Effect of hypothermia on ventilation in anesthetized, spontaneously breathing rats: theoretical implications for mechanical ventilation

Torbati, Dan; Camacho, Maria T.; Raszynski, André; Sussmane, Jeffrey B.; Totapally, Bala R; Hultquist, Karl; Wolfsdorf, Jack

doi:10.1007/s001340051208

Cited by 15 publications

(6 citation statements)

References 28 publications

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“…In the hypothermic cohort, the heart rate was around 15% lower, a physiological response to this condition ( Fig. 1D; Sabharwal et al, 2004;Torbati et al, 2000). Physiological measures otherwise demonstrated no significant differences in the parameters measured throughout the 8-h period (Table 2).…”

Section: Physiological Monitoringmentioning

confidence: 79%

Hypothermia Prior to Decompression: Buying Time for Treatment of Acute Spinal Cord Injury

Batchelor

Kerr

Gatt

et al. 2010

Journal of Neurotrauma

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Human spinal cord injury (SCI) is usually accompanied by persistent cord compression. Experimental data demonstrate that compression of the traumatized cord results in rapid neurological decline over hours. Undertaking decompression in humans within this time frame has proved impractical, with the time to surgery in studies of urgent decompression averaging between 10 and 24 h. There is, therefore, an important need for a therapy to prevent the neurological deterioration of patients prior to decompressive surgery. The aim of this study was to determine if hypothermia prevents compressive SCI, thereby limiting neurological decline. Rats were subjected to a moderate mid-thoracic SCI and spacers were inserted to compress the spinal cord by 45%. Decompression, by removal of the spacer, was performed immediately, and at 2 or 8 h post-injury. Hypothermia (33 degrees C) was commenced in half the animals at 30 mins post-injury and maintained for 7.5 h, with the other half remaining normothermic (37.3 degrees C). Motor recovery was assessed weekly, and the volume and area of tissue damage determined at the end of the 8-week study period. The results demonstrate that hypothermia significantly improves the behavioral and histological outcome of animals undergoing 8 h of compressive injury (the primary outcome measure). The hypothermia-treated group regained weight-supported locomotion (Basso-Beattie-Bresnahan [BBB] locomotor assessment score 9.5 +/- 0.9), while the normothermic group remained severely paraparetic (BBB score 5.3 +/- 0.6; p

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Section: Physiological Monitoringmentioning

confidence: 79%

Hypothermia Prior to Decompression: Buying Time for Treatment of Acute Spinal Cord Injury

Batchelor

Kerr

Gatt

et al. 2010

Journal of Neurotrauma

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“…Data on animals show a reduction of MV after induced MH probably due to a reduction of the respiratory effort 3 4. Our patients did not change MV and TV if different core temperatures were achieved, even if a slight not statistically significant difference in MV, higher in the DH group, was recorded.…”

Section: Discussionmentioning

confidence: 92%

Does pulmonary function change during whole-body deep hypothermia?

Cavallaro

Filippi

Cristofori

et al. 2010

Archives of Disease in Childhood - Fetal and Neonatal Edition

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Whole-body deep hypothermia (DH) could be a new therapeutic strategy for asphyxiated newborn. Aim of this study was to describe how DH (core temperature 30-33°C) modifies the respiratory function if compared with mild hypothermia (MH; core temperature 33-34°C). This is an observational study. Results were obtained from a pilot study of safety of DH and topiramate in neonatal hypoxic-ischaemic encephalopathy. Fifty-seven newborns were enrolled: 29 patients in DH and 28 in MH. Recruitment criteria were moderate-severe hypoxic-ischaemic encephalopathy and gestational age ≥36 weeks. Mechanical ventilation was set to maintain SaO(2) between 92% and 95%. Nineteen patients in DH and 18 in MH required mechanical ventilation. Of these patients, 10 and 12, respectively, did not required oxygen. No significant differences were observed in hours of oxygen and ventilation support, respiratory rate and PaCO(2). Maximum FiO(2), peak inspiratory pressure, positive end-expiratory pressure, minute ventilation and tidal volume during hypothermia were similar. Pulmonary function with different levels of hypothermia was similar.

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“…Notably, despite the increase in RR upon rewarming to normothermia, Vt remained unexpectedly high in certain types of breaths. During the rewarming process, there is a significant increase in carbon dioxide blood levels due to increased metabolic demands, oxygen consumption, and carbon dioxide production ( 39 ). Previous experiments conducted by Torbati et al on anesthetized spontaneously breathing rats, the authors observed a Vt of 7.6 ± 3.1 ml/kg before hypothermia and 10.3 ± 4.2 ml/kg after rewarming ( 39 ).…”

Section: Discussionmentioning

confidence: 99%

Expiratory braking defines the breathing patterns of asphyxiated neonates during therapeutic hypothermia

Papoff,

Caresta,

D’Agostino

et al. 2024

Front. Pediatr.

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IntroductionAlthough neonatal breathing patterns vary after perinatal asphyxia, whether they change during therapeutic hypothermia (TH) remains unclear. We characterized breathing patterns in infants during TH for hypoxic-ischemic encephalopathy (HIE) and normothermia after rewarming.MethodsIn seventeen spontaneously breathing infants receiving TH for HIE and in three who did not receive TH, we analyzed respiratory flow and esophageal pressure tracings for respiratory timing variables, pulmonary mechanics and respiratory effort. Breaths were classified as braked (inspiratory:expiratory ratio ≥1.5) and unbraked (<1.5).ResultsAccording to the expiratory flow shape braked breaths were chategorized into early peak expiratory flow, late peak expiratory flow, slow flow, and post-inspiratory hold flow (PiHF). The most braked breaths had lower rates, larger tidal volume but lower minute ventilation, inspiratory airway resistance and respiratory effort, except for the PiHF, which had higher resistance and respiratory effort. The braked pattern predominated during TH, but not during normothermia or in the uncooled infants.ConclusionsWe speculate that during TH for HIE low respiratory rates favor neonatal braked breathing to preserve lung volume. Given the generally low respiratory effort, it seems reasonable to leave spontaneous breathing unassisted. However, if the PiHF pattern predominates, ventilatory support may be required.

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Effect of hypothermia on ventilation in anesthetized, spontaneously breathing rats: theoretical implications for mechanical ventilation

Cited by 15 publications

References 28 publications

Hypothermia Prior to Decompression: Buying Time for Treatment of Acute Spinal Cord Injury

Hypothermia Prior to Decompression: Buying Time for Treatment of Acute Spinal Cord Injury

Does pulmonary function change during whole-body deep hypothermia?

Expiratory braking defines the breathing patterns of asphyxiated neonates during therapeutic hypothermia

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