title: Comparison of respiratory function during TIVA and isoflurane anaesthesia in ponies Part II: breathing patterns and transdiaphragmatic pressure.
abstract: OBJECTIVE
  To compare breathing patterns and transdiaphragmatic pressure during total intravenous (TIVA) and isoflurane anaesthesia in ponies.
  
  
  METHODS
  Experimental, cross-over study.
  
  
  METHODS
  Six healthy ponies weighing 286 (233-388) ± 61 kg, age 13 (9-16) ± 3 years.
  
  
  METHODS
  Following premedication with romifidine [80 μg kg(-1) intravenously (IV)], general anaesthesia was induced with midazolam (0.06 mg kg(-1) IV) and ketamine (2.5 mg kg(-1) IV) and maintained with either isoflurane (Fe'Iso = 1.1%) (T-ISO) or an IV combination of romifidine (120 μg kg(-1) per hour), midazolam (0.09 mg kg(-1) hour(-1)) and ketamine (3.3 mg kg(-1) hour(-1)) (T-TIVA), while breathing 60% oxygen (FIO(2)). The circumference changes of the rib cage (RC) and abdominal compartment (ABD) were recorded using respiratory ultrasonic plethysmography (RUP). Balloon tipped catheters were placed in the distal oesophagus and the stomach and maximal transdiaphragmatic pressure (Pdi max) was calculated during Mueller's manoeuvre.
  
  
  RESULTS
  The breathing pattern T-ISO was more regular and respiratory rate significantly lower compared with T-TIVA. Ponies in T-TIVA showed regularly appearing sighs, which were never observed in T-ISO. Different contribution of the RC and ABD compartments to the breathing pattern was observed with a smaller participation of the RC to the total volume change during T-ISO. Transdiaphragmatic pressures (mean 13.7 ± SD 8.61 versus 23.4 ± 7.27 cmH(2) O, p < 0.0001) were lower in T-TIVA compared to T-ISO [corrected]. The sum of the RC and ABD circumferential changes was lower during T-TIVA compared to T-ISO (6.32 ± 4.42 versus 11.72 ± 4.38 units, p < 0.0001).
  
  
  CONCLUSIONS
  Marked differences in breathing pattern and transdiaphragmatic pressure exist during inhalation- and TIVA and these should be taken into account for clinical estimation of anaesthetic depth.
authors.affiliation: Anaesthesiology and Perioperative Intensive-Care, Vetmeduni Vienna, Vienna, Austria.
authors.forename: Lidia
authors.initials: L
authors.lastname: Kowalczyk
authors.forename: Barbara
authors.initials: B
authors.lastname: Steblaj
authors.forename: Stijn
authors.initials: S
authors.lastname: Schauvliege
authors.forename: Johannes Peter
authors.initials: JP
authors.lastname: Schramel
authors.forename: Kiriaki
authors.initials: K
authors.lastname: Pavlidou
authors.forename: Ioannis
authors.initials: I
authors.lastname: Savvas
authors.forename: Luc
authors.initials: L
authors.lastname: Duchateau
authors.forename: Frank
authors.initials: F
authors.lastname: Gasthuys
authors.forename: Yves
authors.initials: Y
authors.lastname: Moens
mesh_terms: D000769:Anesthesia, Inhalation / Q000379:methods / Q000662:veterinary*; D000771:Anesthesia, Intravenous / Q000379:methods / Q000662:veterinary*; D019162:Anesthetics, Combined / Q000008:administration & dosage / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000494:pharmacology; D000818:Animals; D018592:Cross-Over Studies; D003964:Diaphragm / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006736:Horses; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology; D007530:Isoflurane / Q000494:pharmacology; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008874:Midazolam / Q000008:administration & dosage / Q000494:pharmacology; D012143:Respiratory Physiological Phenomena / Q000187:drug effects*; D056152:Respiratory Rate / Q000187:drug effects
chemical_list: D019162:Anesthetics, Combined; D018686:Anesthetics, Intravenous; D007093:Imidazoles; D007649:Ketamine; C076257:romifidine; D007530:Isoflurane; D008874:Midazolam
keywords: breathing pattern; isoflurane; ponies; total intravenous anaesthesia; transdiaphragmatic pressure