29
Intraocular Pressure Variations During Extracorporeal Circulation and Some Influencing Factors
Summa ry Intraocular press ure (lOP) varia tions during extra corporeal circulation (ECC) a nd some influencing factors were studied prospectively in 38 patients undergoing cardiovascular surgery. lOPs were measured preoperatively. during EEC after 5 min. 10 min, and then every 15 min and on the first. second and third postoperative days. lOP. haematocrit. art erial perfusion pressur e. part ial O2 pressur e. par tial CO 2 pressur e. plt , and blood bicar bonate levels wer e meas ured simultaneously. After beginni ng ECC. art er ial perfusion pressure and haemato crit values decreas ed suddenly while lOP was ra ised immediately. The sudde n increase of blood volume at the sta rt of ECC is the probable cause of lOP elevation. Afterwards lOP levels decreased to pre-ECClevels. We think that the dro p is due to the effect of manni tol in the priming solution and hyposecretion of aqueous humor due to insufficient nutrition-oxygenation of the corpus ciliaris after the haemodynam ics have stabilised. Veriinder unge n des intraokul aren Dru ckes wiihrend des ex tra kor pora len Kreislau fs An 38 Patienten mit koronar er Herzkrankh eit oder einern Klappenvitium wurden die Veriinderungen des intraokularen Drukkes (lOP) unter extra korpora ler Zirkulation und postoperatl v vom 1. bis zum 3. Tag untersucht, Gleichzeitig mit der intraoku-
laren Druckmessung erfolgte die Bestimmung des Harnatokrits. des arteriellen Perfusionsdruckes. des 1'0 2 und des PC0 2 • des pH und des Bikar bonats piegels. Nach Beginn der extrakorporalen Zirkulation kam es zu einer signifikanten Steiger ung des lOP. wiihrend arterieller Perfusionsdru ck und Iliimatokrit signifikant abfielen. Es konnte keine statistisch gesicherte Beziehung zwischen lOP und den anderen biochemischen Para metern gefunden werden, Bereits nach 25 Minuten Dauer der extrakorporalen Zirkulation normalisierte sich der lOP wieder . Es wird angenornmen. daf der Anstieg des Blutvolumens zu Anfang der extrakorporalen Zirkulation die intraokular e Drucksteiger ung verursac ht. Der dann folgend e Abfall des lOP wird auf das Manni tol im FUllvolumen der Herz-Lungen-Maschine zuriickgefiihrt. Die 10 P-Steigeru ng bei reduziert em art eriellen Perfusionsdruck wahrend der extrakorporalen Zirkulation kann eine Ischarnie des Nervus opticus und eine a nteriore optische Neuro path ie hervorrufen. Solche Veriinderungen wurden aber bei diesen Patienten in keinem Fall beobac htet. Key word s Extracorporeal circulation - Intraocular pressu re - Haemodilution. Aqueous humor - Arterial perfusion pressure
In troduction
Mat erial and Methods
Neuroo phtha lmo logic complications after surgery with ext racorpore al cir culati on (ECC) have been report ed in up to 25.6 % of pati ents postop er at ively (7). Th ese complications ha ve been att ributed to a variety of cha nges that occur during ECC including embolic phen om ena. systemic hypoten sion . cerebra l hypoperfusion , haem odilution. hypotherm ia and redu ced colloida l osmotic pressure. The effects of these changes on intraocular pr essure (lOP) wer e studied during ECC by Larki n et al. (5), and Deu tch et al. studied the lOPcha nges in the post oper ative days ofECC (3). Larkin et al. found an increase of lOP in the first 30 minutes ofECC and concluded that marked ha emodilution is resp on sible for this effect. They ca utione d th at lOP elevation and arte rial hypoperfusion dur ing ECC may cause optic nerv e dam age especially in glaucoma tous pati ents (5). In our st udy. per oper ative and postoper ative lOP cha nges du ring ECC were obser ved and the relati on of lOP cha nges to th e cha nges in blood che mistry wer e studied. To our knowledg e. lOP cha nges duri ng ECC and in the first three post operative days were studied on the same pati ents for the first time.
In this pros pective stud y. the variations in lOP and possible contributing factors were studied in 38 patients undergoing cardiovascular surgery with ECC in Kosuyolo Heart and Resear ch Hospital. The average age was 47.6 years (ra nge 19- 67) while 28 were men (73 .7 %) and 10 were women (26.3%). Coronary art ery bypass surgery was per formed on 25 pat ients . valve replacement surgery was performed on 10 patients. combined coronary a rtery bypass and valve replacement surgery was perform ed on 2 patients. coronar y art ery bypass surgery and mitral annuloplasty was per formed on 1 patient. Diazepam and flunitrozepam were used for premedication while anes thesia was induced by Ilunitrozeparn and fentan yl. Pancuronium bromide was used for muscle relaxation. ECC was maint ained with Cobe CML membrane. Bentley bubble spo nge oxygenators and Cobe. Polystan N S. Bio Medicus or American Optical Corporatio n non-pulsatile pumps. 1300-1800 ml of pum p priming solution was used according to the patients ' age and weight and the dur ation of opera tion. The pump was primed with Ringer 's solution. manni tol. and plasma in 17 patients . Ringer 's solution. mannitol. and human albumin in 19 patients. Ringer 's solution and plasma in 2 patients. The duration of ECC was 66 -197 minutes. Hypothermia was per formed and body temp erature was maint ained at 24- 25 "C. Non-pulsatile art erial perfusion pressure was maintained between 45 and 90 mmHg during ECC.
Thorac. cardiovasc. Surgeon 39 (1991) 29-3 1 © Georg Thieme Verlag Stuttgart -New York
Received for Publication: May 22 , 1990
Downloaded by: University of British Columbia. Copyrighted material.
T. Bavbek, H. Kazokoijlu. and A. Tem el Department of Ophthalmology. Faculty ofMedicine. UniversityofMarmara. Istanbul,Turkey
T. Bavbek , H. Kazokoqlu. and A. Temel
Thom e. eardiovase. Surg eon 39 (1991) All pati ents wer e question ed ab out previous ocula r diseas e a nd eye opera tions. The lOPwas measured with Clement Cla rke Perk ins hand-h eld a pplana tion tonometer by the sa me exa miner. The lOP of righ t a nd left eyes wer e measured on severa l occas ions the day before operatio n. at the beginn ing of the operat ion, after 5 a nd 10 minutes of ECCa nd then in every 15 min utes until the cessation of ECC. lOPs wer e also measur ed on the first , secon d a nd third postoperativ e days. All preoperative and postoperative exa mina tions wer e perform ed between the hours of 6 : 30 and 9 : 00 a. m. Haem atocri t, a rterial perfusion pr ess ur e, pa rtial O2 pressure, partial CO2 pressure, pH, a nd blood bicarb onate levels were measured simultaneously with lOP measurem ent s. In th e postoperati ve peri od, all pati ents wer e as ked a bout visual complaints . Only a few pati en ts complained of eye pr oblem s a nd these und erwent a com plete ocula r exa mina tion. No stati stical differ en ce was found between th e figur es obtai ned from right and left eyes, so only the figures from th e right eyes wer e used for statistical a nalysis. Statisti cal evaluation of th e result s wa s mad e by Stud ent's t and multivari ant analysis tests .
Table 1 Variations in lOP, haematocrit and arterial perfusion pressure
Results
120
After the beginning of ECC , arterial perfusion pressure and ha ematocrit valu es dropped significantly (p < 0.01) whil e lOP increased immediately. The mean lOP elevation after 5 and 10 minutes of ECC was significant (p < 0.01) (Table 1, Fig. 1). We studied our figur es with Multivariat e Analysis test. According to this test , we cons ide re d lOP as dependent variable whil e Hct and arterial perfusion pr essure wer e ind ep end ent variables. We obse rved significant correlation betw een th es e variables after 5 and 10 minutes of ECC (p < 0.01). Ther e was no statistical relati onship between lOP and the othe r biochemi cal parameter s measured . We did not obs erve any postoperative pathological eye process in our pati ents. Th e pati ents with subj ective visual complaints wer e tr eat ed appropriately. Discu ssion Since ECC is a life-saving pro cedure in pati ents und ergoing cardiovascular surgery, it is performed extensively nowadays and com plicatio ns due to ECC have to be ta ken into acco unt. Neuroo pht ha lmological comp lications after cardia c surgery wit h ECC have been reported in up to 25.6 % of pati ents postoperatively (7). Areas of retinal infarction (17.3 %), retinal emboli (2.6 %), visual field defects (2.6 %), reduction of visual acuity (4.5 %) and Horn er's syndrom e (1.3 %) were th e compli cations reported in ECC pati ents. None of th es e neuroophthalmological complications wer e obse rve d in a control group of pati ents und er going maj or peripher al vascular surge ry (7). Th e first study ofI OP levels in ECC wa s don e on pigs and an incr eas e of lOP was obs erved in th e ha emodilution phase with a parallel incr ease of intracranial pressure (4). Lilleaasen and Horven did not find any lOP incr ease during and after open heart surgery in 12 patients. Th ey used Schiotz-indentation tonometers for measurem ents of lOP whi ch is not a reliabl e and accurate method (6). Larkin et al. showed that bypa ss pati ents are at high risk for intraoperative incr eases of lOP. Within 10 minutes of onse t of the cardiopulmonary bypa ss, all pati ents in their study had a ris e in lOP. Th ey concluded that th e red uced protein content of plasma , low colloidal osmoti c pressure, and ha emodilution incr eased aqu eous prod uct ion (5). Deutch et al. st ud ied lOP variations after ECC and showed
Haematocrit Mean (SO) %
lOP Mean (SO) mmHg 13.7 13.6 20.0 18.6 13.6 12.42 11.8 12.0 11.7 12.3 12.5 12.4
Preop. Pre·ECC ECC 5.min ECC 10.min ECC 25.min ECC 40.min ECC 55.min ECC70.min ECC termination Posl.op Lday Posl.op 2.day Posl.op 3.day
(2.42) (2.61) (5.71)' (4.09) (3.72) (2.83) (2.27) (2.34) (2.24) (2.44) (2.25) (2.22)
37.6 22.2 23.5 21.7 23.0 22.3 23.1 23.4 26.0 26.2 27.6
(4.24) (3.95) (3.05) (3.18) (3.00) (4.1 9) (2.93) (4.39) (3.04) (3.56) (5.34)
Arterial perfusion pres. Mean(SO) mmHg 122.1 69.3 65.2 60.6 67.5 72.1 79.9 96.1 111.4 109.5 111.7
(16.34) (18.34) (13.40) (9.05) (9.10) (17.66) (16.81) (16.17) (15.67) (12.51) (12.89)
• Significantchange compared to Pre-ECC value (p < 0.01) 140
100
•
lOP (right eye l Imm Hg)
X
arterial perfusion pressure (mmHg)
+
haemat ocrit 1%)
80 60 40 20
o
~: ,
0
5
10
25
:
:
:
40
55
70
,
,
~
time (minutes
Fig. 1 Variationsof lOP, arterialperfusionpressure, and haematocrit during thecourse of ECC: graphical representation of the mean valuesinTable 1
an lOP elevation in 63 % of pati ent s in th e first postop erative da y (3). lOP elevations have been reported in uremi c pati ents und ergoing haem odialysis. Experimental and clinical st udies in ure mia showe d that the hypotonicity of plasma during haemodialysis ten ds to increase lOP by osmoti c forces (1, 8). In our study, we obs erv ed a sudden decrease in the ha em ato crit level and arterial perfusion pr essure with an imm ediate incr eas e of lOP in the first 10 minutes of ECC. The statistical evaluation revealed that th e changes in arterial perfusion pr essure and ha ematocrit significantly corre lat ed to lOP changes. We think that the ris e of lOP at th e beginning of ECC is due to tr ansfer of wat er from pla sma to aqu eous humor whi ch is relat ed with ha em odiluti on . Haemodilution is du e to the addition of priming solution to blood flow. A sudden incr eas e of 1300-1 800 cc. of circulating blood pr ovokes hypersecretion of aqueous humor (2). lOP returns to its initial, normal level after ab out 10 minutes, even if th e ha em odiluti on and arterial blood pr essure levels persist. One explanation of this dr op can be the beginning of the effect of the mannitol in th e priming solution. In th e course of ECC , the lower ed arterial blood pr essure can supply the corpus ciliaris insufficiently to secrete aqu eous humor. Furthermore, a non-pulsatile blood flow in ECC may cause red uced tissue oxygenation resulting in a decreas e of aqueo us pr odu ction (4).
Downloaded by: University of British Columbia. Copyrighted material.
30
Thora c. cardiovasc. Surgeo n 39 (I991)
Intraocular Press ur e Variations Duri ng Extraco rpo rea l Circulation
References I
2
3
4
5
6
Acknowledgements Tha nks are du e to Assoc. Pr of. Dr . Ahm et Orka n from ISKAR (Research ce nte r for s ta tistics a nd quantitat ive a na lysis) of Ma rmara Unive rs ity for th e sta tistica l an alysis of our dat a. a nd Assoc. Prof. Dr. Cevat Yakut fro m Kosu yolo Heart a nd Research Hosp ital, who allowed us to s tudy his pa tien ts .
7
8
Broekema. N.. O.P. van Bijst erueld. and R. J. C. Boskuil: Intraocular pressu re du ring haemodialysis. Optha lmologica (Basel) 197 (1988) 60-64 Caprioli, 1.: The ciliary epithelia a nd aqueous hum or. In: Moses, R. A., W. M. Hart (eds .]: Adler 's Physiology of the eye. Toronto . CV Mosby Co. (1987) 204 Deut ch, D.. and R. A. Lewis: Intr aocular pressu re after ca rdio pulmon ary bypass su rgery. Am. J. Ophthalmol. 107 (l989) 18-22 Horoen, I.. P. Lilleaasen. A. Aa sen. O. Thoresen. and O. Sto kk e: Intr a-ocular press ure before. du ring a nd after extracorporea l circu lation in pigs. Scan d. J. Thor. Ca rdiovasc. Surg. 15 (1981) 269-272 Larkin. D. F. P.. P. Connally. J. B. Magn er. A. E. Wood. and P. Eustace: Intraocular pr essure during ca rdiopulmonary bypass . Brit.J. Ophtha lmol. 71 (1987) 177- 180 Lilleaas en, P.. and I. Horven: Intra -ocular pr essu re levels during extracorporeal circulation in man . Scand . J. Thor. Cardiovas c. Surg . 16 (1982) 51-53 Shaw. P. J.. D. Bat es. N. E. F. Cartlidge. D. Heavisid e. 1. M. French. D. G. Juli an. and D. A. S haw: Neuro-opht ha lmological complications of corona ry ar tery bypass gra ft surger y. Acta Neurol. Sca nd. 76 (1987)1- 7 Si tprija, V.. J. H. Homes. and P. P. Ellis: Changes in intraocular pr essu re du ring hae modia lysis. Invest. Ophthalmo l. Vis. Sci. 3 (1964) 273-284
Dr. A hme t Temel Department of Ophthalmology University of Marmara Faculty of Medicine Kosuyolu cad. 13-1 5 81 190 Altunizade. Istanbul. Turk ey
Downloaded by: University of British Columbia. Copyrighted material.
Aqueo us hum or is sec reted not only by simple osmotic diffusion mech an isms but also by O2 and ene rgy depend ent active tr an sp ort of sodium (2). For this reason, we need detailed expe rime ntal studies dealing with the effects of decreased arterial perfusi on pr essure, hypothermia. and incre ased blood flow on th ese mechanisms of aqu eous humor secretion. The lOP elevat ion and reduc ed arterial perfusion pr essure during ECC can cause ischemia of th e optic ner ve and anteri or ische mic optic neuropa thy (5). In our study group. none of our pati ent s suffere d visual loss. Fur th er studies on retin al and optic nerve per fusion during ECC will be of benefit.
31
Intraocular Pressure Variations During Extracorporeal Circulation and Some Influencing Factors
Summa ry Intraocular press ure (lOP) varia tions during extra corporeal circulation (ECC) a nd some influencing factors were studied prospectively in 38 patients undergoing cardiovascular surgery. lOPs were measured preoperatively. during EEC after 5 min. 10 min, and then every 15 min and on the first. second and third postoperative days. lOP. haematocrit. art erial perfusion pressur e. part ial O2 pressur e. par tial CO 2 pressur e. plt , and blood bicar bonate levels wer e meas ured simultaneously. After beginni ng ECC. art er ial perfusion pressure and haemato crit values decreas ed suddenly while lOP was ra ised immediately. The sudde n increase of blood volume at the sta rt of ECC is the probable cause of lOP elevation. Afterwards lOP levels decreased to pre-ECClevels. We think that the dro p is due to the effect of manni tol in the priming solution and hyposecretion of aqueous humor due to insufficient nutrition-oxygenation of the corpus ciliaris after the haemodynam ics have stabilised. Veriinder unge n des intraokul aren Dru ckes wiihrend des ex tra kor pora len Kreislau fs An 38 Patienten mit koronar er Herzkrankh eit oder einern Klappenvitium wurden die Veriinderungen des intraokularen Drukkes (lOP) unter extra korpora ler Zirkulation und postoperatl v vom 1. bis zum 3. Tag untersucht, Gleichzeitig mit der intraoku-
laren Druckmessung erfolgte die Bestimmung des Harnatokrits. des arteriellen Perfusionsdruckes. des 1'0 2 und des PC0 2 • des pH und des Bikar bonats piegels. Nach Beginn der extrakorporalen Zirkulation kam es zu einer signifikanten Steiger ung des lOP. wiihrend arterieller Perfusionsdru ck und Iliimatokrit signifikant abfielen. Es konnte keine statistisch gesicherte Beziehung zwischen lOP und den anderen biochemischen Para metern gefunden werden, Bereits nach 25 Minuten Dauer der extrakorporalen Zirkulation normalisierte sich der lOP wieder . Es wird angenornmen. daf der Anstieg des Blutvolumens zu Anfang der extrakorporalen Zirkulation die intraokular e Drucksteiger ung verursac ht. Der dann folgend e Abfall des lOP wird auf das Manni tol im FUllvolumen der Herz-Lungen-Maschine zuriickgefiihrt. Die 10 P-Steigeru ng bei reduziert em art eriellen Perfusionsdruck wahrend der extrakorporalen Zirkulation kann eine Ischarnie des Nervus opticus und eine a nteriore optische Neuro path ie hervorrufen. Solche Veriinderungen wurden aber bei diesen Patienten in keinem Fall beobac htet. Key word s Extracorporeal circulation - Intraocular pressu re - Haemodilution. Aqueous humor - Arterial perfusion pressure
In troduction
Mat erial and Methods
Neuroo phtha lmo logic complications after surgery with ext racorpore al cir culati on (ECC) have been report ed in up to 25.6 % of pati ents postop er at ively (7). Th ese complications ha ve been att ributed to a variety of cha nges that occur during ECC including embolic phen om ena. systemic hypoten sion . cerebra l hypoperfusion , haem odilution. hypotherm ia and redu ced colloida l osmotic pressure. The effects of these changes on intraocular pr essure (lOP) wer e studied during ECC by Larki n et al. (5), and Deu tch et al. studied the lOPcha nges in the post oper ative days ofECC (3). Larkin et al. found an increase of lOP in the first 30 minutes ofECC and concluded that marked ha emodilution is resp on sible for this effect. They ca utione d th at lOP elevation and arte rial hypoperfusion dur ing ECC may cause optic nerv e dam age especially in glaucoma tous pati ents (5). In our st udy. per oper ative and postoper ative lOP cha nges du ring ECC were obser ved and the relati on of lOP cha nges to th e cha nges in blood che mistry wer e studied. To our knowledg e. lOP cha nges duri ng ECC and in the first three post operative days were studied on the same pati ents for the first time.
In this pros pective stud y. the variations in lOP and possible contributing factors were studied in 38 patients undergoing cardiovascular surgery with ECC in Kosuyolo Heart and Resear ch Hospital. The average age was 47.6 years (ra nge 19- 67) while 28 were men (73 .7 %) and 10 were women (26.3%). Coronary art ery bypass surgery was per formed on 25 pat ients . valve replacement surgery was performed on 10 patients. combined coronary a rtery bypass and valve replacement surgery was perform ed on 2 patients. coronar y art ery bypass surgery and mitral annuloplasty was per formed on 1 patient. Diazepam and flunitrozepam were used for premedication while anes thesia was induced by Ilunitrozeparn and fentan yl. Pancuronium bromide was used for muscle relaxation. ECC was maint ained with Cobe CML membrane. Bentley bubble spo nge oxygenators and Cobe. Polystan N S. Bio Medicus or American Optical Corporatio n non-pulsatile pumps. 1300-1800 ml of pum p priming solution was used according to the patients ' age and weight and the dur ation of opera tion. The pump was primed with Ringer 's solution. manni tol. and plasma in 17 patients . Ringer 's solution. mannitol. and human albumin in 19 patients. Ringer 's solution and plasma in 2 patients. The duration of ECC was 66 -197 minutes. Hypothermia was per formed and body temp erature was maint ained at 24- 25 "C. Non-pulsatile art erial perfusion pressure was maintained between 45 and 90 mmHg during ECC.
Thorac. cardiovasc. Surgeon 39 (1991) 29-3 1 © Georg Thieme Verlag Stuttgart -New York
Received for Publication: May 22 , 1990
Downloaded by: University of British Columbia. Copyrighted material.
T. Bavbek, H. Kazokoijlu. and A. Tem el Department of Ophthalmology. Faculty ofMedicine. UniversityofMarmara. Istanbul,Turkey
T. Bavbek , H. Kazokoqlu. and A. Temel
Thom e. eardiovase. Surg eon 39 (1991) All pati ents wer e question ed ab out previous ocula r diseas e a nd eye opera tions. The lOPwas measured with Clement Cla rke Perk ins hand-h eld a pplana tion tonometer by the sa me exa miner. The lOP of righ t a nd left eyes wer e measured on severa l occas ions the day before operatio n. at the beginn ing of the operat ion, after 5 a nd 10 minutes of ECCa nd then in every 15 min utes until the cessation of ECC. lOPs wer e also measur ed on the first , secon d a nd third postoperativ e days. All preoperative and postoperative exa mina tions wer e perform ed between the hours of 6 : 30 and 9 : 00 a. m. Haem atocri t, a rterial perfusion pr ess ur e, pa rtial O2 pressure, partial CO2 pressure, pH, a nd blood bicarb onate levels were measured simultaneously with lOP measurem ent s. In th e postoperati ve peri od, all pati ents wer e as ked a bout visual complaints . Only a few pati en ts complained of eye pr oblem s a nd these und erwent a com plete ocula r exa mina tion. No stati stical differ en ce was found between th e figur es obtai ned from right and left eyes, so only the figures from th e right eyes wer e used for statistical a nalysis. Statisti cal evaluation of th e result s wa s mad e by Stud ent's t and multivari ant analysis tests .
Table 1 Variations in lOP, haematocrit and arterial perfusion pressure
Results
120
After the beginning of ECC , arterial perfusion pressure and ha ematocrit valu es dropped significantly (p < 0.01) whil e lOP increased immediately. The mean lOP elevation after 5 and 10 minutes of ECC was significant (p < 0.01) (Table 1, Fig. 1). We studied our figur es with Multivariat e Analysis test. According to this test , we cons ide re d lOP as dependent variable whil e Hct and arterial perfusion pr essure wer e ind ep end ent variables. We obse rved significant correlation betw een th es e variables after 5 and 10 minutes of ECC (p < 0.01). Ther e was no statistical relati onship between lOP and the othe r biochemi cal parameter s measured . We did not obs erve any postoperative pathological eye process in our pati ents. Th e pati ents with subj ective visual complaints wer e tr eat ed appropriately. Discu ssion Since ECC is a life-saving pro cedure in pati ents und ergoing cardiovascular surgery, it is performed extensively nowadays and com plicatio ns due to ECC have to be ta ken into acco unt. Neuroo pht ha lmological comp lications after cardia c surgery wit h ECC have been reported in up to 25.6 % of pati ents postoperatively (7). Areas of retinal infarction (17.3 %), retinal emboli (2.6 %), visual field defects (2.6 %), reduction of visual acuity (4.5 %) and Horn er's syndrom e (1.3 %) were th e compli cations reported in ECC pati ents. None of th es e neuroophthalmological complications wer e obse rve d in a control group of pati ents und er going maj or peripher al vascular surge ry (7). Th e first study ofI OP levels in ECC wa s don e on pigs and an incr eas e of lOP was obs erved in th e ha emodilution phase with a parallel incr ease of intracranial pressure (4). Lilleaasen and Horven did not find any lOP incr ease during and after open heart surgery in 12 patients. Th ey used Schiotz-indentation tonometers for measurem ents of lOP whi ch is not a reliabl e and accurate method (6). Larkin et al. showed that bypa ss pati ents are at high risk for intraoperative incr eases of lOP. Within 10 minutes of onse t of the cardiopulmonary bypa ss, all pati ents in their study had a ris e in lOP. Th ey concluded that th e red uced protein content of plasma , low colloidal osmoti c pressure, and ha emodilution incr eased aqu eous prod uct ion (5). Deutch et al. st ud ied lOP variations after ECC and showed
Haematocrit Mean (SO) %
lOP Mean (SO) mmHg 13.7 13.6 20.0 18.6 13.6 12.42 11.8 12.0 11.7 12.3 12.5 12.4
Preop. Pre·ECC ECC 5.min ECC 10.min ECC 25.min ECC 40.min ECC 55.min ECC70.min ECC termination Posl.op Lday Posl.op 2.day Posl.op 3.day
(2.42) (2.61) (5.71)' (4.09) (3.72) (2.83) (2.27) (2.34) (2.24) (2.44) (2.25) (2.22)
37.6 22.2 23.5 21.7 23.0 22.3 23.1 23.4 26.0 26.2 27.6
(4.24) (3.95) (3.05) (3.18) (3.00) (4.1 9) (2.93) (4.39) (3.04) (3.56) (5.34)
Arterial perfusion pres. Mean(SO) mmHg 122.1 69.3 65.2 60.6 67.5 72.1 79.9 96.1 111.4 109.5 111.7
(16.34) (18.34) (13.40) (9.05) (9.10) (17.66) (16.81) (16.17) (15.67) (12.51) (12.89)
• Significantchange compared to Pre-ECC value (p < 0.01) 140
100
•
lOP (right eye l Imm Hg)
X
arterial perfusion pressure (mmHg)
+
haemat ocrit 1%)
80 60 40 20
o
~: ,
0
5
10
25
:
:
:
40
55
70
,
,
~
time (minutes
Fig. 1 Variationsof lOP, arterialperfusionpressure, and haematocrit during thecourse of ECC: graphical representation of the mean valuesinTable 1
an lOP elevation in 63 % of pati ent s in th e first postop erative da y (3). lOP elevations have been reported in uremi c pati ents und ergoing haem odialysis. Experimental and clinical st udies in ure mia showe d that the hypotonicity of plasma during haemodialysis ten ds to increase lOP by osmoti c forces (1, 8). In our study, we obs erv ed a sudden decrease in the ha em ato crit level and arterial perfusion pr essure with an imm ediate incr eas e of lOP in the first 10 minutes of ECC. The statistical evaluation revealed that th e changes in arterial perfusion pr essure and ha ematocrit significantly corre lat ed to lOP changes. We think that the ris e of lOP at th e beginning of ECC is due to tr ansfer of wat er from pla sma to aqu eous humor whi ch is relat ed with ha em odiluti on . Haemodilution is du e to the addition of priming solution to blood flow. A sudden incr eas e of 1300-1 800 cc. of circulating blood pr ovokes hypersecretion of aqueous humor (2). lOP returns to its initial, normal level after ab out 10 minutes, even if th e ha em odiluti on and arterial blood pr essure levels persist. One explanation of this dr op can be the beginning of the effect of the mannitol in th e priming solution. In th e course of ECC , the lower ed arterial blood pr essure can supply the corpus ciliaris insufficiently to secrete aqu eous humor. Furthermore, a non-pulsatile blood flow in ECC may cause red uced tissue oxygenation resulting in a decreas e of aqueo us pr odu ction (4).
Downloaded by: University of British Columbia. Copyrighted material.
30
Thora c. cardiovasc. Surgeo n 39 (I991)
Intraocular Press ur e Variations Duri ng Extraco rpo rea l Circulation
References I
2
3
4
5
6
Acknowledgements Tha nks are du e to Assoc. Pr of. Dr . Ahm et Orka n from ISKAR (Research ce nte r for s ta tistics a nd quantitat ive a na lysis) of Ma rmara Unive rs ity for th e sta tistica l an alysis of our dat a. a nd Assoc. Prof. Dr. Cevat Yakut fro m Kosu yolo Heart a nd Research Hosp ital, who allowed us to s tudy his pa tien ts .
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Broekema. N.. O.P. van Bijst erueld. and R. J. C. Boskuil: Intraocular pressu re du ring haemodialysis. Optha lmologica (Basel) 197 (1988) 60-64 Caprioli, 1.: The ciliary epithelia a nd aqueous hum or. In: Moses, R. A., W. M. Hart (eds .]: Adler 's Physiology of the eye. Toronto . CV Mosby Co. (1987) 204 Deut ch, D.. and R. A. Lewis: Intr aocular pressu re after ca rdio pulmon ary bypass su rgery. Am. J. Ophthalmol. 107 (l989) 18-22 Horoen, I.. P. Lilleaasen. A. Aa sen. O. Thoresen. and O. Sto kk e: Intr a-ocular press ure before. du ring a nd after extracorporea l circu lation in pigs. Scan d. J. Thor. Ca rdiovasc. Surg. 15 (1981) 269-272 Larkin. D. F. P.. P. Connally. J. B. Magn er. A. E. Wood. and P. Eustace: Intraocular pr essure during ca rdiopulmonary bypass . Brit.J. Ophtha lmol. 71 (1987) 177- 180 Lilleaas en, P.. and I. Horven: Intra -ocular pr essu re levels during extracorporeal circulation in man . Scand . J. Thor. Cardiovas c. Surg . 16 (1982) 51-53 Shaw. P. J.. D. Bat es. N. E. F. Cartlidge. D. Heavisid e. 1. M. French. D. G. Juli an. and D. A. S haw: Neuro-opht ha lmological complications of corona ry ar tery bypass gra ft surger y. Acta Neurol. Sca nd. 76 (1987)1- 7 Si tprija, V.. J. H. Homes. and P. P. Ellis: Changes in intraocular pr essu re du ring hae modia lysis. Invest. Ophthalmo l. Vis. Sci. 3 (1964) 273-284
Dr. A hme t Temel Department of Ophthalmology University of Marmara Faculty of Medicine Kosuyolu cad. 13-1 5 81 190 Altunizade. Istanbul. Turk ey
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Aqueo us hum or is sec reted not only by simple osmotic diffusion mech an isms but also by O2 and ene rgy depend ent active tr an sp ort of sodium (2). For this reason, we need detailed expe rime ntal studies dealing with the effects of decreased arterial perfusi on pr essure, hypothermia. and incre ased blood flow on th ese mechanisms of aqu eous humor secretion. The lOP elevat ion and reduc ed arterial perfusion pr essure during ECC can cause ischemia of th e optic ner ve and anteri or ische mic optic neuropa thy (5). In our study group. none of our pati ent s suffere d visual loss. Fur th er studies on retin al and optic nerve per fusion during ECC will be of benefit.
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