaluate the effects of abnormal respiratory mechanics and neuromuscular drive on the various components of elastic load compensation, we studied 16 anesthetized patients with kyphoscoliosis whose mean passive and active respiratory elastance (Ers and E'rs, respectively), active respiratory resistance, and peak inspiratory occlusion pressure were, respectively, 89, 84, 100, and 37% greater and inspiratory duration (TI) 13% less than corresponding values in 13 anesthetized controls. Ers comprised approximately 66% of effective elastance (E*rs) in both groups. E'rs, reflecting the role of the force-length properties of the active inspiratory muscles in increasing the internal impedance, comprised 83.8 and 86.1% of E*rs in the kyphoscoliosis patients and controls, respectively (P less than 0.001). This demonstrates the influence of increased intrinsic elastance and resistance and decreased TI on tidal volume defense in kyphoscoliosis patients in the absence of vagal modulation. In some patients the difference between Ers and E*rs was substantial, despite an unchanged or even shortened TI, suggesting that the Hering-Breuer reflex may affect stability through ways other than altering TI (e.g., via graded volume-dependent "terminal inhibition"). Characteristics of elastic load compensation in anesthetized kyphoscoliosis patients are similar to those of anesthetized normal subjects.

Adaptation, Physiological↗
PubMed1987

Partitioning of respiratory mechanics in young adults. Effects of duration of anesthesia.

General anesthesia increases total respiratory elastance and flow resistance within minutes after induction. We determined if respiratory mechanics changed progressively during anesthesia by measuring total respiratory elastance and resistance and their respective lung and chest wall components in 10 young adults free of cardiorespiratory disease at the start and end of premedicated anesthesia administered for orthopedic surgery (isoflurane, enflurane, or halothane, minimal alveolar concentration approximately 1.5 in 60% N2O-40% O2; interval between measurements was 0.42 to 5.0 h, mean +/- SD = 2.08 +/- 1.56 h). Static lung recoil pressure, static total respiratory and lung elastance, dynamic lung elastance, chest wall elastance, and total respiratory and lung and chest wall resistances were measured during steady-state breathing (greater than 10 min after induction). Resistance of the endotracheal tube, pneumotachygraph and connectors were subtracted from the total flow resistance to obtain total intrinsic resistance. Average values of static lung recoil pressure and all elastances and chest wall resistance did not change significantly from start to end of the study, regardless of the elapsed time. Total respiratory and lung resistance increased by 49% (p less than 0.05) and 45% (p less than 0.02), respectively, but were not time-dependent. We conclude that lung static recoil and total respiratory and lung elastances did not change beyond the first 10 min after induction, regardless of duration of anesthesia. The increases in total respiratory and lung resistance were small, independent of duration of anesthesia, and may have been due to accumulated airway secretions.

Adult↗
PubMed1986

Active inspiratory impedance and load compensation: effects of duration of anesthesia.

General anesthesia results in increases in respiratory elastance and flow resistance within 10-15 min after induction. Stabilization (compensation) of the respiratory system in the face of this added load is related to the addition of active (contractile) force-length and force-velocity properties to its internal impedance during inspiration. The difference between active (inspiratory) and passive (relaxation-exhalation) values of elastance and resistance can be used as an index of load compensation. We therefore evaluated the effects of duration of anesthesia on respiratory impedance and stabilization by comparing active elastance (E'rs) and flow resistance (R'rs) to their corresponding passive values (Ers, Rrs) at the beginning and end of steady-state breathing in ten young, healthy anesthetized adults undergoing orthopedic surgery (anesthesia approximately 1.5 MAC of a halogenated anesthetic in 60% N2O-40% O2). Occlusion pressure (P0.1) and components of ventilation also were measured. Duration of anesthesia did not correlate with changes in active or passive mechanics or with control of ventilation. Mean Rrs increased by 76% (P less than 0.025), probably due to a decline of atropine effect; however, R'rs increased by only 17%, indicating near-maximum stabilization of flow-resistive properties at the end. Passive elastance increased 6%, whereas E'rs increased 3.8%, indicating essentially constant volume-elastic stabilization throughout. Occlusion pressure increased 20% and VT/TI 22%, probably due to a decline in effects of sedation and neuromuscular blockade. We conclude that after induction of anesthesia, the reserve available to overcome flow resistance (intrinsic plus equipment) diminishes but is not related to duration of anesthesia. The reserve available to overcome elastic properties remains essentially constant throughout anesthesia.

Adult↗
PubMed1983

Acquired laryngeal deviation associated with cervical spine disease in erosive polyarticular arthritis. Use of the fiberoptic bronchoscope in rheumatoid disease.

Cervical spine disease in patients with erosive polyarticular arthritis often presents difficulties in endotracheal intubation at the time of surgery. After extensive experience with the use of the fiberoptic bronchoscope in such situations, the authors have identified a previously unrecognized and unanticipated tri-plane deviation in which the larynx is displaced caudally, deviated to the left, rotated to the right, and anteriorly angulated. A review of 710 consecutive fiberoptic intubations identified 15 arthritis patients with laryngeal deviation. Documentation was available in seven patients showing that the larynx was initially in a normal position, but was progressively displaced as the cervical spine disease worsened. Vertical penetration of the dens was the most significant underlying pattern of cervical spine disease. Computerized tomography with multiplanar reconstruction elucidated two patterns of deformity but was not necessary to detect the laryngeal deviation. One cause of the deviation was a scoliotic deformity of the trachea and larynx secondary to shortening of the neck resulting from the vertical penetration. The second mechanism was a rotational deformity of the cervical spine occurring from asymmetric bony erosions. Knowledge of this deformity permits it to be easily predicted preoperatively so that appropriate management can be planned.

Adolescent↗
PubMed1981

Anesthesia for the mentally retarded patient.

In summary, their are a great many causes of mental retardation, each of which must be investigated carefully prior to induction of anesthesia. There are a few basic points to be remembered, no matter what the disease: (1) establish how much the patient understands and whether or not the patient can communicate, (2) establish whatever rapport is possible and use that both preoperatively and postoperatively in place of medication if possible, (3) avoid early extubation, and (4) be prepared for fairly long-term ventilation if the child cannot cooperate. The choice of anesthetic agents and preoperative and postoperative medications, their route of administration, and amount will be dictated by the disease entity, its severity, and the scope of the contemplated surgery.

Anesthesia↗