Lung and Chest Wall Mechanics in Anesthetized Children

Abstract

The mechanical behavior of the lung and chest wall has not been determined in preschool children. We therefore obtained static expiratory pressure-volume (P-V) curves of the respiratory system, partitioned into lung and chest wall components using esophageal (Pes) and airway pressure (Paw) registration in 17 anesthetized children (0.2 to 15.5 yr) in the supine and lateral position. From the P-V curves the inspiratory capacity (IC), the chest wall elastance (Ecw), and the maximal compliance of the respiratory system (Crs) and lungs (C(lung)) were calculated and related to growth. At IC (Paw = 30 cm H(2)O), Pes was the same in the two positions: 11 +/- 3 cm H(2)O. In contrast, at end-expiration (Paw = 0), Pes was close to zero in the lateral position, but markedly positive in the supine position (7 +/- 2 cm H(2)O). C(lung) was similar in both positions and increased with growth. Thus, C(lung) in the lateral position (ml/cm H(2)O) = 0.0017 x length(2.26) (cm), r(2) = 0.90. Crs and IC were approximately 20% greater (p </= 0.001) in the supine position than in the lateral, and correlated strongly (r(2) >/= 0.93) with power functions of length in both positions. Ecw expressed as a fraction of total respiratory system elastance (Ecw/Ers) was 33 +/- 12% in the lateral position and 12 +/- 16% supine (p < 0.001). We conclude that the respiratory mechanics in children correlated closely with body size and showed important differences between the supine and lateral positions.

The impact of pneumoperitoneum and Trendelenburg positioning on respiratory system mechanics during laparoscopic pelvic surgery in children: a prospective observational study

“…While static compliance would provide more precise information on respiratory mechanics than the Cdyn measurements we obtained, volume-controlled ventilation is not routinely performed in pediatric anesthetic practice, and more specialized respiratory monitoring equipment is not generally available in clinical practice. 19 The adjustments performed after each surgical intervention to maintain VT/kg also likely had minor (but unmeasured) effects on our results, but these changes were required for clinical care and allowed us to monitor the ventilator adjustments required to maintain control of SpO 2 and EtCO 2 during this type of laparoscopic surgery. Our findings illustrate the effects of this procedure on the parameters available to the anesthesiologist during usual clinical practice, and they illustrate the frequency that ventilation must be adjusted by the anesthesiologist during laparoscopic urological surgery.…”

“…Nevertheless, several studies found no significant differences in oxygenation and respiratory mechanics when comparing pressure vs volume-controlled ventilation during laparoscopic surgery in adults. 18,19 Overall, PCV requires more manipulations than volumecontrolled ventilation.…”

Predicted body weight relationships for protective ventilation – unisex proposals from pre-term through to adult

“…Respiratory system compliance (C rs ) may be correlated with height [28, 29, 32], but this relationship is highly non-linear. It may be speculated that if the non-linear relationship between lean body weight and height was of similar nature to the non-linear relationship between respiratory compliance and height, then scaling tidal volumes to lean body mass in pediatric ventilation may indeed minimize volume trauma throughout the height range.…”

An open-access, very-low-field MRI system for posture-dependent 3He human lung imaging

“…Numerous studies have investigated the effects of posture on pulmonary ventilation and perfusion [16][17][18][19][20][21][22], however these studies all gave global measures of the influence of posture and were incapable of providing regional information. Imaging techniques have been explored in recent times to try and overcome this limitation.…”

“…For pulmonary physiology in particular, there is a need for non-invasive mapping of the regional distribution of ventilation and perfusion as a function of body orientation and posture [16][17][18][19][20][32][33][34][35]. Additionally, significant questions relating to the care and survival of patients with severe lung diseases such as asthma or acute respiratory distress syndrome relate to postural effects [21,22,36] that an open-access lung MRI could help address.…”